xref: /openbmc/linux/drivers/tty/serial/apbuart.c (revision 05bcf503) 
1 /*
2  *  Driver for GRLIB serial ports (APBUART)
3  *
4  *  Based on linux/drivers/serial/amba.c
5  *
6  *  Copyright (C) 2000 Deep Blue Solutions Ltd.
7  *  Copyright (C) 2003 Konrad Eisele <eiselekd@web.de>
8  *  Copyright (C) 2006 Daniel Hellstrom <daniel@gaisler.com>, Aeroflex Gaisler AB
9  *  Copyright (C) 2008 Gilead Kutnick <kutnickg@zin-tech.com>
10  *  Copyright (C) 2009 Kristoffer Glembo <kristoffer@gaisler.com>, Aeroflex Gaisler AB
11  */
12 
13 #if defined(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
14 #define SUPPORT_SYSRQ
15 #endif
16 
17 #include <linux/module.h>
18 #include <linux/tty.h>
19 #include <linux/tty_flip.h>
20 #include <linux/ioport.h>
21 #include <linux/init.h>
22 #include <linux/serial.h>
23 #include <linux/console.h>
24 #include <linux/sysrq.h>
25 #include <linux/kthread.h>
26 #include <linux/device.h>
27 #include <linux/of.h>
28 #include <linux/of_device.h>
29 #include <linux/of_platform.h>
30 #include <linux/of_irq.h>
31 #include <linux/platform_device.h>
32 #include <linux/io.h>
33 #include <linux/serial_core.h>
34 #include <asm/irq.h>
35 
36 #include "apbuart.h"
37 
38 #define SERIAL_APBUART_MAJOR	TTY_MAJOR
39 #define SERIAL_APBUART_MINOR	64
40 #define UART_DUMMY_RSR_RX	0x8000	/* for ignore all read */
41 
42 static void apbuart_tx_chars(struct uart_port *port);
43 
44 static void apbuart_stop_tx(struct uart_port *port)
45 {
46 	unsigned int cr;
47 
48 	cr = UART_GET_CTRL(port);
49 	cr &= ~UART_CTRL_TI;
50 	UART_PUT_CTRL(port, cr);
51 }
52 
53 static void apbuart_start_tx(struct uart_port *port)
54 {
55 	unsigned int cr;
56 
57 	cr = UART_GET_CTRL(port);
58 	cr |= UART_CTRL_TI;
59 	UART_PUT_CTRL(port, cr);
60 
61 	if (UART_GET_STATUS(port) & UART_STATUS_THE)
62 		apbuart_tx_chars(port);
63 }
64 
65 static void apbuart_stop_rx(struct uart_port *port)
66 {
67 	unsigned int cr;
68 
69 	cr = UART_GET_CTRL(port);
70 	cr &= ~(UART_CTRL_RI);
71 	UART_PUT_CTRL(port, cr);
72 }
73 
74 static void apbuart_enable_ms(struct uart_port *port)
75 {
76 	/* No modem status change interrupts for APBUART */
77 }
78 
79 static void apbuart_rx_chars(struct uart_port *port)
80 {
81 	struct tty_struct *tty = port->state->port.tty;
82 	unsigned int status, ch, rsr, flag;
83 	unsigned int max_chars = port->fifosize;
84 
85 	status = UART_GET_STATUS(port);
86 
87 	while (UART_RX_DATA(status) && (max_chars--)) {
88 
89 		ch = UART_GET_CHAR(port);
90 		flag = TTY_NORMAL;
91 
92 		port->icount.rx++;
93 
94 		rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
95 		UART_PUT_STATUS(port, 0);
96 		if (rsr & UART_STATUS_ERR) {
97 
98 			if (rsr & UART_STATUS_BR) {
99 				rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
100 				port->icount.brk++;
101 				if (uart_handle_break(port))
102 					goto ignore_char;
103 			} else if (rsr & UART_STATUS_PE) {
104 				port->icount.parity++;
105 			} else if (rsr & UART_STATUS_FE) {
106 				port->icount.frame++;
107 			}
108 			if (rsr & UART_STATUS_OE)
109 				port->icount.overrun++;
110 
111 			rsr &= port->read_status_mask;
112 
113 			if (rsr & UART_STATUS_PE)
114 				flag = TTY_PARITY;
115 			else if (rsr & UART_STATUS_FE)
116 				flag = TTY_FRAME;
117 		}
118 
119 		if (uart_handle_sysrq_char(port, ch))
120 			goto ignore_char;
121 
122 		uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
123 
124 
125 	      ignore_char:
126 		status = UART_GET_STATUS(port);
127 	}
128 
129 	tty_flip_buffer_push(tty);
130 }
131 
132 static void apbuart_tx_chars(struct uart_port *port)
133 {
134 	struct circ_buf *xmit = &port->state->xmit;
135 	int count;
136 
137 	if (port->x_char) {
138 		UART_PUT_CHAR(port, port->x_char);
139 		port->icount.tx++;
140 		port->x_char = 0;
141 		return;
142 	}
143 
144 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
145 		apbuart_stop_tx(port);
146 		return;
147 	}
148 
149 	/* amba: fill FIFO */
150 	count = port->fifosize >> 1;
151 	do {
152 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
153 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
154 		port->icount.tx++;
155 		if (uart_circ_empty(xmit))
156 			break;
157 	} while (--count > 0);
158 
159 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
160 		uart_write_wakeup(port);
161 
162 	if (uart_circ_empty(xmit))
163 		apbuart_stop_tx(port);
164 }
165 
166 static irqreturn_t apbuart_int(int irq, void *dev_id)
167 {
168 	struct uart_port *port = dev_id;
169 	unsigned int status;
170 
171 	spin_lock(&port->lock);
172 
173 	status = UART_GET_STATUS(port);
174 	if (status & UART_STATUS_DR)
175 		apbuart_rx_chars(port);
176 	if (status & UART_STATUS_THE)
177 		apbuart_tx_chars(port);
178 
179 	spin_unlock(&port->lock);
180 
181 	return IRQ_HANDLED;
182 }
183 
184 static unsigned int apbuart_tx_empty(struct uart_port *port)
185 {
186 	unsigned int status = UART_GET_STATUS(port);
187 	return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
188 }
189 
190 static unsigned int apbuart_get_mctrl(struct uart_port *port)
191 {
192 	/* The GRLIB APBUART handles flow control in hardware */
193 	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
194 }
195 
196 static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
197 {
198 	/* The GRLIB APBUART handles flow control in hardware */
199 }
200 
201 static void apbuart_break_ctl(struct uart_port *port, int break_state)
202 {
203 	/* We don't support sending break */
204 }
205 
206 static int apbuart_startup(struct uart_port *port)
207 {
208 	int retval;
209 	unsigned int cr;
210 
211 	/* Allocate the IRQ */
212 	retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
213 	if (retval)
214 		return retval;
215 
216 	/* Finally, enable interrupts */
217 	cr = UART_GET_CTRL(port);
218 	UART_PUT_CTRL(port,
219 		      cr | UART_CTRL_RE | UART_CTRL_TE |
220 		      UART_CTRL_RI | UART_CTRL_TI);
221 
222 	return 0;
223 }
224 
225 static void apbuart_shutdown(struct uart_port *port)
226 {
227 	unsigned int cr;
228 
229 	/* disable all interrupts, disable the port */
230 	cr = UART_GET_CTRL(port);
231 	UART_PUT_CTRL(port,
232 		      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
233 			     UART_CTRL_RI | UART_CTRL_TI));
234 
235 	/* Free the interrupt */
236 	free_irq(port->irq, port);
237 }
238 
239 static void apbuart_set_termios(struct uart_port *port,
240 				struct ktermios *termios, struct ktermios *old)
241 {
242 	unsigned int cr;
243 	unsigned long flags;
244 	unsigned int baud, quot;
245 
246 	/* Ask the core to calculate the divisor for us. */
247 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
248 	if (baud == 0)
249 		panic("invalid baudrate %i\n", port->uartclk / 16);
250 
251 	/* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
252 	quot = (uart_get_divisor(port, baud)) * 2;
253 	cr = UART_GET_CTRL(port);
254 	cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
255 
256 	if (termios->c_cflag & PARENB) {
257 		cr |= UART_CTRL_PE;
258 		if ((termios->c_cflag & PARODD))
259 			cr |= UART_CTRL_PS;
260 	}
261 
262 	/* Enable flow control. */
263 	if (termios->c_cflag & CRTSCTS)
264 		cr |= UART_CTRL_FL;
265 
266 	spin_lock_irqsave(&port->lock, flags);
267 
268 	/* Update the per-port timeout. */
269 	uart_update_timeout(port, termios->c_cflag, baud);
270 
271 	port->read_status_mask = UART_STATUS_OE;
272 	if (termios->c_iflag & INPCK)
273 		port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
274 
275 	/* Characters to ignore */
276 	port->ignore_status_mask = 0;
277 	if (termios->c_iflag & IGNPAR)
278 		port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
279 
280 	/* Ignore all characters if CREAD is not set. */
281 	if ((termios->c_cflag & CREAD) == 0)
282 		port->ignore_status_mask |= UART_DUMMY_RSR_RX;
283 
284 	/* Set baud rate */
285 	quot -= 1;
286 	UART_PUT_SCAL(port, quot);
287 	UART_PUT_CTRL(port, cr);
288 
289 	spin_unlock_irqrestore(&port->lock, flags);
290 }
291 
292 static const char *apbuart_type(struct uart_port *port)
293 {
294 	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
295 }
296 
297 static void apbuart_release_port(struct uart_port *port)
298 {
299 	release_mem_region(port->mapbase, 0x100);
300 }
301 
302 static int apbuart_request_port(struct uart_port *port)
303 {
304 	return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
305 	    != NULL ? 0 : -EBUSY;
306 	return 0;
307 }
308 
309 /* Configure/autoconfigure the port */
310 static void apbuart_config_port(struct uart_port *port, int flags)
311 {
312 	if (flags & UART_CONFIG_TYPE) {
313 		port->type = PORT_APBUART;
314 		apbuart_request_port(port);
315 	}
316 }
317 
318 /* Verify the new serial_struct (for TIOCSSERIAL) */
319 static int apbuart_verify_port(struct uart_port *port,
320 			       struct serial_struct *ser)
321 {
322 	int ret = 0;
323 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
324 		ret = -EINVAL;
325 	if (ser->irq < 0 || ser->irq >= NR_IRQS)
326 		ret = -EINVAL;
327 	if (ser->baud_base < 9600)
328 		ret = -EINVAL;
329 	return ret;
330 }
331 
332 static struct uart_ops grlib_apbuart_ops = {
333 	.tx_empty = apbuart_tx_empty,
334 	.set_mctrl = apbuart_set_mctrl,
335 	.get_mctrl = apbuart_get_mctrl,
336 	.stop_tx = apbuart_stop_tx,
337 	.start_tx = apbuart_start_tx,
338 	.stop_rx = apbuart_stop_rx,
339 	.enable_ms = apbuart_enable_ms,
340 	.break_ctl = apbuart_break_ctl,
341 	.startup = apbuart_startup,
342 	.shutdown = apbuart_shutdown,
343 	.set_termios = apbuart_set_termios,
344 	.type = apbuart_type,
345 	.release_port = apbuart_release_port,
346 	.request_port = apbuart_request_port,
347 	.config_port = apbuart_config_port,
348 	.verify_port = apbuart_verify_port,
349 };
350 
351 static struct uart_port grlib_apbuart_ports[UART_NR];
352 static struct device_node *grlib_apbuart_nodes[UART_NR];
353 
354 static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
355 {
356 	int ctrl, loop = 0;
357 	int status;
358 	int fifosize;
359 	unsigned long flags;
360 
361 	ctrl = UART_GET_CTRL(port);
362 
363 	/*
364 	 * Enable the transceiver and wait for it to be ready to send data.
365 	 * Clear interrupts so that this process will not be externally
366 	 * interrupted in the middle (which can cause the transceiver to
367 	 * drain prematurely).
368 	 */
369 
370 	local_irq_save(flags);
371 
372 	UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
373 
374 	while (!UART_TX_READY(UART_GET_STATUS(port)))
375 		loop++;
376 
377 	/*
378 	 * Disable the transceiver so data isn't actually sent during the
379 	 * actual test.
380 	 */
381 
382 	UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
383 
384 	fifosize = 1;
385 	UART_PUT_CHAR(port, 0);
386 
387 	/*
388 	 * So long as transmitting a character increments the tranceivier FIFO
389 	 * length the FIFO must be at least that big. These bytes will
390 	 * automatically drain off of the FIFO.
391 	 */
392 
393 	status = UART_GET_STATUS(port);
394 	while (((status >> 20) & 0x3F) == fifosize) {
395 		fifosize++;
396 		UART_PUT_CHAR(port, 0);
397 		status = UART_GET_STATUS(port);
398 	}
399 
400 	fifosize--;
401 
402 	UART_PUT_CTRL(port, ctrl);
403 	local_irq_restore(flags);
404 
405 	if (fifosize == 0)
406 		fifosize = 1;
407 
408 	return fifosize;
409 }
410 
411 static void apbuart_flush_fifo(struct uart_port *port)
412 {
413 	int i;
414 
415 	for (i = 0; i < port->fifosize; i++)
416 		UART_GET_CHAR(port);
417 }
418 
419 
420 /* ======================================================================== */
421 /* Console driver, if enabled                                               */
422 /* ======================================================================== */
423 
424 #ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
425 
426 static void apbuart_console_putchar(struct uart_port *port, int ch)
427 {
428 	unsigned int status;
429 	do {
430 		status = UART_GET_STATUS(port);
431 	} while (!UART_TX_READY(status));
432 	UART_PUT_CHAR(port, ch);
433 }
434 
435 static void
436 apbuart_console_write(struct console *co, const char *s, unsigned int count)
437 {
438 	struct uart_port *port = &grlib_apbuart_ports[co->index];
439 	unsigned int status, old_cr, new_cr;
440 
441 	/* First save the CR then disable the interrupts */
442 	old_cr = UART_GET_CTRL(port);
443 	new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
444 	UART_PUT_CTRL(port, new_cr);
445 
446 	uart_console_write(port, s, count, apbuart_console_putchar);
447 
448 	/*
449 	 *      Finally, wait for transmitter to become empty
450 	 *      and restore the TCR
451 	 */
452 	do {
453 		status = UART_GET_STATUS(port);
454 	} while (!UART_TX_READY(status));
455 	UART_PUT_CTRL(port, old_cr);
456 }
457 
458 static void __init
459 apbuart_console_get_options(struct uart_port *port, int *baud,
460 			    int *parity, int *bits)
461 {
462 	if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
463 
464 		unsigned int quot, status;
465 		status = UART_GET_STATUS(port);
466 
467 		*parity = 'n';
468 		if (status & UART_CTRL_PE) {
469 			if ((status & UART_CTRL_PS) == 0)
470 				*parity = 'e';
471 			else
472 				*parity = 'o';
473 		}
474 
475 		*bits = 8;
476 		quot = UART_GET_SCAL(port) / 8;
477 		*baud = port->uartclk / (16 * (quot + 1));
478 	}
479 }
480 
481 static int __init apbuart_console_setup(struct console *co, char *options)
482 {
483 	struct uart_port *port;
484 	int baud = 38400;
485 	int bits = 8;
486 	int parity = 'n';
487 	int flow = 'n';
488 
489 	pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
490 		 co, co->index, options);
491 
492 	/*
493 	 * Check whether an invalid uart number has been specified, and
494 	 * if so, search for the first available port that does have
495 	 * console support.
496 	 */
497 	if (co->index >= grlib_apbuart_port_nr)
498 		co->index = 0;
499 
500 	port = &grlib_apbuart_ports[co->index];
501 
502 	spin_lock_init(&port->lock);
503 
504 	if (options)
505 		uart_parse_options(options, &baud, &parity, &bits, &flow);
506 	else
507 		apbuart_console_get_options(port, &baud, &parity, &bits);
508 
509 	return uart_set_options(port, co, baud, parity, bits, flow);
510 }
511 
512 static struct uart_driver grlib_apbuart_driver;
513 
514 static struct console grlib_apbuart_console = {
515 	.name = "ttyS",
516 	.write = apbuart_console_write,
517 	.device = uart_console_device,
518 	.setup = apbuart_console_setup,
519 	.flags = CON_PRINTBUFFER,
520 	.index = -1,
521 	.data = &grlib_apbuart_driver,
522 };
523 
524 
525 static int grlib_apbuart_configure(void);
526 
527 static int __init apbuart_console_init(void)
528 {
529 	if (grlib_apbuart_configure())
530 		return -ENODEV;
531 	register_console(&grlib_apbuart_console);
532 	return 0;
533 }
534 
535 console_initcall(apbuart_console_init);
536 
537 #define APBUART_CONSOLE	(&grlib_apbuart_console)
538 #else
539 #define APBUART_CONSOLE	NULL
540 #endif
541 
542 static struct uart_driver grlib_apbuart_driver = {
543 	.owner = THIS_MODULE,
544 	.driver_name = "serial",
545 	.dev_name = "ttyS",
546 	.major = SERIAL_APBUART_MAJOR,
547 	.minor = SERIAL_APBUART_MINOR,
548 	.nr = UART_NR,
549 	.cons = APBUART_CONSOLE,
550 };
551 
552 
553 /* ======================================================================== */
554 /* OF Platform Driver                                                       */
555 /* ======================================================================== */
556 
557 static int __devinit apbuart_probe(struct platform_device *op)
558 {
559 	int i;
560 	struct uart_port *port = NULL;
561 
562 	for (i = 0; i < grlib_apbuart_port_nr; i++) {
563 		if (op->dev.of_node == grlib_apbuart_nodes[i])
564 			break;
565 	}
566 
567 	port = &grlib_apbuart_ports[i];
568 	port->dev = &op->dev;
569 	port->irq = op->archdata.irqs[0];
570 
571 	uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
572 
573 	apbuart_flush_fifo((struct uart_port *) port);
574 
575 	printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
576 	       (unsigned long long) port->mapbase, port->irq);
577 	return 0;
578 }
579 
580 static struct of_device_id apbuart_match[] = {
581 	{
582 	 .name = "GAISLER_APBUART",
583 	 },
584 	{
585 	 .name = "01_00c",
586 	 },
587 	{},
588 };
589 
590 static struct platform_driver grlib_apbuart_of_driver = {
591 	.probe = apbuart_probe,
592 	.driver = {
593 		.owner = THIS_MODULE,
594 		.name = "grlib-apbuart",
595 		.of_match_table = apbuart_match,
596 	},
597 };
598 
599 
600 static int __init grlib_apbuart_configure(void)
601 {
602 	struct device_node *np;
603 	int line = 0;
604 
605 	for_each_matching_node(np, apbuart_match) {
606 		const int *ampopts;
607 		const u32 *freq_hz;
608 		const struct amba_prom_registers *regs;
609 		struct uart_port *port;
610 		unsigned long addr;
611 
612 		ampopts = of_get_property(np, "ampopts", NULL);
613 		if (ampopts && (*ampopts == 0))
614 			continue; /* Ignore if used by another OS instance */
615 		regs = of_get_property(np, "reg", NULL);
616 		/* Frequency of APB Bus is frequency of UART */
617 		freq_hz = of_get_property(np, "freq", NULL);
618 
619 		if (!regs || !freq_hz || (*freq_hz == 0))
620 			continue;
621 
622 		grlib_apbuart_nodes[line] = np;
623 
624 		addr = regs->phys_addr;
625 
626 		port = &grlib_apbuart_ports[line];
627 
628 		port->mapbase = addr;
629 		port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
630 		port->irq = 0;
631 		port->iotype = UPIO_MEM;
632 		port->ops = &grlib_apbuart_ops;
633 		port->flags = UPF_BOOT_AUTOCONF;
634 		port->line = line;
635 		port->uartclk = *freq_hz;
636 		port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
637 		line++;
638 
639 		/* We support maximum UART_NR uarts ... */
640 		if (line == UART_NR)
641 			break;
642 	}
643 
644 	grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
645 	return line ? 0 : -ENODEV;
646 }
647 
648 static int __init grlib_apbuart_init(void)
649 {
650 	int ret;
651 
652 	/* Find all APBUARTS in device the tree and initialize their ports */
653 	ret = grlib_apbuart_configure();
654 	if (ret)
655 		return ret;
656 
657 	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
658 
659 	ret = uart_register_driver(&grlib_apbuart_driver);
660 
661 	if (ret) {
662 		printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
663 		       __FILE__, ret);
664 		return ret;
665 	}
666 
667 	ret = platform_driver_register(&grlib_apbuart_of_driver);
668 	if (ret) {
669 		printk(KERN_ERR
670 		       "%s: platform_driver_register failed (%i)\n",
671 		       __FILE__, ret);
672 		uart_unregister_driver(&grlib_apbuart_driver);
673 		return ret;
674 	}
675 
676 	return ret;
677 }
678 
679 static void __exit grlib_apbuart_exit(void)
680 {
681 	int i;
682 
683 	for (i = 0; i < grlib_apbuart_port_nr; i++)
684 		uart_remove_one_port(&grlib_apbuart_driver,
685 				     &grlib_apbuart_ports[i]);
686 
687 	uart_unregister_driver(&grlib_apbuart_driver);
688 	platform_driver_unregister(&grlib_apbuart_of_driver);
689 }
690 
691 module_init(grlib_apbuart_init);
692 module_exit(grlib_apbuart_exit);
693 
694 MODULE_AUTHOR("Aeroflex Gaisler AB");
695 MODULE_DESCRIPTION("GRLIB APBUART serial driver");
696 MODULE_VERSION("2.1");
697 MODULE_LICENSE("GPL");
698