xref: /openbmc/linux/drivers/tty/serial/serial_core.c (revision 8ffdff6a)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *  Driver core for serial ports
4  *
5  *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
6  *
7  *  Copyright 1999 ARM Limited
8  *  Copyright (C) 2000-2001 Deep Blue Solutions Ltd.
9  */
10 #include <linux/module.h>
11 #include <linux/tty.h>
12 #include <linux/tty_flip.h>
13 #include <linux/slab.h>
14 #include <linux/sched/signal.h>
15 #include <linux/init.h>
16 #include <linux/console.h>
17 #include <linux/gpio/consumer.h>
18 #include <linux/of.h>
19 #include <linux/proc_fs.h>
20 #include <linux/seq_file.h>
21 #include <linux/device.h>
22 #include <linux/serial.h> /* for serial_state and serial_icounter_struct */
23 #include <linux/serial_core.h>
24 #include <linux/sysrq.h>
25 #include <linux/delay.h>
26 #include <linux/mutex.h>
27 #include <linux/security.h>
28 
29 #include <linux/irq.h>
30 #include <linux/uaccess.h>
31 
32 /*
33  * This is used to lock changes in serial line configuration.
34  */
35 static DEFINE_MUTEX(port_mutex);
36 
37 /*
38  * lockdep: port->lock is initialized in two places, but we
39  *          want only one lock-class:
40  */
41 static struct lock_class_key port_lock_key;
42 
43 #define HIGH_BITS_OFFSET	((sizeof(long)-sizeof(int))*8)
44 
45 static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
46 					struct ktermios *old_termios);
47 static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
48 static void uart_change_pm(struct uart_state *state,
49 			   enum uart_pm_state pm_state);
50 
51 static void uart_port_shutdown(struct tty_port *port);
52 
53 static int uart_dcd_enabled(struct uart_port *uport)
54 {
55 	return !!(uport->status & UPSTAT_DCD_ENABLE);
56 }
57 
58 static inline struct uart_port *uart_port_ref(struct uart_state *state)
59 {
60 	if (atomic_add_unless(&state->refcount, 1, 0))
61 		return state->uart_port;
62 	return NULL;
63 }
64 
65 static inline void uart_port_deref(struct uart_port *uport)
66 {
67 	if (atomic_dec_and_test(&uport->state->refcount))
68 		wake_up(&uport->state->remove_wait);
69 }
70 
71 #define uart_port_lock(state, flags)					\
72 	({								\
73 		struct uart_port *__uport = uart_port_ref(state);	\
74 		if (__uport)						\
75 			spin_lock_irqsave(&__uport->lock, flags);	\
76 		__uport;						\
77 	})
78 
79 #define uart_port_unlock(uport, flags)					\
80 	({								\
81 		struct uart_port *__uport = uport;			\
82 		if (__uport) {						\
83 			spin_unlock_irqrestore(&__uport->lock, flags);	\
84 			uart_port_deref(__uport);			\
85 		}							\
86 	})
87 
88 static inline struct uart_port *uart_port_check(struct uart_state *state)
89 {
90 	lockdep_assert_held(&state->port.mutex);
91 	return state->uart_port;
92 }
93 
94 /*
95  * This routine is used by the interrupt handler to schedule processing in
96  * the software interrupt portion of the driver.
97  */
98 void uart_write_wakeup(struct uart_port *port)
99 {
100 	struct uart_state *state = port->state;
101 	/*
102 	 * This means you called this function _after_ the port was
103 	 * closed.  No cookie for you.
104 	 */
105 	BUG_ON(!state);
106 	tty_port_tty_wakeup(&state->port);
107 }
108 
109 static void uart_stop(struct tty_struct *tty)
110 {
111 	struct uart_state *state = tty->driver_data;
112 	struct uart_port *port;
113 	unsigned long flags;
114 
115 	port = uart_port_lock(state, flags);
116 	if (port)
117 		port->ops->stop_tx(port);
118 	uart_port_unlock(port, flags);
119 }
120 
121 static void __uart_start(struct tty_struct *tty)
122 {
123 	struct uart_state *state = tty->driver_data;
124 	struct uart_port *port = state->uart_port;
125 
126 	if (port && !uart_tx_stopped(port))
127 		port->ops->start_tx(port);
128 }
129 
130 static void uart_start(struct tty_struct *tty)
131 {
132 	struct uart_state *state = tty->driver_data;
133 	struct uart_port *port;
134 	unsigned long flags;
135 
136 	port = uart_port_lock(state, flags);
137 	__uart_start(tty);
138 	uart_port_unlock(port, flags);
139 }
140 
141 static void
142 uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
143 {
144 	unsigned long flags;
145 	unsigned int old;
146 
147 	spin_lock_irqsave(&port->lock, flags);
148 	old = port->mctrl;
149 	port->mctrl = (old & ~clear) | set;
150 	if (old != port->mctrl)
151 		port->ops->set_mctrl(port, port->mctrl);
152 	spin_unlock_irqrestore(&port->lock, flags);
153 }
154 
155 #define uart_set_mctrl(port, set)	uart_update_mctrl(port, set, 0)
156 #define uart_clear_mctrl(port, clear)	uart_update_mctrl(port, 0, clear)
157 
158 static void uart_port_dtr_rts(struct uart_port *uport, int raise)
159 {
160 	int rs485_on = uport->rs485_config &&
161 		(uport->rs485.flags & SER_RS485_ENABLED);
162 	int RTS_after_send = !!(uport->rs485.flags & SER_RS485_RTS_AFTER_SEND);
163 
164 	if (raise) {
165 		if (rs485_on && !RTS_after_send) {
166 			uart_set_mctrl(uport, TIOCM_DTR);
167 			uart_clear_mctrl(uport, TIOCM_RTS);
168 		} else {
169 			uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
170 		}
171 	} else {
172 		unsigned int clear = TIOCM_DTR;
173 
174 		clear |= (!rs485_on || !RTS_after_send) ? TIOCM_RTS : 0;
175 		uart_clear_mctrl(uport, clear);
176 	}
177 }
178 
179 /*
180  * Startup the port.  This will be called once per open.  All calls
181  * will be serialised by the per-port mutex.
182  */
183 static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
184 		int init_hw)
185 {
186 	struct uart_port *uport = uart_port_check(state);
187 	unsigned long page;
188 	unsigned long flags = 0;
189 	int retval = 0;
190 
191 	if (uport->type == PORT_UNKNOWN)
192 		return 1;
193 
194 	/*
195 	 * Make sure the device is in D0 state.
196 	 */
197 	uart_change_pm(state, UART_PM_STATE_ON);
198 
199 	/*
200 	 * Initialise and allocate the transmit and temporary
201 	 * buffer.
202 	 */
203 	page = get_zeroed_page(GFP_KERNEL);
204 	if (!page)
205 		return -ENOMEM;
206 
207 	uart_port_lock(state, flags);
208 	if (!state->xmit.buf) {
209 		state->xmit.buf = (unsigned char *) page;
210 		uart_circ_clear(&state->xmit);
211 		uart_port_unlock(uport, flags);
212 	} else {
213 		uart_port_unlock(uport, flags);
214 		/*
215 		 * Do not free() the page under the port lock, see
216 		 * uart_shutdown().
217 		 */
218 		free_page(page);
219 	}
220 
221 	retval = uport->ops->startup(uport);
222 	if (retval == 0) {
223 		if (uart_console(uport) && uport->cons->cflag) {
224 			tty->termios.c_cflag = uport->cons->cflag;
225 			uport->cons->cflag = 0;
226 		}
227 		/*
228 		 * Initialise the hardware port settings.
229 		 */
230 		uart_change_speed(tty, state, NULL);
231 
232 		/*
233 		 * Setup the RTS and DTR signals once the
234 		 * port is open and ready to respond.
235 		 */
236 		if (init_hw && C_BAUD(tty))
237 			uart_port_dtr_rts(uport, 1);
238 	}
239 
240 	/*
241 	 * This is to allow setserial on this port. People may want to set
242 	 * port/irq/type and then reconfigure the port properly if it failed
243 	 * now.
244 	 */
245 	if (retval && capable(CAP_SYS_ADMIN))
246 		return 1;
247 
248 	return retval;
249 }
250 
251 static int uart_startup(struct tty_struct *tty, struct uart_state *state,
252 		int init_hw)
253 {
254 	struct tty_port *port = &state->port;
255 	int retval;
256 
257 	if (tty_port_initialized(port))
258 		return 0;
259 
260 	retval = uart_port_startup(tty, state, init_hw);
261 	if (retval)
262 		set_bit(TTY_IO_ERROR, &tty->flags);
263 
264 	return retval;
265 }
266 
267 /*
268  * This routine will shutdown a serial port; interrupts are disabled, and
269  * DTR is dropped if the hangup on close termio flag is on.  Calls to
270  * uart_shutdown are serialised by the per-port semaphore.
271  *
272  * uport == NULL if uart_port has already been removed
273  */
274 static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
275 {
276 	struct uart_port *uport = uart_port_check(state);
277 	struct tty_port *port = &state->port;
278 	unsigned long flags = 0;
279 	char *xmit_buf = NULL;
280 
281 	/*
282 	 * Set the TTY IO error marker
283 	 */
284 	if (tty)
285 		set_bit(TTY_IO_ERROR, &tty->flags);
286 
287 	if (tty_port_initialized(port)) {
288 		tty_port_set_initialized(port, 0);
289 
290 		/*
291 		 * Turn off DTR and RTS early.
292 		 */
293 		if (uport && uart_console(uport) && tty)
294 			uport->cons->cflag = tty->termios.c_cflag;
295 
296 		if (!tty || C_HUPCL(tty))
297 			uart_port_dtr_rts(uport, 0);
298 
299 		uart_port_shutdown(port);
300 	}
301 
302 	/*
303 	 * It's possible for shutdown to be called after suspend if we get
304 	 * a DCD drop (hangup) at just the right time.  Clear suspended bit so
305 	 * we don't try to resume a port that has been shutdown.
306 	 */
307 	tty_port_set_suspended(port, 0);
308 
309 	/*
310 	 * Do not free() the transmit buffer page under the port lock since
311 	 * this can create various circular locking scenarios. For instance,
312 	 * console driver may need to allocate/free a debug object, which
313 	 * can endup in printk() recursion.
314 	 */
315 	uart_port_lock(state, flags);
316 	xmit_buf = state->xmit.buf;
317 	state->xmit.buf = NULL;
318 	uart_port_unlock(uport, flags);
319 
320 	if (xmit_buf)
321 		free_page((unsigned long)xmit_buf);
322 }
323 
324 /**
325  *	uart_update_timeout - update per-port FIFO timeout.
326  *	@port:  uart_port structure describing the port
327  *	@cflag: termios cflag value
328  *	@baud:  speed of the port
329  *
330  *	Set the port FIFO timeout value.  The @cflag value should
331  *	reflect the actual hardware settings.
332  */
333 void
334 uart_update_timeout(struct uart_port *port, unsigned int cflag,
335 		    unsigned int baud)
336 {
337 	unsigned int bits;
338 
339 	/* byte size and parity */
340 	switch (cflag & CSIZE) {
341 	case CS5:
342 		bits = 7;
343 		break;
344 	case CS6:
345 		bits = 8;
346 		break;
347 	case CS7:
348 		bits = 9;
349 		break;
350 	default:
351 		bits = 10;
352 		break; /* CS8 */
353 	}
354 
355 	if (cflag & CSTOPB)
356 		bits++;
357 	if (cflag & PARENB)
358 		bits++;
359 
360 	/*
361 	 * The total number of bits to be transmitted in the fifo.
362 	 */
363 	bits = bits * port->fifosize;
364 
365 	/*
366 	 * Figure the timeout to send the above number of bits.
367 	 * Add .02 seconds of slop
368 	 */
369 	port->timeout = (HZ * bits) / baud + HZ/50;
370 }
371 
372 EXPORT_SYMBOL(uart_update_timeout);
373 
374 /**
375  *	uart_get_baud_rate - return baud rate for a particular port
376  *	@port: uart_port structure describing the port in question.
377  *	@termios: desired termios settings.
378  *	@old: old termios (or NULL)
379  *	@min: minimum acceptable baud rate
380  *	@max: maximum acceptable baud rate
381  *
382  *	Decode the termios structure into a numeric baud rate,
383  *	taking account of the magic 38400 baud rate (with spd_*
384  *	flags), and mapping the %B0 rate to 9600 baud.
385  *
386  *	If the new baud rate is invalid, try the old termios setting.
387  *	If it's still invalid, we try 9600 baud.
388  *
389  *	Update the @termios structure to reflect the baud rate
390  *	we're actually going to be using. Don't do this for the case
391  *	where B0 is requested ("hang up").
392  */
393 unsigned int
394 uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
395 		   struct ktermios *old, unsigned int min, unsigned int max)
396 {
397 	unsigned int try;
398 	unsigned int baud;
399 	unsigned int altbaud;
400 	int hung_up = 0;
401 	upf_t flags = port->flags & UPF_SPD_MASK;
402 
403 	switch (flags) {
404 	case UPF_SPD_HI:
405 		altbaud = 57600;
406 		break;
407 	case UPF_SPD_VHI:
408 		altbaud = 115200;
409 		break;
410 	case UPF_SPD_SHI:
411 		altbaud = 230400;
412 		break;
413 	case UPF_SPD_WARP:
414 		altbaud = 460800;
415 		break;
416 	default:
417 		altbaud = 38400;
418 		break;
419 	}
420 
421 	for (try = 0; try < 2; try++) {
422 		baud = tty_termios_baud_rate(termios);
423 
424 		/*
425 		 * The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
426 		 * Die! Die! Die!
427 		 */
428 		if (try == 0 && baud == 38400)
429 			baud = altbaud;
430 
431 		/*
432 		 * Special case: B0 rate.
433 		 */
434 		if (baud == 0) {
435 			hung_up = 1;
436 			baud = 9600;
437 		}
438 
439 		if (baud >= min && baud <= max)
440 			return baud;
441 
442 		/*
443 		 * Oops, the quotient was zero.  Try again with
444 		 * the old baud rate if possible.
445 		 */
446 		termios->c_cflag &= ~CBAUD;
447 		if (old) {
448 			baud = tty_termios_baud_rate(old);
449 			if (!hung_up)
450 				tty_termios_encode_baud_rate(termios,
451 								baud, baud);
452 			old = NULL;
453 			continue;
454 		}
455 
456 		/*
457 		 * As a last resort, if the range cannot be met then clip to
458 		 * the nearest chip supported rate.
459 		 */
460 		if (!hung_up) {
461 			if (baud <= min)
462 				tty_termios_encode_baud_rate(termios,
463 							min + 1, min + 1);
464 			else
465 				tty_termios_encode_baud_rate(termios,
466 							max - 1, max - 1);
467 		}
468 	}
469 	/* Should never happen */
470 	WARN_ON(1);
471 	return 0;
472 }
473 
474 EXPORT_SYMBOL(uart_get_baud_rate);
475 
476 /**
477  *	uart_get_divisor - return uart clock divisor
478  *	@port: uart_port structure describing the port.
479  *	@baud: desired baud rate
480  *
481  *	Calculate the uart clock divisor for the port.
482  */
483 unsigned int
484 uart_get_divisor(struct uart_port *port, unsigned int baud)
485 {
486 	unsigned int quot;
487 
488 	/*
489 	 * Old custom speed handling.
490 	 */
491 	if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST)
492 		quot = port->custom_divisor;
493 	else
494 		quot = DIV_ROUND_CLOSEST(port->uartclk, 16 * baud);
495 
496 	return quot;
497 }
498 
499 EXPORT_SYMBOL(uart_get_divisor);
500 
501 /* Caller holds port mutex */
502 static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
503 					struct ktermios *old_termios)
504 {
505 	struct uart_port *uport = uart_port_check(state);
506 	struct ktermios *termios;
507 	int hw_stopped;
508 
509 	/*
510 	 * If we have no tty, termios, or the port does not exist,
511 	 * then we can't set the parameters for this port.
512 	 */
513 	if (!tty || uport->type == PORT_UNKNOWN)
514 		return;
515 
516 	termios = &tty->termios;
517 	uport->ops->set_termios(uport, termios, old_termios);
518 
519 	/*
520 	 * Set modem status enables based on termios cflag
521 	 */
522 	spin_lock_irq(&uport->lock);
523 	if (termios->c_cflag & CRTSCTS)
524 		uport->status |= UPSTAT_CTS_ENABLE;
525 	else
526 		uport->status &= ~UPSTAT_CTS_ENABLE;
527 
528 	if (termios->c_cflag & CLOCAL)
529 		uport->status &= ~UPSTAT_DCD_ENABLE;
530 	else
531 		uport->status |= UPSTAT_DCD_ENABLE;
532 
533 	/* reset sw-assisted CTS flow control based on (possibly) new mode */
534 	hw_stopped = uport->hw_stopped;
535 	uport->hw_stopped = uart_softcts_mode(uport) &&
536 				!(uport->ops->get_mctrl(uport) & TIOCM_CTS);
537 	if (uport->hw_stopped) {
538 		if (!hw_stopped)
539 			uport->ops->stop_tx(uport);
540 	} else {
541 		if (hw_stopped)
542 			__uart_start(tty);
543 	}
544 	spin_unlock_irq(&uport->lock);
545 }
546 
547 static int uart_put_char(struct tty_struct *tty, unsigned char c)
548 {
549 	struct uart_state *state = tty->driver_data;
550 	struct uart_port *port;
551 	struct circ_buf *circ;
552 	unsigned long flags;
553 	int ret = 0;
554 
555 	circ = &state->xmit;
556 	port = uart_port_lock(state, flags);
557 	if (!circ->buf) {
558 		uart_port_unlock(port, flags);
559 		return 0;
560 	}
561 
562 	if (port && uart_circ_chars_free(circ) != 0) {
563 		circ->buf[circ->head] = c;
564 		circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
565 		ret = 1;
566 	}
567 	uart_port_unlock(port, flags);
568 	return ret;
569 }
570 
571 static void uart_flush_chars(struct tty_struct *tty)
572 {
573 	uart_start(tty);
574 }
575 
576 static int uart_write(struct tty_struct *tty,
577 					const unsigned char *buf, int count)
578 {
579 	struct uart_state *state = tty->driver_data;
580 	struct uart_port *port;
581 	struct circ_buf *circ;
582 	unsigned long flags;
583 	int c, ret = 0;
584 
585 	/*
586 	 * This means you called this function _after_ the port was
587 	 * closed.  No cookie for you.
588 	 */
589 	if (!state) {
590 		WARN_ON(1);
591 		return -EL3HLT;
592 	}
593 
594 	port = uart_port_lock(state, flags);
595 	circ = &state->xmit;
596 	if (!circ->buf) {
597 		uart_port_unlock(port, flags);
598 		return 0;
599 	}
600 
601 	while (port) {
602 		c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
603 		if (count < c)
604 			c = count;
605 		if (c <= 0)
606 			break;
607 		memcpy(circ->buf + circ->head, buf, c);
608 		circ->head = (circ->head + c) & (UART_XMIT_SIZE - 1);
609 		buf += c;
610 		count -= c;
611 		ret += c;
612 	}
613 
614 	__uart_start(tty);
615 	uart_port_unlock(port, flags);
616 	return ret;
617 }
618 
619 static int uart_write_room(struct tty_struct *tty)
620 {
621 	struct uart_state *state = tty->driver_data;
622 	struct uart_port *port;
623 	unsigned long flags;
624 	int ret;
625 
626 	port = uart_port_lock(state, flags);
627 	ret = uart_circ_chars_free(&state->xmit);
628 	uart_port_unlock(port, flags);
629 	return ret;
630 }
631 
632 static int uart_chars_in_buffer(struct tty_struct *tty)
633 {
634 	struct uart_state *state = tty->driver_data;
635 	struct uart_port *port;
636 	unsigned long flags;
637 	int ret;
638 
639 	port = uart_port_lock(state, flags);
640 	ret = uart_circ_chars_pending(&state->xmit);
641 	uart_port_unlock(port, flags);
642 	return ret;
643 }
644 
645 static void uart_flush_buffer(struct tty_struct *tty)
646 {
647 	struct uart_state *state = tty->driver_data;
648 	struct uart_port *port;
649 	unsigned long flags;
650 
651 	/*
652 	 * This means you called this function _after_ the port was
653 	 * closed.  No cookie for you.
654 	 */
655 	if (!state) {
656 		WARN_ON(1);
657 		return;
658 	}
659 
660 	pr_debug("uart_flush_buffer(%d) called\n", tty->index);
661 
662 	port = uart_port_lock(state, flags);
663 	if (!port)
664 		return;
665 	uart_circ_clear(&state->xmit);
666 	if (port->ops->flush_buffer)
667 		port->ops->flush_buffer(port);
668 	uart_port_unlock(port, flags);
669 	tty_port_tty_wakeup(&state->port);
670 }
671 
672 /*
673  * This function is used to send a high-priority XON/XOFF character to
674  * the device
675  */
676 static void uart_send_xchar(struct tty_struct *tty, char ch)
677 {
678 	struct uart_state *state = tty->driver_data;
679 	struct uart_port *port;
680 	unsigned long flags;
681 
682 	port = uart_port_ref(state);
683 	if (!port)
684 		return;
685 
686 	if (port->ops->send_xchar)
687 		port->ops->send_xchar(port, ch);
688 	else {
689 		spin_lock_irqsave(&port->lock, flags);
690 		port->x_char = ch;
691 		if (ch)
692 			port->ops->start_tx(port);
693 		spin_unlock_irqrestore(&port->lock, flags);
694 	}
695 	uart_port_deref(port);
696 }
697 
698 static void uart_throttle(struct tty_struct *tty)
699 {
700 	struct uart_state *state = tty->driver_data;
701 	upstat_t mask = UPSTAT_SYNC_FIFO;
702 	struct uart_port *port;
703 
704 	port = uart_port_ref(state);
705 	if (!port)
706 		return;
707 
708 	if (I_IXOFF(tty))
709 		mask |= UPSTAT_AUTOXOFF;
710 	if (C_CRTSCTS(tty))
711 		mask |= UPSTAT_AUTORTS;
712 
713 	if (port->status & mask) {
714 		port->ops->throttle(port);
715 		mask &= ~port->status;
716 	}
717 
718 	if (mask & UPSTAT_AUTORTS)
719 		uart_clear_mctrl(port, TIOCM_RTS);
720 
721 	if (mask & UPSTAT_AUTOXOFF)
722 		uart_send_xchar(tty, STOP_CHAR(tty));
723 
724 	uart_port_deref(port);
725 }
726 
727 static void uart_unthrottle(struct tty_struct *tty)
728 {
729 	struct uart_state *state = tty->driver_data;
730 	upstat_t mask = UPSTAT_SYNC_FIFO;
731 	struct uart_port *port;
732 
733 	port = uart_port_ref(state);
734 	if (!port)
735 		return;
736 
737 	if (I_IXOFF(tty))
738 		mask |= UPSTAT_AUTOXOFF;
739 	if (C_CRTSCTS(tty))
740 		mask |= UPSTAT_AUTORTS;
741 
742 	if (port->status & mask) {
743 		port->ops->unthrottle(port);
744 		mask &= ~port->status;
745 	}
746 
747 	if (mask & UPSTAT_AUTORTS)
748 		uart_set_mctrl(port, TIOCM_RTS);
749 
750 	if (mask & UPSTAT_AUTOXOFF)
751 		uart_send_xchar(tty, START_CHAR(tty));
752 
753 	uart_port_deref(port);
754 }
755 
756 static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
757 {
758 	struct uart_state *state = container_of(port, struct uart_state, port);
759 	struct uart_port *uport;
760 	int ret = -ENODEV;
761 
762 	memset(retinfo, 0, sizeof(*retinfo));
763 
764 	/*
765 	 * Ensure the state we copy is consistent and no hardware changes
766 	 * occur as we go
767 	 */
768 	mutex_lock(&port->mutex);
769 	uport = uart_port_check(state);
770 	if (!uport)
771 		goto out;
772 
773 	retinfo->type	    = uport->type;
774 	retinfo->line	    = uport->line;
775 	retinfo->port	    = uport->iobase;
776 	if (HIGH_BITS_OFFSET)
777 		retinfo->port_high = (long) uport->iobase >> HIGH_BITS_OFFSET;
778 	retinfo->irq		    = uport->irq;
779 	retinfo->flags	    = (__force int)uport->flags;
780 	retinfo->xmit_fifo_size  = uport->fifosize;
781 	retinfo->baud_base	    = uport->uartclk / 16;
782 	retinfo->close_delay	    = jiffies_to_msecs(port->close_delay) / 10;
783 	retinfo->closing_wait    = port->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
784 				ASYNC_CLOSING_WAIT_NONE :
785 				jiffies_to_msecs(port->closing_wait) / 10;
786 	retinfo->custom_divisor  = uport->custom_divisor;
787 	retinfo->hub6	    = uport->hub6;
788 	retinfo->io_type         = uport->iotype;
789 	retinfo->iomem_reg_shift = uport->regshift;
790 	retinfo->iomem_base      = (void *)(unsigned long)uport->mapbase;
791 
792 	ret = 0;
793 out:
794 	mutex_unlock(&port->mutex);
795 	return ret;
796 }
797 
798 static int uart_get_info_user(struct tty_struct *tty,
799 			 struct serial_struct *ss)
800 {
801 	struct uart_state *state = tty->driver_data;
802 	struct tty_port *port = &state->port;
803 
804 	return uart_get_info(port, ss) < 0 ? -EIO : 0;
805 }
806 
807 static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
808 			 struct uart_state *state,
809 			 struct serial_struct *new_info)
810 {
811 	struct uart_port *uport = uart_port_check(state);
812 	unsigned long new_port;
813 	unsigned int change_irq, change_port, closing_wait;
814 	unsigned int old_custom_divisor, close_delay;
815 	upf_t old_flags, new_flags;
816 	int retval = 0;
817 
818 	if (!uport)
819 		return -EIO;
820 
821 	new_port = new_info->port;
822 	if (HIGH_BITS_OFFSET)
823 		new_port += (unsigned long) new_info->port_high << HIGH_BITS_OFFSET;
824 
825 	new_info->irq = irq_canonicalize(new_info->irq);
826 	close_delay = msecs_to_jiffies(new_info->close_delay * 10);
827 	closing_wait = new_info->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
828 			ASYNC_CLOSING_WAIT_NONE :
829 			msecs_to_jiffies(new_info->closing_wait * 10);
830 
831 
832 	change_irq  = !(uport->flags & UPF_FIXED_PORT)
833 		&& new_info->irq != uport->irq;
834 
835 	/*
836 	 * Since changing the 'type' of the port changes its resource
837 	 * allocations, we should treat type changes the same as
838 	 * IO port changes.
839 	 */
840 	change_port = !(uport->flags & UPF_FIXED_PORT)
841 		&& (new_port != uport->iobase ||
842 		    (unsigned long)new_info->iomem_base != uport->mapbase ||
843 		    new_info->hub6 != uport->hub6 ||
844 		    new_info->io_type != uport->iotype ||
845 		    new_info->iomem_reg_shift != uport->regshift ||
846 		    new_info->type != uport->type);
847 
848 	old_flags = uport->flags;
849 	new_flags = (__force upf_t)new_info->flags;
850 	old_custom_divisor = uport->custom_divisor;
851 
852 	if (!capable(CAP_SYS_ADMIN)) {
853 		retval = -EPERM;
854 		if (change_irq || change_port ||
855 		    (new_info->baud_base != uport->uartclk / 16) ||
856 		    (close_delay != port->close_delay) ||
857 		    (closing_wait != port->closing_wait) ||
858 		    (new_info->xmit_fifo_size &&
859 		     new_info->xmit_fifo_size != uport->fifosize) ||
860 		    (((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
861 			goto exit;
862 		uport->flags = ((uport->flags & ~UPF_USR_MASK) |
863 			       (new_flags & UPF_USR_MASK));
864 		uport->custom_divisor = new_info->custom_divisor;
865 		goto check_and_exit;
866 	}
867 
868 	retval = security_locked_down(LOCKDOWN_TIOCSSERIAL);
869 	if (retval && (change_irq || change_port))
870 		goto exit;
871 
872 	/*
873 	 * Ask the low level driver to verify the settings.
874 	 */
875 	if (uport->ops->verify_port)
876 		retval = uport->ops->verify_port(uport, new_info);
877 
878 	if ((new_info->irq >= nr_irqs) || (new_info->irq < 0) ||
879 	    (new_info->baud_base < 9600))
880 		retval = -EINVAL;
881 
882 	if (retval)
883 		goto exit;
884 
885 	if (change_port || change_irq) {
886 		retval = -EBUSY;
887 
888 		/*
889 		 * Make sure that we are the sole user of this port.
890 		 */
891 		if (tty_port_users(port) > 1)
892 			goto exit;
893 
894 		/*
895 		 * We need to shutdown the serial port at the old
896 		 * port/type/irq combination.
897 		 */
898 		uart_shutdown(tty, state);
899 	}
900 
901 	if (change_port) {
902 		unsigned long old_iobase, old_mapbase;
903 		unsigned int old_type, old_iotype, old_hub6, old_shift;
904 
905 		old_iobase = uport->iobase;
906 		old_mapbase = uport->mapbase;
907 		old_type = uport->type;
908 		old_hub6 = uport->hub6;
909 		old_iotype = uport->iotype;
910 		old_shift = uport->regshift;
911 
912 		/*
913 		 * Free and release old regions
914 		 */
915 		if (old_type != PORT_UNKNOWN && uport->ops->release_port)
916 			uport->ops->release_port(uport);
917 
918 		uport->iobase = new_port;
919 		uport->type = new_info->type;
920 		uport->hub6 = new_info->hub6;
921 		uport->iotype = new_info->io_type;
922 		uport->regshift = new_info->iomem_reg_shift;
923 		uport->mapbase = (unsigned long)new_info->iomem_base;
924 
925 		/*
926 		 * Claim and map the new regions
927 		 */
928 		if (uport->type != PORT_UNKNOWN && uport->ops->request_port) {
929 			retval = uport->ops->request_port(uport);
930 		} else {
931 			/* Always success - Jean II */
932 			retval = 0;
933 		}
934 
935 		/*
936 		 * If we fail to request resources for the
937 		 * new port, try to restore the old settings.
938 		 */
939 		if (retval) {
940 			uport->iobase = old_iobase;
941 			uport->type = old_type;
942 			uport->hub6 = old_hub6;
943 			uport->iotype = old_iotype;
944 			uport->regshift = old_shift;
945 			uport->mapbase = old_mapbase;
946 
947 			if (old_type != PORT_UNKNOWN) {
948 				retval = uport->ops->request_port(uport);
949 				/*
950 				 * If we failed to restore the old settings,
951 				 * we fail like this.
952 				 */
953 				if (retval)
954 					uport->type = PORT_UNKNOWN;
955 
956 				/*
957 				 * We failed anyway.
958 				 */
959 				retval = -EBUSY;
960 			}
961 
962 			/* Added to return the correct error -Ram Gupta */
963 			goto exit;
964 		}
965 	}
966 
967 	if (change_irq)
968 		uport->irq      = new_info->irq;
969 	if (!(uport->flags & UPF_FIXED_PORT))
970 		uport->uartclk  = new_info->baud_base * 16;
971 	uport->flags            = (uport->flags & ~UPF_CHANGE_MASK) |
972 				 (new_flags & UPF_CHANGE_MASK);
973 	uport->custom_divisor   = new_info->custom_divisor;
974 	port->close_delay     = close_delay;
975 	port->closing_wait    = closing_wait;
976 	if (new_info->xmit_fifo_size)
977 		uport->fifosize = new_info->xmit_fifo_size;
978 
979  check_and_exit:
980 	retval = 0;
981 	if (uport->type == PORT_UNKNOWN)
982 		goto exit;
983 	if (tty_port_initialized(port)) {
984 		if (((old_flags ^ uport->flags) & UPF_SPD_MASK) ||
985 		    old_custom_divisor != uport->custom_divisor) {
986 			/*
987 			 * If they're setting up a custom divisor or speed,
988 			 * instead of clearing it, then bitch about it.
989 			 */
990 			if (uport->flags & UPF_SPD_MASK) {
991 				dev_notice_ratelimited(uport->dev,
992 				       "%s sets custom speed on %s. This is deprecated.\n",
993 				      current->comm,
994 				      tty_name(port->tty));
995 			}
996 			uart_change_speed(tty, state, NULL);
997 		}
998 	} else {
999 		retval = uart_startup(tty, state, 1);
1000 		if (retval == 0)
1001 			tty_port_set_initialized(port, true);
1002 		if (retval > 0)
1003 			retval = 0;
1004 	}
1005  exit:
1006 	return retval;
1007 }
1008 
1009 static int uart_set_info_user(struct tty_struct *tty, struct serial_struct *ss)
1010 {
1011 	struct uart_state *state = tty->driver_data;
1012 	struct tty_port *port = &state->port;
1013 	int retval;
1014 
1015 	down_write(&tty->termios_rwsem);
1016 	/*
1017 	 * This semaphore protects port->count.  It is also
1018 	 * very useful to prevent opens.  Also, take the
1019 	 * port configuration semaphore to make sure that a
1020 	 * module insertion/removal doesn't change anything
1021 	 * under us.
1022 	 */
1023 	mutex_lock(&port->mutex);
1024 	retval = uart_set_info(tty, port, state, ss);
1025 	mutex_unlock(&port->mutex);
1026 	up_write(&tty->termios_rwsem);
1027 	return retval;
1028 }
1029 
1030 /**
1031  *	uart_get_lsr_info	-	get line status register info
1032  *	@tty: tty associated with the UART
1033  *	@state: UART being queried
1034  *	@value: returned modem value
1035  */
1036 static int uart_get_lsr_info(struct tty_struct *tty,
1037 			struct uart_state *state, unsigned int __user *value)
1038 {
1039 	struct uart_port *uport = uart_port_check(state);
1040 	unsigned int result;
1041 
1042 	result = uport->ops->tx_empty(uport);
1043 
1044 	/*
1045 	 * If we're about to load something into the transmit
1046 	 * register, we'll pretend the transmitter isn't empty to
1047 	 * avoid a race condition (depending on when the transmit
1048 	 * interrupt happens).
1049 	 */
1050 	if (uport->x_char ||
1051 	    ((uart_circ_chars_pending(&state->xmit) > 0) &&
1052 	     !uart_tx_stopped(uport)))
1053 		result &= ~TIOCSER_TEMT;
1054 
1055 	return put_user(result, value);
1056 }
1057 
1058 static int uart_tiocmget(struct tty_struct *tty)
1059 {
1060 	struct uart_state *state = tty->driver_data;
1061 	struct tty_port *port = &state->port;
1062 	struct uart_port *uport;
1063 	int result = -EIO;
1064 
1065 	mutex_lock(&port->mutex);
1066 	uport = uart_port_check(state);
1067 	if (!uport)
1068 		goto out;
1069 
1070 	if (!tty_io_error(tty)) {
1071 		result = uport->mctrl;
1072 		spin_lock_irq(&uport->lock);
1073 		result |= uport->ops->get_mctrl(uport);
1074 		spin_unlock_irq(&uport->lock);
1075 	}
1076 out:
1077 	mutex_unlock(&port->mutex);
1078 	return result;
1079 }
1080 
1081 static int
1082 uart_tiocmset(struct tty_struct *tty, unsigned int set, unsigned int clear)
1083 {
1084 	struct uart_state *state = tty->driver_data;
1085 	struct tty_port *port = &state->port;
1086 	struct uart_port *uport;
1087 	int ret = -EIO;
1088 
1089 	mutex_lock(&port->mutex);
1090 	uport = uart_port_check(state);
1091 	if (!uport)
1092 		goto out;
1093 
1094 	if (!tty_io_error(tty)) {
1095 		uart_update_mctrl(uport, set, clear);
1096 		ret = 0;
1097 	}
1098 out:
1099 	mutex_unlock(&port->mutex);
1100 	return ret;
1101 }
1102 
1103 static int uart_break_ctl(struct tty_struct *tty, int break_state)
1104 {
1105 	struct uart_state *state = tty->driver_data;
1106 	struct tty_port *port = &state->port;
1107 	struct uart_port *uport;
1108 	int ret = -EIO;
1109 
1110 	mutex_lock(&port->mutex);
1111 	uport = uart_port_check(state);
1112 	if (!uport)
1113 		goto out;
1114 
1115 	if (uport->type != PORT_UNKNOWN && uport->ops->break_ctl)
1116 		uport->ops->break_ctl(uport, break_state);
1117 	ret = 0;
1118 out:
1119 	mutex_unlock(&port->mutex);
1120 	return ret;
1121 }
1122 
1123 static int uart_do_autoconfig(struct tty_struct *tty, struct uart_state *state)
1124 {
1125 	struct tty_port *port = &state->port;
1126 	struct uart_port *uport;
1127 	int flags, ret;
1128 
1129 	if (!capable(CAP_SYS_ADMIN))
1130 		return -EPERM;
1131 
1132 	/*
1133 	 * Take the per-port semaphore.  This prevents count from
1134 	 * changing, and hence any extra opens of the port while
1135 	 * we're auto-configuring.
1136 	 */
1137 	if (mutex_lock_interruptible(&port->mutex))
1138 		return -ERESTARTSYS;
1139 
1140 	uport = uart_port_check(state);
1141 	if (!uport) {
1142 		ret = -EIO;
1143 		goto out;
1144 	}
1145 
1146 	ret = -EBUSY;
1147 	if (tty_port_users(port) == 1) {
1148 		uart_shutdown(tty, state);
1149 
1150 		/*
1151 		 * If we already have a port type configured,
1152 		 * we must release its resources.
1153 		 */
1154 		if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
1155 			uport->ops->release_port(uport);
1156 
1157 		flags = UART_CONFIG_TYPE;
1158 		if (uport->flags & UPF_AUTO_IRQ)
1159 			flags |= UART_CONFIG_IRQ;
1160 
1161 		/*
1162 		 * This will claim the ports resources if
1163 		 * a port is found.
1164 		 */
1165 		uport->ops->config_port(uport, flags);
1166 
1167 		ret = uart_startup(tty, state, 1);
1168 		if (ret == 0)
1169 			tty_port_set_initialized(port, true);
1170 		if (ret > 0)
1171 			ret = 0;
1172 	}
1173 out:
1174 	mutex_unlock(&port->mutex);
1175 	return ret;
1176 }
1177 
1178 static void uart_enable_ms(struct uart_port *uport)
1179 {
1180 	/*
1181 	 * Force modem status interrupts on
1182 	 */
1183 	if (uport->ops->enable_ms)
1184 		uport->ops->enable_ms(uport);
1185 }
1186 
1187 /*
1188  * Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
1189  * - mask passed in arg for lines of interest
1190  *   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
1191  * Caller should use TIOCGICOUNT to see which one it was
1192  *
1193  * FIXME: This wants extracting into a common all driver implementation
1194  * of TIOCMWAIT using tty_port.
1195  */
1196 static int uart_wait_modem_status(struct uart_state *state, unsigned long arg)
1197 {
1198 	struct uart_port *uport;
1199 	struct tty_port *port = &state->port;
1200 	DECLARE_WAITQUEUE(wait, current);
1201 	struct uart_icount cprev, cnow;
1202 	int ret;
1203 
1204 	/*
1205 	 * note the counters on entry
1206 	 */
1207 	uport = uart_port_ref(state);
1208 	if (!uport)
1209 		return -EIO;
1210 	spin_lock_irq(&uport->lock);
1211 	memcpy(&cprev, &uport->icount, sizeof(struct uart_icount));
1212 	uart_enable_ms(uport);
1213 	spin_unlock_irq(&uport->lock);
1214 
1215 	add_wait_queue(&port->delta_msr_wait, &wait);
1216 	for (;;) {
1217 		spin_lock_irq(&uport->lock);
1218 		memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
1219 		spin_unlock_irq(&uport->lock);
1220 
1221 		set_current_state(TASK_INTERRUPTIBLE);
1222 
1223 		if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
1224 		    ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
1225 		    ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
1226 		    ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {
1227 			ret = 0;
1228 			break;
1229 		}
1230 
1231 		schedule();
1232 
1233 		/* see if a signal did it */
1234 		if (signal_pending(current)) {
1235 			ret = -ERESTARTSYS;
1236 			break;
1237 		}
1238 
1239 		cprev = cnow;
1240 	}
1241 	__set_current_state(TASK_RUNNING);
1242 	remove_wait_queue(&port->delta_msr_wait, &wait);
1243 	uart_port_deref(uport);
1244 
1245 	return ret;
1246 }
1247 
1248 /*
1249  * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
1250  * Return: write counters to the user passed counter struct
1251  * NB: both 1->0 and 0->1 transitions are counted except for
1252  *     RI where only 0->1 is counted.
1253  */
1254 static int uart_get_icount(struct tty_struct *tty,
1255 			  struct serial_icounter_struct *icount)
1256 {
1257 	struct uart_state *state = tty->driver_data;
1258 	struct uart_icount cnow;
1259 	struct uart_port *uport;
1260 
1261 	uport = uart_port_ref(state);
1262 	if (!uport)
1263 		return -EIO;
1264 	spin_lock_irq(&uport->lock);
1265 	memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
1266 	spin_unlock_irq(&uport->lock);
1267 	uart_port_deref(uport);
1268 
1269 	icount->cts         = cnow.cts;
1270 	icount->dsr         = cnow.dsr;
1271 	icount->rng         = cnow.rng;
1272 	icount->dcd         = cnow.dcd;
1273 	icount->rx          = cnow.rx;
1274 	icount->tx          = cnow.tx;
1275 	icount->frame       = cnow.frame;
1276 	icount->overrun     = cnow.overrun;
1277 	icount->parity      = cnow.parity;
1278 	icount->brk         = cnow.brk;
1279 	icount->buf_overrun = cnow.buf_overrun;
1280 
1281 	return 0;
1282 }
1283 
1284 static int uart_get_rs485_config(struct uart_port *port,
1285 			 struct serial_rs485 __user *rs485)
1286 {
1287 	unsigned long flags;
1288 	struct serial_rs485 aux;
1289 
1290 	spin_lock_irqsave(&port->lock, flags);
1291 	aux = port->rs485;
1292 	spin_unlock_irqrestore(&port->lock, flags);
1293 
1294 	if (copy_to_user(rs485, &aux, sizeof(aux)))
1295 		return -EFAULT;
1296 
1297 	return 0;
1298 }
1299 
1300 static int uart_set_rs485_config(struct uart_port *port,
1301 			 struct serial_rs485 __user *rs485_user)
1302 {
1303 	struct serial_rs485 rs485;
1304 	int ret;
1305 	unsigned long flags;
1306 
1307 	if (!port->rs485_config)
1308 		return -ENOIOCTLCMD;
1309 
1310 	if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
1311 		return -EFAULT;
1312 
1313 	spin_lock_irqsave(&port->lock, flags);
1314 	ret = port->rs485_config(port, &rs485);
1315 	spin_unlock_irqrestore(&port->lock, flags);
1316 	if (ret)
1317 		return ret;
1318 
1319 	if (copy_to_user(rs485_user, &port->rs485, sizeof(port->rs485)))
1320 		return -EFAULT;
1321 
1322 	return 0;
1323 }
1324 
1325 static int uart_get_iso7816_config(struct uart_port *port,
1326 				   struct serial_iso7816 __user *iso7816)
1327 {
1328 	unsigned long flags;
1329 	struct serial_iso7816 aux;
1330 
1331 	if (!port->iso7816_config)
1332 		return -ENOIOCTLCMD;
1333 
1334 	spin_lock_irqsave(&port->lock, flags);
1335 	aux = port->iso7816;
1336 	spin_unlock_irqrestore(&port->lock, flags);
1337 
1338 	if (copy_to_user(iso7816, &aux, sizeof(aux)))
1339 		return -EFAULT;
1340 
1341 	return 0;
1342 }
1343 
1344 static int uart_set_iso7816_config(struct uart_port *port,
1345 				   struct serial_iso7816 __user *iso7816_user)
1346 {
1347 	struct serial_iso7816 iso7816;
1348 	int i, ret;
1349 	unsigned long flags;
1350 
1351 	if (!port->iso7816_config)
1352 		return -ENOIOCTLCMD;
1353 
1354 	if (copy_from_user(&iso7816, iso7816_user, sizeof(*iso7816_user)))
1355 		return -EFAULT;
1356 
1357 	/*
1358 	 * There are 5 words reserved for future use. Check that userspace
1359 	 * doesn't put stuff in there to prevent breakages in the future.
1360 	 */
1361 	for (i = 0; i < 5; i++)
1362 		if (iso7816.reserved[i])
1363 			return -EINVAL;
1364 
1365 	spin_lock_irqsave(&port->lock, flags);
1366 	ret = port->iso7816_config(port, &iso7816);
1367 	spin_unlock_irqrestore(&port->lock, flags);
1368 	if (ret)
1369 		return ret;
1370 
1371 	if (copy_to_user(iso7816_user, &port->iso7816, sizeof(port->iso7816)))
1372 		return -EFAULT;
1373 
1374 	return 0;
1375 }
1376 
1377 /*
1378  * Called via sys_ioctl.  We can use spin_lock_irq() here.
1379  */
1380 static int
1381 uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
1382 {
1383 	struct uart_state *state = tty->driver_data;
1384 	struct tty_port *port = &state->port;
1385 	struct uart_port *uport;
1386 	void __user *uarg = (void __user *)arg;
1387 	int ret = -ENOIOCTLCMD;
1388 
1389 
1390 	/*
1391 	 * These ioctls don't rely on the hardware to be present.
1392 	 */
1393 	switch (cmd) {
1394 	case TIOCSERCONFIG:
1395 		down_write(&tty->termios_rwsem);
1396 		ret = uart_do_autoconfig(tty, state);
1397 		up_write(&tty->termios_rwsem);
1398 		break;
1399 	}
1400 
1401 	if (ret != -ENOIOCTLCMD)
1402 		goto out;
1403 
1404 	if (tty_io_error(tty)) {
1405 		ret = -EIO;
1406 		goto out;
1407 	}
1408 
1409 	/*
1410 	 * The following should only be used when hardware is present.
1411 	 */
1412 	switch (cmd) {
1413 	case TIOCMIWAIT:
1414 		ret = uart_wait_modem_status(state, arg);
1415 		break;
1416 	}
1417 
1418 	if (ret != -ENOIOCTLCMD)
1419 		goto out;
1420 
1421 	mutex_lock(&port->mutex);
1422 	uport = uart_port_check(state);
1423 
1424 	if (!uport || tty_io_error(tty)) {
1425 		ret = -EIO;
1426 		goto out_up;
1427 	}
1428 
1429 	/*
1430 	 * All these rely on hardware being present and need to be
1431 	 * protected against the tty being hung up.
1432 	 */
1433 
1434 	switch (cmd) {
1435 	case TIOCSERGETLSR: /* Get line status register */
1436 		ret = uart_get_lsr_info(tty, state, uarg);
1437 		break;
1438 
1439 	case TIOCGRS485:
1440 		ret = uart_get_rs485_config(uport, uarg);
1441 		break;
1442 
1443 	case TIOCSRS485:
1444 		ret = uart_set_rs485_config(uport, uarg);
1445 		break;
1446 
1447 	case TIOCSISO7816:
1448 		ret = uart_set_iso7816_config(state->uart_port, uarg);
1449 		break;
1450 
1451 	case TIOCGISO7816:
1452 		ret = uart_get_iso7816_config(state->uart_port, uarg);
1453 		break;
1454 	default:
1455 		if (uport->ops->ioctl)
1456 			ret = uport->ops->ioctl(uport, cmd, arg);
1457 		break;
1458 	}
1459 out_up:
1460 	mutex_unlock(&port->mutex);
1461 out:
1462 	return ret;
1463 }
1464 
1465 static void uart_set_ldisc(struct tty_struct *tty)
1466 {
1467 	struct uart_state *state = tty->driver_data;
1468 	struct uart_port *uport;
1469 	struct tty_port *port = &state->port;
1470 
1471 	if (!tty_port_initialized(port))
1472 		return;
1473 
1474 	mutex_lock(&state->port.mutex);
1475 	uport = uart_port_check(state);
1476 	if (uport && uport->ops->set_ldisc)
1477 		uport->ops->set_ldisc(uport, &tty->termios);
1478 	mutex_unlock(&state->port.mutex);
1479 }
1480 
1481 static void uart_set_termios(struct tty_struct *tty,
1482 						struct ktermios *old_termios)
1483 {
1484 	struct uart_state *state = tty->driver_data;
1485 	struct uart_port *uport;
1486 	unsigned int cflag = tty->termios.c_cflag;
1487 	unsigned int iflag_mask = IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK;
1488 	bool sw_changed = false;
1489 
1490 	mutex_lock(&state->port.mutex);
1491 	uport = uart_port_check(state);
1492 	if (!uport)
1493 		goto out;
1494 
1495 	/*
1496 	 * Drivers doing software flow control also need to know
1497 	 * about changes to these input settings.
1498 	 */
1499 	if (uport->flags & UPF_SOFT_FLOW) {
1500 		iflag_mask |= IXANY|IXON|IXOFF;
1501 		sw_changed =
1502 		   tty->termios.c_cc[VSTART] != old_termios->c_cc[VSTART] ||
1503 		   tty->termios.c_cc[VSTOP] != old_termios->c_cc[VSTOP];
1504 	}
1505 
1506 	/*
1507 	 * These are the bits that are used to setup various
1508 	 * flags in the low level driver. We can ignore the Bfoo
1509 	 * bits in c_cflag; c_[io]speed will always be set
1510 	 * appropriately by set_termios() in tty_ioctl.c
1511 	 */
1512 	if ((cflag ^ old_termios->c_cflag) == 0 &&
1513 	    tty->termios.c_ospeed == old_termios->c_ospeed &&
1514 	    tty->termios.c_ispeed == old_termios->c_ispeed &&
1515 	    ((tty->termios.c_iflag ^ old_termios->c_iflag) & iflag_mask) == 0 &&
1516 	    !sw_changed) {
1517 		goto out;
1518 	}
1519 
1520 	uart_change_speed(tty, state, old_termios);
1521 	/* reload cflag from termios; port driver may have overridden flags */
1522 	cflag = tty->termios.c_cflag;
1523 
1524 	/* Handle transition to B0 status */
1525 	if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD))
1526 		uart_clear_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
1527 	/* Handle transition away from B0 status */
1528 	else if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
1529 		unsigned int mask = TIOCM_DTR;
1530 
1531 		if (!(cflag & CRTSCTS) || !tty_throttled(tty))
1532 			mask |= TIOCM_RTS;
1533 		uart_set_mctrl(uport, mask);
1534 	}
1535 out:
1536 	mutex_unlock(&state->port.mutex);
1537 }
1538 
1539 /*
1540  * Calls to uart_close() are serialised via the tty_lock in
1541  *   drivers/tty/tty_io.c:tty_release()
1542  *   drivers/tty/tty_io.c:do_tty_hangup()
1543  */
1544 static void uart_close(struct tty_struct *tty, struct file *filp)
1545 {
1546 	struct uart_state *state = tty->driver_data;
1547 
1548 	if (!state) {
1549 		struct uart_driver *drv = tty->driver->driver_state;
1550 		struct tty_port *port;
1551 
1552 		state = drv->state + tty->index;
1553 		port = &state->port;
1554 		spin_lock_irq(&port->lock);
1555 		--port->count;
1556 		spin_unlock_irq(&port->lock);
1557 		return;
1558 	}
1559 
1560 	pr_debug("uart_close(%d) called\n", tty->index);
1561 
1562 	tty_port_close(tty->port, tty, filp);
1563 }
1564 
1565 static void uart_tty_port_shutdown(struct tty_port *port)
1566 {
1567 	struct uart_state *state = container_of(port, struct uart_state, port);
1568 	struct uart_port *uport = uart_port_check(state);
1569 
1570 	/*
1571 	 * At this point, we stop accepting input.  To do this, we
1572 	 * disable the receive line status interrupts.
1573 	 */
1574 	if (WARN(!uport, "detached port still initialized!\n"))
1575 		return;
1576 
1577 	spin_lock_irq(&uport->lock);
1578 	uport->ops->stop_rx(uport);
1579 	spin_unlock_irq(&uport->lock);
1580 
1581 	uart_port_shutdown(port);
1582 
1583 	/*
1584 	 * It's possible for shutdown to be called after suspend if we get
1585 	 * a DCD drop (hangup) at just the right time.  Clear suspended bit so
1586 	 * we don't try to resume a port that has been shutdown.
1587 	 */
1588 	tty_port_set_suspended(port, 0);
1589 
1590 	uart_change_pm(state, UART_PM_STATE_OFF);
1591 
1592 }
1593 
1594 static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
1595 {
1596 	struct uart_state *state = tty->driver_data;
1597 	struct uart_port *port;
1598 	unsigned long char_time, expire;
1599 
1600 	port = uart_port_ref(state);
1601 	if (!port)
1602 		return;
1603 
1604 	if (port->type == PORT_UNKNOWN || port->fifosize == 0) {
1605 		uart_port_deref(port);
1606 		return;
1607 	}
1608 
1609 	/*
1610 	 * Set the check interval to be 1/5 of the estimated time to
1611 	 * send a single character, and make it at least 1.  The check
1612 	 * interval should also be less than the timeout.
1613 	 *
1614 	 * Note: we have to use pretty tight timings here to satisfy
1615 	 * the NIST-PCTS.
1616 	 */
1617 	char_time = (port->timeout - HZ/50) / port->fifosize;
1618 	char_time = char_time / 5;
1619 	if (char_time == 0)
1620 		char_time = 1;
1621 	if (timeout && timeout < char_time)
1622 		char_time = timeout;
1623 
1624 	/*
1625 	 * If the transmitter hasn't cleared in twice the approximate
1626 	 * amount of time to send the entire FIFO, it probably won't
1627 	 * ever clear.  This assumes the UART isn't doing flow
1628 	 * control, which is currently the case.  Hence, if it ever
1629 	 * takes longer than port->timeout, this is probably due to a
1630 	 * UART bug of some kind.  So, we clamp the timeout parameter at
1631 	 * 2*port->timeout.
1632 	 */
1633 	if (timeout == 0 || timeout > 2 * port->timeout)
1634 		timeout = 2 * port->timeout;
1635 
1636 	expire = jiffies + timeout;
1637 
1638 	pr_debug("uart_wait_until_sent(%d), jiffies=%lu, expire=%lu...\n",
1639 		port->line, jiffies, expire);
1640 
1641 	/*
1642 	 * Check whether the transmitter is empty every 'char_time'.
1643 	 * 'timeout' / 'expire' give us the maximum amount of time
1644 	 * we wait.
1645 	 */
1646 	while (!port->ops->tx_empty(port)) {
1647 		msleep_interruptible(jiffies_to_msecs(char_time));
1648 		if (signal_pending(current))
1649 			break;
1650 		if (time_after(jiffies, expire))
1651 			break;
1652 	}
1653 	uart_port_deref(port);
1654 }
1655 
1656 /*
1657  * Calls to uart_hangup() are serialised by the tty_lock in
1658  *   drivers/tty/tty_io.c:do_tty_hangup()
1659  * This runs from a workqueue and can sleep for a _short_ time only.
1660  */
1661 static void uart_hangup(struct tty_struct *tty)
1662 {
1663 	struct uart_state *state = tty->driver_data;
1664 	struct tty_port *port = &state->port;
1665 	struct uart_port *uport;
1666 	unsigned long flags;
1667 
1668 	pr_debug("uart_hangup(%d)\n", tty->index);
1669 
1670 	mutex_lock(&port->mutex);
1671 	uport = uart_port_check(state);
1672 	WARN(!uport, "hangup of detached port!\n");
1673 
1674 	if (tty_port_active(port)) {
1675 		uart_flush_buffer(tty);
1676 		uart_shutdown(tty, state);
1677 		spin_lock_irqsave(&port->lock, flags);
1678 		port->count = 0;
1679 		spin_unlock_irqrestore(&port->lock, flags);
1680 		tty_port_set_active(port, 0);
1681 		tty_port_tty_set(port, NULL);
1682 		if (uport && !uart_console(uport))
1683 			uart_change_pm(state, UART_PM_STATE_OFF);
1684 		wake_up_interruptible(&port->open_wait);
1685 		wake_up_interruptible(&port->delta_msr_wait);
1686 	}
1687 	mutex_unlock(&port->mutex);
1688 }
1689 
1690 /* uport == NULL if uart_port has already been removed */
1691 static void uart_port_shutdown(struct tty_port *port)
1692 {
1693 	struct uart_state *state = container_of(port, struct uart_state, port);
1694 	struct uart_port *uport = uart_port_check(state);
1695 
1696 	/*
1697 	 * clear delta_msr_wait queue to avoid mem leaks: we may free
1698 	 * the irq here so the queue might never be woken up.  Note
1699 	 * that we won't end up waiting on delta_msr_wait again since
1700 	 * any outstanding file descriptors should be pointing at
1701 	 * hung_up_tty_fops now.
1702 	 */
1703 	wake_up_interruptible(&port->delta_msr_wait);
1704 
1705 	/*
1706 	 * Free the IRQ and disable the port.
1707 	 */
1708 	if (uport)
1709 		uport->ops->shutdown(uport);
1710 
1711 	/*
1712 	 * Ensure that the IRQ handler isn't running on another CPU.
1713 	 */
1714 	if (uport)
1715 		synchronize_irq(uport->irq);
1716 }
1717 
1718 static int uart_carrier_raised(struct tty_port *port)
1719 {
1720 	struct uart_state *state = container_of(port, struct uart_state, port);
1721 	struct uart_port *uport;
1722 	int mctrl;
1723 
1724 	uport = uart_port_ref(state);
1725 	/*
1726 	 * Should never observe uport == NULL since checks for hangup should
1727 	 * abort the tty_port_block_til_ready() loop before checking for carrier
1728 	 * raised -- but report carrier raised if it does anyway so open will
1729 	 * continue and not sleep
1730 	 */
1731 	if (WARN_ON(!uport))
1732 		return 1;
1733 	spin_lock_irq(&uport->lock);
1734 	uart_enable_ms(uport);
1735 	mctrl = uport->ops->get_mctrl(uport);
1736 	spin_unlock_irq(&uport->lock);
1737 	uart_port_deref(uport);
1738 	if (mctrl & TIOCM_CAR)
1739 		return 1;
1740 	return 0;
1741 }
1742 
1743 static void uart_dtr_rts(struct tty_port *port, int raise)
1744 {
1745 	struct uart_state *state = container_of(port, struct uart_state, port);
1746 	struct uart_port *uport;
1747 
1748 	uport = uart_port_ref(state);
1749 	if (!uport)
1750 		return;
1751 	uart_port_dtr_rts(uport, raise);
1752 	uart_port_deref(uport);
1753 }
1754 
1755 static int uart_install(struct tty_driver *driver, struct tty_struct *tty)
1756 {
1757 	struct uart_driver *drv = driver->driver_state;
1758 	struct uart_state *state = drv->state + tty->index;
1759 
1760 	tty->driver_data = state;
1761 
1762 	return tty_standard_install(driver, tty);
1763 }
1764 
1765 /*
1766  * Calls to uart_open are serialised by the tty_lock in
1767  *   drivers/tty/tty_io.c:tty_open()
1768  * Note that if this fails, then uart_close() _will_ be called.
1769  *
1770  * In time, we want to scrap the "opening nonpresent ports"
1771  * behaviour and implement an alternative way for setserial
1772  * to set base addresses/ports/types.  This will allow us to
1773  * get rid of a certain amount of extra tests.
1774  */
1775 static int uart_open(struct tty_struct *tty, struct file *filp)
1776 {
1777 	struct uart_state *state = tty->driver_data;
1778 	int retval;
1779 
1780 	retval = tty_port_open(&state->port, tty, filp);
1781 	if (retval > 0)
1782 		retval = 0;
1783 
1784 	return retval;
1785 }
1786 
1787 static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
1788 {
1789 	struct uart_state *state = container_of(port, struct uart_state, port);
1790 	struct uart_port *uport;
1791 	int ret;
1792 
1793 	uport = uart_port_check(state);
1794 	if (!uport || uport->flags & UPF_DEAD)
1795 		return -ENXIO;
1796 
1797 	/*
1798 	 * Start up the serial port.
1799 	 */
1800 	ret = uart_startup(tty, state, 0);
1801 	if (ret > 0)
1802 		tty_port_set_active(port, 1);
1803 
1804 	return ret;
1805 }
1806 
1807 static const char *uart_type(struct uart_port *port)
1808 {
1809 	const char *str = NULL;
1810 
1811 	if (port->ops->type)
1812 		str = port->ops->type(port);
1813 
1814 	if (!str)
1815 		str = "unknown";
1816 
1817 	return str;
1818 }
1819 
1820 #ifdef CONFIG_PROC_FS
1821 
1822 static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i)
1823 {
1824 	struct uart_state *state = drv->state + i;
1825 	struct tty_port *port = &state->port;
1826 	enum uart_pm_state pm_state;
1827 	struct uart_port *uport;
1828 	char stat_buf[32];
1829 	unsigned int status;
1830 	int mmio;
1831 
1832 	mutex_lock(&port->mutex);
1833 	uport = uart_port_check(state);
1834 	if (!uport)
1835 		goto out;
1836 
1837 	mmio = uport->iotype >= UPIO_MEM;
1838 	seq_printf(m, "%d: uart:%s %s%08llX irq:%d",
1839 			uport->line, uart_type(uport),
1840 			mmio ? "mmio:0x" : "port:",
1841 			mmio ? (unsigned long long)uport->mapbase
1842 			     : (unsigned long long)uport->iobase,
1843 			uport->irq);
1844 
1845 	if (uport->type == PORT_UNKNOWN) {
1846 		seq_putc(m, '\n');
1847 		goto out;
1848 	}
1849 
1850 	if (capable(CAP_SYS_ADMIN)) {
1851 		pm_state = state->pm_state;
1852 		if (pm_state != UART_PM_STATE_ON)
1853 			uart_change_pm(state, UART_PM_STATE_ON);
1854 		spin_lock_irq(&uport->lock);
1855 		status = uport->ops->get_mctrl(uport);
1856 		spin_unlock_irq(&uport->lock);
1857 		if (pm_state != UART_PM_STATE_ON)
1858 			uart_change_pm(state, pm_state);
1859 
1860 		seq_printf(m, " tx:%d rx:%d",
1861 				uport->icount.tx, uport->icount.rx);
1862 		if (uport->icount.frame)
1863 			seq_printf(m, " fe:%d",	uport->icount.frame);
1864 		if (uport->icount.parity)
1865 			seq_printf(m, " pe:%d",	uport->icount.parity);
1866 		if (uport->icount.brk)
1867 			seq_printf(m, " brk:%d", uport->icount.brk);
1868 		if (uport->icount.overrun)
1869 			seq_printf(m, " oe:%d", uport->icount.overrun);
1870 		if (uport->icount.buf_overrun)
1871 			seq_printf(m, " bo:%d", uport->icount.buf_overrun);
1872 
1873 #define INFOBIT(bit, str) \
1874 	if (uport->mctrl & (bit)) \
1875 		strncat(stat_buf, (str), sizeof(stat_buf) - \
1876 			strlen(stat_buf) - 2)
1877 #define STATBIT(bit, str) \
1878 	if (status & (bit)) \
1879 		strncat(stat_buf, (str), sizeof(stat_buf) - \
1880 		       strlen(stat_buf) - 2)
1881 
1882 		stat_buf[0] = '\0';
1883 		stat_buf[1] = '\0';
1884 		INFOBIT(TIOCM_RTS, "|RTS");
1885 		STATBIT(TIOCM_CTS, "|CTS");
1886 		INFOBIT(TIOCM_DTR, "|DTR");
1887 		STATBIT(TIOCM_DSR, "|DSR");
1888 		STATBIT(TIOCM_CAR, "|CD");
1889 		STATBIT(TIOCM_RNG, "|RI");
1890 		if (stat_buf[0])
1891 			stat_buf[0] = ' ';
1892 
1893 		seq_puts(m, stat_buf);
1894 	}
1895 	seq_putc(m, '\n');
1896 #undef STATBIT
1897 #undef INFOBIT
1898 out:
1899 	mutex_unlock(&port->mutex);
1900 }
1901 
1902 static int uart_proc_show(struct seq_file *m, void *v)
1903 {
1904 	struct tty_driver *ttydrv = m->private;
1905 	struct uart_driver *drv = ttydrv->driver_state;
1906 	int i;
1907 
1908 	seq_printf(m, "serinfo:1.0 driver%s%s revision:%s\n", "", "", "");
1909 	for (i = 0; i < drv->nr; i++)
1910 		uart_line_info(m, drv, i);
1911 	return 0;
1912 }
1913 #endif
1914 
1915 static inline bool uart_console_enabled(struct uart_port *port)
1916 {
1917 	return uart_console(port) && (port->cons->flags & CON_ENABLED);
1918 }
1919 
1920 static void uart_port_spin_lock_init(struct uart_port *port)
1921 {
1922 	spin_lock_init(&port->lock);
1923 	lockdep_set_class(&port->lock, &port_lock_key);
1924 }
1925 
1926 #if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(CONFIG_CONSOLE_POLL)
1927 /**
1928  *	uart_console_write - write a console message to a serial port
1929  *	@port: the port to write the message
1930  *	@s: array of characters
1931  *	@count: number of characters in string to write
1932  *	@putchar: function to write character to port
1933  */
1934 void uart_console_write(struct uart_port *port, const char *s,
1935 			unsigned int count,
1936 			void (*putchar)(struct uart_port *, int))
1937 {
1938 	unsigned int i;
1939 
1940 	for (i = 0; i < count; i++, s++) {
1941 		if (*s == '\n')
1942 			putchar(port, '\r');
1943 		putchar(port, *s);
1944 	}
1945 }
1946 EXPORT_SYMBOL_GPL(uart_console_write);
1947 
1948 /*
1949  *	Check whether an invalid uart number has been specified, and
1950  *	if so, search for the first available port that does have
1951  *	console support.
1952  */
1953 struct uart_port * __init
1954 uart_get_console(struct uart_port *ports, int nr, struct console *co)
1955 {
1956 	int idx = co->index;
1957 
1958 	if (idx < 0 || idx >= nr || (ports[idx].iobase == 0 &&
1959 				     ports[idx].membase == NULL))
1960 		for (idx = 0; idx < nr; idx++)
1961 			if (ports[idx].iobase != 0 ||
1962 			    ports[idx].membase != NULL)
1963 				break;
1964 
1965 	co->index = idx;
1966 
1967 	return ports + idx;
1968 }
1969 
1970 /**
1971  *	uart_parse_earlycon - Parse earlycon options
1972  *	@p:	  ptr to 2nd field (ie., just beyond '<name>,')
1973  *	@iotype:  ptr for decoded iotype (out)
1974  *	@addr:    ptr for decoded mapbase/iobase (out)
1975  *	@options: ptr for <options> field; NULL if not present (out)
1976  *
1977  *	Decodes earlycon kernel command line parameters of the form
1978  *	   earlycon=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
1979  *	   console=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
1980  *
1981  *	The optional form
1982  *
1983  *	   earlycon=<name>,0x<addr>,<options>
1984  *	   console=<name>,0x<addr>,<options>
1985  *
1986  *	is also accepted; the returned @iotype will be UPIO_MEM.
1987  *
1988  *	Returns 0 on success or -EINVAL on failure
1989  */
1990 int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,
1991 			char **options)
1992 {
1993 	if (strncmp(p, "mmio,", 5) == 0) {
1994 		*iotype = UPIO_MEM;
1995 		p += 5;
1996 	} else if (strncmp(p, "mmio16,", 7) == 0) {
1997 		*iotype = UPIO_MEM16;
1998 		p += 7;
1999 	} else if (strncmp(p, "mmio32,", 7) == 0) {
2000 		*iotype = UPIO_MEM32;
2001 		p += 7;
2002 	} else if (strncmp(p, "mmio32be,", 9) == 0) {
2003 		*iotype = UPIO_MEM32BE;
2004 		p += 9;
2005 	} else if (strncmp(p, "mmio32native,", 13) == 0) {
2006 		*iotype = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) ?
2007 			UPIO_MEM32BE : UPIO_MEM32;
2008 		p += 13;
2009 	} else if (strncmp(p, "io,", 3) == 0) {
2010 		*iotype = UPIO_PORT;
2011 		p += 3;
2012 	} else if (strncmp(p, "0x", 2) == 0) {
2013 		*iotype = UPIO_MEM;
2014 	} else {
2015 		return -EINVAL;
2016 	}
2017 
2018 	/*
2019 	 * Before you replace it with kstrtoull(), think about options separator
2020 	 * (',') it will not tolerate
2021 	 */
2022 	*addr = simple_strtoull(p, NULL, 0);
2023 	p = strchr(p, ',');
2024 	if (p)
2025 		p++;
2026 
2027 	*options = p;
2028 	return 0;
2029 }
2030 EXPORT_SYMBOL_GPL(uart_parse_earlycon);
2031 
2032 /**
2033  *	uart_parse_options - Parse serial port baud/parity/bits/flow control.
2034  *	@options: pointer to option string
2035  *	@baud: pointer to an 'int' variable for the baud rate.
2036  *	@parity: pointer to an 'int' variable for the parity.
2037  *	@bits: pointer to an 'int' variable for the number of data bits.
2038  *	@flow: pointer to an 'int' variable for the flow control character.
2039  *
2040  *	uart_parse_options decodes a string containing the serial console
2041  *	options.  The format of the string is <baud><parity><bits><flow>,
2042  *	eg: 115200n8r
2043  */
2044 void
2045 uart_parse_options(const char *options, int *baud, int *parity,
2046 		   int *bits, int *flow)
2047 {
2048 	const char *s = options;
2049 
2050 	*baud = simple_strtoul(s, NULL, 10);
2051 	while (*s >= '0' && *s <= '9')
2052 		s++;
2053 	if (*s)
2054 		*parity = *s++;
2055 	if (*s)
2056 		*bits = *s++ - '0';
2057 	if (*s)
2058 		*flow = *s;
2059 }
2060 EXPORT_SYMBOL_GPL(uart_parse_options);
2061 
2062 /**
2063  *	uart_set_options - setup the serial console parameters
2064  *	@port: pointer to the serial ports uart_port structure
2065  *	@co: console pointer
2066  *	@baud: baud rate
2067  *	@parity: parity character - 'n' (none), 'o' (odd), 'e' (even)
2068  *	@bits: number of data bits
2069  *	@flow: flow control character - 'r' (rts)
2070  */
2071 int
2072 uart_set_options(struct uart_port *port, struct console *co,
2073 		 int baud, int parity, int bits, int flow)
2074 {
2075 	struct ktermios termios;
2076 	static struct ktermios dummy;
2077 
2078 	/*
2079 	 * Ensure that the serial-console lock is initialised early.
2080 	 *
2081 	 * Note that the console-enabled check is needed because of kgdboc,
2082 	 * which can end up calling uart_set_options() for an already enabled
2083 	 * console via tty_find_polling_driver() and uart_poll_init().
2084 	 */
2085 	if (!uart_console_enabled(port) && !port->console_reinit)
2086 		uart_port_spin_lock_init(port);
2087 
2088 	memset(&termios, 0, sizeof(struct ktermios));
2089 
2090 	termios.c_cflag |= CREAD | HUPCL | CLOCAL;
2091 	tty_termios_encode_baud_rate(&termios, baud, baud);
2092 
2093 	if (bits == 7)
2094 		termios.c_cflag |= CS7;
2095 	else
2096 		termios.c_cflag |= CS8;
2097 
2098 	switch (parity) {
2099 	case 'o': case 'O':
2100 		termios.c_cflag |= PARODD;
2101 		fallthrough;
2102 	case 'e': case 'E':
2103 		termios.c_cflag |= PARENB;
2104 		break;
2105 	}
2106 
2107 	if (flow == 'r')
2108 		termios.c_cflag |= CRTSCTS;
2109 
2110 	/*
2111 	 * some uarts on other side don't support no flow control.
2112 	 * So we set * DTR in host uart to make them happy
2113 	 */
2114 	port->mctrl |= TIOCM_DTR;
2115 
2116 	port->ops->set_termios(port, &termios, &dummy);
2117 	/*
2118 	 * Allow the setting of the UART parameters with a NULL console
2119 	 * too:
2120 	 */
2121 	if (co)
2122 		co->cflag = termios.c_cflag;
2123 
2124 	return 0;
2125 }
2126 EXPORT_SYMBOL_GPL(uart_set_options);
2127 #endif /* CONFIG_SERIAL_CORE_CONSOLE */
2128 
2129 /**
2130  * uart_change_pm - set power state of the port
2131  *
2132  * @state: port descriptor
2133  * @pm_state: new state
2134  *
2135  * Locking: port->mutex has to be held
2136  */
2137 static void uart_change_pm(struct uart_state *state,
2138 			   enum uart_pm_state pm_state)
2139 {
2140 	struct uart_port *port = uart_port_check(state);
2141 
2142 	if (state->pm_state != pm_state) {
2143 		if (port && port->ops->pm)
2144 			port->ops->pm(port, pm_state, state->pm_state);
2145 		state->pm_state = pm_state;
2146 	}
2147 }
2148 
2149 struct uart_match {
2150 	struct uart_port *port;
2151 	struct uart_driver *driver;
2152 };
2153 
2154 static int serial_match_port(struct device *dev, void *data)
2155 {
2156 	struct uart_match *match = data;
2157 	struct tty_driver *tty_drv = match->driver->tty_driver;
2158 	dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
2159 		match->port->line;
2160 
2161 	return dev->devt == devt; /* Actually, only one tty per port */
2162 }
2163 
2164 int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
2165 {
2166 	struct uart_state *state = drv->state + uport->line;
2167 	struct tty_port *port = &state->port;
2168 	struct device *tty_dev;
2169 	struct uart_match match = {uport, drv};
2170 
2171 	mutex_lock(&port->mutex);
2172 
2173 	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
2174 	if (tty_dev && device_may_wakeup(tty_dev)) {
2175 		enable_irq_wake(uport->irq);
2176 		put_device(tty_dev);
2177 		mutex_unlock(&port->mutex);
2178 		return 0;
2179 	}
2180 	put_device(tty_dev);
2181 
2182 	/* Nothing to do if the console is not suspending */
2183 	if (!console_suspend_enabled && uart_console(uport))
2184 		goto unlock;
2185 
2186 	uport->suspended = 1;
2187 
2188 	if (tty_port_initialized(port)) {
2189 		const struct uart_ops *ops = uport->ops;
2190 		int tries;
2191 
2192 		tty_port_set_suspended(port, 1);
2193 		tty_port_set_initialized(port, 0);
2194 
2195 		spin_lock_irq(&uport->lock);
2196 		ops->stop_tx(uport);
2197 		ops->set_mctrl(uport, 0);
2198 		ops->stop_rx(uport);
2199 		spin_unlock_irq(&uport->lock);
2200 
2201 		/*
2202 		 * Wait for the transmitter to empty.
2203 		 */
2204 		for (tries = 3; !ops->tx_empty(uport) && tries; tries--)
2205 			msleep(10);
2206 		if (!tries)
2207 			dev_err(uport->dev, "%s: Unable to drain transmitter\n",
2208 				uport->name);
2209 
2210 		ops->shutdown(uport);
2211 	}
2212 
2213 	/*
2214 	 * Disable the console device before suspending.
2215 	 */
2216 	if (uart_console(uport))
2217 		console_stop(uport->cons);
2218 
2219 	uart_change_pm(state, UART_PM_STATE_OFF);
2220 unlock:
2221 	mutex_unlock(&port->mutex);
2222 
2223 	return 0;
2224 }
2225 
2226 int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
2227 {
2228 	struct uart_state *state = drv->state + uport->line;
2229 	struct tty_port *port = &state->port;
2230 	struct device *tty_dev;
2231 	struct uart_match match = {uport, drv};
2232 	struct ktermios termios;
2233 
2234 	mutex_lock(&port->mutex);
2235 
2236 	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
2237 	if (!uport->suspended && device_may_wakeup(tty_dev)) {
2238 		if (irqd_is_wakeup_set(irq_get_irq_data((uport->irq))))
2239 			disable_irq_wake(uport->irq);
2240 		put_device(tty_dev);
2241 		mutex_unlock(&port->mutex);
2242 		return 0;
2243 	}
2244 	put_device(tty_dev);
2245 	uport->suspended = 0;
2246 
2247 	/*
2248 	 * Re-enable the console device after suspending.
2249 	 */
2250 	if (uart_console(uport)) {
2251 		/*
2252 		 * First try to use the console cflag setting.
2253 		 */
2254 		memset(&termios, 0, sizeof(struct ktermios));
2255 		termios.c_cflag = uport->cons->cflag;
2256 
2257 		/*
2258 		 * If that's unset, use the tty termios setting.
2259 		 */
2260 		if (port->tty && termios.c_cflag == 0)
2261 			termios = port->tty->termios;
2262 
2263 		if (console_suspend_enabled)
2264 			uart_change_pm(state, UART_PM_STATE_ON);
2265 		uport->ops->set_termios(uport, &termios, NULL);
2266 		if (console_suspend_enabled)
2267 			console_start(uport->cons);
2268 	}
2269 
2270 	if (tty_port_suspended(port)) {
2271 		const struct uart_ops *ops = uport->ops;
2272 		int ret;
2273 
2274 		uart_change_pm(state, UART_PM_STATE_ON);
2275 		spin_lock_irq(&uport->lock);
2276 		ops->set_mctrl(uport, 0);
2277 		spin_unlock_irq(&uport->lock);
2278 		if (console_suspend_enabled || !uart_console(uport)) {
2279 			/* Protected by port mutex for now */
2280 			struct tty_struct *tty = port->tty;
2281 
2282 			ret = ops->startup(uport);
2283 			if (ret == 0) {
2284 				if (tty)
2285 					uart_change_speed(tty, state, NULL);
2286 				spin_lock_irq(&uport->lock);
2287 				ops->set_mctrl(uport, uport->mctrl);
2288 				ops->start_tx(uport);
2289 				spin_unlock_irq(&uport->lock);
2290 				tty_port_set_initialized(port, 1);
2291 			} else {
2292 				/*
2293 				 * Failed to resume - maybe hardware went away?
2294 				 * Clear the "initialized" flag so we won't try
2295 				 * to call the low level drivers shutdown method.
2296 				 */
2297 				uart_shutdown(tty, state);
2298 			}
2299 		}
2300 
2301 		tty_port_set_suspended(port, 0);
2302 	}
2303 
2304 	mutex_unlock(&port->mutex);
2305 
2306 	return 0;
2307 }
2308 
2309 static inline void
2310 uart_report_port(struct uart_driver *drv, struct uart_port *port)
2311 {
2312 	char address[64];
2313 
2314 	switch (port->iotype) {
2315 	case UPIO_PORT:
2316 		snprintf(address, sizeof(address), "I/O 0x%lx", port->iobase);
2317 		break;
2318 	case UPIO_HUB6:
2319 		snprintf(address, sizeof(address),
2320 			 "I/O 0x%lx offset 0x%x", port->iobase, port->hub6);
2321 		break;
2322 	case UPIO_MEM:
2323 	case UPIO_MEM16:
2324 	case UPIO_MEM32:
2325 	case UPIO_MEM32BE:
2326 	case UPIO_AU:
2327 	case UPIO_TSI:
2328 		snprintf(address, sizeof(address),
2329 			 "MMIO 0x%llx", (unsigned long long)port->mapbase);
2330 		break;
2331 	default:
2332 		strlcpy(address, "*unknown*", sizeof(address));
2333 		break;
2334 	}
2335 
2336 	pr_info("%s%s%s at %s (irq = %d, base_baud = %d) is a %s\n",
2337 	       port->dev ? dev_name(port->dev) : "",
2338 	       port->dev ? ": " : "",
2339 	       port->name,
2340 	       address, port->irq, port->uartclk / 16, uart_type(port));
2341 }
2342 
2343 static void
2344 uart_configure_port(struct uart_driver *drv, struct uart_state *state,
2345 		    struct uart_port *port)
2346 {
2347 	unsigned int flags;
2348 
2349 	/*
2350 	 * If there isn't a port here, don't do anything further.
2351 	 */
2352 	if (!port->iobase && !port->mapbase && !port->membase)
2353 		return;
2354 
2355 	/*
2356 	 * Now do the auto configuration stuff.  Note that config_port
2357 	 * is expected to claim the resources and map the port for us.
2358 	 */
2359 	flags = 0;
2360 	if (port->flags & UPF_AUTO_IRQ)
2361 		flags |= UART_CONFIG_IRQ;
2362 	if (port->flags & UPF_BOOT_AUTOCONF) {
2363 		if (!(port->flags & UPF_FIXED_TYPE)) {
2364 			port->type = PORT_UNKNOWN;
2365 			flags |= UART_CONFIG_TYPE;
2366 		}
2367 		port->ops->config_port(port, flags);
2368 	}
2369 
2370 	if (port->type != PORT_UNKNOWN) {
2371 		unsigned long flags;
2372 
2373 		uart_report_port(drv, port);
2374 
2375 		/* Power up port for set_mctrl() */
2376 		uart_change_pm(state, UART_PM_STATE_ON);
2377 
2378 		/*
2379 		 * Ensure that the modem control lines are de-activated.
2380 		 * keep the DTR setting that is set in uart_set_options()
2381 		 * We probably don't need a spinlock around this, but
2382 		 */
2383 		spin_lock_irqsave(&port->lock, flags);
2384 		port->ops->set_mctrl(port, port->mctrl & TIOCM_DTR);
2385 		spin_unlock_irqrestore(&port->lock, flags);
2386 
2387 		/*
2388 		 * If this driver supports console, and it hasn't been
2389 		 * successfully registered yet, try to re-register it.
2390 		 * It may be that the port was not available.
2391 		 */
2392 		if (port->cons && !(port->cons->flags & CON_ENABLED))
2393 			register_console(port->cons);
2394 
2395 		/*
2396 		 * Power down all ports by default, except the
2397 		 * console if we have one.
2398 		 */
2399 		if (!uart_console(port))
2400 			uart_change_pm(state, UART_PM_STATE_OFF);
2401 	}
2402 }
2403 
2404 #ifdef CONFIG_CONSOLE_POLL
2405 
2406 static int uart_poll_init(struct tty_driver *driver, int line, char *options)
2407 {
2408 	struct uart_driver *drv = driver->driver_state;
2409 	struct uart_state *state = drv->state + line;
2410 	struct tty_port *tport;
2411 	struct uart_port *port;
2412 	int baud = 9600;
2413 	int bits = 8;
2414 	int parity = 'n';
2415 	int flow = 'n';
2416 	int ret = 0;
2417 
2418 	tport = &state->port;
2419 	mutex_lock(&tport->mutex);
2420 
2421 	port = uart_port_check(state);
2422 	if (!port || !(port->ops->poll_get_char && port->ops->poll_put_char)) {
2423 		ret = -1;
2424 		goto out;
2425 	}
2426 
2427 	if (port->ops->poll_init) {
2428 		/*
2429 		 * We don't set initialized as we only initialized the hw,
2430 		 * e.g. state->xmit is still uninitialized.
2431 		 */
2432 		if (!tty_port_initialized(tport))
2433 			ret = port->ops->poll_init(port);
2434 	}
2435 
2436 	if (!ret && options) {
2437 		uart_parse_options(options, &baud, &parity, &bits, &flow);
2438 		ret = uart_set_options(port, NULL, baud, parity, bits, flow);
2439 	}
2440 out:
2441 	mutex_unlock(&tport->mutex);
2442 	return ret;
2443 }
2444 
2445 static int uart_poll_get_char(struct tty_driver *driver, int line)
2446 {
2447 	struct uart_driver *drv = driver->driver_state;
2448 	struct uart_state *state = drv->state + line;
2449 	struct uart_port *port;
2450 	int ret = -1;
2451 
2452 	port = uart_port_ref(state);
2453 	if (port) {
2454 		ret = port->ops->poll_get_char(port);
2455 		uart_port_deref(port);
2456 	}
2457 
2458 	return ret;
2459 }
2460 
2461 static void uart_poll_put_char(struct tty_driver *driver, int line, char ch)
2462 {
2463 	struct uart_driver *drv = driver->driver_state;
2464 	struct uart_state *state = drv->state + line;
2465 	struct uart_port *port;
2466 
2467 	port = uart_port_ref(state);
2468 	if (!port)
2469 		return;
2470 
2471 	if (ch == '\n')
2472 		port->ops->poll_put_char(port, '\r');
2473 	port->ops->poll_put_char(port, ch);
2474 	uart_port_deref(port);
2475 }
2476 #endif
2477 
2478 static const struct tty_operations uart_ops = {
2479 	.install	= uart_install,
2480 	.open		= uart_open,
2481 	.close		= uart_close,
2482 	.write		= uart_write,
2483 	.put_char	= uart_put_char,
2484 	.flush_chars	= uart_flush_chars,
2485 	.write_room	= uart_write_room,
2486 	.chars_in_buffer= uart_chars_in_buffer,
2487 	.flush_buffer	= uart_flush_buffer,
2488 	.ioctl		= uart_ioctl,
2489 	.throttle	= uart_throttle,
2490 	.unthrottle	= uart_unthrottle,
2491 	.send_xchar	= uart_send_xchar,
2492 	.set_termios	= uart_set_termios,
2493 	.set_ldisc	= uart_set_ldisc,
2494 	.stop		= uart_stop,
2495 	.start		= uart_start,
2496 	.hangup		= uart_hangup,
2497 	.break_ctl	= uart_break_ctl,
2498 	.wait_until_sent= uart_wait_until_sent,
2499 #ifdef CONFIG_PROC_FS
2500 	.proc_show	= uart_proc_show,
2501 #endif
2502 	.tiocmget	= uart_tiocmget,
2503 	.tiocmset	= uart_tiocmset,
2504 	.set_serial	= uart_set_info_user,
2505 	.get_serial	= uart_get_info_user,
2506 	.get_icount	= uart_get_icount,
2507 #ifdef CONFIG_CONSOLE_POLL
2508 	.poll_init	= uart_poll_init,
2509 	.poll_get_char	= uart_poll_get_char,
2510 	.poll_put_char	= uart_poll_put_char,
2511 #endif
2512 };
2513 
2514 static const struct tty_port_operations uart_port_ops = {
2515 	.carrier_raised = uart_carrier_raised,
2516 	.dtr_rts	= uart_dtr_rts,
2517 	.activate	= uart_port_activate,
2518 	.shutdown	= uart_tty_port_shutdown,
2519 };
2520 
2521 /**
2522  *	uart_register_driver - register a driver with the uart core layer
2523  *	@drv: low level driver structure
2524  *
2525  *	Register a uart driver with the core driver.  We in turn register
2526  *	with the tty layer, and initialise the core driver per-port state.
2527  *
2528  *	We have a proc file in /proc/tty/driver which is named after the
2529  *	normal driver.
2530  *
2531  *	drv->port should be NULL, and the per-port structures should be
2532  *	registered using uart_add_one_port after this call has succeeded.
2533  */
2534 int uart_register_driver(struct uart_driver *drv)
2535 {
2536 	struct tty_driver *normal;
2537 	int i, retval = -ENOMEM;
2538 
2539 	BUG_ON(drv->state);
2540 
2541 	/*
2542 	 * Maybe we should be using a slab cache for this, especially if
2543 	 * we have a large number of ports to handle.
2544 	 */
2545 	drv->state = kcalloc(drv->nr, sizeof(struct uart_state), GFP_KERNEL);
2546 	if (!drv->state)
2547 		goto out;
2548 
2549 	normal = alloc_tty_driver(drv->nr);
2550 	if (!normal)
2551 		goto out_kfree;
2552 
2553 	drv->tty_driver = normal;
2554 
2555 	normal->driver_name	= drv->driver_name;
2556 	normal->name		= drv->dev_name;
2557 	normal->major		= drv->major;
2558 	normal->minor_start	= drv->minor;
2559 	normal->type		= TTY_DRIVER_TYPE_SERIAL;
2560 	normal->subtype		= SERIAL_TYPE_NORMAL;
2561 	normal->init_termios	= tty_std_termios;
2562 	normal->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
2563 	normal->init_termios.c_ispeed = normal->init_termios.c_ospeed = 9600;
2564 	normal->flags		= TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
2565 	normal->driver_state    = drv;
2566 	tty_set_operations(normal, &uart_ops);
2567 
2568 	/*
2569 	 * Initialise the UART state(s).
2570 	 */
2571 	for (i = 0; i < drv->nr; i++) {
2572 		struct uart_state *state = drv->state + i;
2573 		struct tty_port *port = &state->port;
2574 
2575 		tty_port_init(port);
2576 		port->ops = &uart_port_ops;
2577 	}
2578 
2579 	retval = tty_register_driver(normal);
2580 	if (retval >= 0)
2581 		return retval;
2582 
2583 	for (i = 0; i < drv->nr; i++)
2584 		tty_port_destroy(&drv->state[i].port);
2585 	put_tty_driver(normal);
2586 out_kfree:
2587 	kfree(drv->state);
2588 out:
2589 	return retval;
2590 }
2591 
2592 /**
2593  *	uart_unregister_driver - remove a driver from the uart core layer
2594  *	@drv: low level driver structure
2595  *
2596  *	Remove all references to a driver from the core driver.  The low
2597  *	level driver must have removed all its ports via the
2598  *	uart_remove_one_port() if it registered them with uart_add_one_port().
2599  *	(ie, drv->port == NULL)
2600  */
2601 void uart_unregister_driver(struct uart_driver *drv)
2602 {
2603 	struct tty_driver *p = drv->tty_driver;
2604 	unsigned int i;
2605 
2606 	tty_unregister_driver(p);
2607 	put_tty_driver(p);
2608 	for (i = 0; i < drv->nr; i++)
2609 		tty_port_destroy(&drv->state[i].port);
2610 	kfree(drv->state);
2611 	drv->state = NULL;
2612 	drv->tty_driver = NULL;
2613 }
2614 
2615 struct tty_driver *uart_console_device(struct console *co, int *index)
2616 {
2617 	struct uart_driver *p = co->data;
2618 	*index = co->index;
2619 	return p->tty_driver;
2620 }
2621 EXPORT_SYMBOL_GPL(uart_console_device);
2622 
2623 static ssize_t uartclk_show(struct device *dev,
2624 	struct device_attribute *attr, char *buf)
2625 {
2626 	struct serial_struct tmp;
2627 	struct tty_port *port = dev_get_drvdata(dev);
2628 
2629 	uart_get_info(port, &tmp);
2630 	return sprintf(buf, "%d\n", tmp.baud_base * 16);
2631 }
2632 
2633 static ssize_t type_show(struct device *dev,
2634 	struct device_attribute *attr, char *buf)
2635 {
2636 	struct serial_struct tmp;
2637 	struct tty_port *port = dev_get_drvdata(dev);
2638 
2639 	uart_get_info(port, &tmp);
2640 	return sprintf(buf, "%d\n", tmp.type);
2641 }
2642 
2643 static ssize_t line_show(struct device *dev,
2644 	struct device_attribute *attr, char *buf)
2645 {
2646 	struct serial_struct tmp;
2647 	struct tty_port *port = dev_get_drvdata(dev);
2648 
2649 	uart_get_info(port, &tmp);
2650 	return sprintf(buf, "%d\n", tmp.line);
2651 }
2652 
2653 static ssize_t port_show(struct device *dev,
2654 	struct device_attribute *attr, char *buf)
2655 {
2656 	struct serial_struct tmp;
2657 	struct tty_port *port = dev_get_drvdata(dev);
2658 	unsigned long ioaddr;
2659 
2660 	uart_get_info(port, &tmp);
2661 	ioaddr = tmp.port;
2662 	if (HIGH_BITS_OFFSET)
2663 		ioaddr |= (unsigned long)tmp.port_high << HIGH_BITS_OFFSET;
2664 	return sprintf(buf, "0x%lX\n", ioaddr);
2665 }
2666 
2667 static ssize_t irq_show(struct device *dev,
2668 	struct device_attribute *attr, char *buf)
2669 {
2670 	struct serial_struct tmp;
2671 	struct tty_port *port = dev_get_drvdata(dev);
2672 
2673 	uart_get_info(port, &tmp);
2674 	return sprintf(buf, "%d\n", tmp.irq);
2675 }
2676 
2677 static ssize_t flags_show(struct device *dev,
2678 	struct device_attribute *attr, char *buf)
2679 {
2680 	struct serial_struct tmp;
2681 	struct tty_port *port = dev_get_drvdata(dev);
2682 
2683 	uart_get_info(port, &tmp);
2684 	return sprintf(buf, "0x%X\n", tmp.flags);
2685 }
2686 
2687 static ssize_t xmit_fifo_size_show(struct device *dev,
2688 	struct device_attribute *attr, char *buf)
2689 {
2690 	struct serial_struct tmp;
2691 	struct tty_port *port = dev_get_drvdata(dev);
2692 
2693 	uart_get_info(port, &tmp);
2694 	return sprintf(buf, "%d\n", tmp.xmit_fifo_size);
2695 }
2696 
2697 static ssize_t close_delay_show(struct device *dev,
2698 	struct device_attribute *attr, char *buf)
2699 {
2700 	struct serial_struct tmp;
2701 	struct tty_port *port = dev_get_drvdata(dev);
2702 
2703 	uart_get_info(port, &tmp);
2704 	return sprintf(buf, "%d\n", tmp.close_delay);
2705 }
2706 
2707 static ssize_t closing_wait_show(struct device *dev,
2708 	struct device_attribute *attr, char *buf)
2709 {
2710 	struct serial_struct tmp;
2711 	struct tty_port *port = dev_get_drvdata(dev);
2712 
2713 	uart_get_info(port, &tmp);
2714 	return sprintf(buf, "%d\n", tmp.closing_wait);
2715 }
2716 
2717 static ssize_t custom_divisor_show(struct device *dev,
2718 	struct device_attribute *attr, char *buf)
2719 {
2720 	struct serial_struct tmp;
2721 	struct tty_port *port = dev_get_drvdata(dev);
2722 
2723 	uart_get_info(port, &tmp);
2724 	return sprintf(buf, "%d\n", tmp.custom_divisor);
2725 }
2726 
2727 static ssize_t io_type_show(struct device *dev,
2728 	struct device_attribute *attr, char *buf)
2729 {
2730 	struct serial_struct tmp;
2731 	struct tty_port *port = dev_get_drvdata(dev);
2732 
2733 	uart_get_info(port, &tmp);
2734 	return sprintf(buf, "%d\n", tmp.io_type);
2735 }
2736 
2737 static ssize_t iomem_base_show(struct device *dev,
2738 	struct device_attribute *attr, char *buf)
2739 {
2740 	struct serial_struct tmp;
2741 	struct tty_port *port = dev_get_drvdata(dev);
2742 
2743 	uart_get_info(port, &tmp);
2744 	return sprintf(buf, "0x%lX\n", (unsigned long)tmp.iomem_base);
2745 }
2746 
2747 static ssize_t iomem_reg_shift_show(struct device *dev,
2748 	struct device_attribute *attr, char *buf)
2749 {
2750 	struct serial_struct tmp;
2751 	struct tty_port *port = dev_get_drvdata(dev);
2752 
2753 	uart_get_info(port, &tmp);
2754 	return sprintf(buf, "%d\n", tmp.iomem_reg_shift);
2755 }
2756 
2757 static ssize_t console_show(struct device *dev,
2758 	struct device_attribute *attr, char *buf)
2759 {
2760 	struct tty_port *port = dev_get_drvdata(dev);
2761 	struct uart_state *state = container_of(port, struct uart_state, port);
2762 	struct uart_port *uport;
2763 	bool console = false;
2764 
2765 	mutex_lock(&port->mutex);
2766 	uport = uart_port_check(state);
2767 	if (uport)
2768 		console = uart_console_enabled(uport);
2769 	mutex_unlock(&port->mutex);
2770 
2771 	return sprintf(buf, "%c\n", console ? 'Y' : 'N');
2772 }
2773 
2774 static ssize_t console_store(struct device *dev,
2775 	struct device_attribute *attr, const char *buf, size_t count)
2776 {
2777 	struct tty_port *port = dev_get_drvdata(dev);
2778 	struct uart_state *state = container_of(port, struct uart_state, port);
2779 	struct uart_port *uport;
2780 	bool oldconsole, newconsole;
2781 	int ret;
2782 
2783 	ret = kstrtobool(buf, &newconsole);
2784 	if (ret)
2785 		return ret;
2786 
2787 	mutex_lock(&port->mutex);
2788 	uport = uart_port_check(state);
2789 	if (uport) {
2790 		oldconsole = uart_console_enabled(uport);
2791 		if (oldconsole && !newconsole) {
2792 			ret = unregister_console(uport->cons);
2793 		} else if (!oldconsole && newconsole) {
2794 			if (uart_console(uport)) {
2795 				uport->console_reinit = 1;
2796 				register_console(uport->cons);
2797 			} else {
2798 				ret = -ENOENT;
2799 			}
2800 		}
2801 	} else {
2802 		ret = -ENXIO;
2803 	}
2804 	mutex_unlock(&port->mutex);
2805 
2806 	return ret < 0 ? ret : count;
2807 }
2808 
2809 static DEVICE_ATTR_RO(uartclk);
2810 static DEVICE_ATTR_RO(type);
2811 static DEVICE_ATTR_RO(line);
2812 static DEVICE_ATTR_RO(port);
2813 static DEVICE_ATTR_RO(irq);
2814 static DEVICE_ATTR_RO(flags);
2815 static DEVICE_ATTR_RO(xmit_fifo_size);
2816 static DEVICE_ATTR_RO(close_delay);
2817 static DEVICE_ATTR_RO(closing_wait);
2818 static DEVICE_ATTR_RO(custom_divisor);
2819 static DEVICE_ATTR_RO(io_type);
2820 static DEVICE_ATTR_RO(iomem_base);
2821 static DEVICE_ATTR_RO(iomem_reg_shift);
2822 static DEVICE_ATTR_RW(console);
2823 
2824 static struct attribute *tty_dev_attrs[] = {
2825 	&dev_attr_uartclk.attr,
2826 	&dev_attr_type.attr,
2827 	&dev_attr_line.attr,
2828 	&dev_attr_port.attr,
2829 	&dev_attr_irq.attr,
2830 	&dev_attr_flags.attr,
2831 	&dev_attr_xmit_fifo_size.attr,
2832 	&dev_attr_close_delay.attr,
2833 	&dev_attr_closing_wait.attr,
2834 	&dev_attr_custom_divisor.attr,
2835 	&dev_attr_io_type.attr,
2836 	&dev_attr_iomem_base.attr,
2837 	&dev_attr_iomem_reg_shift.attr,
2838 	&dev_attr_console.attr,
2839 	NULL
2840 };
2841 
2842 static const struct attribute_group tty_dev_attr_group = {
2843 	.attrs = tty_dev_attrs,
2844 };
2845 
2846 /**
2847  *	uart_add_one_port - attach a driver-defined port structure
2848  *	@drv: pointer to the uart low level driver structure for this port
2849  *	@uport: uart port structure to use for this port.
2850  *
2851  *	Context: task context, might sleep
2852  *
2853  *	This allows the driver to register its own uart_port structure
2854  *	with the core driver.  The main purpose is to allow the low
2855  *	level uart drivers to expand uart_port, rather than having yet
2856  *	more levels of structures.
2857  */
2858 int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
2859 {
2860 	struct uart_state *state;
2861 	struct tty_port *port;
2862 	int ret = 0;
2863 	struct device *tty_dev;
2864 	int num_groups;
2865 
2866 	if (uport->line >= drv->nr)
2867 		return -EINVAL;
2868 
2869 	state = drv->state + uport->line;
2870 	port = &state->port;
2871 
2872 	mutex_lock(&port_mutex);
2873 	mutex_lock(&port->mutex);
2874 	if (state->uart_port) {
2875 		ret = -EINVAL;
2876 		goto out;
2877 	}
2878 
2879 	/* Link the port to the driver state table and vice versa */
2880 	atomic_set(&state->refcount, 1);
2881 	init_waitqueue_head(&state->remove_wait);
2882 	state->uart_port = uport;
2883 	uport->state = state;
2884 
2885 	state->pm_state = UART_PM_STATE_UNDEFINED;
2886 	uport->cons = drv->cons;
2887 	uport->minor = drv->tty_driver->minor_start + uport->line;
2888 	uport->name = kasprintf(GFP_KERNEL, "%s%d", drv->dev_name,
2889 				drv->tty_driver->name_base + uport->line);
2890 	if (!uport->name) {
2891 		ret = -ENOMEM;
2892 		goto out;
2893 	}
2894 
2895 	/*
2896 	 * If this port is in use as a console then the spinlock is already
2897 	 * initialised.
2898 	 */
2899 	if (!uart_console_enabled(uport))
2900 		uart_port_spin_lock_init(uport);
2901 
2902 	if (uport->cons && uport->dev)
2903 		of_console_check(uport->dev->of_node, uport->cons->name, uport->line);
2904 
2905 	tty_port_link_device(port, drv->tty_driver, uport->line);
2906 	uart_configure_port(drv, state, uport);
2907 
2908 	port->console = uart_console(uport);
2909 
2910 	num_groups = 2;
2911 	if (uport->attr_group)
2912 		num_groups++;
2913 
2914 	uport->tty_groups = kcalloc(num_groups, sizeof(*uport->tty_groups),
2915 				    GFP_KERNEL);
2916 	if (!uport->tty_groups) {
2917 		ret = -ENOMEM;
2918 		goto out;
2919 	}
2920 	uport->tty_groups[0] = &tty_dev_attr_group;
2921 	if (uport->attr_group)
2922 		uport->tty_groups[1] = uport->attr_group;
2923 
2924 	/*
2925 	 * Register the port whether it's detected or not.  This allows
2926 	 * setserial to be used to alter this port's parameters.
2927 	 */
2928 	tty_dev = tty_port_register_device_attr_serdev(port, drv->tty_driver,
2929 			uport->line, uport->dev, port, uport->tty_groups);
2930 	if (!IS_ERR(tty_dev)) {
2931 		device_set_wakeup_capable(tty_dev, 1);
2932 	} else {
2933 		dev_err(uport->dev, "Cannot register tty device on line %d\n",
2934 		       uport->line);
2935 	}
2936 
2937 	/*
2938 	 * Ensure UPF_DEAD is not set.
2939 	 */
2940 	uport->flags &= ~UPF_DEAD;
2941 
2942  out:
2943 	mutex_unlock(&port->mutex);
2944 	mutex_unlock(&port_mutex);
2945 
2946 	return ret;
2947 }
2948 
2949 /**
2950  *	uart_remove_one_port - detach a driver defined port structure
2951  *	@drv: pointer to the uart low level driver structure for this port
2952  *	@uport: uart port structure for this port
2953  *
2954  *	Context: task context, might sleep
2955  *
2956  *	This unhooks (and hangs up) the specified port structure from the
2957  *	core driver.  No further calls will be made to the low-level code
2958  *	for this port.
2959  */
2960 int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
2961 {
2962 	struct uart_state *state = drv->state + uport->line;
2963 	struct tty_port *port = &state->port;
2964 	struct uart_port *uart_port;
2965 	struct tty_struct *tty;
2966 	int ret = 0;
2967 
2968 	mutex_lock(&port_mutex);
2969 
2970 	/*
2971 	 * Mark the port "dead" - this prevents any opens from
2972 	 * succeeding while we shut down the port.
2973 	 */
2974 	mutex_lock(&port->mutex);
2975 	uart_port = uart_port_check(state);
2976 	if (uart_port != uport)
2977 		dev_alert(uport->dev, "Removing wrong port: %p != %p\n",
2978 			  uart_port, uport);
2979 
2980 	if (!uart_port) {
2981 		mutex_unlock(&port->mutex);
2982 		ret = -EINVAL;
2983 		goto out;
2984 	}
2985 	uport->flags |= UPF_DEAD;
2986 	mutex_unlock(&port->mutex);
2987 
2988 	/*
2989 	 * Remove the devices from the tty layer
2990 	 */
2991 	tty_port_unregister_device(port, drv->tty_driver, uport->line);
2992 
2993 	tty = tty_port_tty_get(port);
2994 	if (tty) {
2995 		tty_vhangup(port->tty);
2996 		tty_kref_put(tty);
2997 	}
2998 
2999 	/*
3000 	 * If the port is used as a console, unregister it
3001 	 */
3002 	if (uart_console(uport))
3003 		unregister_console(uport->cons);
3004 
3005 	/*
3006 	 * Free the port IO and memory resources, if any.
3007 	 */
3008 	if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
3009 		uport->ops->release_port(uport);
3010 	kfree(uport->tty_groups);
3011 	kfree(uport->name);
3012 
3013 	/*
3014 	 * Indicate that there isn't a port here anymore.
3015 	 */
3016 	uport->type = PORT_UNKNOWN;
3017 
3018 	mutex_lock(&port->mutex);
3019 	WARN_ON(atomic_dec_return(&state->refcount) < 0);
3020 	wait_event(state->remove_wait, !atomic_read(&state->refcount));
3021 	state->uart_port = NULL;
3022 	mutex_unlock(&port->mutex);
3023 out:
3024 	mutex_unlock(&port_mutex);
3025 
3026 	return ret;
3027 }
3028 
3029 /*
3030  *	Are the two ports equivalent?
3031  */
3032 int uart_match_port(struct uart_port *port1, struct uart_port *port2)
3033 {
3034 	if (port1->iotype != port2->iotype)
3035 		return 0;
3036 
3037 	switch (port1->iotype) {
3038 	case UPIO_PORT:
3039 		return (port1->iobase == port2->iobase);
3040 	case UPIO_HUB6:
3041 		return (port1->iobase == port2->iobase) &&
3042 		       (port1->hub6   == port2->hub6);
3043 	case UPIO_MEM:
3044 	case UPIO_MEM16:
3045 	case UPIO_MEM32:
3046 	case UPIO_MEM32BE:
3047 	case UPIO_AU:
3048 	case UPIO_TSI:
3049 		return (port1->mapbase == port2->mapbase);
3050 	}
3051 	return 0;
3052 }
3053 EXPORT_SYMBOL(uart_match_port);
3054 
3055 /**
3056  *	uart_handle_dcd_change - handle a change of carrier detect state
3057  *	@uport: uart_port structure for the open port
3058  *	@status: new carrier detect status, nonzero if active
3059  *
3060  *	Caller must hold uport->lock
3061  */
3062 void uart_handle_dcd_change(struct uart_port *uport, unsigned int status)
3063 {
3064 	struct tty_port *port = &uport->state->port;
3065 	struct tty_struct *tty = port->tty;
3066 	struct tty_ldisc *ld;
3067 
3068 	lockdep_assert_held_once(&uport->lock);
3069 
3070 	if (tty) {
3071 		ld = tty_ldisc_ref(tty);
3072 		if (ld) {
3073 			if (ld->ops->dcd_change)
3074 				ld->ops->dcd_change(tty, status);
3075 			tty_ldisc_deref(ld);
3076 		}
3077 	}
3078 
3079 	uport->icount.dcd++;
3080 
3081 	if (uart_dcd_enabled(uport)) {
3082 		if (status)
3083 			wake_up_interruptible(&port->open_wait);
3084 		else if (tty)
3085 			tty_hangup(tty);
3086 	}
3087 }
3088 EXPORT_SYMBOL_GPL(uart_handle_dcd_change);
3089 
3090 /**
3091  *	uart_handle_cts_change - handle a change of clear-to-send state
3092  *	@uport: uart_port structure for the open port
3093  *	@status: new clear to send status, nonzero if active
3094  *
3095  *	Caller must hold uport->lock
3096  */
3097 void uart_handle_cts_change(struct uart_port *uport, unsigned int status)
3098 {
3099 	lockdep_assert_held_once(&uport->lock);
3100 
3101 	uport->icount.cts++;
3102 
3103 	if (uart_softcts_mode(uport)) {
3104 		if (uport->hw_stopped) {
3105 			if (status) {
3106 				uport->hw_stopped = 0;
3107 				uport->ops->start_tx(uport);
3108 				uart_write_wakeup(uport);
3109 			}
3110 		} else {
3111 			if (!status) {
3112 				uport->hw_stopped = 1;
3113 				uport->ops->stop_tx(uport);
3114 			}
3115 		}
3116 
3117 	}
3118 }
3119 EXPORT_SYMBOL_GPL(uart_handle_cts_change);
3120 
3121 /**
3122  * uart_insert_char - push a char to the uart layer
3123  *
3124  * User is responsible to call tty_flip_buffer_push when they are done with
3125  * insertion.
3126  *
3127  * @port: corresponding port
3128  * @status: state of the serial port RX buffer (LSR for 8250)
3129  * @overrun: mask of overrun bits in @status
3130  * @ch: character to push
3131  * @flag: flag for the character (see TTY_NORMAL and friends)
3132  */
3133 void uart_insert_char(struct uart_port *port, unsigned int status,
3134 		 unsigned int overrun, unsigned int ch, unsigned int flag)
3135 {
3136 	struct tty_port *tport = &port->state->port;
3137 
3138 	if ((status & port->ignore_status_mask & ~overrun) == 0)
3139 		if (tty_insert_flip_char(tport, ch, flag) == 0)
3140 			++port->icount.buf_overrun;
3141 
3142 	/*
3143 	 * Overrun is special.  Since it's reported immediately,
3144 	 * it doesn't affect the current character.
3145 	 */
3146 	if (status & ~port->ignore_status_mask & overrun)
3147 		if (tty_insert_flip_char(tport, 0, TTY_OVERRUN) == 0)
3148 			++port->icount.buf_overrun;
3149 }
3150 EXPORT_SYMBOL_GPL(uart_insert_char);
3151 
3152 #ifdef CONFIG_MAGIC_SYSRQ_SERIAL
3153 static const char sysrq_toggle_seq[] = CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE;
3154 
3155 static void uart_sysrq_on(struct work_struct *w)
3156 {
3157 	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
3158 
3159 	sysrq_toggle_support(1);
3160 	pr_info("SysRq is enabled by magic sequence '%*pE' on serial\n",
3161 		sysrq_toggle_seq_len, sysrq_toggle_seq);
3162 }
3163 static DECLARE_WORK(sysrq_enable_work, uart_sysrq_on);
3164 
3165 /**
3166  *	uart_try_toggle_sysrq - Enables SysRq from serial line
3167  *	@port: uart_port structure where char(s) after BREAK met
3168  *	@ch: new character in the sequence after received BREAK
3169  *
3170  *	Enables magic SysRq when the required sequence is met on port
3171  *	(see CONFIG_MAGIC_SYSRQ_SERIAL_SEQUENCE).
3172  *
3173  *	Returns false if @ch is out of enabling sequence and should be
3174  *	handled some other way, true if @ch was consumed.
3175  */
3176 bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch)
3177 {
3178 	int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
3179 
3180 	if (!sysrq_toggle_seq_len)
3181 		return false;
3182 
3183 	BUILD_BUG_ON(ARRAY_SIZE(sysrq_toggle_seq) >= U8_MAX);
3184 	if (sysrq_toggle_seq[port->sysrq_seq] != ch) {
3185 		port->sysrq_seq = 0;
3186 		return false;
3187 	}
3188 
3189 	if (++port->sysrq_seq < sysrq_toggle_seq_len) {
3190 		port->sysrq = jiffies + SYSRQ_TIMEOUT;
3191 		return true;
3192 	}
3193 
3194 	schedule_work(&sysrq_enable_work);
3195 
3196 	port->sysrq = 0;
3197 	return true;
3198 }
3199 EXPORT_SYMBOL_GPL(uart_try_toggle_sysrq);
3200 #endif
3201 
3202 EXPORT_SYMBOL(uart_write_wakeup);
3203 EXPORT_SYMBOL(uart_register_driver);
3204 EXPORT_SYMBOL(uart_unregister_driver);
3205 EXPORT_SYMBOL(uart_suspend_port);
3206 EXPORT_SYMBOL(uart_resume_port);
3207 EXPORT_SYMBOL(uart_add_one_port);
3208 EXPORT_SYMBOL(uart_remove_one_port);
3209 
3210 /**
3211  * uart_get_rs485_mode() - retrieve rs485 properties for given uart
3212  * @port: uart device's target port
3213  *
3214  * This function implements the device tree binding described in
3215  * Documentation/devicetree/bindings/serial/rs485.txt.
3216  */
3217 int uart_get_rs485_mode(struct uart_port *port)
3218 {
3219 	struct serial_rs485 *rs485conf = &port->rs485;
3220 	struct device *dev = port->dev;
3221 	u32 rs485_delay[2];
3222 	int ret;
3223 
3224 	ret = device_property_read_u32_array(dev, "rs485-rts-delay",
3225 					     rs485_delay, 2);
3226 	if (!ret) {
3227 		rs485conf->delay_rts_before_send = rs485_delay[0];
3228 		rs485conf->delay_rts_after_send = rs485_delay[1];
3229 	} else {
3230 		rs485conf->delay_rts_before_send = 0;
3231 		rs485conf->delay_rts_after_send = 0;
3232 	}
3233 
3234 	/*
3235 	 * Clear full-duplex and enabled flags, set RTS polarity to active high
3236 	 * to get to a defined state with the following properties:
3237 	 */
3238 	rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED |
3239 			      SER_RS485_TERMINATE_BUS |
3240 			      SER_RS485_RTS_AFTER_SEND);
3241 	rs485conf->flags |= SER_RS485_RTS_ON_SEND;
3242 
3243 	if (device_property_read_bool(dev, "rs485-rx-during-tx"))
3244 		rs485conf->flags |= SER_RS485_RX_DURING_TX;
3245 
3246 	if (device_property_read_bool(dev, "linux,rs485-enabled-at-boot-time"))
3247 		rs485conf->flags |= SER_RS485_ENABLED;
3248 
3249 	if (device_property_read_bool(dev, "rs485-rts-active-low")) {
3250 		rs485conf->flags &= ~SER_RS485_RTS_ON_SEND;
3251 		rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
3252 	}
3253 
3254 	/*
3255 	 * Disabling termination by default is the safe choice:  Else if many
3256 	 * bus participants enable it, no communication is possible at all.
3257 	 * Works fine for short cables and users may enable for longer cables.
3258 	 */
3259 	port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term",
3260 							GPIOD_OUT_LOW);
3261 	if (IS_ERR(port->rs485_term_gpio)) {
3262 		ret = PTR_ERR(port->rs485_term_gpio);
3263 		port->rs485_term_gpio = NULL;
3264 		return dev_err_probe(dev, ret, "Cannot get rs485-term-gpios\n");
3265 	}
3266 
3267 	return 0;
3268 }
3269 EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
3270 
3271 MODULE_DESCRIPTION("Serial driver core");
3272 MODULE_LICENSE("GPL");
3273