xref: /openbmc/linux/drivers/tty/serial/apbuart.c (revision 97da55fc) 
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 	unsigned int status, ch, rsr, flag;
82 	unsigned int max_chars = port->fifosize;
83 
84 	status = UART_GET_STATUS(port);
85 
86 	while (UART_RX_DATA(status) && (max_chars--)) {
87 
88 		ch = UART_GET_CHAR(port);
89 		flag = TTY_NORMAL;
90 
91 		port->icount.rx++;
92 
93 		rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
94 		UART_PUT_STATUS(port, 0);
95 		if (rsr & UART_STATUS_ERR) {
96 
97 			if (rsr & UART_STATUS_BR) {
98 				rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
99 				port->icount.brk++;
100 				if (uart_handle_break(port))
101 					goto ignore_char;
102 			} else if (rsr & UART_STATUS_PE) {
103 				port->icount.parity++;
104 			} else if (rsr & UART_STATUS_FE) {
105 				port->icount.frame++;
106 			}
107 			if (rsr & UART_STATUS_OE)
108 				port->icount.overrun++;
109 
110 			rsr &= port->read_status_mask;
111 
112 			if (rsr & UART_STATUS_PE)
113 				flag = TTY_PARITY;
114 			else if (rsr & UART_STATUS_FE)
115 				flag = TTY_FRAME;
116 		}
117 
118 		if (uart_handle_sysrq_char(port, ch))
119 			goto ignore_char;
120 
121 		uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
122 
123 
124 	      ignore_char:
125 		status = UART_GET_STATUS(port);
126 	}
127 
128 	tty_flip_buffer_push(&port->state->port);
129 }
130 
131 static void apbuart_tx_chars(struct uart_port *port)
132 {
133 	struct circ_buf *xmit = &port->state->xmit;
134 	int count;
135 
136 	if (port->x_char) {
137 		UART_PUT_CHAR(port, port->x_char);
138 		port->icount.tx++;
139 		port->x_char = 0;
140 		return;
141 	}
142 
143 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
144 		apbuart_stop_tx(port);
145 		return;
146 	}
147 
148 	/* amba: fill FIFO */
149 	count = port->fifosize >> 1;
150 	do {
151 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
152 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
153 		port->icount.tx++;
154 		if (uart_circ_empty(xmit))
155 			break;
156 	} while (--count > 0);
157 
158 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
159 		uart_write_wakeup(port);
160 
161 	if (uart_circ_empty(xmit))
162 		apbuart_stop_tx(port);
163 }
164 
165 static irqreturn_t apbuart_int(int irq, void *dev_id)
166 {
167 	struct uart_port *port = dev_id;
168 	unsigned int status;
169 
170 	spin_lock(&port->lock);
171 
172 	status = UART_GET_STATUS(port);
173 	if (status & UART_STATUS_DR)
174 		apbuart_rx_chars(port);
175 	if (status & UART_STATUS_THE)
176 		apbuart_tx_chars(port);
177 
178 	spin_unlock(&port->lock);
179 
180 	return IRQ_HANDLED;
181 }
182 
183 static unsigned int apbuart_tx_empty(struct uart_port *port)
184 {
185 	unsigned int status = UART_GET_STATUS(port);
186 	return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
187 }
188 
189 static unsigned int apbuart_get_mctrl(struct uart_port *port)
190 {
191 	/* The GRLIB APBUART handles flow control in hardware */
192 	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
193 }
194 
195 static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
196 {
197 	/* The GRLIB APBUART handles flow control in hardware */
198 }
199 
200 static void apbuart_break_ctl(struct uart_port *port, int break_state)
201 {
202 	/* We don't support sending break */
203 }
204 
205 static int apbuart_startup(struct uart_port *port)
206 {
207 	int retval;
208 	unsigned int cr;
209 
210 	/* Allocate the IRQ */
211 	retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
212 	if (retval)
213 		return retval;
214 
215 	/* Finally, enable interrupts */
216 	cr = UART_GET_CTRL(port);
217 	UART_PUT_CTRL(port,
218 		      cr | UART_CTRL_RE | UART_CTRL_TE |
219 		      UART_CTRL_RI | UART_CTRL_TI);
220 
221 	return 0;
222 }
223 
224 static void apbuart_shutdown(struct uart_port *port)
225 {
226 	unsigned int cr;
227 
228 	/* disable all interrupts, disable the port */
229 	cr = UART_GET_CTRL(port);
230 	UART_PUT_CTRL(port,
231 		      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
232 			     UART_CTRL_RI | UART_CTRL_TI));
233 
234 	/* Free the interrupt */
235 	free_irq(port->irq, port);
236 }
237 
238 static void apbuart_set_termios(struct uart_port *port,
239 				struct ktermios *termios, struct ktermios *old)
240 {
241 	unsigned int cr;
242 	unsigned long flags;
243 	unsigned int baud, quot;
244 
245 	/* Ask the core to calculate the divisor for us. */
246 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
247 	if (baud == 0)
248 		panic("invalid baudrate %i\n", port->uartclk / 16);
249 
250 	/* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
251 	quot = (uart_get_divisor(port, baud)) * 2;
252 	cr = UART_GET_CTRL(port);
253 	cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
254 
255 	if (termios->c_cflag & PARENB) {
256 		cr |= UART_CTRL_PE;
257 		if ((termios->c_cflag & PARODD))
258 			cr |= UART_CTRL_PS;
259 	}
260 
261 	/* Enable flow control. */
262 	if (termios->c_cflag & CRTSCTS)
263 		cr |= UART_CTRL_FL;
264 
265 	spin_lock_irqsave(&port->lock, flags);
266 
267 	/* Update the per-port timeout. */
268 	uart_update_timeout(port, termios->c_cflag, baud);
269 
270 	port->read_status_mask = UART_STATUS_OE;
271 	if (termios->c_iflag & INPCK)
272 		port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
273 
274 	/* Characters to ignore */
275 	port->ignore_status_mask = 0;
276 	if (termios->c_iflag & IGNPAR)
277 		port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
278 
279 	/* Ignore all characters if CREAD is not set. */
280 	if ((termios->c_cflag & CREAD) == 0)
281 		port->ignore_status_mask |= UART_DUMMY_RSR_RX;
282 
283 	/* Set baud rate */
284 	quot -= 1;
285 	UART_PUT_SCAL(port, quot);
286 	UART_PUT_CTRL(port, cr);
287 
288 	spin_unlock_irqrestore(&port->lock, flags);
289 }
290 
291 static const char *apbuart_type(struct uart_port *port)
292 {
293 	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
294 }
295 
296 static void apbuart_release_port(struct uart_port *port)
297 {
298 	release_mem_region(port->mapbase, 0x100);
299 }
300 
301 static int apbuart_request_port(struct uart_port *port)
302 {
303 	return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
304 	    != NULL ? 0 : -EBUSY;
305 	return 0;
306 }
307 
308 /* Configure/autoconfigure the port */
309 static void apbuart_config_port(struct uart_port *port, int flags)
310 {
311 	if (flags & UART_CONFIG_TYPE) {
312 		port->type = PORT_APBUART;
313 		apbuart_request_port(port);
314 	}
315 }
316 
317 /* Verify the new serial_struct (for TIOCSSERIAL) */
318 static int apbuart_verify_port(struct uart_port *port,
319 			       struct serial_struct *ser)
320 {
321 	int ret = 0;
322 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
323 		ret = -EINVAL;
324 	if (ser->irq < 0 || ser->irq >= NR_IRQS)
325 		ret = -EINVAL;
326 	if (ser->baud_base < 9600)
327 		ret = -EINVAL;
328 	return ret;
329 }
330 
331 static struct uart_ops grlib_apbuart_ops = {
332 	.tx_empty = apbuart_tx_empty,
333 	.set_mctrl = apbuart_set_mctrl,
334 	.get_mctrl = apbuart_get_mctrl,
335 	.stop_tx = apbuart_stop_tx,
336 	.start_tx = apbuart_start_tx,
337 	.stop_rx = apbuart_stop_rx,
338 	.enable_ms = apbuart_enable_ms,
339 	.break_ctl = apbuart_break_ctl,
340 	.startup = apbuart_startup,
341 	.shutdown = apbuart_shutdown,
342 	.set_termios = apbuart_set_termios,
343 	.type = apbuart_type,
344 	.release_port = apbuart_release_port,
345 	.request_port = apbuart_request_port,
346 	.config_port = apbuart_config_port,
347 	.verify_port = apbuart_verify_port,
348 };
349 
350 static struct uart_port grlib_apbuart_ports[UART_NR];
351 static struct device_node *grlib_apbuart_nodes[UART_NR];
352 
353 static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
354 {
355 	int ctrl, loop = 0;
356 	int status;
357 	int fifosize;
358 	unsigned long flags;
359 
360 	ctrl = UART_GET_CTRL(port);
361 
362 	/*
363 	 * Enable the transceiver and wait for it to be ready to send data.
364 	 * Clear interrupts so that this process will not be externally
365 	 * interrupted in the middle (which can cause the transceiver to
366 	 * drain prematurely).
367 	 */
368 
369 	local_irq_save(flags);
370 
371 	UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
372 
373 	while (!UART_TX_READY(UART_GET_STATUS(port)))
374 		loop++;
375 
376 	/*
377 	 * Disable the transceiver so data isn't actually sent during the
378 	 * actual test.
379 	 */
380 
381 	UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
382 
383 	fifosize = 1;
384 	UART_PUT_CHAR(port, 0);
385 
386 	/*
387 	 * So long as transmitting a character increments the tranceivier FIFO
388 	 * length the FIFO must be at least that big. These bytes will
389 	 * automatically drain off of the FIFO.
390 	 */
391 
392 	status = UART_GET_STATUS(port);
393 	while (((status >> 20) & 0x3F) == fifosize) {
394 		fifosize++;
395 		UART_PUT_CHAR(port, 0);
396 		status = UART_GET_STATUS(port);
397 	}
398 
399 	fifosize--;
400 
401 	UART_PUT_CTRL(port, ctrl);
402 	local_irq_restore(flags);
403 
404 	if (fifosize == 0)
405 		fifosize = 1;
406 
407 	return fifosize;
408 }
409 
410 static void apbuart_flush_fifo(struct uart_port *port)
411 {
412 	int i;
413 
414 	for (i = 0; i < port->fifosize; i++)
415 		UART_GET_CHAR(port);
416 }
417 
418 
419 /* ======================================================================== */
420 /* Console driver, if enabled                                               */
421 /* ======================================================================== */
422 
423 #ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
424 
425 static void apbuart_console_putchar(struct uart_port *port, int ch)
426 {
427 	unsigned int status;
428 	do {
429 		status = UART_GET_STATUS(port);
430 	} while (!UART_TX_READY(status));
431 	UART_PUT_CHAR(port, ch);
432 }
433 
434 static void
435 apbuart_console_write(struct console *co, const char *s, unsigned int count)
436 {
437 	struct uart_port *port = &grlib_apbuart_ports[co->index];
438 	unsigned int status, old_cr, new_cr;
439 
440 	/* First save the CR then disable the interrupts */
441 	old_cr = UART_GET_CTRL(port);
442 	new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
443 	UART_PUT_CTRL(port, new_cr);
444 
445 	uart_console_write(port, s, count, apbuart_console_putchar);
446 
447 	/*
448 	 *      Finally, wait for transmitter to become empty
449 	 *      and restore the TCR
450 	 */
451 	do {
452 		status = UART_GET_STATUS(port);
453 	} while (!UART_TX_READY(status));
454 	UART_PUT_CTRL(port, old_cr);
455 }
456 
457 static void __init
458 apbuart_console_get_options(struct uart_port *port, int *baud,
459 			    int *parity, int *bits)
460 {
461 	if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
462 
463 		unsigned int quot, status;
464 		status = UART_GET_STATUS(port);
465 
466 		*parity = 'n';
467 		if (status & UART_CTRL_PE) {
468 			if ((status & UART_CTRL_PS) == 0)
469 				*parity = 'e';
470 			else
471 				*parity = 'o';
472 		}
473 
474 		*bits = 8;
475 		quot = UART_GET_SCAL(port) / 8;
476 		*baud = port->uartclk / (16 * (quot + 1));
477 	}
478 }
479 
480 static int __init apbuart_console_setup(struct console *co, char *options)
481 {
482 	struct uart_port *port;
483 	int baud = 38400;
484 	int bits = 8;
485 	int parity = 'n';
486 	int flow = 'n';
487 
488 	pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
489 		 co, co->index, options);
490 
491 	/*
492 	 * Check whether an invalid uart number has been specified, and
493 	 * if so, search for the first available port that does have
494 	 * console support.
495 	 */
496 	if (co->index >= grlib_apbuart_port_nr)
497 		co->index = 0;
498 
499 	port = &grlib_apbuart_ports[co->index];
500 
501 	spin_lock_init(&port->lock);
502 
503 	if (options)
504 		uart_parse_options(options, &baud, &parity, &bits, &flow);
505 	else
506 		apbuart_console_get_options(port, &baud, &parity, &bits);
507 
508 	return uart_set_options(port, co, baud, parity, bits, flow);
509 }
510 
511 static struct uart_driver grlib_apbuart_driver;
512 
513 static struct console grlib_apbuart_console = {
514 	.name = "ttyS",
515 	.write = apbuart_console_write,
516 	.device = uart_console_device,
517 	.setup = apbuart_console_setup,
518 	.flags = CON_PRINTBUFFER,
519 	.index = -1,
520 	.data = &grlib_apbuart_driver,
521 };
522 
523 
524 static int grlib_apbuart_configure(void);
525 
526 static int __init apbuart_console_init(void)
527 {
528 	if (grlib_apbuart_configure())
529 		return -ENODEV;
530 	register_console(&grlib_apbuart_console);
531 	return 0;
532 }
533 
534 console_initcall(apbuart_console_init);
535 
536 #define APBUART_CONSOLE	(&grlib_apbuart_console)
537 #else
538 #define APBUART_CONSOLE	NULL
539 #endif
540 
541 static struct uart_driver grlib_apbuart_driver = {
542 	.owner = THIS_MODULE,
543 	.driver_name = "serial",
544 	.dev_name = "ttyS",
545 	.major = SERIAL_APBUART_MAJOR,
546 	.minor = SERIAL_APBUART_MINOR,
547 	.nr = UART_NR,
548 	.cons = APBUART_CONSOLE,
549 };
550 
551 
552 /* ======================================================================== */
553 /* OF Platform Driver                                                       */
554 /* ======================================================================== */
555 
556 static int apbuart_probe(struct platform_device *op)
557 {
558 	int i;
559 	struct uart_port *port = NULL;
560 
561 	for (i = 0; i < grlib_apbuart_port_nr; i++) {
562 		if (op->dev.of_node == grlib_apbuart_nodes[i])
563 			break;
564 	}
565 
566 	port = &grlib_apbuart_ports[i];
567 	port->dev = &op->dev;
568 	port->irq = op->archdata.irqs[0];
569 
570 	uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
571 
572 	apbuart_flush_fifo((struct uart_port *) port);
573 
574 	printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
575 	       (unsigned long long) port->mapbase, port->irq);
576 	return 0;
577 }
578 
579 static struct of_device_id apbuart_match[] = {
580 	{
581 	 .name = "GAISLER_APBUART",
582 	 },
583 	{
584 	 .name = "01_00c",
585 	 },
586 	{},
587 };
588 
589 static struct platform_driver grlib_apbuart_of_driver = {
590 	.probe = apbuart_probe,
591 	.driver = {
592 		.owner = THIS_MODULE,
593 		.name = "grlib-apbuart",
594 		.of_match_table = apbuart_match,
595 	},
596 };
597 
598 
599 static int __init grlib_apbuart_configure(void)
600 {
601 	struct device_node *np;
602 	int line = 0;
603 
604 	for_each_matching_node(np, apbuart_match) {
605 		const int *ampopts;
606 		const u32 *freq_hz;
607 		const struct amba_prom_registers *regs;
608 		struct uart_port *port;
609 		unsigned long addr;
610 
611 		ampopts = of_get_property(np, "ampopts", NULL);
612 		if (ampopts && (*ampopts == 0))
613 			continue; /* Ignore if used by another OS instance */
614 		regs = of_get_property(np, "reg", NULL);
615 		/* Frequency of APB Bus is frequency of UART */
616 		freq_hz = of_get_property(np, "freq", NULL);
617 
618 		if (!regs || !freq_hz || (*freq_hz == 0))
619 			continue;
620 
621 		grlib_apbuart_nodes[line] = np;
622 
623 		addr = regs->phys_addr;
624 
625 		port = &grlib_apbuart_ports[line];
626 
627 		port->mapbase = addr;
628 		port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
629 		port->irq = 0;
630 		port->iotype = UPIO_MEM;
631 		port->ops = &grlib_apbuart_ops;
632 		port->flags = UPF_BOOT_AUTOCONF;
633 		port->line = line;
634 		port->uartclk = *freq_hz;
635 		port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
636 		line++;
637 
638 		/* We support maximum UART_NR uarts ... */
639 		if (line == UART_NR)
640 			break;
641 	}
642 
643 	grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
644 	return line ? 0 : -ENODEV;
645 }
646 
647 static int __init grlib_apbuart_init(void)
648 {
649 	int ret;
650 
651 	/* Find all APBUARTS in device the tree and initialize their ports */
652 	ret = grlib_apbuart_configure();
653 	if (ret)
654 		return ret;
655 
656 	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
657 
658 	ret = uart_register_driver(&grlib_apbuart_driver);
659 
660 	if (ret) {
661 		printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
662 		       __FILE__, ret);
663 		return ret;
664 	}
665 
666 	ret = platform_driver_register(&grlib_apbuart_of_driver);
667 	if (ret) {
668 		printk(KERN_ERR
669 		       "%s: platform_driver_register failed (%i)\n",
670 		       __FILE__, ret);
671 		uart_unregister_driver(&grlib_apbuart_driver);
672 		return ret;
673 	}
674 
675 	return ret;
676 }
677 
678 static void __exit grlib_apbuart_exit(void)
679 {
680 	int i;
681 
682 	for (i = 0; i < grlib_apbuart_port_nr; i++)
683 		uart_remove_one_port(&grlib_apbuart_driver,
684 				     &grlib_apbuart_ports[i]);
685 
686 	uart_unregister_driver(&grlib_apbuart_driver);
687 	platform_driver_unregister(&grlib_apbuart_of_driver);
688 }
689 
690 module_init(grlib_apbuart_init);
691 module_exit(grlib_apbuart_exit);
692 
693 MODULE_AUTHOR("Aeroflex Gaisler AB");
694 MODULE_DESCRIPTION("GRLIB APBUART serial driver");
695 MODULE_VERSION("2.1");
696 MODULE_LICENSE("GPL");
697