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
42static void apbuart_tx_chars(struct uart_port *port);
43
44static 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
53static 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
65static 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
74static 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
128static 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
162static 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
180static 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
186static 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
192static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
193{
194	/* The GRLIB APBUART handles flow control in hardware */
195}
196
197static void apbuart_break_ctl(struct uart_port *port, int break_state)
198{
199	/* We don't support sending break */
200}
201
202static 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
221static 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
235static 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
288static const char *apbuart_type(struct uart_port *port)
289{
290	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
291}
292
293static void apbuart_release_port(struct uart_port *port)
294{
295	release_mem_region(port->mapbase, 0x100);
296}
297
298static 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 */
306static 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) */
315static 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
328static 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
346static struct uart_port grlib_apbuart_ports[UART_NR];
347static struct device_node *grlib_apbuart_nodes[UART_NR];
348
349static 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
406static 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
421static 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
430static void
431apbuart_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
453static void __init
454apbuart_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
476static 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
507static struct uart_driver grlib_apbuart_driver;
508
509static 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
520static int grlib_apbuart_configure(void);
521
522static 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
530console_initcall(apbuart_console_init);
531
532#define APBUART_CONSOLE	(&grlib_apbuart_console)
533#else
534#define APBUART_CONSOLE	NULL
535#endif
536
537static 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
552static 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
575static struct of_device_id apbuart_match[] = {
576	{
577	 .name = "GAISLER_APBUART",
578	 },
579	{
580	 .name = "01_00c",
581	 },
582	{},
583};
584
585static struct platform_driver grlib_apbuart_of_driver = {
586	.probe = apbuart_probe,
587	.driver = {
588		.owner = THIS_MODULE,
589		.name = "grlib-apbuart",
590		.of_match_table = apbuart_match,
591	},
592};
593
594
595static 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
643static 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
674static 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
686module_init(grlib_apbuart_init);
687module_exit(grlib_apbuart_exit);
688
689MODULE_AUTHOR("Aeroflex Gaisler AB");
690MODULE_DESCRIPTION("GRLIB APBUART serial driver");
691MODULE_VERSION("2.1");
692MODULE_LICENSE("GPL");
693