xref: /openbmc/linux/drivers/tty/serial/uartlite.c (revision 8fdff1dc) 
1 /*
2  * uartlite.c: Serial driver for Xilinx uartlite serial controller
3  *
4  * Copyright (C) 2006 Peter Korsgaard <jacmet@sunsite.dk>
5  * Copyright (C) 2007 Secret Lab Technologies Ltd.
6  *
7  * This file is licensed under the terms of the GNU General Public License
8  * version 2.  This program is licensed "as is" without any warranty of any
9  * kind, whether express or implied.
10  */
11 
12 #include <linux/platform_device.h>
13 #include <linux/module.h>
14 #include <linux/console.h>
15 #include <linux/serial.h>
16 #include <linux/serial_core.h>
17 #include <linux/tty.h>
18 #include <linux/tty_flip.h>
19 #include <linux/delay.h>
20 #include <linux/interrupt.h>
21 #include <linux/init.h>
22 #include <asm/io.h>
23 #include <linux/of.h>
24 #include <linux/of_address.h>
25 #include <linux/of_device.h>
26 #include <linux/of_platform.h>
27 
28 #define ULITE_NAME		"ttyUL"
29 #define ULITE_MAJOR		204
30 #define ULITE_MINOR		187
31 #define ULITE_NR_UARTS		4
32 
33 /* ---------------------------------------------------------------------
34  * Register definitions
35  *
36  * For register details see datasheet:
37  * http://www.xilinx.com/support/documentation/ip_documentation/opb_uartlite.pdf
38  */
39 
40 #define ULITE_RX		0x00
41 #define ULITE_TX		0x04
42 #define ULITE_STATUS		0x08
43 #define ULITE_CONTROL		0x0c
44 
45 #define ULITE_REGION		16
46 
47 #define ULITE_STATUS_RXVALID	0x01
48 #define ULITE_STATUS_RXFULL	0x02
49 #define ULITE_STATUS_TXEMPTY	0x04
50 #define ULITE_STATUS_TXFULL	0x08
51 #define ULITE_STATUS_IE		0x10
52 #define ULITE_STATUS_OVERRUN	0x20
53 #define ULITE_STATUS_FRAME	0x40
54 #define ULITE_STATUS_PARITY	0x80
55 
56 #define ULITE_CONTROL_RST_TX	0x01
57 #define ULITE_CONTROL_RST_RX	0x02
58 #define ULITE_CONTROL_IE	0x10
59 
60 
61 static struct uart_port ulite_ports[ULITE_NR_UARTS];
62 
63 /* ---------------------------------------------------------------------
64  * Core UART driver operations
65  */
66 
67 static int ulite_receive(struct uart_port *port, int stat)
68 {
69 	struct tty_struct *tty = port->state->port.tty;
70 	unsigned char ch = 0;
71 	char flag = TTY_NORMAL;
72 
73 	if ((stat & (ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
74 		     | ULITE_STATUS_FRAME)) == 0)
75 		return 0;
76 
77 	/* stats */
78 	if (stat & ULITE_STATUS_RXVALID) {
79 		port->icount.rx++;
80 		ch = ioread32be(port->membase + ULITE_RX);
81 
82 		if (stat & ULITE_STATUS_PARITY)
83 			port->icount.parity++;
84 	}
85 
86 	if (stat & ULITE_STATUS_OVERRUN)
87 		port->icount.overrun++;
88 
89 	if (stat & ULITE_STATUS_FRAME)
90 		port->icount.frame++;
91 
92 
93 	/* drop byte with parity error if IGNPAR specificed */
94 	if (stat & port->ignore_status_mask & ULITE_STATUS_PARITY)
95 		stat &= ~ULITE_STATUS_RXVALID;
96 
97 	stat &= port->read_status_mask;
98 
99 	if (stat & ULITE_STATUS_PARITY)
100 		flag = TTY_PARITY;
101 
102 
103 	stat &= ~port->ignore_status_mask;
104 
105 	if (stat & ULITE_STATUS_RXVALID)
106 		tty_insert_flip_char(tty, ch, flag);
107 
108 	if (stat & ULITE_STATUS_FRAME)
109 		tty_insert_flip_char(tty, 0, TTY_FRAME);
110 
111 	if (stat & ULITE_STATUS_OVERRUN)
112 		tty_insert_flip_char(tty, 0, TTY_OVERRUN);
113 
114 	return 1;
115 }
116 
117 static int ulite_transmit(struct uart_port *port, int stat)
118 {
119 	struct circ_buf *xmit  = &port->state->xmit;
120 
121 	if (stat & ULITE_STATUS_TXFULL)
122 		return 0;
123 
124 	if (port->x_char) {
125 		iowrite32be(port->x_char, port->membase + ULITE_TX);
126 		port->x_char = 0;
127 		port->icount.tx++;
128 		return 1;
129 	}
130 
131 	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
132 		return 0;
133 
134 	iowrite32be(xmit->buf[xmit->tail], port->membase + ULITE_TX);
135 	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
136 	port->icount.tx++;
137 
138 	/* wake up */
139 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
140 		uart_write_wakeup(port);
141 
142 	return 1;
143 }
144 
145 static irqreturn_t ulite_isr(int irq, void *dev_id)
146 {
147 	struct uart_port *port = dev_id;
148 	int busy, n = 0;
149 
150 	do {
151 		int stat = ioread32be(port->membase + ULITE_STATUS);
152 		busy  = ulite_receive(port, stat);
153 		busy |= ulite_transmit(port, stat);
154 		n++;
155 	} while (busy);
156 
157 	/* work done? */
158 	if (n > 1) {
159 		tty_flip_buffer_push(port->state->port.tty);
160 		return IRQ_HANDLED;
161 	} else {
162 		return IRQ_NONE;
163 	}
164 }
165 
166 static unsigned int ulite_tx_empty(struct uart_port *port)
167 {
168 	unsigned long flags;
169 	unsigned int ret;
170 
171 	spin_lock_irqsave(&port->lock, flags);
172 	ret = ioread32be(port->membase + ULITE_STATUS);
173 	spin_unlock_irqrestore(&port->lock, flags);
174 
175 	return ret & ULITE_STATUS_TXEMPTY ? TIOCSER_TEMT : 0;
176 }
177 
178 static unsigned int ulite_get_mctrl(struct uart_port *port)
179 {
180 	return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
181 }
182 
183 static void ulite_set_mctrl(struct uart_port *port, unsigned int mctrl)
184 {
185 	/* N/A */
186 }
187 
188 static void ulite_stop_tx(struct uart_port *port)
189 {
190 	/* N/A */
191 }
192 
193 static void ulite_start_tx(struct uart_port *port)
194 {
195 	ulite_transmit(port, ioread32be(port->membase + ULITE_STATUS));
196 }
197 
198 static void ulite_stop_rx(struct uart_port *port)
199 {
200 	/* don't forward any more data (like !CREAD) */
201 	port->ignore_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
202 		| ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
203 }
204 
205 static void ulite_enable_ms(struct uart_port *port)
206 {
207 	/* N/A */
208 }
209 
210 static void ulite_break_ctl(struct uart_port *port, int ctl)
211 {
212 	/* N/A */
213 }
214 
215 static int ulite_startup(struct uart_port *port)
216 {
217 	int ret;
218 
219 	ret = request_irq(port->irq, ulite_isr, IRQF_SHARED, "uartlite", port);
220 	if (ret)
221 		return ret;
222 
223 	iowrite32be(ULITE_CONTROL_RST_RX | ULITE_CONTROL_RST_TX,
224 	       port->membase + ULITE_CONTROL);
225 	iowrite32be(ULITE_CONTROL_IE, port->membase + ULITE_CONTROL);
226 
227 	return 0;
228 }
229 
230 static void ulite_shutdown(struct uart_port *port)
231 {
232 	iowrite32be(0, port->membase + ULITE_CONTROL);
233 	ioread32be(port->membase + ULITE_CONTROL); /* dummy */
234 	free_irq(port->irq, port);
235 }
236 
237 static void ulite_set_termios(struct uart_port *port, struct ktermios *termios,
238 			      struct ktermios *old)
239 {
240 	unsigned long flags;
241 	unsigned int baud;
242 
243 	spin_lock_irqsave(&port->lock, flags);
244 
245 	port->read_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
246 		| ULITE_STATUS_TXFULL;
247 
248 	if (termios->c_iflag & INPCK)
249 		port->read_status_mask |=
250 			ULITE_STATUS_PARITY | ULITE_STATUS_FRAME;
251 
252 	port->ignore_status_mask = 0;
253 	if (termios->c_iflag & IGNPAR)
254 		port->ignore_status_mask |= ULITE_STATUS_PARITY
255 			| ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
256 
257 	/* ignore all characters if CREAD is not set */
258 	if ((termios->c_cflag & CREAD) == 0)
259 		port->ignore_status_mask |=
260 			ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
261 			| ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
262 
263 	/* update timeout */
264 	baud = uart_get_baud_rate(port, termios, old, 0, 460800);
265 	uart_update_timeout(port, termios->c_cflag, baud);
266 
267 	spin_unlock_irqrestore(&port->lock, flags);
268 }
269 
270 static const char *ulite_type(struct uart_port *port)
271 {
272 	return port->type == PORT_UARTLITE ? "uartlite" : NULL;
273 }
274 
275 static void ulite_release_port(struct uart_port *port)
276 {
277 	release_mem_region(port->mapbase, ULITE_REGION);
278 	iounmap(port->membase);
279 	port->membase = NULL;
280 }
281 
282 static int ulite_request_port(struct uart_port *port)
283 {
284 	pr_debug("ulite console: port=%p; port->mapbase=%llx\n",
285 		 port, (unsigned long long) port->mapbase);
286 
287 	if (!request_mem_region(port->mapbase, ULITE_REGION, "uartlite")) {
288 		dev_err(port->dev, "Memory region busy\n");
289 		return -EBUSY;
290 	}
291 
292 	port->membase = ioremap(port->mapbase, ULITE_REGION);
293 	if (!port->membase) {
294 		dev_err(port->dev, "Unable to map registers\n");
295 		release_mem_region(port->mapbase, ULITE_REGION);
296 		return -EBUSY;
297 	}
298 
299 	return 0;
300 }
301 
302 static void ulite_config_port(struct uart_port *port, int flags)
303 {
304 	if (!ulite_request_port(port))
305 		port->type = PORT_UARTLITE;
306 }
307 
308 static int ulite_verify_port(struct uart_port *port, struct serial_struct *ser)
309 {
310 	/* we don't want the core code to modify any port params */
311 	return -EINVAL;
312 }
313 
314 #ifdef CONFIG_CONSOLE_POLL
315 static int ulite_get_poll_char(struct uart_port *port)
316 {
317 	if (!(ioread32be(port->membase + ULITE_STATUS)
318 						& ULITE_STATUS_RXVALID))
319 		return NO_POLL_CHAR;
320 
321 	return ioread32be(port->membase + ULITE_RX);
322 }
323 
324 static void ulite_put_poll_char(struct uart_port *port, unsigned char ch)
325 {
326 	while (ioread32be(port->membase + ULITE_STATUS) & ULITE_STATUS_TXFULL)
327 		cpu_relax();
328 
329 	/* write char to device */
330 	iowrite32be(ch, port->membase + ULITE_TX);
331 }
332 #endif
333 
334 static struct uart_ops ulite_ops = {
335 	.tx_empty	= ulite_tx_empty,
336 	.set_mctrl	= ulite_set_mctrl,
337 	.get_mctrl	= ulite_get_mctrl,
338 	.stop_tx	= ulite_stop_tx,
339 	.start_tx	= ulite_start_tx,
340 	.stop_rx	= ulite_stop_rx,
341 	.enable_ms	= ulite_enable_ms,
342 	.break_ctl	= ulite_break_ctl,
343 	.startup	= ulite_startup,
344 	.shutdown	= ulite_shutdown,
345 	.set_termios	= ulite_set_termios,
346 	.type		= ulite_type,
347 	.release_port	= ulite_release_port,
348 	.request_port	= ulite_request_port,
349 	.config_port	= ulite_config_port,
350 	.verify_port	= ulite_verify_port,
351 #ifdef CONFIG_CONSOLE_POLL
352 	.poll_get_char	= ulite_get_poll_char,
353 	.poll_put_char	= ulite_put_poll_char,
354 #endif
355 };
356 
357 /* ---------------------------------------------------------------------
358  * Console driver operations
359  */
360 
361 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
362 static void ulite_console_wait_tx(struct uart_port *port)
363 {
364 	int i;
365 	u8 val;
366 
367 	/* Spin waiting for TX fifo to have space available */
368 	for (i = 0; i < 100000; i++) {
369 		val = ioread32be(port->membase + ULITE_STATUS);
370 		if ((val & ULITE_STATUS_TXFULL) == 0)
371 			break;
372 		cpu_relax();
373 	}
374 }
375 
376 static void ulite_console_putchar(struct uart_port *port, int ch)
377 {
378 	ulite_console_wait_tx(port);
379 	iowrite32be(ch, port->membase + ULITE_TX);
380 }
381 
382 static void ulite_console_write(struct console *co, const char *s,
383 				unsigned int count)
384 {
385 	struct uart_port *port = &ulite_ports[co->index];
386 	unsigned long flags;
387 	unsigned int ier;
388 	int locked = 1;
389 
390 	if (oops_in_progress) {
391 		locked = spin_trylock_irqsave(&port->lock, flags);
392 	} else
393 		spin_lock_irqsave(&port->lock, flags);
394 
395 	/* save and disable interrupt */
396 	ier = ioread32be(port->membase + ULITE_STATUS) & ULITE_STATUS_IE;
397 	iowrite32be(0, port->membase + ULITE_CONTROL);
398 
399 	uart_console_write(port, s, count, ulite_console_putchar);
400 
401 	ulite_console_wait_tx(port);
402 
403 	/* restore interrupt state */
404 	if (ier)
405 		iowrite32be(ULITE_CONTROL_IE, port->membase + ULITE_CONTROL);
406 
407 	if (locked)
408 		spin_unlock_irqrestore(&port->lock, flags);
409 }
410 
411 static int ulite_console_setup(struct console *co, char *options)
412 {
413 	struct uart_port *port;
414 	int baud = 9600;
415 	int bits = 8;
416 	int parity = 'n';
417 	int flow = 'n';
418 
419 	if (co->index < 0 || co->index >= ULITE_NR_UARTS)
420 		return -EINVAL;
421 
422 	port = &ulite_ports[co->index];
423 
424 	/* Has the device been initialized yet? */
425 	if (!port->mapbase) {
426 		pr_debug("console on ttyUL%i not present\n", co->index);
427 		return -ENODEV;
428 	}
429 
430 	/* not initialized yet? */
431 	if (!port->membase) {
432 		if (ulite_request_port(port))
433 			return -ENODEV;
434 	}
435 
436 	if (options)
437 		uart_parse_options(options, &baud, &parity, &bits, &flow);
438 
439 	return uart_set_options(port, co, baud, parity, bits, flow);
440 }
441 
442 static struct uart_driver ulite_uart_driver;
443 
444 static struct console ulite_console = {
445 	.name	= ULITE_NAME,
446 	.write	= ulite_console_write,
447 	.device	= uart_console_device,
448 	.setup	= ulite_console_setup,
449 	.flags	= CON_PRINTBUFFER,
450 	.index	= -1, /* Specified on the cmdline (e.g. console=ttyUL0 ) */
451 	.data	= &ulite_uart_driver,
452 };
453 
454 static int __init ulite_console_init(void)
455 {
456 	register_console(&ulite_console);
457 	return 0;
458 }
459 
460 console_initcall(ulite_console_init);
461 
462 #endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */
463 
464 static struct uart_driver ulite_uart_driver = {
465 	.owner		= THIS_MODULE,
466 	.driver_name	= "uartlite",
467 	.dev_name	= ULITE_NAME,
468 	.major		= ULITE_MAJOR,
469 	.minor		= ULITE_MINOR,
470 	.nr		= ULITE_NR_UARTS,
471 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
472 	.cons		= &ulite_console,
473 #endif
474 };
475 
476 /* ---------------------------------------------------------------------
477  * Port assignment functions (mapping devices to uart_port structures)
478  */
479 
480 /** ulite_assign: register a uartlite device with the driver
481  *
482  * @dev: pointer to device structure
483  * @id: requested id number.  Pass -1 for automatic port assignment
484  * @base: base address of uartlite registers
485  * @irq: irq number for uartlite
486  *
487  * Returns: 0 on success, <0 otherwise
488  */
489 static int ulite_assign(struct device *dev, int id, u32 base, int irq)
490 {
491 	struct uart_port *port;
492 	int rc;
493 
494 	/* if id = -1; then scan for a free id and use that */
495 	if (id < 0) {
496 		for (id = 0; id < ULITE_NR_UARTS; id++)
497 			if (ulite_ports[id].mapbase == 0)
498 				break;
499 	}
500 	if (id < 0 || id >= ULITE_NR_UARTS) {
501 		dev_err(dev, "%s%i too large\n", ULITE_NAME, id);
502 		return -EINVAL;
503 	}
504 
505 	if ((ulite_ports[id].mapbase) && (ulite_ports[id].mapbase != base)) {
506 		dev_err(dev, "cannot assign to %s%i; it is already in use\n",
507 			ULITE_NAME, id);
508 		return -EBUSY;
509 	}
510 
511 	port = &ulite_ports[id];
512 
513 	spin_lock_init(&port->lock);
514 	port->fifosize = 16;
515 	port->regshift = 2;
516 	port->iotype = UPIO_MEM;
517 	port->iobase = 1; /* mark port in use */
518 	port->mapbase = base;
519 	port->membase = NULL;
520 	port->ops = &ulite_ops;
521 	port->irq = irq;
522 	port->flags = UPF_BOOT_AUTOCONF;
523 	port->dev = dev;
524 	port->type = PORT_UNKNOWN;
525 	port->line = id;
526 
527 	dev_set_drvdata(dev, port);
528 
529 	/* Register the port */
530 	rc = uart_add_one_port(&ulite_uart_driver, port);
531 	if (rc) {
532 		dev_err(dev, "uart_add_one_port() failed; err=%i\n", rc);
533 		port->mapbase = 0;
534 		dev_set_drvdata(dev, NULL);
535 		return rc;
536 	}
537 
538 	return 0;
539 }
540 
541 /** ulite_release: register a uartlite device with the driver
542  *
543  * @dev: pointer to device structure
544  */
545 static int ulite_release(struct device *dev)
546 {
547 	struct uart_port *port = dev_get_drvdata(dev);
548 	int rc = 0;
549 
550 	if (port) {
551 		rc = uart_remove_one_port(&ulite_uart_driver, port);
552 		dev_set_drvdata(dev, NULL);
553 		port->mapbase = 0;
554 	}
555 
556 	return rc;
557 }
558 
559 /* ---------------------------------------------------------------------
560  * Platform bus binding
561  */
562 
563 #if defined(CONFIG_OF)
564 /* Match table for of_platform binding */
565 static struct of_device_id ulite_of_match[] = {
566 	{ .compatible = "xlnx,opb-uartlite-1.00.b", },
567 	{ .compatible = "xlnx,xps-uartlite-1.00.a", },
568 	{}
569 };
570 MODULE_DEVICE_TABLE(of, ulite_of_match);
571 #endif /* CONFIG_OF */
572 
573 static int ulite_probe(struct platform_device *pdev)
574 {
575 	struct resource *res, *res2;
576 	int id = pdev->id;
577 #ifdef CONFIG_OF
578 	const __be32 *prop;
579 
580 	prop = of_get_property(pdev->dev.of_node, "port-number", NULL);
581 	if (prop)
582 		id = be32_to_cpup(prop);
583 #endif
584 
585 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
586 	if (!res)
587 		return -ENODEV;
588 
589 	res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
590 	if (!res2)
591 		return -ENODEV;
592 
593 	return ulite_assign(&pdev->dev, id, res->start, res2->start);
594 }
595 
596 static int ulite_remove(struct platform_device *pdev)
597 {
598 	return ulite_release(&pdev->dev);
599 }
600 
601 /* work with hotplug and coldplug */
602 MODULE_ALIAS("platform:uartlite");
603 
604 static struct platform_driver ulite_platform_driver = {
605 	.probe = ulite_probe,
606 	.remove = ulite_remove,
607 	.driver = {
608 		.owner = THIS_MODULE,
609 		.name  = "uartlite",
610 		.of_match_table = of_match_ptr(ulite_of_match),
611 	},
612 };
613 
614 /* ---------------------------------------------------------------------
615  * Module setup/teardown
616  */
617 
618 int __init ulite_init(void)
619 {
620 	int ret;
621 
622 	pr_debug("uartlite: calling uart_register_driver()\n");
623 	ret = uart_register_driver(&ulite_uart_driver);
624 	if (ret)
625 		goto err_uart;
626 
627 	pr_debug("uartlite: calling platform_driver_register()\n");
628 	ret = platform_driver_register(&ulite_platform_driver);
629 	if (ret)
630 		goto err_plat;
631 
632 	return 0;
633 
634 err_plat:
635 	uart_unregister_driver(&ulite_uart_driver);
636 err_uart:
637 	printk(KERN_ERR "registering uartlite driver failed: err=%i", ret);
638 	return ret;
639 }
640 
641 void __exit ulite_exit(void)
642 {
643 	platform_driver_unregister(&ulite_platform_driver);
644 	uart_unregister_driver(&ulite_uart_driver);
645 }
646 
647 module_init(ulite_init);
648 module_exit(ulite_exit);
649 
650 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
651 MODULE_DESCRIPTION("Xilinx uartlite serial driver");
652 MODULE_LICENSE("GPL");
653