xref: /openbmc/linux/drivers/tty/serial/uartlite.c (revision 8c0b9ee8) 
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 <linux/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 struct uartlite_reg_ops {
61 	u32 (*in)(void __iomem *addr);
62 	void (*out)(u32 val, void __iomem *addr);
63 };
64 
65 static u32 uartlite_inbe32(void __iomem *addr)
66 {
67 	return ioread32be(addr);
68 }
69 
70 static void uartlite_outbe32(u32 val, void __iomem *addr)
71 {
72 	iowrite32be(val, addr);
73 }
74 
75 static struct uartlite_reg_ops uartlite_be = {
76 	.in = uartlite_inbe32,
77 	.out = uartlite_outbe32,
78 };
79 
80 static u32 uartlite_inle32(void __iomem *addr)
81 {
82 	return ioread32(addr);
83 }
84 
85 static void uartlite_outle32(u32 val, void __iomem *addr)
86 {
87 	iowrite32(val, addr);
88 }
89 
90 static struct uartlite_reg_ops uartlite_le = {
91 	.in = uartlite_inle32,
92 	.out = uartlite_outle32,
93 };
94 
95 static inline u32 uart_in32(u32 offset, struct uart_port *port)
96 {
97 	struct uartlite_reg_ops *reg_ops = port->private_data;
98 
99 	return reg_ops->in(port->membase + offset);
100 }
101 
102 static inline void uart_out32(u32 val, u32 offset, struct uart_port *port)
103 {
104 	struct uartlite_reg_ops *reg_ops = port->private_data;
105 
106 	reg_ops->out(val, port->membase + offset);
107 }
108 
109 static struct uart_port ulite_ports[ULITE_NR_UARTS];
110 
111 /* ---------------------------------------------------------------------
112  * Core UART driver operations
113  */
114 
115 static int ulite_receive(struct uart_port *port, int stat)
116 {
117 	struct tty_port *tport = &port->state->port;
118 	unsigned char ch = 0;
119 	char flag = TTY_NORMAL;
120 
121 	if ((stat & (ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
122 		     | ULITE_STATUS_FRAME)) == 0)
123 		return 0;
124 
125 	/* stats */
126 	if (stat & ULITE_STATUS_RXVALID) {
127 		port->icount.rx++;
128 		ch = uart_in32(ULITE_RX, port);
129 
130 		if (stat & ULITE_STATUS_PARITY)
131 			port->icount.parity++;
132 	}
133 
134 	if (stat & ULITE_STATUS_OVERRUN)
135 		port->icount.overrun++;
136 
137 	if (stat & ULITE_STATUS_FRAME)
138 		port->icount.frame++;
139 
140 
141 	/* drop byte with parity error if IGNPAR specificed */
142 	if (stat & port->ignore_status_mask & ULITE_STATUS_PARITY)
143 		stat &= ~ULITE_STATUS_RXVALID;
144 
145 	stat &= port->read_status_mask;
146 
147 	if (stat & ULITE_STATUS_PARITY)
148 		flag = TTY_PARITY;
149 
150 
151 	stat &= ~port->ignore_status_mask;
152 
153 	if (stat & ULITE_STATUS_RXVALID)
154 		tty_insert_flip_char(tport, ch, flag);
155 
156 	if (stat & ULITE_STATUS_FRAME)
157 		tty_insert_flip_char(tport, 0, TTY_FRAME);
158 
159 	if (stat & ULITE_STATUS_OVERRUN)
160 		tty_insert_flip_char(tport, 0, TTY_OVERRUN);
161 
162 	return 1;
163 }
164 
165 static int ulite_transmit(struct uart_port *port, int stat)
166 {
167 	struct circ_buf *xmit  = &port->state->xmit;
168 
169 	if (stat & ULITE_STATUS_TXFULL)
170 		return 0;
171 
172 	if (port->x_char) {
173 		uart_out32(port->x_char, ULITE_TX, port);
174 		port->x_char = 0;
175 		port->icount.tx++;
176 		return 1;
177 	}
178 
179 	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
180 		return 0;
181 
182 	uart_out32(xmit->buf[xmit->tail], ULITE_TX, port);
183 	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
184 	port->icount.tx++;
185 
186 	/* wake up */
187 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
188 		uart_write_wakeup(port);
189 
190 	return 1;
191 }
192 
193 static irqreturn_t ulite_isr(int irq, void *dev_id)
194 {
195 	struct uart_port *port = dev_id;
196 	int busy, n = 0;
197 
198 	do {
199 		int stat = uart_in32(ULITE_STATUS, port);
200 		busy  = ulite_receive(port, stat);
201 		busy |= ulite_transmit(port, stat);
202 		n++;
203 	} while (busy);
204 
205 	/* work done? */
206 	if (n > 1) {
207 		tty_flip_buffer_push(&port->state->port);
208 		return IRQ_HANDLED;
209 	} else {
210 		return IRQ_NONE;
211 	}
212 }
213 
214 static unsigned int ulite_tx_empty(struct uart_port *port)
215 {
216 	unsigned long flags;
217 	unsigned int ret;
218 
219 	spin_lock_irqsave(&port->lock, flags);
220 	ret = uart_in32(ULITE_STATUS, port);
221 	spin_unlock_irqrestore(&port->lock, flags);
222 
223 	return ret & ULITE_STATUS_TXEMPTY ? TIOCSER_TEMT : 0;
224 }
225 
226 static unsigned int ulite_get_mctrl(struct uart_port *port)
227 {
228 	return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
229 }
230 
231 static void ulite_set_mctrl(struct uart_port *port, unsigned int mctrl)
232 {
233 	/* N/A */
234 }
235 
236 static void ulite_stop_tx(struct uart_port *port)
237 {
238 	/* N/A */
239 }
240 
241 static void ulite_start_tx(struct uart_port *port)
242 {
243 	ulite_transmit(port, uart_in32(ULITE_STATUS, port));
244 }
245 
246 static void ulite_stop_rx(struct uart_port *port)
247 {
248 	/* don't forward any more data (like !CREAD) */
249 	port->ignore_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
250 		| ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
251 }
252 
253 static void ulite_break_ctl(struct uart_port *port, int ctl)
254 {
255 	/* N/A */
256 }
257 
258 static int ulite_startup(struct uart_port *port)
259 {
260 	int ret;
261 
262 	ret = request_irq(port->irq, ulite_isr, IRQF_SHARED, "uartlite", port);
263 	if (ret)
264 		return ret;
265 
266 	uart_out32(ULITE_CONTROL_RST_RX | ULITE_CONTROL_RST_TX,
267 		ULITE_CONTROL, port);
268 	uart_out32(ULITE_CONTROL_IE, ULITE_CONTROL, port);
269 
270 	return 0;
271 }
272 
273 static void ulite_shutdown(struct uart_port *port)
274 {
275 	uart_out32(0, ULITE_CONTROL, port);
276 	uart_in32(ULITE_CONTROL, port); /* dummy */
277 	free_irq(port->irq, port);
278 }
279 
280 static void ulite_set_termios(struct uart_port *port, struct ktermios *termios,
281 			      struct ktermios *old)
282 {
283 	unsigned long flags;
284 	unsigned int baud;
285 
286 	spin_lock_irqsave(&port->lock, flags);
287 
288 	port->read_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
289 		| ULITE_STATUS_TXFULL;
290 
291 	if (termios->c_iflag & INPCK)
292 		port->read_status_mask |=
293 			ULITE_STATUS_PARITY | ULITE_STATUS_FRAME;
294 
295 	port->ignore_status_mask = 0;
296 	if (termios->c_iflag & IGNPAR)
297 		port->ignore_status_mask |= ULITE_STATUS_PARITY
298 			| ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
299 
300 	/* ignore all characters if CREAD is not set */
301 	if ((termios->c_cflag & CREAD) == 0)
302 		port->ignore_status_mask |=
303 			ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
304 			| ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
305 
306 	/* update timeout */
307 	baud = uart_get_baud_rate(port, termios, old, 0, 460800);
308 	uart_update_timeout(port, termios->c_cflag, baud);
309 
310 	spin_unlock_irqrestore(&port->lock, flags);
311 }
312 
313 static const char *ulite_type(struct uart_port *port)
314 {
315 	return port->type == PORT_UARTLITE ? "uartlite" : NULL;
316 }
317 
318 static void ulite_release_port(struct uart_port *port)
319 {
320 	release_mem_region(port->mapbase, ULITE_REGION);
321 	iounmap(port->membase);
322 	port->membase = NULL;
323 }
324 
325 static int ulite_request_port(struct uart_port *port)
326 {
327 	int ret;
328 
329 	pr_debug("ulite console: port=%p; port->mapbase=%llx\n",
330 		 port, (unsigned long long) port->mapbase);
331 
332 	if (!request_mem_region(port->mapbase, ULITE_REGION, "uartlite")) {
333 		dev_err(port->dev, "Memory region busy\n");
334 		return -EBUSY;
335 	}
336 
337 	port->membase = ioremap(port->mapbase, ULITE_REGION);
338 	if (!port->membase) {
339 		dev_err(port->dev, "Unable to map registers\n");
340 		release_mem_region(port->mapbase, ULITE_REGION);
341 		return -EBUSY;
342 	}
343 
344 	port->private_data = &uartlite_be;
345 	ret = uart_in32(ULITE_CONTROL, port);
346 	uart_out32(ULITE_CONTROL_RST_TX, ULITE_CONTROL, port);
347 	ret = uart_in32(ULITE_STATUS, port);
348 	/* Endianess detection */
349 	if ((ret & ULITE_STATUS_TXEMPTY) != ULITE_STATUS_TXEMPTY)
350 		port->private_data = &uartlite_le;
351 
352 	return 0;
353 }
354 
355 static void ulite_config_port(struct uart_port *port, int flags)
356 {
357 	if (!ulite_request_port(port))
358 		port->type = PORT_UARTLITE;
359 }
360 
361 static int ulite_verify_port(struct uart_port *port, struct serial_struct *ser)
362 {
363 	/* we don't want the core code to modify any port params */
364 	return -EINVAL;
365 }
366 
367 #ifdef CONFIG_CONSOLE_POLL
368 static int ulite_get_poll_char(struct uart_port *port)
369 {
370 	if (!(uart_in32(ULITE_STATUS, port) & ULITE_STATUS_RXVALID))
371 		return NO_POLL_CHAR;
372 
373 	return uart_in32(ULITE_RX, port);
374 }
375 
376 static void ulite_put_poll_char(struct uart_port *port, unsigned char ch)
377 {
378 	while (uart_in32(ULITE_STATUS, port) & ULITE_STATUS_TXFULL)
379 		cpu_relax();
380 
381 	/* write char to device */
382 	uart_out32(ch, ULITE_TX, port);
383 }
384 #endif
385 
386 static struct uart_ops ulite_ops = {
387 	.tx_empty	= ulite_tx_empty,
388 	.set_mctrl	= ulite_set_mctrl,
389 	.get_mctrl	= ulite_get_mctrl,
390 	.stop_tx	= ulite_stop_tx,
391 	.start_tx	= ulite_start_tx,
392 	.stop_rx	= ulite_stop_rx,
393 	.break_ctl	= ulite_break_ctl,
394 	.startup	= ulite_startup,
395 	.shutdown	= ulite_shutdown,
396 	.set_termios	= ulite_set_termios,
397 	.type		= ulite_type,
398 	.release_port	= ulite_release_port,
399 	.request_port	= ulite_request_port,
400 	.config_port	= ulite_config_port,
401 	.verify_port	= ulite_verify_port,
402 #ifdef CONFIG_CONSOLE_POLL
403 	.poll_get_char	= ulite_get_poll_char,
404 	.poll_put_char	= ulite_put_poll_char,
405 #endif
406 };
407 
408 /* ---------------------------------------------------------------------
409  * Console driver operations
410  */
411 
412 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
413 static void ulite_console_wait_tx(struct uart_port *port)
414 {
415 	u8 val;
416 	unsigned long timeout;
417 
418 	/*
419 	 * Spin waiting for TX fifo to have space available.
420 	 * When using the Microblaze Debug Module this can take up to 1s
421 	 */
422 	timeout = jiffies + msecs_to_jiffies(1000);
423 	while (1) {
424 		val = uart_in32(ULITE_STATUS, port);
425 		if ((val & ULITE_STATUS_TXFULL) == 0)
426 			break;
427 		if (time_after(jiffies, timeout)) {
428 			dev_warn(port->dev,
429 				 "timeout waiting for TX buffer empty\n");
430 			break;
431 		}
432 		cpu_relax();
433 	}
434 }
435 
436 static void ulite_console_putchar(struct uart_port *port, int ch)
437 {
438 	ulite_console_wait_tx(port);
439 	uart_out32(ch, ULITE_TX, port);
440 }
441 
442 static void ulite_console_write(struct console *co, const char *s,
443 				unsigned int count)
444 {
445 	struct uart_port *port = &ulite_ports[co->index];
446 	unsigned long flags;
447 	unsigned int ier;
448 	int locked = 1;
449 
450 	if (oops_in_progress) {
451 		locked = spin_trylock_irqsave(&port->lock, flags);
452 	} else
453 		spin_lock_irqsave(&port->lock, flags);
454 
455 	/* save and disable interrupt */
456 	ier = uart_in32(ULITE_STATUS, port) & ULITE_STATUS_IE;
457 	uart_out32(0, ULITE_CONTROL, port);
458 
459 	uart_console_write(port, s, count, ulite_console_putchar);
460 
461 	ulite_console_wait_tx(port);
462 
463 	/* restore interrupt state */
464 	if (ier)
465 		uart_out32(ULITE_CONTROL_IE, ULITE_CONTROL, port);
466 
467 	if (locked)
468 		spin_unlock_irqrestore(&port->lock, flags);
469 }
470 
471 static int ulite_console_setup(struct console *co, char *options)
472 {
473 	struct uart_port *port;
474 	int baud = 9600;
475 	int bits = 8;
476 	int parity = 'n';
477 	int flow = 'n';
478 
479 	if (co->index < 0 || co->index >= ULITE_NR_UARTS)
480 		return -EINVAL;
481 
482 	port = &ulite_ports[co->index];
483 
484 	/* Has the device been initialized yet? */
485 	if (!port->mapbase) {
486 		pr_debug("console on ttyUL%i not present\n", co->index);
487 		return -ENODEV;
488 	}
489 
490 	/* not initialized yet? */
491 	if (!port->membase) {
492 		if (ulite_request_port(port))
493 			return -ENODEV;
494 	}
495 
496 	if (options)
497 		uart_parse_options(options, &baud, &parity, &bits, &flow);
498 
499 	return uart_set_options(port, co, baud, parity, bits, flow);
500 }
501 
502 static struct uart_driver ulite_uart_driver;
503 
504 static struct console ulite_console = {
505 	.name	= ULITE_NAME,
506 	.write	= ulite_console_write,
507 	.device	= uart_console_device,
508 	.setup	= ulite_console_setup,
509 	.flags	= CON_PRINTBUFFER,
510 	.index	= -1, /* Specified on the cmdline (e.g. console=ttyUL0 ) */
511 	.data	= &ulite_uart_driver,
512 };
513 
514 static int __init ulite_console_init(void)
515 {
516 	register_console(&ulite_console);
517 	return 0;
518 }
519 
520 console_initcall(ulite_console_init);
521 
522 #endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */
523 
524 static struct uart_driver ulite_uart_driver = {
525 	.owner		= THIS_MODULE,
526 	.driver_name	= "uartlite",
527 	.dev_name	= ULITE_NAME,
528 	.major		= ULITE_MAJOR,
529 	.minor		= ULITE_MINOR,
530 	.nr		= ULITE_NR_UARTS,
531 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
532 	.cons		= &ulite_console,
533 #endif
534 };
535 
536 /* ---------------------------------------------------------------------
537  * Port assignment functions (mapping devices to uart_port structures)
538  */
539 
540 /** ulite_assign: register a uartlite device with the driver
541  *
542  * @dev: pointer to device structure
543  * @id: requested id number.  Pass -1 for automatic port assignment
544  * @base: base address of uartlite registers
545  * @irq: irq number for uartlite
546  *
547  * Returns: 0 on success, <0 otherwise
548  */
549 static int ulite_assign(struct device *dev, int id, u32 base, int irq)
550 {
551 	struct uart_port *port;
552 	int rc;
553 
554 	/* if id = -1; then scan for a free id and use that */
555 	if (id < 0) {
556 		for (id = 0; id < ULITE_NR_UARTS; id++)
557 			if (ulite_ports[id].mapbase == 0)
558 				break;
559 	}
560 	if (id < 0 || id >= ULITE_NR_UARTS) {
561 		dev_err(dev, "%s%i too large\n", ULITE_NAME, id);
562 		return -EINVAL;
563 	}
564 
565 	if ((ulite_ports[id].mapbase) && (ulite_ports[id].mapbase != base)) {
566 		dev_err(dev, "cannot assign to %s%i; it is already in use\n",
567 			ULITE_NAME, id);
568 		return -EBUSY;
569 	}
570 
571 	port = &ulite_ports[id];
572 
573 	spin_lock_init(&port->lock);
574 	port->fifosize = 16;
575 	port->regshift = 2;
576 	port->iotype = UPIO_MEM;
577 	port->iobase = 1; /* mark port in use */
578 	port->mapbase = base;
579 	port->membase = NULL;
580 	port->ops = &ulite_ops;
581 	port->irq = irq;
582 	port->flags = UPF_BOOT_AUTOCONF;
583 	port->dev = dev;
584 	port->type = PORT_UNKNOWN;
585 	port->line = id;
586 
587 	dev_set_drvdata(dev, port);
588 
589 	/* Register the port */
590 	rc = uart_add_one_port(&ulite_uart_driver, port);
591 	if (rc) {
592 		dev_err(dev, "uart_add_one_port() failed; err=%i\n", rc);
593 		port->mapbase = 0;
594 		dev_set_drvdata(dev, NULL);
595 		return rc;
596 	}
597 
598 	return 0;
599 }
600 
601 /** ulite_release: register a uartlite device with the driver
602  *
603  * @dev: pointer to device structure
604  */
605 static int ulite_release(struct device *dev)
606 {
607 	struct uart_port *port = dev_get_drvdata(dev);
608 	int rc = 0;
609 
610 	if (port) {
611 		rc = uart_remove_one_port(&ulite_uart_driver, port);
612 		dev_set_drvdata(dev, NULL);
613 		port->mapbase = 0;
614 	}
615 
616 	return rc;
617 }
618 
619 /* ---------------------------------------------------------------------
620  * Platform bus binding
621  */
622 
623 #if defined(CONFIG_OF)
624 /* Match table for of_platform binding */
625 static struct of_device_id ulite_of_match[] = {
626 	{ .compatible = "xlnx,opb-uartlite-1.00.b", },
627 	{ .compatible = "xlnx,xps-uartlite-1.00.a", },
628 	{}
629 };
630 MODULE_DEVICE_TABLE(of, ulite_of_match);
631 #endif /* CONFIG_OF */
632 
633 static int ulite_probe(struct platform_device *pdev)
634 {
635 	struct resource *res, *res2;
636 	int id = pdev->id;
637 #ifdef CONFIG_OF
638 	const __be32 *prop;
639 
640 	prop = of_get_property(pdev->dev.of_node, "port-number", NULL);
641 	if (prop)
642 		id = be32_to_cpup(prop);
643 #endif
644 
645 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
646 	if (!res)
647 		return -ENODEV;
648 
649 	res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
650 	if (!res2)
651 		return -ENODEV;
652 
653 	return ulite_assign(&pdev->dev, id, res->start, res2->start);
654 }
655 
656 static int ulite_remove(struct platform_device *pdev)
657 {
658 	return ulite_release(&pdev->dev);
659 }
660 
661 /* work with hotplug and coldplug */
662 MODULE_ALIAS("platform:uartlite");
663 
664 static struct platform_driver ulite_platform_driver = {
665 	.probe = ulite_probe,
666 	.remove = ulite_remove,
667 	.driver = {
668 		.name  = "uartlite",
669 		.of_match_table = of_match_ptr(ulite_of_match),
670 	},
671 };
672 
673 /* ---------------------------------------------------------------------
674  * Module setup/teardown
675  */
676 
677 static int __init ulite_init(void)
678 {
679 	int ret;
680 
681 	pr_debug("uartlite: calling uart_register_driver()\n");
682 	ret = uart_register_driver(&ulite_uart_driver);
683 	if (ret)
684 		goto err_uart;
685 
686 	pr_debug("uartlite: calling platform_driver_register()\n");
687 	ret = platform_driver_register(&ulite_platform_driver);
688 	if (ret)
689 		goto err_plat;
690 
691 	return 0;
692 
693 err_plat:
694 	uart_unregister_driver(&ulite_uart_driver);
695 err_uart:
696 	pr_err("registering uartlite driver failed: err=%i", ret);
697 	return ret;
698 }
699 
700 static void __exit ulite_exit(void)
701 {
702 	platform_driver_unregister(&ulite_platform_driver);
703 	uart_unregister_driver(&ulite_uart_driver);
704 }
705 
706 module_init(ulite_init);
707 module_exit(ulite_exit);
708 
709 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
710 MODULE_DESCRIPTION("Xilinx uartlite serial driver");
711 MODULE_LICENSE("GPL");
712