1// SPDX-License-Identifier: GPL-2.0
2/*
3 *  Driver for GRLIB serial ports (APBUART)
4 *
5 *  Based on linux/drivers/serial/amba.c
6 *
7 *  Copyright (C) 2000 Deep Blue Solutions Ltd.
8 *  Copyright (C) 2003 Konrad Eisele <eiselekd@web.de>
9 *  Copyright (C) 2006 Daniel Hellstrom <daniel@gaisler.com>, Aeroflex Gaisler AB
10 *  Copyright (C) 2008 Gilead Kutnick <kutnickg@zin-tech.com>
11 *  Copyright (C) 2009 Kristoffer Glembo <kristoffer@gaisler.com>, Aeroflex Gaisler AB
12 */
13
14#include <linux/module.h>
15#include <linux/tty.h>
16#include <linux/tty_flip.h>
17#include <linux/ioport.h>
18#include <linux/init.h>
19#include <linux/serial.h>
20#include <linux/console.h>
21#include <linux/sysrq.h>
22#include <linux/kthread.h>
23#include <linux/device.h>
24#include <linux/of.h>
25#include <linux/of_device.h>
26#include <linux/of_platform.h>
27#include <linux/of_irq.h>
28#include <linux/platform_device.h>
29#include <linux/io.h>
30#include <linux/serial_core.h>
31#include <asm/irq.h>
32
33#include "apbuart.h"
34
35#define SERIAL_APBUART_MAJOR	TTY_MAJOR
36#define SERIAL_APBUART_MINOR	64
37#define UART_DUMMY_RSR_RX	0x8000	/* for ignore all read */
38
39static void apbuart_tx_chars(struct uart_port *port);
40
41static void apbuart_stop_tx(struct uart_port *port)
42{
43	unsigned int cr;
44
45	cr = UART_GET_CTRL(port);
46	cr &= ~UART_CTRL_TI;
47	UART_PUT_CTRL(port, cr);
48}
49
50static void apbuart_start_tx(struct uart_port *port)
51{
52	unsigned int cr;
53
54	cr = UART_GET_CTRL(port);
55	cr |= UART_CTRL_TI;
56	UART_PUT_CTRL(port, cr);
57
58	if (UART_GET_STATUS(port) & UART_STATUS_THE)
59		apbuart_tx_chars(port);
60}
61
62static void apbuart_stop_rx(struct uart_port *port)
63{
64	unsigned int cr;
65
66	cr = UART_GET_CTRL(port);
67	cr &= ~(UART_CTRL_RI);
68	UART_PUT_CTRL(port, cr);
69}
70
71static void apbuart_rx_chars(struct uart_port *port)
72{
73	unsigned int status, ch, rsr, flag;
74	unsigned int max_chars = port->fifosize;
75
76	status = UART_GET_STATUS(port);
77
78	while (UART_RX_DATA(status) && (max_chars--)) {
79
80		ch = UART_GET_CHAR(port);
81		flag = TTY_NORMAL;
82
83		port->icount.rx++;
84
85		rsr = UART_GET_STATUS(port) | UART_DUMMY_RSR_RX;
86		UART_PUT_STATUS(port, 0);
87		if (rsr & UART_STATUS_ERR) {
88
89			if (rsr & UART_STATUS_BR) {
90				rsr &= ~(UART_STATUS_FE | UART_STATUS_PE);
91				port->icount.brk++;
92				if (uart_handle_break(port))
93					goto ignore_char;
94			} else if (rsr & UART_STATUS_PE) {
95				port->icount.parity++;
96			} else if (rsr & UART_STATUS_FE) {
97				port->icount.frame++;
98			}
99			if (rsr & UART_STATUS_OE)
100				port->icount.overrun++;
101
102			rsr &= port->read_status_mask;
103
104			if (rsr & UART_STATUS_PE)
105				flag = TTY_PARITY;
106			else if (rsr & UART_STATUS_FE)
107				flag = TTY_FRAME;
108		}
109
110		if (uart_handle_sysrq_char(port, ch))
111			goto ignore_char;
112
113		uart_insert_char(port, rsr, UART_STATUS_OE, ch, flag);
114
115
116	      ignore_char:
117		status = UART_GET_STATUS(port);
118	}
119
120	spin_unlock(&port->lock);
121	tty_flip_buffer_push(&port->state->port);
122	spin_lock(&port->lock);
123}
124
125static void apbuart_tx_chars(struct uart_port *port)
126{
127	struct circ_buf *xmit = &port->state->xmit;
128	int count;
129
130	if (port->x_char) {
131		UART_PUT_CHAR(port, port->x_char);
132		port->icount.tx++;
133		port->x_char = 0;
134		return;
135	}
136
137	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
138		apbuart_stop_tx(port);
139		return;
140	}
141
142	/* amba: fill FIFO */
143	count = port->fifosize >> 1;
144	do {
145		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
146		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
147		port->icount.tx++;
148		if (uart_circ_empty(xmit))
149			break;
150	} while (--count > 0);
151
152	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
153		uart_write_wakeup(port);
154
155	if (uart_circ_empty(xmit))
156		apbuart_stop_tx(port);
157}
158
159static irqreturn_t apbuart_int(int irq, void *dev_id)
160{
161	struct uart_port *port = dev_id;
162	unsigned int status;
163
164	spin_lock(&port->lock);
165
166	status = UART_GET_STATUS(port);
167	if (status & UART_STATUS_DR)
168		apbuart_rx_chars(port);
169	if (status & UART_STATUS_THE)
170		apbuart_tx_chars(port);
171
172	spin_unlock(&port->lock);
173
174	return IRQ_HANDLED;
175}
176
177static unsigned int apbuart_tx_empty(struct uart_port *port)
178{
179	unsigned int status = UART_GET_STATUS(port);
180	return status & UART_STATUS_THE ? TIOCSER_TEMT : 0;
181}
182
183static unsigned int apbuart_get_mctrl(struct uart_port *port)
184{
185	/* The GRLIB APBUART handles flow control in hardware */
186	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
187}
188
189static void apbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
190{
191	/* The GRLIB APBUART handles flow control in hardware */
192}
193
194static void apbuart_break_ctl(struct uart_port *port, int break_state)
195{
196	/* We don't support sending break */
197}
198
199static int apbuart_startup(struct uart_port *port)
200{
201	int retval;
202	unsigned int cr;
203
204	/* Allocate the IRQ */
205	retval = request_irq(port->irq, apbuart_int, 0, "apbuart", port);
206	if (retval)
207		return retval;
208
209	/* Finally, enable interrupts */
210	cr = UART_GET_CTRL(port);
211	UART_PUT_CTRL(port,
212		      cr | UART_CTRL_RE | UART_CTRL_TE |
213		      UART_CTRL_RI | UART_CTRL_TI);
214
215	return 0;
216}
217
218static void apbuart_shutdown(struct uart_port *port)
219{
220	unsigned int cr;
221
222	/* disable all interrupts, disable the port */
223	cr = UART_GET_CTRL(port);
224	UART_PUT_CTRL(port,
225		      cr & ~(UART_CTRL_RE | UART_CTRL_TE |
226			     UART_CTRL_RI | UART_CTRL_TI));
227
228	/* Free the interrupt */
229	free_irq(port->irq, port);
230}
231
232static void apbuart_set_termios(struct uart_port *port,
233				struct ktermios *termios, struct ktermios *old)
234{
235	unsigned int cr;
236	unsigned long flags;
237	unsigned int baud, quot;
238
239	/* Ask the core to calculate the divisor for us. */
240	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
241	if (baud == 0)
242		panic("invalid baudrate %i\n", port->uartclk / 16);
243
244	/* uart_get_divisor calc a *16 uart freq, apbuart is *8 */
245	quot = (uart_get_divisor(port, baud)) * 2;
246	cr = UART_GET_CTRL(port);
247	cr &= ~(UART_CTRL_PE | UART_CTRL_PS);
248
249	if (termios->c_cflag & PARENB) {
250		cr |= UART_CTRL_PE;
251		if ((termios->c_cflag & PARODD))
252			cr |= UART_CTRL_PS;
253	}
254
255	/* Enable flow control. */
256	if (termios->c_cflag & CRTSCTS)
257		cr |= UART_CTRL_FL;
258
259	spin_lock_irqsave(&port->lock, flags);
260
261	/* Update the per-port timeout. */
262	uart_update_timeout(port, termios->c_cflag, baud);
263
264	port->read_status_mask = UART_STATUS_OE;
265	if (termios->c_iflag & INPCK)
266		port->read_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
267
268	/* Characters to ignore */
269	port->ignore_status_mask = 0;
270	if (termios->c_iflag & IGNPAR)
271		port->ignore_status_mask |= UART_STATUS_FE | UART_STATUS_PE;
272
273	/* Ignore all characters if CREAD is not set. */
274	if ((termios->c_cflag & CREAD) == 0)
275		port->ignore_status_mask |= UART_DUMMY_RSR_RX;
276
277	/* Set baud rate */
278	quot -= 1;
279	UART_PUT_SCAL(port, quot);
280	UART_PUT_CTRL(port, cr);
281
282	spin_unlock_irqrestore(&port->lock, flags);
283}
284
285static const char *apbuart_type(struct uart_port *port)
286{
287	return port->type == PORT_APBUART ? "GRLIB/APBUART" : NULL;
288}
289
290static void apbuart_release_port(struct uart_port *port)
291{
292	release_mem_region(port->mapbase, 0x100);
293}
294
295static int apbuart_request_port(struct uart_port *port)
296{
297	return request_mem_region(port->mapbase, 0x100, "grlib-apbuart")
298	    != NULL ? 0 : -EBUSY;
299	return 0;
300}
301
302/* Configure/autoconfigure the port */
303static void apbuart_config_port(struct uart_port *port, int flags)
304{
305	if (flags & UART_CONFIG_TYPE) {
306		port->type = PORT_APBUART;
307		apbuart_request_port(port);
308	}
309}
310
311/* Verify the new serial_struct (for TIOCSSERIAL) */
312static int apbuart_verify_port(struct uart_port *port,
313			       struct serial_struct *ser)
314{
315	int ret = 0;
316	if (ser->type != PORT_UNKNOWN && ser->type != PORT_APBUART)
317		ret = -EINVAL;
318	if (ser->irq < 0 || ser->irq >= NR_IRQS)
319		ret = -EINVAL;
320	if (ser->baud_base < 9600)
321		ret = -EINVAL;
322	return ret;
323}
324
325static const struct uart_ops grlib_apbuart_ops = {
326	.tx_empty = apbuart_tx_empty,
327	.set_mctrl = apbuart_set_mctrl,
328	.get_mctrl = apbuart_get_mctrl,
329	.stop_tx = apbuart_stop_tx,
330	.start_tx = apbuart_start_tx,
331	.stop_rx = apbuart_stop_rx,
332	.break_ctl = apbuart_break_ctl,
333	.startup = apbuart_startup,
334	.shutdown = apbuart_shutdown,
335	.set_termios = apbuart_set_termios,
336	.type = apbuart_type,
337	.release_port = apbuart_release_port,
338	.request_port = apbuart_request_port,
339	.config_port = apbuart_config_port,
340	.verify_port = apbuart_verify_port,
341};
342
343static struct uart_port grlib_apbuart_ports[UART_NR];
344static struct device_node *grlib_apbuart_nodes[UART_NR];
345
346static int apbuart_scan_fifo_size(struct uart_port *port, int portnumber)
347{
348	int ctrl, loop = 0;
349	int status;
350	int fifosize;
351	unsigned long flags;
352
353	ctrl = UART_GET_CTRL(port);
354
355	/*
356	 * Enable the transceiver and wait for it to be ready to send data.
357	 * Clear interrupts so that this process will not be externally
358	 * interrupted in the middle (which can cause the transceiver to
359	 * drain prematurely).
360	 */
361
362	local_irq_save(flags);
363
364	UART_PUT_CTRL(port, ctrl | UART_CTRL_TE);
365
366	while (!UART_TX_READY(UART_GET_STATUS(port)))
367		loop++;
368
369	/*
370	 * Disable the transceiver so data isn't actually sent during the
371	 * actual test.
372	 */
373
374	UART_PUT_CTRL(port, ctrl & ~(UART_CTRL_TE));
375
376	fifosize = 1;
377	UART_PUT_CHAR(port, 0);
378
379	/*
380	 * So long as transmitting a character increments the tranceivier FIFO
381	 * length the FIFO must be at least that big. These bytes will
382	 * automatically drain off of the FIFO.
383	 */
384
385	status = UART_GET_STATUS(port);
386	while (((status >> 20) & 0x3F) == fifosize) {
387		fifosize++;
388		UART_PUT_CHAR(port, 0);
389		status = UART_GET_STATUS(port);
390	}
391
392	fifosize--;
393
394	UART_PUT_CTRL(port, ctrl);
395	local_irq_restore(flags);
396
397	if (fifosize == 0)
398		fifosize = 1;
399
400	return fifosize;
401}
402
403static void apbuart_flush_fifo(struct uart_port *port)
404{
405	int i;
406
407	for (i = 0; i < port->fifosize; i++)
408		UART_GET_CHAR(port);
409}
410
411
412/* ======================================================================== */
413/* Console driver, if enabled                                               */
414/* ======================================================================== */
415
416#ifdef CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
417
418static void apbuart_console_putchar(struct uart_port *port, int ch)
419{
420	unsigned int status;
421	do {
422		status = UART_GET_STATUS(port);
423	} while (!UART_TX_READY(status));
424	UART_PUT_CHAR(port, ch);
425}
426
427static void
428apbuart_console_write(struct console *co, const char *s, unsigned int count)
429{
430	struct uart_port *port = &grlib_apbuart_ports[co->index];
431	unsigned int status, old_cr, new_cr;
432
433	/* First save the CR then disable the interrupts */
434	old_cr = UART_GET_CTRL(port);
435	new_cr = old_cr & ~(UART_CTRL_RI | UART_CTRL_TI);
436	UART_PUT_CTRL(port, new_cr);
437
438	uart_console_write(port, s, count, apbuart_console_putchar);
439
440	/*
441	 *      Finally, wait for transmitter to become empty
442	 *      and restore the TCR
443	 */
444	do {
445		status = UART_GET_STATUS(port);
446	} while (!UART_TX_READY(status));
447	UART_PUT_CTRL(port, old_cr);
448}
449
450static void __init
451apbuart_console_get_options(struct uart_port *port, int *baud,
452			    int *parity, int *bits)
453{
454	if (UART_GET_CTRL(port) & (UART_CTRL_RE | UART_CTRL_TE)) {
455
456		unsigned int quot, status;
457		status = UART_GET_STATUS(port);
458
459		*parity = 'n';
460		if (status & UART_CTRL_PE) {
461			if ((status & UART_CTRL_PS) == 0)
462				*parity = 'e';
463			else
464				*parity = 'o';
465		}
466
467		*bits = 8;
468		quot = UART_GET_SCAL(port) / 8;
469		*baud = port->uartclk / (16 * (quot + 1));
470	}
471}
472
473static int __init apbuart_console_setup(struct console *co, char *options)
474{
475	struct uart_port *port;
476	int baud = 38400;
477	int bits = 8;
478	int parity = 'n';
479	int flow = 'n';
480
481	pr_debug("apbuart_console_setup co=%p, co->index=%i, options=%s\n",
482		 co, co->index, options);
483
484	/*
485	 * Check whether an invalid uart number has been specified, and
486	 * if so, search for the first available port that does have
487	 * console support.
488	 */
489	if (co->index >= grlib_apbuart_port_nr)
490		co->index = 0;
491
492	port = &grlib_apbuart_ports[co->index];
493
494	spin_lock_init(&port->lock);
495
496	if (options)
497		uart_parse_options(options, &baud, &parity, &bits, &flow);
498	else
499		apbuart_console_get_options(port, &baud, &parity, &bits);
500
501	return uart_set_options(port, co, baud, parity, bits, flow);
502}
503
504static struct uart_driver grlib_apbuart_driver;
505
506static struct console grlib_apbuart_console = {
507	.name = "ttyS",
508	.write = apbuart_console_write,
509	.device = uart_console_device,
510	.setup = apbuart_console_setup,
511	.flags = CON_PRINTBUFFER,
512	.index = -1,
513	.data = &grlib_apbuart_driver,
514};
515
516
517static int grlib_apbuart_configure(void);
518
519static int __init apbuart_console_init(void)
520{
521	if (grlib_apbuart_configure())
522		return -ENODEV;
523	register_console(&grlib_apbuart_console);
524	return 0;
525}
526
527console_initcall(apbuart_console_init);
528
529#define APBUART_CONSOLE	(&grlib_apbuart_console)
530#else
531#define APBUART_CONSOLE	NULL
532#endif
533
534static struct uart_driver grlib_apbuart_driver = {
535	.owner = THIS_MODULE,
536	.driver_name = "serial",
537	.dev_name = "ttyS",
538	.major = SERIAL_APBUART_MAJOR,
539	.minor = SERIAL_APBUART_MINOR,
540	.nr = UART_NR,
541	.cons = APBUART_CONSOLE,
542};
543
544
545/* ======================================================================== */
546/* OF Platform Driver                                                       */
547/* ======================================================================== */
548
549static int apbuart_probe(struct platform_device *op)
550{
551	int i;
552	struct uart_port *port = NULL;
553
554	for (i = 0; i < grlib_apbuart_port_nr; i++) {
555		if (op->dev.of_node == grlib_apbuart_nodes[i])
556			break;
557	}
558
559	port = &grlib_apbuart_ports[i];
560	port->dev = &op->dev;
561	port->irq = op->archdata.irqs[0];
562
563	uart_add_one_port(&grlib_apbuart_driver, (struct uart_port *) port);
564
565	apbuart_flush_fifo((struct uart_port *) port);
566
567	printk(KERN_INFO "grlib-apbuart at 0x%llx, irq %d\n",
568	       (unsigned long long) port->mapbase, port->irq);
569	return 0;
570}
571
572static const struct of_device_id apbuart_match[] = {
573	{
574	 .name = "GAISLER_APBUART",
575	 },
576	{
577	 .name = "01_00c",
578	 },
579	{},
580};
581MODULE_DEVICE_TABLE(of, apbuart_match);
582
583static struct platform_driver grlib_apbuart_of_driver = {
584	.probe = apbuart_probe,
585	.driver = {
586		.name = "grlib-apbuart",
587		.of_match_table = apbuart_match,
588	},
589};
590
591
592static int __init grlib_apbuart_configure(void)
593{
594	struct device_node *np;
595	int line = 0;
596
597	for_each_matching_node(np, apbuart_match) {
598		const int *ampopts;
599		const u32 *freq_hz;
600		const struct amba_prom_registers *regs;
601		struct uart_port *port;
602		unsigned long addr;
603
604		ampopts = of_get_property(np, "ampopts", NULL);
605		if (ampopts && (*ampopts == 0))
606			continue; /* Ignore if used by another OS instance */
607		regs = of_get_property(np, "reg", NULL);
608		/* Frequency of APB Bus is frequency of UART */
609		freq_hz = of_get_property(np, "freq", NULL);
610
611		if (!regs || !freq_hz || (*freq_hz == 0))
612			continue;
613
614		grlib_apbuart_nodes[line] = np;
615
616		addr = regs->phys_addr;
617
618		port = &grlib_apbuart_ports[line];
619
620		port->mapbase = addr;
621		port->membase = ioremap(addr, sizeof(struct grlib_apbuart_regs_map));
622		port->irq = 0;
623		port->iotype = UPIO_MEM;
624		port->ops = &grlib_apbuart_ops;
625		port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_GRLIB_GAISLER_APBUART_CONSOLE);
626		port->flags = UPF_BOOT_AUTOCONF;
627		port->line = line;
628		port->uartclk = *freq_hz;
629		port->fifosize = apbuart_scan_fifo_size((struct uart_port *) port, line);
630		line++;
631
632		/* We support maximum UART_NR uarts ... */
633		if (line == UART_NR)
634			break;
635	}
636
637	grlib_apbuart_driver.nr = grlib_apbuart_port_nr = line;
638	return line ? 0 : -ENODEV;
639}
640
641static int __init grlib_apbuart_init(void)
642{
643	int ret;
644
645	/* Find all APBUARTS in device the tree and initialize their ports */
646	ret = grlib_apbuart_configure();
647	if (ret)
648		return ret;
649
650	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
651
652	ret = uart_register_driver(&grlib_apbuart_driver);
653
654	if (ret) {
655		printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
656		       __FILE__, ret);
657		return ret;
658	}
659
660	ret = platform_driver_register(&grlib_apbuart_of_driver);
661	if (ret) {
662		printk(KERN_ERR
663		       "%s: platform_driver_register failed (%i)\n",
664		       __FILE__, ret);
665		uart_unregister_driver(&grlib_apbuart_driver);
666		return ret;
667	}
668
669	return ret;
670}
671
672static void __exit grlib_apbuart_exit(void)
673{
674	int i;
675
676	for (i = 0; i < grlib_apbuart_port_nr; i++)
677		uart_remove_one_port(&grlib_apbuart_driver,
678				     &grlib_apbuart_ports[i]);
679
680	uart_unregister_driver(&grlib_apbuart_driver);
681	platform_driver_unregister(&grlib_apbuart_of_driver);
682}
683
684module_init(grlib_apbuart_init);
685module_exit(grlib_apbuart_exit);
686
687MODULE_AUTHOR("Aeroflex Gaisler AB");
688MODULE_DESCRIPTION("GRLIB APBUART serial driver");
689MODULE_VERSION("2.1");
690MODULE_LICENSE("GPL");
691