xref: /openbmc/linux/drivers/mmc/core/sdio_uart.c (revision 95713967)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * SDIO UART/GPS driver
4  *
5  * Based on drivers/serial/8250.c and drivers/serial/serial_core.c
6  * by Russell King.
7  *
8  * Author:	Nicolas Pitre
9  * Created:	June 15, 2007
10  * Copyright:	MontaVista Software, Inc.
11  */
12 
13 /*
14  * Note: Although this driver assumes a 16550A-like UART implementation,
15  * it is not possible to leverage the common 8250/16550 driver, nor the
16  * core UART infrastructure, as they assumes direct access to the hardware
17  * registers, often under a spinlock.  This is not possible in the SDIO
18  * context as SDIO access functions must be able to sleep.
19  *
20  * Because we need to lock the SDIO host to ensure an exclusive access to
21  * the card, we simply rely on that lock to also prevent and serialize
22  * concurrent access to the same port.
23  */
24 
25 #include <linux/module.h>
26 #include <linux/init.h>
27 #include <linux/kernel.h>
28 #include <linux/sched.h>
29 #include <linux/mutex.h>
30 #include <linux/seq_file.h>
31 #include <linux/serial.h>
32 #include <linux/serial_reg.h>
33 #include <linux/circ_buf.h>
34 #include <linux/tty.h>
35 #include <linux/tty_flip.h>
36 #include <linux/kfifo.h>
37 #include <linux/slab.h>
38 
39 #include <linux/mmc/core.h>
40 #include <linux/mmc/card.h>
41 #include <linux/mmc/sdio_func.h>
42 #include <linux/mmc/sdio_ids.h>
43 
44 
45 #define UART_NR		8	/* Number of UARTs this driver can handle */
46 
47 
48 #define FIFO_SIZE	PAGE_SIZE
49 #define WAKEUP_CHARS	256
50 
51 struct uart_icount {
52 	__u32	cts;
53 	__u32	dsr;
54 	__u32	rng;
55 	__u32	dcd;
56 	__u32	rx;
57 	__u32	tx;
58 	__u32	frame;
59 	__u32	overrun;
60 	__u32	parity;
61 	__u32	brk;
62 };
63 
64 struct sdio_uart_port {
65 	struct tty_port		port;
66 	unsigned int		index;
67 	struct sdio_func	*func;
68 	struct mutex		func_lock;
69 	struct task_struct	*in_sdio_uart_irq;
70 	unsigned int		regs_offset;
71 	struct kfifo		xmit_fifo;
72 	spinlock_t		write_lock;
73 	struct uart_icount	icount;
74 	unsigned int		uartclk;
75 	unsigned int		mctrl;
76 	unsigned int		rx_mctrl;
77 	unsigned int		read_status_mask;
78 	unsigned int		ignore_status_mask;
79 	unsigned char		x_char;
80 	unsigned char           ier;
81 	unsigned char           lcr;
82 };
83 
84 static struct sdio_uart_port *sdio_uart_table[UART_NR];
85 static DEFINE_SPINLOCK(sdio_uart_table_lock);
86 
sdio_uart_add_port(struct sdio_uart_port * port)87 static int sdio_uart_add_port(struct sdio_uart_port *port)
88 {
89 	int index, ret = -EBUSY;
90 
91 	mutex_init(&port->func_lock);
92 	spin_lock_init(&port->write_lock);
93 	if (kfifo_alloc(&port->xmit_fifo, FIFO_SIZE, GFP_KERNEL))
94 		return -ENOMEM;
95 
96 	spin_lock(&sdio_uart_table_lock);
97 	for (index = 0; index < UART_NR; index++) {
98 		if (!sdio_uart_table[index]) {
99 			port->index = index;
100 			sdio_uart_table[index] = port;
101 			ret = 0;
102 			break;
103 		}
104 	}
105 	spin_unlock(&sdio_uart_table_lock);
106 
107 	return ret;
108 }
109 
sdio_uart_port_get(unsigned index)110 static struct sdio_uart_port *sdio_uart_port_get(unsigned index)
111 {
112 	struct sdio_uart_port *port;
113 
114 	if (index >= UART_NR)
115 		return NULL;
116 
117 	spin_lock(&sdio_uart_table_lock);
118 	port = sdio_uart_table[index];
119 	if (port)
120 		tty_port_get(&port->port);
121 	spin_unlock(&sdio_uart_table_lock);
122 
123 	return port;
124 }
125 
sdio_uart_port_put(struct sdio_uart_port * port)126 static void sdio_uart_port_put(struct sdio_uart_port *port)
127 {
128 	tty_port_put(&port->port);
129 }
130 
sdio_uart_port_remove(struct sdio_uart_port * port)131 static void sdio_uart_port_remove(struct sdio_uart_port *port)
132 {
133 	struct sdio_func *func;
134 
135 	spin_lock(&sdio_uart_table_lock);
136 	sdio_uart_table[port->index] = NULL;
137 	spin_unlock(&sdio_uart_table_lock);
138 
139 	/*
140 	 * We're killing a port that potentially still is in use by
141 	 * the tty layer. Be careful to prevent any further access
142 	 * to the SDIO function and arrange for the tty layer to
143 	 * give up on that port ASAP.
144 	 * Beware: the lock ordering is critical.
145 	 */
146 	mutex_lock(&port->port.mutex);
147 	mutex_lock(&port->func_lock);
148 	func = port->func;
149 	sdio_claim_host(func);
150 	port->func = NULL;
151 	mutex_unlock(&port->func_lock);
152 	/* tty_hangup is async so is this safe as is ?? */
153 	tty_port_tty_hangup(&port->port, false);
154 	mutex_unlock(&port->port.mutex);
155 	sdio_release_irq(func);
156 	sdio_disable_func(func);
157 	sdio_release_host(func);
158 
159 	sdio_uart_port_put(port);
160 }
161 
sdio_uart_claim_func(struct sdio_uart_port * port)162 static int sdio_uart_claim_func(struct sdio_uart_port *port)
163 {
164 	mutex_lock(&port->func_lock);
165 	if (unlikely(!port->func)) {
166 		mutex_unlock(&port->func_lock);
167 		return -ENODEV;
168 	}
169 	if (likely(port->in_sdio_uart_irq != current))
170 		sdio_claim_host(port->func);
171 	mutex_unlock(&port->func_lock);
172 	return 0;
173 }
174 
sdio_uart_release_func(struct sdio_uart_port * port)175 static inline void sdio_uart_release_func(struct sdio_uart_port *port)
176 {
177 	if (likely(port->in_sdio_uart_irq != current))
178 		sdio_release_host(port->func);
179 }
180 
sdio_in(struct sdio_uart_port * port,int offset)181 static inline unsigned int sdio_in(struct sdio_uart_port *port, int offset)
182 {
183 	unsigned char c;
184 	c = sdio_readb(port->func, port->regs_offset + offset, NULL);
185 	return c;
186 }
187 
sdio_out(struct sdio_uart_port * port,int offset,int value)188 static inline void sdio_out(struct sdio_uart_port *port, int offset, int value)
189 {
190 	sdio_writeb(port->func, value, port->regs_offset + offset, NULL);
191 }
192 
sdio_uart_get_mctrl(struct sdio_uart_port * port)193 static unsigned int sdio_uart_get_mctrl(struct sdio_uart_port *port)
194 {
195 	unsigned char status;
196 	unsigned int ret;
197 
198 	/* FIXME: What stops this losing the delta bits and breaking
199 	   sdio_uart_check_modem_status ? */
200 	status = sdio_in(port, UART_MSR);
201 
202 	ret = 0;
203 	if (status & UART_MSR_DCD)
204 		ret |= TIOCM_CAR;
205 	if (status & UART_MSR_RI)
206 		ret |= TIOCM_RNG;
207 	if (status & UART_MSR_DSR)
208 		ret |= TIOCM_DSR;
209 	if (status & UART_MSR_CTS)
210 		ret |= TIOCM_CTS;
211 	return ret;
212 }
213 
sdio_uart_write_mctrl(struct sdio_uart_port * port,unsigned int mctrl)214 static void sdio_uart_write_mctrl(struct sdio_uart_port *port,
215 				  unsigned int mctrl)
216 {
217 	unsigned char mcr = 0;
218 
219 	if (mctrl & TIOCM_RTS)
220 		mcr |= UART_MCR_RTS;
221 	if (mctrl & TIOCM_DTR)
222 		mcr |= UART_MCR_DTR;
223 	if (mctrl & TIOCM_OUT1)
224 		mcr |= UART_MCR_OUT1;
225 	if (mctrl & TIOCM_OUT2)
226 		mcr |= UART_MCR_OUT2;
227 	if (mctrl & TIOCM_LOOP)
228 		mcr |= UART_MCR_LOOP;
229 
230 	sdio_out(port, UART_MCR, mcr);
231 }
232 
sdio_uart_update_mctrl(struct sdio_uart_port * port,unsigned int set,unsigned int clear)233 static inline void sdio_uart_update_mctrl(struct sdio_uart_port *port,
234 					  unsigned int set, unsigned int clear)
235 {
236 	unsigned int old;
237 
238 	old = port->mctrl;
239 	port->mctrl = (old & ~clear) | set;
240 	if (old != port->mctrl)
241 		sdio_uart_write_mctrl(port, port->mctrl);
242 }
243 
244 #define sdio_uart_set_mctrl(port, x)	sdio_uart_update_mctrl(port, x, 0)
245 #define sdio_uart_clear_mctrl(port, x)	sdio_uart_update_mctrl(port, 0, x)
246 
sdio_uart_change_speed(struct sdio_uart_port * port,struct ktermios * termios,const struct ktermios * old)247 static void sdio_uart_change_speed(struct sdio_uart_port *port,
248 				   struct ktermios *termios,
249 				   const struct ktermios *old)
250 {
251 	unsigned char cval, fcr = 0;
252 	unsigned int baud, quot;
253 
254 	cval = UART_LCR_WLEN(tty_get_char_size(termios->c_cflag));
255 
256 	if (termios->c_cflag & CSTOPB)
257 		cval |= UART_LCR_STOP;
258 	if (termios->c_cflag & PARENB)
259 		cval |= UART_LCR_PARITY;
260 	if (!(termios->c_cflag & PARODD))
261 		cval |= UART_LCR_EPAR;
262 
263 	for (;;) {
264 		baud = tty_termios_baud_rate(termios);
265 		if (baud == 0)
266 			baud = 9600;  /* Special case: B0 rate. */
267 		if (baud <= port->uartclk)
268 			break;
269 		/*
270 		 * Oops, the quotient was zero.  Try again with the old
271 		 * baud rate if possible, otherwise default to 9600.
272 		 */
273 		termios->c_cflag &= ~CBAUD;
274 		if (old) {
275 			termios->c_cflag |= old->c_cflag & CBAUD;
276 			old = NULL;
277 		} else
278 			termios->c_cflag |= B9600;
279 	}
280 	quot = (2 * port->uartclk + baud) / (2 * baud);
281 
282 	if (baud < 2400)
283 		fcr = UART_FCR_ENABLE_FIFO | UART_FCR_TRIGGER_1;
284 	else
285 		fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10;
286 
287 	port->read_status_mask = UART_LSR_OE | UART_LSR_THRE | UART_LSR_DR;
288 	if (termios->c_iflag & INPCK)
289 		port->read_status_mask |= UART_LSR_FE | UART_LSR_PE;
290 	if (termios->c_iflag & (BRKINT | PARMRK))
291 		port->read_status_mask |= UART_LSR_BI;
292 
293 	/*
294 	 * Characters to ignore
295 	 */
296 	port->ignore_status_mask = 0;
297 	if (termios->c_iflag & IGNPAR)
298 		port->ignore_status_mask |= UART_LSR_PE | UART_LSR_FE;
299 	if (termios->c_iflag & IGNBRK) {
300 		port->ignore_status_mask |= UART_LSR_BI;
301 		/*
302 		 * If we're ignoring parity and break indicators,
303 		 * ignore overruns too (for real raw support).
304 		 */
305 		if (termios->c_iflag & IGNPAR)
306 			port->ignore_status_mask |= UART_LSR_OE;
307 	}
308 
309 	/*
310 	 * ignore all characters if CREAD is not set
311 	 */
312 	if ((termios->c_cflag & CREAD) == 0)
313 		port->ignore_status_mask |= UART_LSR_DR;
314 
315 	/*
316 	 * CTS flow control flag and modem status interrupts
317 	 */
318 	port->ier &= ~UART_IER_MSI;
319 	if ((termios->c_cflag & CRTSCTS) || !(termios->c_cflag & CLOCAL))
320 		port->ier |= UART_IER_MSI;
321 
322 	port->lcr = cval;
323 
324 	sdio_out(port, UART_IER, port->ier);
325 	sdio_out(port, UART_LCR, cval | UART_LCR_DLAB);
326 	sdio_out(port, UART_DLL, quot & 0xff);
327 	sdio_out(port, UART_DLM, quot >> 8);
328 	sdio_out(port, UART_LCR, cval);
329 	sdio_out(port, UART_FCR, fcr);
330 
331 	sdio_uart_write_mctrl(port, port->mctrl);
332 }
333 
sdio_uart_start_tx(struct sdio_uart_port * port)334 static void sdio_uart_start_tx(struct sdio_uart_port *port)
335 {
336 	if (!(port->ier & UART_IER_THRI)) {
337 		port->ier |= UART_IER_THRI;
338 		sdio_out(port, UART_IER, port->ier);
339 	}
340 }
341 
sdio_uart_stop_tx(struct sdio_uart_port * port)342 static void sdio_uart_stop_tx(struct sdio_uart_port *port)
343 {
344 	if (port->ier & UART_IER_THRI) {
345 		port->ier &= ~UART_IER_THRI;
346 		sdio_out(port, UART_IER, port->ier);
347 	}
348 }
349 
sdio_uart_stop_rx(struct sdio_uart_port * port)350 static void sdio_uart_stop_rx(struct sdio_uart_port *port)
351 {
352 	port->ier &= ~UART_IER_RLSI;
353 	port->read_status_mask &= ~UART_LSR_DR;
354 	sdio_out(port, UART_IER, port->ier);
355 }
356 
sdio_uart_receive_chars(struct sdio_uart_port * port,unsigned int * status)357 static void sdio_uart_receive_chars(struct sdio_uart_port *port,
358 				    unsigned int *status)
359 {
360 	unsigned int ch, flag;
361 	int max_count = 256;
362 
363 	do {
364 		ch = sdio_in(port, UART_RX);
365 		flag = TTY_NORMAL;
366 		port->icount.rx++;
367 
368 		if (unlikely(*status & (UART_LSR_BI | UART_LSR_PE |
369 					UART_LSR_FE | UART_LSR_OE))) {
370 			/*
371 			 * For statistics only
372 			 */
373 			if (*status & UART_LSR_BI) {
374 				*status &= ~(UART_LSR_FE | UART_LSR_PE);
375 				port->icount.brk++;
376 			} else if (*status & UART_LSR_PE)
377 				port->icount.parity++;
378 			else if (*status & UART_LSR_FE)
379 				port->icount.frame++;
380 			if (*status & UART_LSR_OE)
381 				port->icount.overrun++;
382 
383 			/*
384 			 * Mask off conditions which should be ignored.
385 			 */
386 			*status &= port->read_status_mask;
387 			if (*status & UART_LSR_BI)
388 				flag = TTY_BREAK;
389 			else if (*status & UART_LSR_PE)
390 				flag = TTY_PARITY;
391 			else if (*status & UART_LSR_FE)
392 				flag = TTY_FRAME;
393 		}
394 
395 		if ((*status & port->ignore_status_mask & ~UART_LSR_OE) == 0)
396 			tty_insert_flip_char(&port->port, ch, flag);
397 
398 		/*
399 		 * Overrun is special.  Since it's reported immediately,
400 		 * it doesn't affect the current character.
401 		 */
402 		if (*status & ~port->ignore_status_mask & UART_LSR_OE)
403 			tty_insert_flip_char(&port->port, 0, TTY_OVERRUN);
404 
405 		*status = sdio_in(port, UART_LSR);
406 	} while ((*status & UART_LSR_DR) && (max_count-- > 0));
407 
408 	tty_flip_buffer_push(&port->port);
409 }
410 
sdio_uart_transmit_chars(struct sdio_uart_port * port)411 static void sdio_uart_transmit_chars(struct sdio_uart_port *port)
412 {
413 	struct kfifo *xmit = &port->xmit_fifo;
414 	int count;
415 	struct tty_struct *tty;
416 	u8 iobuf[16];
417 	int len;
418 
419 	if (port->x_char) {
420 		sdio_out(port, UART_TX, port->x_char);
421 		port->icount.tx++;
422 		port->x_char = 0;
423 		return;
424 	}
425 
426 	tty = tty_port_tty_get(&port->port);
427 
428 	if (tty == NULL || !kfifo_len(xmit) ||
429 				tty->flow.stopped || tty->hw_stopped) {
430 		sdio_uart_stop_tx(port);
431 		tty_kref_put(tty);
432 		return;
433 	}
434 
435 	len = kfifo_out_locked(xmit, iobuf, 16, &port->write_lock);
436 	for (count = 0; count < len; count++) {
437 		sdio_out(port, UART_TX, iobuf[count]);
438 		port->icount.tx++;
439 	}
440 
441 	len = kfifo_len(xmit);
442 	if (len < WAKEUP_CHARS) {
443 		tty_wakeup(tty);
444 		if (len == 0)
445 			sdio_uart_stop_tx(port);
446 	}
447 	tty_kref_put(tty);
448 }
449 
sdio_uart_check_modem_status(struct sdio_uart_port * port)450 static void sdio_uart_check_modem_status(struct sdio_uart_port *port)
451 {
452 	int status;
453 	struct tty_struct *tty;
454 
455 	status = sdio_in(port, UART_MSR);
456 
457 	if ((status & UART_MSR_ANY_DELTA) == 0)
458 		return;
459 
460 	if (status & UART_MSR_TERI)
461 		port->icount.rng++;
462 	if (status & UART_MSR_DDSR)
463 		port->icount.dsr++;
464 	if (status & UART_MSR_DDCD) {
465 		port->icount.dcd++;
466 		/* DCD raise - wake for open */
467 		if (status & UART_MSR_DCD)
468 			wake_up_interruptible(&port->port.open_wait);
469 		else {
470 			/* DCD drop - hang up if tty attached */
471 			tty_port_tty_hangup(&port->port, false);
472 		}
473 	}
474 	if (status & UART_MSR_DCTS) {
475 		port->icount.cts++;
476 		tty = tty_port_tty_get(&port->port);
477 		if (tty && C_CRTSCTS(tty)) {
478 			int cts = (status & UART_MSR_CTS);
479 			if (tty->hw_stopped) {
480 				if (cts) {
481 					tty->hw_stopped = false;
482 					sdio_uart_start_tx(port);
483 					tty_wakeup(tty);
484 				}
485 			} else {
486 				if (!cts) {
487 					tty->hw_stopped = true;
488 					sdio_uart_stop_tx(port);
489 				}
490 			}
491 		}
492 		tty_kref_put(tty);
493 	}
494 }
495 
496 /*
497  * This handles the interrupt from one port.
498  */
sdio_uart_irq(struct sdio_func * func)499 static void sdio_uart_irq(struct sdio_func *func)
500 {
501 	struct sdio_uart_port *port = sdio_get_drvdata(func);
502 	unsigned int iir, lsr;
503 
504 	/*
505 	 * In a few places sdio_uart_irq() is called directly instead of
506 	 * waiting for the actual interrupt to be raised and the SDIO IRQ
507 	 * thread scheduled in order to reduce latency.  However, some
508 	 * interaction with the tty core may end up calling us back
509 	 * (serial echo, flow control, etc.) through those same places
510 	 * causing undesirable effects.  Let's stop the recursion here.
511 	 */
512 	if (unlikely(port->in_sdio_uart_irq == current))
513 		return;
514 
515 	iir = sdio_in(port, UART_IIR);
516 	if (iir & UART_IIR_NO_INT)
517 		return;
518 
519 	port->in_sdio_uart_irq = current;
520 	lsr = sdio_in(port, UART_LSR);
521 	if (lsr & UART_LSR_DR)
522 		sdio_uart_receive_chars(port, &lsr);
523 	sdio_uart_check_modem_status(port);
524 	if (lsr & UART_LSR_THRE)
525 		sdio_uart_transmit_chars(port);
526 	port->in_sdio_uart_irq = NULL;
527 }
528 
uart_carrier_raised(struct tty_port * tport)529 static bool uart_carrier_raised(struct tty_port *tport)
530 {
531 	struct sdio_uart_port *port =
532 			container_of(tport, struct sdio_uart_port, port);
533 	unsigned int ret = sdio_uart_claim_func(port);
534 	if (ret)	/* Missing hardware shouldn't block for carrier */
535 		return 1;
536 	ret = sdio_uart_get_mctrl(port);
537 	sdio_uart_release_func(port);
538 
539 	return ret & TIOCM_CAR;
540 }
541 
542 /**
543  *	uart_dtr_rts		-	 port helper to set uart signals
544  *	@tport: tty port to be updated
545  *	@active: set to turn on DTR/RTS
546  *
547  *	Called by the tty port helpers when the modem signals need to be
548  *	adjusted during an open, close and hangup.
549  */
550 
uart_dtr_rts(struct tty_port * tport,bool active)551 static void uart_dtr_rts(struct tty_port *tport, bool active)
552 {
553 	struct sdio_uart_port *port =
554 			container_of(tport, struct sdio_uart_port, port);
555 	int ret = sdio_uart_claim_func(port);
556 	if (ret)
557 		return;
558 	if (!active)
559 		sdio_uart_clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
560 	else
561 		sdio_uart_set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
562 	sdio_uart_release_func(port);
563 }
564 
565 /**
566  *	sdio_uart_activate	-	start up hardware
567  *	@tport: tty port to activate
568  *	@tty: tty bound to this port
569  *
570  *	Activate a tty port. The port locking guarantees us this will be
571  *	run exactly once per set of opens, and if successful will see the
572  *	shutdown method run exactly once to match. Start up and shutdown are
573  *	protected from each other by the internal locking and will not run
574  *	at the same time even during a hangup event.
575  *
576  *	If we successfully start up the port we take an extra kref as we
577  *	will keep it around until shutdown when the kref is dropped.
578  */
579 
sdio_uart_activate(struct tty_port * tport,struct tty_struct * tty)580 static int sdio_uart_activate(struct tty_port *tport, struct tty_struct *tty)
581 {
582 	struct sdio_uart_port *port =
583 			container_of(tport, struct sdio_uart_port, port);
584 	int ret;
585 
586 	/*
587 	 * Set the TTY IO error marker - we will only clear this
588 	 * once we have successfully opened the port.
589 	 */
590 	set_bit(TTY_IO_ERROR, &tty->flags);
591 
592 	kfifo_reset(&port->xmit_fifo);
593 
594 	ret = sdio_uart_claim_func(port);
595 	if (ret)
596 		return ret;
597 	ret = sdio_enable_func(port->func);
598 	if (ret)
599 		goto err1;
600 	ret = sdio_claim_irq(port->func, sdio_uart_irq);
601 	if (ret)
602 		goto err2;
603 
604 	/*
605 	 * Clear the FIFO buffers and disable them.
606 	 * (they will be reenabled in sdio_change_speed())
607 	 */
608 	sdio_out(port, UART_FCR, UART_FCR_ENABLE_FIFO);
609 	sdio_out(port, UART_FCR, UART_FCR_ENABLE_FIFO |
610 		       UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
611 	sdio_out(port, UART_FCR, 0);
612 
613 	/*
614 	 * Clear the interrupt registers.
615 	 */
616 	(void) sdio_in(port, UART_LSR);
617 	(void) sdio_in(port, UART_RX);
618 	(void) sdio_in(port, UART_IIR);
619 	(void) sdio_in(port, UART_MSR);
620 
621 	/*
622 	 * Now, initialize the UART
623 	 */
624 	sdio_out(port, UART_LCR, UART_LCR_WLEN8);
625 
626 	port->ier = UART_IER_RLSI|UART_IER_RDI|UART_IER_RTOIE|UART_IER_UUE;
627 	port->mctrl = TIOCM_OUT2;
628 
629 	sdio_uart_change_speed(port, &tty->termios, NULL);
630 
631 	if (C_BAUD(tty))
632 		sdio_uart_set_mctrl(port, TIOCM_RTS | TIOCM_DTR);
633 
634 	if (C_CRTSCTS(tty))
635 		if (!(sdio_uart_get_mctrl(port) & TIOCM_CTS))
636 			tty->hw_stopped = true;
637 
638 	clear_bit(TTY_IO_ERROR, &tty->flags);
639 
640 	/* Kick the IRQ handler once while we're still holding the host lock */
641 	sdio_uart_irq(port->func);
642 
643 	sdio_uart_release_func(port);
644 	return 0;
645 
646 err2:
647 	sdio_disable_func(port->func);
648 err1:
649 	sdio_uart_release_func(port);
650 	return ret;
651 }
652 
653 /**
654  *	sdio_uart_shutdown	-	stop hardware
655  *	@tport: tty port to shut down
656  *
657  *	Deactivate a tty port. The port locking guarantees us this will be
658  *	run only if a successful matching activate already ran. The two are
659  *	protected from each other by the internal locking and will not run
660  *	at the same time even during a hangup event.
661  */
662 
sdio_uart_shutdown(struct tty_port * tport)663 static void sdio_uart_shutdown(struct tty_port *tport)
664 {
665 	struct sdio_uart_port *port =
666 			container_of(tport, struct sdio_uart_port, port);
667 	int ret;
668 
669 	ret = sdio_uart_claim_func(port);
670 	if (ret)
671 		return;
672 
673 	sdio_uart_stop_rx(port);
674 
675 	/* Disable interrupts from this port */
676 	sdio_release_irq(port->func);
677 	port->ier = 0;
678 	sdio_out(port, UART_IER, 0);
679 
680 	sdio_uart_clear_mctrl(port, TIOCM_OUT2);
681 
682 	/* Disable break condition and FIFOs. */
683 	port->lcr &= ~UART_LCR_SBC;
684 	sdio_out(port, UART_LCR, port->lcr);
685 	sdio_out(port, UART_FCR, UART_FCR_ENABLE_FIFO |
686 				 UART_FCR_CLEAR_RCVR |
687 				 UART_FCR_CLEAR_XMIT);
688 	sdio_out(port, UART_FCR, 0);
689 
690 	sdio_disable_func(port->func);
691 
692 	sdio_uart_release_func(port);
693 }
694 
sdio_uart_port_destroy(struct tty_port * tport)695 static void sdio_uart_port_destroy(struct tty_port *tport)
696 {
697 	struct sdio_uart_port *port =
698 		container_of(tport, struct sdio_uart_port, port);
699 	kfifo_free(&port->xmit_fifo);
700 	kfree(port);
701 }
702 
703 /**
704  *	sdio_uart_install	-	install method
705  *	@driver: the driver in use (sdio_uart in our case)
706  *	@tty: the tty being bound
707  *
708  *	Look up and bind the tty and the driver together. Initialize
709  *	any needed private data (in our case the termios)
710  */
711 
sdio_uart_install(struct tty_driver * driver,struct tty_struct * tty)712 static int sdio_uart_install(struct tty_driver *driver, struct tty_struct *tty)
713 {
714 	int idx = tty->index;
715 	struct sdio_uart_port *port = sdio_uart_port_get(idx);
716 	int ret = tty_standard_install(driver, tty);
717 
718 	if (ret == 0)
719 		/* This is the ref sdio_uart_port get provided */
720 		tty->driver_data = port;
721 	else
722 		sdio_uart_port_put(port);
723 	return ret;
724 }
725 
726 /**
727  *	sdio_uart_cleanup	-	called on the last tty kref drop
728  *	@tty: the tty being destroyed
729  *
730  *	Called asynchronously when the last reference to the tty is dropped.
731  *	We cannot destroy the tty->driver_data port kref until this point
732  */
733 
sdio_uart_cleanup(struct tty_struct * tty)734 static void sdio_uart_cleanup(struct tty_struct *tty)
735 {
736 	struct sdio_uart_port *port = tty->driver_data;
737 	tty->driver_data = NULL;	/* Bug trap */
738 	sdio_uart_port_put(port);
739 }
740 
741 /*
742  *	Open/close/hangup is now entirely boilerplate
743  */
744 
sdio_uart_open(struct tty_struct * tty,struct file * filp)745 static int sdio_uart_open(struct tty_struct *tty, struct file *filp)
746 {
747 	struct sdio_uart_port *port = tty->driver_data;
748 	return tty_port_open(&port->port, tty, filp);
749 }
750 
sdio_uart_close(struct tty_struct * tty,struct file * filp)751 static void sdio_uart_close(struct tty_struct *tty, struct file * filp)
752 {
753 	struct sdio_uart_port *port = tty->driver_data;
754 	tty_port_close(&port->port, tty, filp);
755 }
756 
sdio_uart_hangup(struct tty_struct * tty)757 static void sdio_uart_hangup(struct tty_struct *tty)
758 {
759 	struct sdio_uart_port *port = tty->driver_data;
760 	tty_port_hangup(&port->port);
761 }
762 
sdio_uart_write(struct tty_struct * tty,const u8 * buf,size_t count)763 static ssize_t sdio_uart_write(struct tty_struct *tty, const u8 *buf,
764 			      size_t count)
765 {
766 	struct sdio_uart_port *port = tty->driver_data;
767 	int ret;
768 
769 	if (!port->func)
770 		return -ENODEV;
771 
772 	ret = kfifo_in_locked(&port->xmit_fifo, buf, count, &port->write_lock);
773 	if (!(port->ier & UART_IER_THRI)) {
774 		int err = sdio_uart_claim_func(port);
775 		if (!err) {
776 			sdio_uart_start_tx(port);
777 			sdio_uart_irq(port->func);
778 			sdio_uart_release_func(port);
779 		} else
780 			ret = err;
781 	}
782 
783 	return ret;
784 }
785 
sdio_uart_write_room(struct tty_struct * tty)786 static unsigned int sdio_uart_write_room(struct tty_struct *tty)
787 {
788 	struct sdio_uart_port *port = tty->driver_data;
789 	return FIFO_SIZE - kfifo_len(&port->xmit_fifo);
790 }
791 
sdio_uart_chars_in_buffer(struct tty_struct * tty)792 static unsigned int sdio_uart_chars_in_buffer(struct tty_struct *tty)
793 {
794 	struct sdio_uart_port *port = tty->driver_data;
795 	return kfifo_len(&port->xmit_fifo);
796 }
797 
sdio_uart_send_xchar(struct tty_struct * tty,char ch)798 static void sdio_uart_send_xchar(struct tty_struct *tty, char ch)
799 {
800 	struct sdio_uart_port *port = tty->driver_data;
801 
802 	port->x_char = ch;
803 	if (ch && !(port->ier & UART_IER_THRI)) {
804 		if (sdio_uart_claim_func(port) != 0)
805 			return;
806 		sdio_uart_start_tx(port);
807 		sdio_uart_irq(port->func);
808 		sdio_uart_release_func(port);
809 	}
810 }
811 
sdio_uart_throttle(struct tty_struct * tty)812 static void sdio_uart_throttle(struct tty_struct *tty)
813 {
814 	struct sdio_uart_port *port = tty->driver_data;
815 
816 	if (!I_IXOFF(tty) && !C_CRTSCTS(tty))
817 		return;
818 
819 	if (sdio_uart_claim_func(port) != 0)
820 		return;
821 
822 	if (I_IXOFF(tty)) {
823 		port->x_char = STOP_CHAR(tty);
824 		sdio_uart_start_tx(port);
825 	}
826 
827 	if (C_CRTSCTS(tty))
828 		sdio_uart_clear_mctrl(port, TIOCM_RTS);
829 
830 	sdio_uart_irq(port->func);
831 	sdio_uart_release_func(port);
832 }
833 
sdio_uart_unthrottle(struct tty_struct * tty)834 static void sdio_uart_unthrottle(struct tty_struct *tty)
835 {
836 	struct sdio_uart_port *port = tty->driver_data;
837 
838 	if (!I_IXOFF(tty) && !C_CRTSCTS(tty))
839 		return;
840 
841 	if (sdio_uart_claim_func(port) != 0)
842 		return;
843 
844 	if (I_IXOFF(tty)) {
845 		if (port->x_char) {
846 			port->x_char = 0;
847 		} else {
848 			port->x_char = START_CHAR(tty);
849 			sdio_uart_start_tx(port);
850 		}
851 	}
852 
853 	if (C_CRTSCTS(tty))
854 		sdio_uart_set_mctrl(port, TIOCM_RTS);
855 
856 	sdio_uart_irq(port->func);
857 	sdio_uart_release_func(port);
858 }
859 
sdio_uart_set_termios(struct tty_struct * tty,const struct ktermios * old_termios)860 static void sdio_uart_set_termios(struct tty_struct *tty,
861 				  const struct ktermios *old_termios)
862 {
863 	struct sdio_uart_port *port = tty->driver_data;
864 	unsigned int cflag = tty->termios.c_cflag;
865 
866 	if (sdio_uart_claim_func(port) != 0)
867 		return;
868 
869 	sdio_uart_change_speed(port, &tty->termios, old_termios);
870 
871 	/* Handle transition to B0 status */
872 	if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD))
873 		sdio_uart_clear_mctrl(port, TIOCM_RTS | TIOCM_DTR);
874 
875 	/* Handle transition away from B0 status */
876 	if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
877 		unsigned int mask = TIOCM_DTR;
878 		if (!(cflag & CRTSCTS) || !tty_throttled(tty))
879 			mask |= TIOCM_RTS;
880 		sdio_uart_set_mctrl(port, mask);
881 	}
882 
883 	/* Handle turning off CRTSCTS */
884 	if ((old_termios->c_cflag & CRTSCTS) && !(cflag & CRTSCTS)) {
885 		tty->hw_stopped = false;
886 		sdio_uart_start_tx(port);
887 	}
888 
889 	/* Handle turning on CRTSCTS */
890 	if (!(old_termios->c_cflag & CRTSCTS) && (cflag & CRTSCTS)) {
891 		if (!(sdio_uart_get_mctrl(port) & TIOCM_CTS)) {
892 			tty->hw_stopped = true;
893 			sdio_uart_stop_tx(port);
894 		}
895 	}
896 
897 	sdio_uart_release_func(port);
898 }
899 
sdio_uart_break_ctl(struct tty_struct * tty,int break_state)900 static int sdio_uart_break_ctl(struct tty_struct *tty, int break_state)
901 {
902 	struct sdio_uart_port *port = tty->driver_data;
903 	int result;
904 
905 	result = sdio_uart_claim_func(port);
906 	if (result != 0)
907 		return result;
908 
909 	if (break_state == -1)
910 		port->lcr |= UART_LCR_SBC;
911 	else
912 		port->lcr &= ~UART_LCR_SBC;
913 	sdio_out(port, UART_LCR, port->lcr);
914 
915 	sdio_uart_release_func(port);
916 	return 0;
917 }
918 
sdio_uart_tiocmget(struct tty_struct * tty)919 static int sdio_uart_tiocmget(struct tty_struct *tty)
920 {
921 	struct sdio_uart_port *port = tty->driver_data;
922 	int result;
923 
924 	result = sdio_uart_claim_func(port);
925 	if (!result) {
926 		result = port->mctrl | sdio_uart_get_mctrl(port);
927 		sdio_uart_release_func(port);
928 	}
929 
930 	return result;
931 }
932 
sdio_uart_tiocmset(struct tty_struct * tty,unsigned int set,unsigned int clear)933 static int sdio_uart_tiocmset(struct tty_struct *tty,
934 			      unsigned int set, unsigned int clear)
935 {
936 	struct sdio_uart_port *port = tty->driver_data;
937 	int result;
938 
939 	result = sdio_uart_claim_func(port);
940 	if (!result) {
941 		sdio_uart_update_mctrl(port, set, clear);
942 		sdio_uart_release_func(port);
943 	}
944 
945 	return result;
946 }
947 
sdio_uart_proc_show(struct seq_file * m,void * v)948 static int sdio_uart_proc_show(struct seq_file *m, void *v)
949 {
950 	int i;
951 
952 	seq_printf(m, "serinfo:1.0 driver%s%s revision:%s\n",
953 		       "", "", "");
954 	for (i = 0; i < UART_NR; i++) {
955 		struct sdio_uart_port *port = sdio_uart_port_get(i);
956 		if (port) {
957 			seq_printf(m, "%d: uart:SDIO", i);
958 			if (capable(CAP_SYS_ADMIN)) {
959 				seq_printf(m, " tx:%d rx:%d",
960 					      port->icount.tx, port->icount.rx);
961 				if (port->icount.frame)
962 					seq_printf(m, " fe:%d",
963 						      port->icount.frame);
964 				if (port->icount.parity)
965 					seq_printf(m, " pe:%d",
966 						      port->icount.parity);
967 				if (port->icount.brk)
968 					seq_printf(m, " brk:%d",
969 						      port->icount.brk);
970 				if (port->icount.overrun)
971 					seq_printf(m, " oe:%d",
972 						      port->icount.overrun);
973 				if (port->icount.cts)
974 					seq_printf(m, " cts:%d",
975 						      port->icount.cts);
976 				if (port->icount.dsr)
977 					seq_printf(m, " dsr:%d",
978 						      port->icount.dsr);
979 				if (port->icount.rng)
980 					seq_printf(m, " rng:%d",
981 						      port->icount.rng);
982 				if (port->icount.dcd)
983 					seq_printf(m, " dcd:%d",
984 						      port->icount.dcd);
985 			}
986 			sdio_uart_port_put(port);
987 			seq_putc(m, '\n');
988 		}
989 	}
990 	return 0;
991 }
992 
993 static const struct tty_port_operations sdio_uart_port_ops = {
994 	.dtr_rts = uart_dtr_rts,
995 	.carrier_raised = uart_carrier_raised,
996 	.shutdown = sdio_uart_shutdown,
997 	.activate = sdio_uart_activate,
998 	.destruct = sdio_uart_port_destroy,
999 };
1000 
1001 static const struct tty_operations sdio_uart_ops = {
1002 	.open			= sdio_uart_open,
1003 	.close			= sdio_uart_close,
1004 	.write			= sdio_uart_write,
1005 	.write_room		= sdio_uart_write_room,
1006 	.chars_in_buffer	= sdio_uart_chars_in_buffer,
1007 	.send_xchar		= sdio_uart_send_xchar,
1008 	.throttle		= sdio_uart_throttle,
1009 	.unthrottle		= sdio_uart_unthrottle,
1010 	.set_termios		= sdio_uart_set_termios,
1011 	.hangup			= sdio_uart_hangup,
1012 	.break_ctl		= sdio_uart_break_ctl,
1013 	.tiocmget		= sdio_uart_tiocmget,
1014 	.tiocmset		= sdio_uart_tiocmset,
1015 	.install		= sdio_uart_install,
1016 	.cleanup		= sdio_uart_cleanup,
1017 	.proc_show		= sdio_uart_proc_show,
1018 };
1019 
1020 static struct tty_driver *sdio_uart_tty_driver;
1021 
sdio_uart_probe(struct sdio_func * func,const struct sdio_device_id * id)1022 static int sdio_uart_probe(struct sdio_func *func,
1023 			   const struct sdio_device_id *id)
1024 {
1025 	struct sdio_uart_port *port;
1026 	int ret;
1027 
1028 	port = kzalloc(sizeof(struct sdio_uart_port), GFP_KERNEL);
1029 	if (!port)
1030 		return -ENOMEM;
1031 
1032 	if (func->class == SDIO_CLASS_UART) {
1033 		pr_warn("%s: need info on UART class basic setup\n",
1034 			sdio_func_id(func));
1035 		kfree(port);
1036 		return -ENOSYS;
1037 	} else if (func->class == SDIO_CLASS_GPS) {
1038 		/*
1039 		 * We need tuple 0x91.  It contains SUBTPL_SIOREG
1040 		 * and SUBTPL_RCVCAPS.
1041 		 */
1042 		struct sdio_func_tuple *tpl;
1043 		for (tpl = func->tuples; tpl; tpl = tpl->next) {
1044 			if (tpl->code != 0x91)
1045 				continue;
1046 			if (tpl->size < 10)
1047 				continue;
1048 			if (tpl->data[1] == 0)  /* SUBTPL_SIOREG */
1049 				break;
1050 		}
1051 		if (!tpl) {
1052 			pr_warn("%s: can't find tuple 0x91 subtuple 0 (SUBTPL_SIOREG) for GPS class\n",
1053 				sdio_func_id(func));
1054 			kfree(port);
1055 			return -EINVAL;
1056 		}
1057 		pr_debug("%s: Register ID = 0x%02x, Exp ID = 0x%02x\n",
1058 		       sdio_func_id(func), tpl->data[2], tpl->data[3]);
1059 		port->regs_offset = (tpl->data[4] << 0) |
1060 				    (tpl->data[5] << 8) |
1061 				    (tpl->data[6] << 16);
1062 		pr_debug("%s: regs offset = 0x%x\n",
1063 		       sdio_func_id(func), port->regs_offset);
1064 		port->uartclk = tpl->data[7] * 115200;
1065 		if (port->uartclk == 0)
1066 			port->uartclk = 115200;
1067 		pr_debug("%s: clk %d baudcode %u 4800-div %u\n",
1068 		       sdio_func_id(func), port->uartclk,
1069 		       tpl->data[7], tpl->data[8] | (tpl->data[9] << 8));
1070 	} else {
1071 		kfree(port);
1072 		return -EINVAL;
1073 	}
1074 
1075 	port->func = func;
1076 	sdio_set_drvdata(func, port);
1077 	tty_port_init(&port->port);
1078 	port->port.ops = &sdio_uart_port_ops;
1079 
1080 	ret = sdio_uart_add_port(port);
1081 	if (ret) {
1082 		kfree(port);
1083 	} else {
1084 		struct device *dev;
1085 		dev = tty_port_register_device(&port->port,
1086 				sdio_uart_tty_driver, port->index, &func->dev);
1087 		if (IS_ERR(dev)) {
1088 			sdio_uart_port_remove(port);
1089 			ret = PTR_ERR(dev);
1090 		}
1091 	}
1092 
1093 	return ret;
1094 }
1095 
sdio_uart_remove(struct sdio_func * func)1096 static void sdio_uart_remove(struct sdio_func *func)
1097 {
1098 	struct sdio_uart_port *port = sdio_get_drvdata(func);
1099 
1100 	tty_unregister_device(sdio_uart_tty_driver, port->index);
1101 	sdio_uart_port_remove(port);
1102 }
1103 
1104 static const struct sdio_device_id sdio_uart_ids[] = {
1105 	{ SDIO_DEVICE_CLASS(SDIO_CLASS_UART)		},
1106 	{ SDIO_DEVICE_CLASS(SDIO_CLASS_GPS)		},
1107 	{ /* end: all zeroes */				},
1108 };
1109 
1110 MODULE_DEVICE_TABLE(sdio, sdio_uart_ids);
1111 
1112 static struct sdio_driver sdio_uart_driver = {
1113 	.probe		= sdio_uart_probe,
1114 	.remove		= sdio_uart_remove,
1115 	.name		= "sdio_uart",
1116 	.id_table	= sdio_uart_ids,
1117 };
1118 
sdio_uart_init(void)1119 static int __init sdio_uart_init(void)
1120 {
1121 	int ret;
1122 	struct tty_driver *tty_drv;
1123 
1124 	sdio_uart_tty_driver = tty_drv = tty_alloc_driver(UART_NR,
1125 			TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV);
1126 	if (IS_ERR(tty_drv))
1127 		return PTR_ERR(tty_drv);
1128 
1129 	tty_drv->driver_name = "sdio_uart";
1130 	tty_drv->name =   "ttySDIO";
1131 	tty_drv->major = 0;  /* dynamically allocated */
1132 	tty_drv->minor_start = 0;
1133 	tty_drv->type = TTY_DRIVER_TYPE_SERIAL;
1134 	tty_drv->subtype = SERIAL_TYPE_NORMAL;
1135 	tty_drv->init_termios = tty_std_termios;
1136 	tty_drv->init_termios.c_cflag = B4800 | CS8 | CREAD | HUPCL | CLOCAL;
1137 	tty_drv->init_termios.c_ispeed = 4800;
1138 	tty_drv->init_termios.c_ospeed = 4800;
1139 	tty_set_operations(tty_drv, &sdio_uart_ops);
1140 
1141 	ret = tty_register_driver(tty_drv);
1142 	if (ret)
1143 		goto err1;
1144 
1145 	ret = sdio_register_driver(&sdio_uart_driver);
1146 	if (ret)
1147 		goto err2;
1148 
1149 	return 0;
1150 
1151 err2:
1152 	tty_unregister_driver(tty_drv);
1153 err1:
1154 	tty_driver_kref_put(tty_drv);
1155 	return ret;
1156 }
1157 
sdio_uart_exit(void)1158 static void __exit sdio_uart_exit(void)
1159 {
1160 	sdio_unregister_driver(&sdio_uart_driver);
1161 	tty_unregister_driver(sdio_uart_tty_driver);
1162 	tty_driver_kref_put(sdio_uart_tty_driver);
1163 }
1164 
1165 module_init(sdio_uart_init);
1166 module_exit(sdio_uart_exit);
1167 
1168 MODULE_AUTHOR("Nicolas Pitre");
1169 MODULE_LICENSE("GPL");
1170