apbuart.c revision ab4382d27412e7e3e7c936e8d50d8888dfac3df8 
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/ioport.h>
20#include <linux/init.h>
21#include <linux/serial.h>
22#include <linux/console.h>
23#include <linux/sysrq.h>
24#include <linux/kthread.h>
25#include <linux/device.h>
26#include <linux/of.h>
27#include <linux/of_device.h>
28#include <linux/of_platform.h>
29#include <linux/of_irq.h>
30#include <linux/platform_device.h>
31#include <linux/io.h>
32#include <linux/serial_core.h>
33#include <asm/irq.h>
34
35#include "apbuart.h"
36
37#define SERIAL_APBUART_MAJOR	TTY_MAJOR
38#define SERIAL_APBUART_MINOR	64
39#define UART_DUMMY_RSR_RX	0x8000	/* for ignore all read */
40
41static void apbuart_tx_chars(struct uart_port *port);
42
43static void apbuart_stop_tx(struct uart_port *port)
44{
45	unsigned int cr;
46
47	cr = UART_GET_CTRL(port);
48	cr &= ~UART_CTRL_TI;
49	UART_PUT_CTRL(port, cr);
50}
51
52static void apbuart_start_tx(struct uart_port *port)
53{
54	unsigned int cr;
55
56	cr = UART_GET_CTRL(port);
57	cr |= UART_CTRL_TI;
58	UART_PUT_CTRL(port, cr);
59
60	if (UART_GET_STATUS(port) & UART_STATUS_THE)
61		apbuart_tx_chars(port);
62}
63
64static void apbuart_stop_rx(struct uart_port *port)
65{
66	unsigned int cr;
67
68	cr = UART_GET_CTRL(port);
69	cr &= ~(UART_CTRL_RI);
70	UART_PUT_CTRL(port, cr);
71}
72
73static void apbuart_enable_ms(struct uart_port *port)
74{
75	/* No modem status change interrupts for APBUART */
76}
77
78static void apbuart_rx_chars(struct uart_port *port)
79{
80	struct tty_struct *tty = port->state->port.tty;
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(tty);
129}
130
131static 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
165static 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
183static 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
189static 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
195static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
196{
197	/* The GRLIB APBUART handles flow control in hardware */
198}
199
200static void apbuart_break_ctl(struct uart_port *port, int break_state)
201{
202	/* We don't support sending break */
203}
204
205static 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
224static 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
238static 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
291static const char *apbuart_type(struct uart_port *port)
292{
293	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
294}
295
296static void apbuart_release_port(struct uart_port *port)
297{
298	release_mem_region(port->mapbase, 0x100);
299}
300
301static 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 */
309static 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) */
318static 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
331static 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
350static struct uart_port grlib_apbuart_ports[UART_NR];
351static struct device_node *grlib_apbuart_nodes[UART_NR];
352
353static 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
410static 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
425static 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
434static void
435apbuart_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
457static void __init
458apbuart_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
480static 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
511static struct uart_driver grlib_apbuart_driver;
512
513static 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
524static int grlib_apbuart_configure(void);
525
526static 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
534console_initcall(apbuart_console_init);
535
536#define APBUART_CONSOLE	(&grlib_apbuart_console)
537#else
538#define APBUART_CONSOLE	NULL
539#endif
540
541static 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
556static int __devinit apbuart_probe(struct platform_device *op,
557				   const struct of_device_id *match)
558{
559	int i = -1;
560	struct uart_port *port = NULL;
561
562	i = 0;
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
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
580static struct of_device_id __initdata apbuart_match[] = {
581	{
582	 .name = "GAISLER_APBUART",
583	 },
584	{
585	 .name = "01_00c",
586	 },
587	{},
588};
589
590static struct of_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
600static int grlib_apbuart_configure(void)
601{
602	struct device_node *np, *rp;
603	const u32 *prop;
604	int freq_khz, line = 0;
605
606	/* Get bus frequency */
607	rp = of_find_node_by_path("/");
608	if (!rp)
609		return -ENODEV;
610	rp = of_get_next_child(rp, NULL);
611	if (!rp)
612		return -ENODEV;
613	prop = of_get_property(rp, "clock-frequency", NULL);
614	if (!prop)
615		return -ENODEV;
616	freq_khz = *prop;
617
618	for_each_matching_node(np, apbuart_match) {
619		const int *irqs, *ampopts;
620		const struct amba_prom_registers *regs;
621		struct uart_port *port;
622		unsigned long addr;
623
624		ampopts = of_get_property(np, "ampopts", NULL);
625		if (ampopts && (*ampopts == 0))
626			continue; /* Ignore if used by another OS instance */
627
628		irqs = of_get_property(np, "interrupts", NULL);
629		regs = of_get_property(np, "reg", NULL);
630
631		if (!irqs || !regs)
632			continue;
633
634		grlib_apbuart_nodes[line] = np;
635
636		addr = regs->phys_addr;
637
638		port = &grlib_apbuart_ports[line];
639
640		port->mapbase = addr;
641		port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
642		port->irq = *irqs;
643		port->iotype = UPIO_MEM;
644		port->ops = &grlib_apbuart_ops;
645		port->flags = UPF_BOOT_AUTOCONF;
646		port->line = line;
647		port->uartclk = freq_khz * 1000;
648		port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
649		line++;
650
651		/* We support maximum UART_NR uarts ... */
652		if (line == UART_NR)
653			break;
654	}
655
656	grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
657	return line ? 0 : -ENODEV;
658}
659
660static int __init grlib_apbuart_init(void)
661{
662	int ret;
663
664	/* Find all APBUARTS in device the tree and initialize their ports */
665	ret = grlib_apbuart_configure();
666	if (ret)
667		return ret;
668
669	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
670
671	ret = uart_register_driver(&grlib_apbuart_driver);
672
673	if (ret) {
674		printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
675		       __FILE__, ret);
676		return ret;
677	}
678
679	ret = of_register_platform_driver(&grlib_apbuart_of_driver);
680	if (ret) {
681		printk(KERN_ERR
682		       "%s: of_register_platform_driver failed (%i)\n",
683		       __FILE__, ret);
684		uart_unregister_driver(&grlib_apbuart_driver);
685		return ret;
686	}
687
688	return ret;
689}
690
691static void __exit grlib_apbuart_exit(void)
692{
693	int i;
694
695	for (i = 0; i < grlib_apbuart_port_nr; i++)
696		uart_remove_one_port(&grlib_apbuart_driver,
697				     &grlib_apbuart_ports[i]);
698
699	uart_unregister_driver(&grlib_apbuart_driver);
700	of_unregister_platform_driver(&grlib_apbuart_of_driver);
701}
702
703module_init(grlib_apbuart_init);
704module_exit(grlib_apbuart_exit);
705
706MODULE_AUTHOR("Aeroflex Gaisler AB");
707MODULE_DESCRIPTION("GRLIB APBUART serial driver");
708MODULE_VERSION("2.1");
709MODULE_LICENSE("GPL");
710