xref: /openbmc/linux/drivers/tty/serial/apbuart.c (revision 089a49b6) 
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 	spin_unlock(&port->lock);
129 	tty_flip_buffer_push(&port->state->port);
130 	spin_lock(&port->lock);
131 }
132 
133 static void apbuart_tx_chars(struct uart_port *port)
134 {
135 	struct circ_buf *xmit = &port->state->xmit;
136 	int count;
137 
138 	if (port->x_char) {
139 		UART_PUT_CHAR(port, port->x_char);
140 		port->icount.tx++;
141 		port->x_char = 0;
142 		return;
143 	}
144 
145 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
146 		apbuart_stop_tx(port);
147 		return;
148 	}
149 
150 	/* amba: fill FIFO */
151 	count = port->fifosize >> 1;
152 	do {
153 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
154 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
155 		port->icount.tx++;
156 		if (uart_circ_empty(xmit))
157 			break;
158 	} while (--count > 0);
159 
160 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
161 		uart_write_wakeup(port);
162 
163 	if (uart_circ_empty(xmit))
164 		apbuart_stop_tx(port);
165 }
166 
167 static irqreturn_t apbuart_int(int irq, void *dev_id)
168 {
169 	struct uart_port *port = dev_id;
170 	unsigned int status;
171 
172 	spin_lock(&port->lock);
173 
174 	status = UART_GET_STATUS(port);
175 	if (status & UART_STATUS_DR)
176 		apbuart_rx_chars(port);
177 	if (status & UART_STATUS_THE)
178 		apbuart_tx_chars(port);
179 
180 	spin_unlock(&port->lock);
181 
182 	return IRQ_HANDLED;
183 }
184 
185 static unsigned int apbuart_tx_empty(struct uart_port *port)
186 {
187 	unsigned int status = UART_GET_STATUS(port);
188 	return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
189 }
190 
191 static unsigned int apbuart_get_mctrl(struct uart_port *port)
192 {
193 	/* The GRLIB APBUART handles flow control in hardware */
194 	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
195 }
196 
197 static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
198 {
199 	/* The GRLIB APBUART handles flow control in hardware */
200 }
201 
202 static void apbuart_break_ctl(struct uart_port *port, int break_state)
203 {
204 	/* We don't support sending break */
205 }
206 
207 static int apbuart_startup(struct uart_port *port)
208 {
209 	int retval;
210 	unsigned int cr;
211 
212 	/* Allocate the IRQ */
213 	retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
214 	if (retval)
215 		return retval;
216 
217 	/* Finally, enable interrupts */
218 	cr = UART_GET_CTRL(port);
219 	UART_PUT_CTRL(port,
220 		      cr | UART_CTRL_RE | UART_CTRL_TE |
221 		      UART_CTRL_RI | UART_CTRL_TI);
222 
223 	return 0;
224 }
225 
226 static void apbuart_shutdown(struct uart_port *port)
227 {
228 	unsigned int cr;
229 
230 	/* disable all interrupts, disable the port */
231 	cr = UART_GET_CTRL(port);
232 	UART_PUT_CTRL(port,
233 		      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
234 			     UART_CTRL_RI | UART_CTRL_TI));
235 
236 	/* Free the interrupt */
237 	free_irq(port->irq, port);
238 }
239 
240 static void apbuart_set_termios(struct uart_port *port,
241 				struct ktermios *termios, struct ktermios *old)
242 {
243 	unsigned int cr;
244 	unsigned long flags;
245 	unsigned int baud, quot;
246 
247 	/* Ask the core to calculate the divisor for us. */
248 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
249 	if (baud == 0)
250 		panic("invalid baudrate %i\n", port->uartclk / 16);
251 
252 	/* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
253 	quot = (uart_get_divisor(port, baud)) * 2;
254 	cr = UART_GET_CTRL(port);
255 	cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
256 
257 	if (termios->c_cflag & PARENB) {
258 		cr |= UART_CTRL_PE;
259 		if ((termios->c_cflag & PARODD))
260 			cr |= UART_CTRL_PS;
261 	}
262 
263 	/* Enable flow control. */
264 	if (termios->c_cflag & CRTSCTS)
265 		cr |= UART_CTRL_FL;
266 
267 	spin_lock_irqsave(&port->lock, flags);
268 
269 	/* Update the per-port timeout. */
270 	uart_update_timeout(port, termios->c_cflag, baud);
271 
272 	port->read_status_mask = UART_STATUS_OE;
273 	if (termios->c_iflag & INPCK)
274 		port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
275 
276 	/* Characters to ignore */
277 	port->ignore_status_mask = 0;
278 	if (termios->c_iflag & IGNPAR)
279 		port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
280 
281 	/* Ignore all characters if CREAD is not set. */
282 	if ((termios->c_cflag & CREAD) == 0)
283 		port->ignore_status_mask |= UART_DUMMY_RSR_RX;
284 
285 	/* Set baud rate */
286 	quot -= 1;
287 	UART_PUT_SCAL(port, quot);
288 	UART_PUT_CTRL(port, cr);
289 
290 	spin_unlock_irqrestore(&port->lock, flags);
291 }
292 
293 static const char *apbuart_type(struct uart_port *port)
294 {
295 	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
296 }
297 
298 static void apbuart_release_port(struct uart_port *port)
299 {
300 	release_mem_region(port->mapbase, 0x100);
301 }
302 
303 static int apbuart_request_port(struct uart_port *port)
304 {
305 	return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
306 	    != NULL ? 0 : -EBUSY;
307 	return 0;
308 }
309 
310 /* Configure/autoconfigure the port */
311 static void apbuart_config_port(struct uart_port *port, int flags)
312 {
313 	if (flags & UART_CONFIG_TYPE) {
314 		port->type = PORT_APBUART;
315 		apbuart_request_port(port);
316 	}
317 }
318 
319 /* Verify the new serial_struct (for TIOCSSERIAL) */
320 static int apbuart_verify_port(struct uart_port *port,
321 			       struct serial_struct *ser)
322 {
323 	int ret = 0;
324 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
325 		ret = -EINVAL;
326 	if (ser->irq < 0 || ser->irq >= NR_IRQS)
327 		ret = -EINVAL;
328 	if (ser->baud_base < 9600)
329 		ret = -EINVAL;
330 	return ret;
331 }
332 
333 static struct uart_ops grlib_apbuart_ops = {
334 	.tx_empty = apbuart_tx_empty,
335 	.set_mctrl = apbuart_set_mctrl,
336 	.get_mctrl = apbuart_get_mctrl,
337 	.stop_tx = apbuart_stop_tx,
338 	.start_tx = apbuart_start_tx,
339 	.stop_rx = apbuart_stop_rx,
340 	.enable_ms = apbuart_enable_ms,
341 	.break_ctl = apbuart_break_ctl,
342 	.startup = apbuart_startup,
343 	.shutdown = apbuart_shutdown,
344 	.set_termios = apbuart_set_termios,
345 	.type = apbuart_type,
346 	.release_port = apbuart_release_port,
347 	.request_port = apbuart_request_port,
348 	.config_port = apbuart_config_port,
349 	.verify_port = apbuart_verify_port,
350 };
351 
352 static struct uart_port grlib_apbuart_ports[UART_NR];
353 static struct device_node *grlib_apbuart_nodes[UART_NR];
354 
355 static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
356 {
357 	int ctrl, loop = 0;
358 	int status;
359 	int fifosize;
360 	unsigned long flags;
361 
362 	ctrl = UART_GET_CTRL(port);
363 
364 	/*
365 	 * Enable the transceiver and wait for it to be ready to send data.
366 	 * Clear interrupts so that this process will not be externally
367 	 * interrupted in the middle (which can cause the transceiver to
368 	 * drain prematurely).
369 	 */
370 
371 	local_irq_save(flags);
372 
373 	UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
374 
375 	while (!UART_TX_READY(UART_GET_STATUS(port)))
376 		loop++;
377 
378 	/*
379 	 * Disable the transceiver so data isn't actually sent during the
380 	 * actual test.
381 	 */
382 
383 	UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
384 
385 	fifosize = 1;
386 	UART_PUT_CHAR(port, 0);
387 
388 	/*
389 	 * So long as transmitting a character increments the tranceivier FIFO
390 	 * length the FIFO must be at least that big. These bytes will
391 	 * automatically drain off of the FIFO.
392 	 */
393 
394 	status = UART_GET_STATUS(port);
395 	while (((status >> 20) & 0x3F) == fifosize) {
396 		fifosize++;
397 		UART_PUT_CHAR(port, 0);
398 		status = UART_GET_STATUS(port);
399 	}
400 
401 	fifosize--;
402 
403 	UART_PUT_CTRL(port, ctrl);
404 	local_irq_restore(flags);
405 
406 	if (fifosize == 0)
407 		fifosize = 1;
408 
409 	return fifosize;
410 }
411 
412 static void apbuart_flush_fifo(struct uart_port *port)
413 {
414 	int i;
415 
416 	for (i = 0; i < port->fifosize; i++)
417 		UART_GET_CHAR(port);
418 }
419 
420 
421 /* ======================================================================== */
422 /* Console driver, if enabled                                               */
423 /* ======================================================================== */
424 
425 #ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
426 
427 static void apbuart_console_putchar(struct uart_port *port, int ch)
428 {
429 	unsigned int status;
430 	do {
431 		status = UART_GET_STATUS(port);
432 	} while (!UART_TX_READY(status));
433 	UART_PUT_CHAR(port, ch);
434 }
435 
436 static void
437 apbuart_console_write(struct console *co, const char *s, unsigned int count)
438 {
439 	struct uart_port *port = &grlib_apbuart_ports[co->index];
440 	unsigned int status, old_cr, new_cr;
441 
442 	/* First save the CR then disable the interrupts */
443 	old_cr = UART_GET_CTRL(port);
444 	new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
445 	UART_PUT_CTRL(port, new_cr);
446 
447 	uart_console_write(port, s, count, apbuart_console_putchar);
448 
449 	/*
450 	 *      Finally, wait for transmitter to become empty
451 	 *      and restore the TCR
452 	 */
453 	do {
454 		status = UART_GET_STATUS(port);
455 	} while (!UART_TX_READY(status));
456 	UART_PUT_CTRL(port, old_cr);
457 }
458 
459 static void __init
460 apbuart_console_get_options(struct uart_port *port, int *baud,
461 			    int *parity, int *bits)
462 {
463 	if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
464 
465 		unsigned int quot, status;
466 		status = UART_GET_STATUS(port);
467 
468 		*parity = 'n';
469 		if (status & UART_CTRL_PE) {
470 			if ((status & UART_CTRL_PS) == 0)
471 				*parity = 'e';
472 			else
473 				*parity = 'o';
474 		}
475 
476 		*bits = 8;
477 		quot = UART_GET_SCAL(port) / 8;
478 		*baud = port->uartclk / (16 * (quot + 1));
479 	}
480 }
481 
482 static int __init apbuart_console_setup(struct console *co, char *options)
483 {
484 	struct uart_port *port;
485 	int baud = 38400;
486 	int bits = 8;
487 	int parity = 'n';
488 	int flow = 'n';
489 
490 	pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
491 		 co, co->index, options);
492 
493 	/*
494 	 * Check whether an invalid uart number has been specified, and
495 	 * if so, search for the first available port that does have
496 	 * console support.
497 	 */
498 	if (co->index >= grlib_apbuart_port_nr)
499 		co->index = 0;
500 
501 	port = &grlib_apbuart_ports[co->index];
502 
503 	spin_lock_init(&port->lock);
504 
505 	if (options)
506 		uart_parse_options(options, &baud, &parity, &bits, &flow);
507 	else
508 		apbuart_console_get_options(port, &baud, &parity, &bits);
509 
510 	return uart_set_options(port, co, baud, parity, bits, flow);
511 }
512 
513 static struct uart_driver grlib_apbuart_driver;
514 
515 static struct console grlib_apbuart_console = {
516 	.name = "ttyS",
517 	.write = apbuart_console_write,
518 	.device = uart_console_device,
519 	.setup = apbuart_console_setup,
520 	.flags = CON_PRINTBUFFER,
521 	.index = -1,
522 	.data = &grlib_apbuart_driver,
523 };
524 
525 
526 static int grlib_apbuart_configure(void);
527 
528 static int __init apbuart_console_init(void)
529 {
530 	if (grlib_apbuart_configure())
531 		return -ENODEV;
532 	register_console(&grlib_apbuart_console);
533 	return 0;
534 }
535 
536 console_initcall(apbuart_console_init);
537 
538 #define APBUART_CONSOLE	(&grlib_apbuart_console)
539 #else
540 #define APBUART_CONSOLE	NULL
541 #endif
542 
543 static struct uart_driver grlib_apbuart_driver = {
544 	.owner = THIS_MODULE,
545 	.driver_name = "serial",
546 	.dev_name = "ttyS",
547 	.major = SERIAL_APBUART_MAJOR,
548 	.minor = SERIAL_APBUART_MINOR,
549 	.nr = UART_NR,
550 	.cons = APBUART_CONSOLE,
551 };
552 
553 
554 /* ======================================================================== */
555 /* OF Platform Driver                                                       */
556 /* ======================================================================== */
557 
558 static int apbuart_probe(struct platform_device *op)
559 {
560 	int i;
561 	struct uart_port *port = NULL;
562 
563 	for (i = 0; i < grlib_apbuart_port_nr; i++) {
564 		if (op->dev.of_node == grlib_apbuart_nodes[i])
565 			break;
566 	}
567 
568 	port = &grlib_apbuart_ports[i];
569 	port->dev = &op->dev;
570 	port->irq = op->archdata.irqs[0];
571 
572 	uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
573 
574 	apbuart_flush_fifo((struct uart_port *) port);
575 
576 	printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
577 	       (unsigned long long) port->mapbase, port->irq);
578 	return 0;
579 }
580 
581 static struct of_device_id apbuart_match[] = {
582 	{
583 	 .name = "GAISLER_APBUART",
584 	 },
585 	{
586 	 .name = "01_00c",
587 	 },
588 	{},
589 };
590 
591 static struct platform_driver grlib_apbuart_of_driver = {
592 	.probe = apbuart_probe,
593 	.driver = {
594 		.owner = THIS_MODULE,
595 		.name = "grlib-apbuart",
596 		.of_match_table = apbuart_match,
597 	},
598 };
599 
600 
601 static int __init grlib_apbuart_configure(void)
602 {
603 	struct device_node *np;
604 	int line = 0;
605 
606 	for_each_matching_node(np, apbuart_match) {
607 		const int *ampopts;
608 		const u32 *freq_hz;
609 		const struct amba_prom_registers *regs;
610 		struct uart_port *port;
611 		unsigned long addr;
612 
613 		ampopts = of_get_property(np, "ampopts", NULL);
614 		if (ampopts && (*ampopts == 0))
615 			continue; /* Ignore if used by another OS instance */
616 		regs = of_get_property(np, "reg", NULL);
617 		/* Frequency of APB Bus is frequency of UART */
618 		freq_hz = of_get_property(np, "freq", NULL);
619 
620 		if (!regs || !freq_hz || (*freq_hz == 0))
621 			continue;
622 
623 		grlib_apbuart_nodes[line] = np;
624 
625 		addr = regs->phys_addr;
626 
627 		port = &grlib_apbuart_ports[line];
628 
629 		port->mapbase = addr;
630 		port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
631 		port->irq = 0;
632 		port->iotype = UPIO_MEM;
633 		port->ops = &grlib_apbuart_ops;
634 		port->flags = UPF_BOOT_AUTOCONF;
635 		port->line = line;
636 		port->uartclk = *freq_hz;
637 		port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
638 		line++;
639 
640 		/* We support maximum UART_NR uarts ... */
641 		if (line == UART_NR)
642 			break;
643 	}
644 
645 	grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
646 	return line ? 0 : -ENODEV;
647 }
648 
649 static int __init grlib_apbuart_init(void)
650 {
651 	int ret;
652 
653 	/* Find all APBUARTS in device the tree and initialize their ports */
654 	ret = grlib_apbuart_configure();
655 	if (ret)
656 		return ret;
657 
658 	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
659 
660 	ret = uart_register_driver(&grlib_apbuart_driver);
661 
662 	if (ret) {
663 		printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
664 		       __FILE__, ret);
665 		return ret;
666 	}
667 
668 	ret = platform_driver_register(&grlib_apbuart_of_driver);
669 	if (ret) {
670 		printk(KERN_ERR
671 		       "%s: platform_driver_register failed (%i)\n",
672 		       __FILE__, ret);
673 		uart_unregister_driver(&grlib_apbuart_driver);
674 		return ret;
675 	}
676 
677 	return ret;
678 }
679 
680 static void __exit grlib_apbuart_exit(void)
681 {
682 	int i;
683 
684 	for (i = 0; i < grlib_apbuart_port_nr; i++)
685 		uart_remove_one_port(&grlib_apbuart_driver,
686 				     &grlib_apbuart_ports[i]);
687 
688 	uart_unregister_driver(&grlib_apbuart_driver);
689 	platform_driver_unregister(&grlib_apbuart_of_driver);
690 }
691 
692 module_init(grlib_apbuart_init);
693 module_exit(grlib_apbuart_exit);
694 
695 MODULE_AUTHOR("Aeroflex Gaisler AB");
696 MODULE_DESCRIPTION("GRLIB APBUART serial driver");
697 MODULE_VERSION("2.1");
698 MODULE_LICENSE("GPL");
699