xref: /openbmc/linux/drivers/tty/serial/apbuart.c (revision 799a545b) 
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_rx_chars(struct uart_port *port)
75 {
76 	unsigned int status, ch, rsr, flag;
77 	unsigned int max_chars = port->fifosize;
78 
79 	status = UART_GET_STATUS(port);
80 
81 	while (UART_RX_DATA(status) && (max_chars--)) {
82 
83 		ch = UART_GET_CHAR(port);
84 		flag = TTY_NORMAL;
85 
86 		port->icount.rx++;
87 
88 		rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
89 		UART_PUT_STATUS(port, 0);
90 		if (rsr & UART_STATUS_ERR) {
91 
92 			if (rsr & UART_STATUS_BR) {
93 				rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
94 				port->icount.brk++;
95 				if (uart_handle_break(port))
96 					goto ignore_char;
97 			} else if (rsr & UART_STATUS_PE) {
98 				port->icount.parity++;
99 			} else if (rsr & UART_STATUS_FE) {
100 				port->icount.frame++;
101 			}
102 			if (rsr & UART_STATUS_OE)
103 				port->icount.overrun++;
104 
105 			rsr &= port->read_status_mask;
106 
107 			if (rsr & UART_STATUS_PE)
108 				flag = TTY_PARITY;
109 			else if (rsr & UART_STATUS_FE)
110 				flag = TTY_FRAME;
111 		}
112 
113 		if (uart_handle_sysrq_char(port, ch))
114 			goto ignore_char;
115 
116 		uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
117 
118 
119 	      ignore_char:
120 		status = UART_GET_STATUS(port);
121 	}
122 
123 	spin_unlock(&port->lock);
124 	tty_flip_buffer_push(&port->state->port);
125 	spin_lock(&port->lock);
126 }
127 
128 static void apbuart_tx_chars(struct uart_port *port)
129 {
130 	struct circ_buf *xmit = &port->state->xmit;
131 	int count;
132 
133 	if (port->x_char) {
134 		UART_PUT_CHAR(port, port->x_char);
135 		port->icount.tx++;
136 		port->x_char = 0;
137 		return;
138 	}
139 
140 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
141 		apbuart_stop_tx(port);
142 		return;
143 	}
144 
145 	/* amba: fill FIFO */
146 	count = port->fifosize >> 1;
147 	do {
148 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
149 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
150 		port->icount.tx++;
151 		if (uart_circ_empty(xmit))
152 			break;
153 	} while (--count > 0);
154 
155 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
156 		uart_write_wakeup(port);
157 
158 	if (uart_circ_empty(xmit))
159 		apbuart_stop_tx(port);
160 }
161 
162 static irqreturn_t apbuart_int(int irq, void *dev_id)
163 {
164 	struct uart_port *port = dev_id;
165 	unsigned int status;
166 
167 	spin_lock(&port->lock);
168 
169 	status = UART_GET_STATUS(port);
170 	if (status & UART_STATUS_DR)
171 		apbuart_rx_chars(port);
172 	if (status & UART_STATUS_THE)
173 		apbuart_tx_chars(port);
174 
175 	spin_unlock(&port->lock);
176 
177 	return IRQ_HANDLED;
178 }
179 
180 static unsigned int apbuart_tx_empty(struct uart_port *port)
181 {
182 	unsigned int status = UART_GET_STATUS(port);
183 	return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
184 }
185 
186 static unsigned int apbuart_get_mctrl(struct uart_port *port)
187 {
188 	/* The GRLIB APBUART handles flow control in hardware */
189 	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
190 }
191 
192 static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
193 {
194 	/* The GRLIB APBUART handles flow control in hardware */
195 }
196 
197 static void apbuart_break_ctl(struct uart_port *port, int break_state)
198 {
199 	/* We don't support sending break */
200 }
201 
202 static int apbuart_startup(struct uart_port *port)
203 {
204 	int retval;
205 	unsigned int cr;
206 
207 	/* Allocate the IRQ */
208 	retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
209 	if (retval)
210 		return retval;
211 
212 	/* Finally, enable interrupts */
213 	cr = UART_GET_CTRL(port);
214 	UART_PUT_CTRL(port,
215 		      cr | UART_CTRL_RE | UART_CTRL_TE |
216 		      UART_CTRL_RI | UART_CTRL_TI);
217 
218 	return 0;
219 }
220 
221 static void apbuart_shutdown(struct uart_port *port)
222 {
223 	unsigned int cr;
224 
225 	/* disable all interrupts, disable the port */
226 	cr = UART_GET_CTRL(port);
227 	UART_PUT_CTRL(port,
228 		      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
229 			     UART_CTRL_RI | UART_CTRL_TI));
230 
231 	/* Free the interrupt */
232 	free_irq(port->irq, port);
233 }
234 
235 static void apbuart_set_termios(struct uart_port *port,
236 				struct ktermios *termios, struct ktermios *old)
237 {
238 	unsigned int cr;
239 	unsigned long flags;
240 	unsigned int baud, quot;
241 
242 	/* Ask the core to calculate the divisor for us. */
243 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
244 	if (baud == 0)
245 		panic("invalid baudrate %i\n", port->uartclk / 16);
246 
247 	/* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
248 	quot = (uart_get_divisor(port, baud)) * 2;
249 	cr = UART_GET_CTRL(port);
250 	cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
251 
252 	if (termios->c_cflag & PARENB) {
253 		cr |= UART_CTRL_PE;
254 		if ((termios->c_cflag & PARODD))
255 			cr |= UART_CTRL_PS;
256 	}
257 
258 	/* Enable flow control. */
259 	if (termios->c_cflag & CRTSCTS)
260 		cr |= UART_CTRL_FL;
261 
262 	spin_lock_irqsave(&port->lock, flags);
263 
264 	/* Update the per-port timeout. */
265 	uart_update_timeout(port, termios->c_cflag, baud);
266 
267 	port->read_status_mask = UART_STATUS_OE;
268 	if (termios->c_iflag & INPCK)
269 		port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
270 
271 	/* Characters to ignore */
272 	port->ignore_status_mask = 0;
273 	if (termios->c_iflag & IGNPAR)
274 		port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
275 
276 	/* Ignore all characters if CREAD is not set. */
277 	if ((termios->c_cflag & CREAD) == 0)
278 		port->ignore_status_mask |= UART_DUMMY_RSR_RX;
279 
280 	/* Set baud rate */
281 	quot -= 1;
282 	UART_PUT_SCAL(port, quot);
283 	UART_PUT_CTRL(port, cr);
284 
285 	spin_unlock_irqrestore(&port->lock, flags);
286 }
287 
288 static const char *apbuart_type(struct uart_port *port)
289 {
290 	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
291 }
292 
293 static void apbuart_release_port(struct uart_port *port)
294 {
295 	release_mem_region(port->mapbase, 0x100);
296 }
297 
298 static int apbuart_request_port(struct uart_port *port)
299 {
300 	return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
301 	    != NULL ? 0 : -EBUSY;
302 	return 0;
303 }
304 
305 /* Configure/autoconfigure the port */
306 static void apbuart_config_port(struct uart_port *port, int flags)
307 {
308 	if (flags & UART_CONFIG_TYPE) {
309 		port->type = PORT_APBUART;
310 		apbuart_request_port(port);
311 	}
312 }
313 
314 /* Verify the new serial_struct (for TIOCSSERIAL) */
315 static int apbuart_verify_port(struct uart_port *port,
316 			       struct serial_struct *ser)
317 {
318 	int ret = 0;
319 	if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
320 		ret = -EINVAL;
321 	if (ser->irq < 0 || ser->irq >= NR_IRQS)
322 		ret = -EINVAL;
323 	if (ser->baud_base < 9600)
324 		ret = -EINVAL;
325 	return ret;
326 }
327 
328 static struct uart_ops grlib_apbuart_ops = {
329 	.tx_empty = apbuart_tx_empty,
330 	.set_mctrl = apbuart_set_mctrl,
331 	.get_mctrl = apbuart_get_mctrl,
332 	.stop_tx = apbuart_stop_tx,
333 	.start_tx = apbuart_start_tx,
334 	.stop_rx = apbuart_stop_rx,
335 	.break_ctl = apbuart_break_ctl,
336 	.startup = apbuart_startup,
337 	.shutdown = apbuart_shutdown,
338 	.set_termios = apbuart_set_termios,
339 	.type = apbuart_type,
340 	.release_port = apbuart_release_port,
341 	.request_port = apbuart_request_port,
342 	.config_port = apbuart_config_port,
343 	.verify_port = apbuart_verify_port,
344 };
345 
346 static struct uart_port grlib_apbuart_ports[UART_NR];
347 static struct device_node *grlib_apbuart_nodes[UART_NR];
348 
349 static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
350 {
351 	int ctrl, loop = 0;
352 	int status;
353 	int fifosize;
354 	unsigned long flags;
355 
356 	ctrl = UART_GET_CTRL(port);
357 
358 	/*
359 	 * Enable the transceiver and wait for it to be ready to send data.
360 	 * Clear interrupts so that this process will not be externally
361 	 * interrupted in the middle (which can cause the transceiver to
362 	 * drain prematurely).
363 	 */
364 
365 	local_irq_save(flags);
366 
367 	UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
368 
369 	while (!UART_TX_READY(UART_GET_STATUS(port)))
370 		loop++;
371 
372 	/*
373 	 * Disable the transceiver so data isn't actually sent during the
374 	 * actual test.
375 	 */
376 
377 	UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
378 
379 	fifosize = 1;
380 	UART_PUT_CHAR(port, 0);
381 
382 	/*
383 	 * So long as transmitting a character increments the tranceivier FIFO
384 	 * length the FIFO must be at least that big. These bytes will
385 	 * automatically drain off of the FIFO.
386 	 */
387 
388 	status = UART_GET_STATUS(port);
389 	while (((status >> 20) & 0x3F) == fifosize) {
390 		fifosize++;
391 		UART_PUT_CHAR(port, 0);
392 		status = UART_GET_STATUS(port);
393 	}
394 
395 	fifosize--;
396 
397 	UART_PUT_CTRL(port, ctrl);
398 	local_irq_restore(flags);
399 
400 	if (fifosize == 0)
401 		fifosize = 1;
402 
403 	return fifosize;
404 }
405 
406 static void apbuart_flush_fifo(struct uart_port *port)
407 {
408 	int i;
409 
410 	for (i = 0; i < port->fifosize; i++)
411 		UART_GET_CHAR(port);
412 }
413 
414 
415 /* ======================================================================== */
416 /* Console driver, if enabled                                               */
417 /* ======================================================================== */
418 
419 #ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
420 
421 static void apbuart_console_putchar(struct uart_port *port, int ch)
422 {
423 	unsigned int status;
424 	do {
425 		status = UART_GET_STATUS(port);
426 	} while (!UART_TX_READY(status));
427 	UART_PUT_CHAR(port, ch);
428 }
429 
430 static void
431 apbuart_console_write(struct console *co, const char *s, unsigned int count)
432 {
433 	struct uart_port *port = &grlib_apbuart_ports[co->index];
434 	unsigned int status, old_cr, new_cr;
435 
436 	/* First save the CR then disable the interrupts */
437 	old_cr = UART_GET_CTRL(port);
438 	new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
439 	UART_PUT_CTRL(port, new_cr);
440 
441 	uart_console_write(port, s, count, apbuart_console_putchar);
442 
443 	/*
444 	 *      Finally, wait for transmitter to become empty
445 	 *      and restore the TCR
446 	 */
447 	do {
448 		status = UART_GET_STATUS(port);
449 	} while (!UART_TX_READY(status));
450 	UART_PUT_CTRL(port, old_cr);
451 }
452 
453 static void __init
454 apbuart_console_get_options(struct uart_port *port, int *baud,
455 			    int *parity, int *bits)
456 {
457 	if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
458 
459 		unsigned int quot, status;
460 		status = UART_GET_STATUS(port);
461 
462 		*parity = 'n';
463 		if (status & UART_CTRL_PE) {
464 			if ((status & UART_CTRL_PS) == 0)
465 				*parity = 'e';
466 			else
467 				*parity = 'o';
468 		}
469 
470 		*bits = 8;
471 		quot = UART_GET_SCAL(port) / 8;
472 		*baud = port->uartclk / (16 * (quot + 1));
473 	}
474 }
475 
476 static int __init apbuart_console_setup(struct console *co, char *options)
477 {
478 	struct uart_port *port;
479 	int baud = 38400;
480 	int bits = 8;
481 	int parity = 'n';
482 	int flow = 'n';
483 
484 	pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
485 		 co, co->index, options);
486 
487 	/*
488 	 * Check whether an invalid uart number has been specified, and
489 	 * if so, search for the first available port that does have
490 	 * console support.
491 	 */
492 	if (co->index >= grlib_apbuart_port_nr)
493 		co->index = 0;
494 
495 	port = &grlib_apbuart_ports[co->index];
496 
497 	spin_lock_init(&port->lock);
498 
499 	if (options)
500 		uart_parse_options(options, &baud, &parity, &bits, &flow);
501 	else
502 		apbuart_console_get_options(port, &baud, &parity, &bits);
503 
504 	return uart_set_options(port, co, baud, parity, bits, flow);
505 }
506 
507 static struct uart_driver grlib_apbuart_driver;
508 
509 static struct console grlib_apbuart_console = {
510 	.name = "ttyS",
511 	.write = apbuart_console_write,
512 	.device = uart_console_device,
513 	.setup = apbuart_console_setup,
514 	.flags = CON_PRINTBUFFER,
515 	.index = -1,
516 	.data = &grlib_apbuart_driver,
517 };
518 
519 
520 static int grlib_apbuart_configure(void);
521 
522 static int __init apbuart_console_init(void)
523 {
524 	if (grlib_apbuart_configure())
525 		return -ENODEV;
526 	register_console(&grlib_apbuart_console);
527 	return 0;
528 }
529 
530 console_initcall(apbuart_console_init);
531 
532 #define APBUART_CONSOLE	(&grlib_apbuart_console)
533 #else
534 #define APBUART_CONSOLE	NULL
535 #endif
536 
537 static struct uart_driver grlib_apbuart_driver = {
538 	.owner = THIS_MODULE,
539 	.driver_name = "serial",
540 	.dev_name = "ttyS",
541 	.major = SERIAL_APBUART_MAJOR,
542 	.minor = SERIAL_APBUART_MINOR,
543 	.nr = UART_NR,
544 	.cons = APBUART_CONSOLE,
545 };
546 
547 
548 /* ======================================================================== */
549 /* OF Platform Driver                                                       */
550 /* ======================================================================== */
551 
552 static int apbuart_probe(struct platform_device *op)
553 {
554 	int i;
555 	struct uart_port *port = NULL;
556 
557 	for (i = 0; i < grlib_apbuart_port_nr; i++) {
558 		if (op->dev.of_node == grlib_apbuart_nodes[i])
559 			break;
560 	}
561 
562 	port = &grlib_apbuart_ports[i];
563 	port->dev = &op->dev;
564 	port->irq = op->archdata.irqs[0];
565 
566 	uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
567 
568 	apbuart_flush_fifo((struct uart_port *) port);
569 
570 	printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
571 	       (unsigned long long) port->mapbase, port->irq);
572 	return 0;
573 }
574 
575 static const struct of_device_id apbuart_match[] = {
576 	{
577 	 .name = "GAISLER_APBUART",
578 	 },
579 	{
580 	 .name = "01_00c",
581 	 },
582 	{},
583 };
584 MODULE_DEVICE_TABLE(of, apbuart_match);
585 
586 static struct platform_driver grlib_apbuart_of_driver = {
587 	.probe = apbuart_probe,
588 	.driver = {
589 		.name = "grlib-apbuart",
590 		.of_match_table = apbuart_match,
591 	},
592 };
593 
594 
595 static int __init grlib_apbuart_configure(void)
596 {
597 	struct device_node *np;
598 	int line = 0;
599 
600 	for_each_matching_node(np, apbuart_match) {
601 		const int *ampopts;
602 		const u32 *freq_hz;
603 		const struct amba_prom_registers *regs;
604 		struct uart_port *port;
605 		unsigned long addr;
606 
607 		ampopts = of_get_property(np, "ampopts", NULL);
608 		if (ampopts && (*ampopts == 0))
609 			continue; /* Ignore if used by another OS instance */
610 		regs = of_get_property(np, "reg", NULL);
611 		/* Frequency of APB Bus is frequency of UART */
612 		freq_hz = of_get_property(np, "freq", NULL);
613 
614 		if (!regs || !freq_hz || (*freq_hz == 0))
615 			continue;
616 
617 		grlib_apbuart_nodes[line] = np;
618 
619 		addr = regs->phys_addr;
620 
621 		port = &grlib_apbuart_ports[line];
622 
623 		port->mapbase = addr;
624 		port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
625 		port->irq = 0;
626 		port->iotype = UPIO_MEM;
627 		port->ops = &grlib_apbuart_ops;
628 		port->flags = UPF_BOOT_AUTOCONF;
629 		port->line = line;
630 		port->uartclk = *freq_hz;
631 		port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
632 		line++;
633 
634 		/* We support maximum UART_NR uarts ... */
635 		if (line == UART_NR)
636 			break;
637 	}
638 
639 	grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
640 	return line ? 0 : -ENODEV;
641 }
642 
643 static int __init grlib_apbuart_init(void)
644 {
645 	int ret;
646 
647 	/* Find all APBUARTS in device the tree and initialize their ports */
648 	ret = grlib_apbuart_configure();
649 	if (ret)
650 		return ret;
651 
652 	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
653 
654 	ret = uart_register_driver(&grlib_apbuart_driver);
655 
656 	if (ret) {
657 		printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
658 		       __FILE__, ret);
659 		return ret;
660 	}
661 
662 	ret = platform_driver_register(&grlib_apbuart_of_driver);
663 	if (ret) {
664 		printk(KERN_ERR
665 		       "%s: platform_driver_register failed (%i)\n",
666 		       __FILE__, ret);
667 		uart_unregister_driver(&grlib_apbuart_driver);
668 		return ret;
669 	}
670 
671 	return ret;
672 }
673 
674 static void __exit grlib_apbuart_exit(void)
675 {
676 	int i;
677 
678 	for (i = 0; i < grlib_apbuart_port_nr; i++)
679 		uart_remove_one_port(&grlib_apbuart_driver,
680 				     &grlib_apbuart_ports[i]);
681 
682 	uart_unregister_driver(&grlib_apbuart_driver);
683 	platform_driver_unregister(&grlib_apbuart_of_driver);
684 }
685 
686 module_init(grlib_apbuart_init);
687 module_exit(grlib_apbuart_exit);
688 
689 MODULE_AUTHOR("Aeroflex Gaisler AB");
690 MODULE_DESCRIPTION("GRLIB APBUART serial driver");
691 MODULE_VERSION("2.1");
692 MODULE_LICENSE("GPL");
693