altera_jtaguart.c revision 3d1c90d48cbe335a47a6a5a05ff731a86eacf6fb 
1/*
2 * altera_jtaguart.c -- Altera JTAG UART driver
3 *
4 * Based on mcf.c -- Freescale ColdFire UART driver
5 *
6 * (C) Copyright 2003-2007, Greg Ungerer <gerg@snapgear.com>
7 * (C) Copyright 2008, Thomas Chou <thomas@wytron.com.tw>
8 * (C) Copyright 2010, Tobias Klauser <tklauser@distanz.ch>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
14 */
15
16#include <linux/kernel.h>
17#include <linux/init.h>
18#include <linux/interrupt.h>
19#include <linux/module.h>
20#include <linux/console.h>
21#include <linux/of.h>
22#include <linux/tty.h>
23#include <linux/tty_flip.h>
24#include <linux/serial.h>
25#include <linux/serial_core.h>
26#include <linux/platform_device.h>
27#include <linux/io.h>
28#include <linux/altera_jtaguart.h>
29
30#define DRV_NAME "altera_jtaguart"
31
32/*
33 * Altera JTAG UART register definitions according to the Altera JTAG UART
34 * datasheet: http://www.altera.com/literature/hb/nios2/n2cpu_nii51009.pdf
35 */
36
37#define ALTERA_JTAGUART_SIZE			8
38
39#define ALTERA_JTAGUART_DATA_REG		0
40
41#define ALTERA_JTAGUART_DATA_DATA_MSK		0x000000FF
42#define ALTERA_JTAGUART_DATA_RVALID_MSK		0x00008000
43#define ALTERA_JTAGUART_DATA_RAVAIL_MSK		0xFFFF0000
44#define ALTERA_JTAGUART_DATA_RAVAIL_OFF		16
45
46#define ALTERA_JTAGUART_CONTROL_REG		4
47
48#define ALTERA_JTAGUART_CONTROL_RE_MSK		0x00000001
49#define ALTERA_JTAGUART_CONTROL_WE_MSK		0x00000002
50#define ALTERA_JTAGUART_CONTROL_RI_MSK		0x00000100
51#define ALTERA_JTAGUART_CONTROL_RI_OFF		8
52#define ALTERA_JTAGUART_CONTROL_WI_MSK		0x00000200
53#define ALTERA_JTAGUART_CONTROL_AC_MSK		0x00000400
54#define ALTERA_JTAGUART_CONTROL_WSPACE_MSK	0xFFFF0000
55#define ALTERA_JTAGUART_CONTROL_WSPACE_OFF	16
56
57/*
58 * Local per-uart structure.
59 */
60struct altera_jtaguart {
61	struct uart_port port;
62	unsigned int sigs;	/* Local copy of line sigs */
63	unsigned long imr;	/* Local IMR mirror */
64};
65
66static unsigned int altera_jtaguart_tx_empty(struct uart_port *port)
67{
68	return (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
69		ALTERA_JTAGUART_CONTROL_WSPACE_MSK) ? TIOCSER_TEMT : 0;
70}
71
72static unsigned int altera_jtaguart_get_mctrl(struct uart_port *port)
73{
74	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
75}
76
77static void altera_jtaguart_set_mctrl(struct uart_port *port, unsigned int sigs)
78{
79}
80
81static void altera_jtaguart_start_tx(struct uart_port *port)
82{
83	struct altera_jtaguart *pp =
84	    container_of(port, struct altera_jtaguart, port);
85
86	pp->imr |= ALTERA_JTAGUART_CONTROL_WE_MSK;
87	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
88}
89
90static void altera_jtaguart_stop_tx(struct uart_port *port)
91{
92	struct altera_jtaguart *pp =
93	    container_of(port, struct altera_jtaguart, port);
94
95	pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
96	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
97}
98
99static void altera_jtaguart_stop_rx(struct uart_port *port)
100{
101	struct altera_jtaguart *pp =
102	    container_of(port, struct altera_jtaguart, port);
103
104	pp->imr &= ~ALTERA_JTAGUART_CONTROL_RE_MSK;
105	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
106}
107
108static void altera_jtaguart_break_ctl(struct uart_port *port, int break_state)
109{
110}
111
112static void altera_jtaguart_set_termios(struct uart_port *port,
113					struct ktermios *termios,
114					struct ktermios *old)
115{
116	/* Just copy the old termios settings back */
117	if (old)
118		tty_termios_copy_hw(termios, old);
119}
120
121static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
122{
123	struct uart_port *port = &pp->port;
124	unsigned char ch, flag;
125	unsigned long status;
126
127	while ((status = readl(port->membase + ALTERA_JTAGUART_DATA_REG)) &
128	       ALTERA_JTAGUART_DATA_RVALID_MSK) {
129		ch = status & ALTERA_JTAGUART_DATA_DATA_MSK;
130		flag = TTY_NORMAL;
131		port->icount.rx++;
132
133		if (uart_handle_sysrq_char(port, ch))
134			continue;
135		uart_insert_char(port, 0, 0, ch, flag);
136	}
137
138	spin_unlock(&port->lock);
139	tty_flip_buffer_push(&port->state->port);
140	spin_lock(&port->lock);
141}
142
143static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
144{
145	struct uart_port *port = &pp->port;
146	struct circ_buf *xmit = &port->state->xmit;
147	unsigned int pending, count;
148
149	if (port->x_char) {
150		/* Send special char - probably flow control */
151		writel(port->x_char, port->membase + ALTERA_JTAGUART_DATA_REG);
152		port->x_char = 0;
153		port->icount.tx++;
154		return;
155	}
156
157	pending = uart_circ_chars_pending(xmit);
158	if (pending > 0) {
159		count = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
160				ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >>
161			ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
162		if (count > pending)
163			count = pending;
164		if (count > 0) {
165			pending -= count;
166			while (count--) {
167				writel(xmit->buf[xmit->tail],
168				       port->membase + ALTERA_JTAGUART_DATA_REG);
169				xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
170				port->icount.tx++;
171			}
172			if (pending < WAKEUP_CHARS)
173				uart_write_wakeup(port);
174		}
175	}
176
177	if (pending == 0) {
178		pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
179		writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
180	}
181}
182
183static irqreturn_t altera_jtaguart_interrupt(int irq, void *data)
184{
185	struct uart_port *port = data;
186	struct altera_jtaguart *pp =
187	    container_of(port, struct altera_jtaguart, port);
188	unsigned int isr;
189
190	isr = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) >>
191	       ALTERA_JTAGUART_CONTROL_RI_OFF) & pp->imr;
192
193	spin_lock(&port->lock);
194
195	if (isr & ALTERA_JTAGUART_CONTROL_RE_MSK)
196		altera_jtaguart_rx_chars(pp);
197	if (isr & ALTERA_JTAGUART_CONTROL_WE_MSK)
198		altera_jtaguart_tx_chars(pp);
199
200	spin_unlock(&port->lock);
201
202	return IRQ_RETVAL(isr);
203}
204
205static void altera_jtaguart_config_port(struct uart_port *port, int flags)
206{
207	port->type = PORT_ALTERA_JTAGUART;
208
209	/* Clear mask, so no surprise interrupts. */
210	writel(0, port->membase + ALTERA_JTAGUART_CONTROL_REG);
211}
212
213static int altera_jtaguart_startup(struct uart_port *port)
214{
215	struct altera_jtaguart *pp =
216	    container_of(port, struct altera_jtaguart, port);
217	unsigned long flags;
218	int ret;
219
220	ret = request_irq(port->irq, altera_jtaguart_interrupt, 0,
221			DRV_NAME, port);
222	if (ret) {
223		pr_err(DRV_NAME ": unable to attach Altera JTAG UART %d "
224		       "interrupt vector=%d\n", port->line, port->irq);
225		return ret;
226	}
227
228	spin_lock_irqsave(&port->lock, flags);
229
230	/* Enable RX interrupts now */
231	pp->imr = ALTERA_JTAGUART_CONTROL_RE_MSK;
232	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
233
234	spin_unlock_irqrestore(&port->lock, flags);
235
236	return 0;
237}
238
239static void altera_jtaguart_shutdown(struct uart_port *port)
240{
241	struct altera_jtaguart *pp =
242	    container_of(port, struct altera_jtaguart, port);
243	unsigned long flags;
244
245	spin_lock_irqsave(&port->lock, flags);
246
247	/* Disable all interrupts now */
248	pp->imr = 0;
249	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
250
251	spin_unlock_irqrestore(&port->lock, flags);
252
253	free_irq(port->irq, port);
254}
255
256static const char *altera_jtaguart_type(struct uart_port *port)
257{
258	return (port->type == PORT_ALTERA_JTAGUART) ? "Altera JTAG UART" : NULL;
259}
260
261static int altera_jtaguart_request_port(struct uart_port *port)
262{
263	/* UARTs always present */
264	return 0;
265}
266
267static void altera_jtaguart_release_port(struct uart_port *port)
268{
269	/* Nothing to release... */
270}
271
272static int altera_jtaguart_verify_port(struct uart_port *port,
273				       struct serial_struct *ser)
274{
275	if (ser->type != PORT_UNKNOWN && ser->type != PORT_ALTERA_JTAGUART)
276		return -EINVAL;
277	return 0;
278}
279
280/*
281 *	Define the basic serial functions we support.
282 */
283static struct uart_ops altera_jtaguart_ops = {
284	.tx_empty	= altera_jtaguart_tx_empty,
285	.get_mctrl	= altera_jtaguart_get_mctrl,
286	.set_mctrl	= altera_jtaguart_set_mctrl,
287	.start_tx	= altera_jtaguart_start_tx,
288	.stop_tx	= altera_jtaguart_stop_tx,
289	.stop_rx	= altera_jtaguart_stop_rx,
290	.break_ctl	= altera_jtaguart_break_ctl,
291	.startup	= altera_jtaguart_startup,
292	.shutdown	= altera_jtaguart_shutdown,
293	.set_termios	= altera_jtaguart_set_termios,
294	.type		= altera_jtaguart_type,
295	.request_port	= altera_jtaguart_request_port,
296	.release_port	= altera_jtaguart_release_port,
297	.config_port	= altera_jtaguart_config_port,
298	.verify_port	= altera_jtaguart_verify_port,
299};
300
301#define ALTERA_JTAGUART_MAXPORTS 1
302static struct altera_jtaguart altera_jtaguart_ports[ALTERA_JTAGUART_MAXPORTS];
303
304#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)
305
306#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
307static void altera_jtaguart_console_putc(struct console *co, int c)
308{
309	struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
310	unsigned long status;
311	unsigned long flags;
312
313	spin_lock_irqsave(&port->lock, flags);
314	while (((status = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG)) &
315		ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
316		if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) {
317			spin_unlock_irqrestore(&port->lock, flags);
318			return;	/* no connection activity */
319		}
320		spin_unlock_irqrestore(&port->lock, flags);
321		cpu_relax();
322		spin_lock_irqsave(&port->lock, flags);
323	}
324	writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
325	spin_unlock_irqrestore(&port->lock, flags);
326}
327#else
328static void altera_jtaguart_console_putc(struct console *co, int c)
329{
330	struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
331	unsigned long flags;
332
333	spin_lock_irqsave(&port->lock, flags);
334	while ((readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
335		ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
336		spin_unlock_irqrestore(&port->lock, flags);
337		cpu_relax();
338		spin_lock_irqsave(&port->lock, flags);
339	}
340	writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
341	spin_unlock_irqrestore(&port->lock, flags);
342}
343#endif
344
345static void altera_jtaguart_console_write(struct console *co, const char *s,
346					  unsigned int count)
347{
348	struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
349
350	uart_console_write(port, s, count, altera_jtaguart_console_putc);
351}
352
353static int __init altera_jtaguart_console_setup(struct console *co,
354						char *options)
355{
356	struct uart_port *port;
357
358	if (co->index < 0 || co->index >= ALTERA_JTAGUART_MAXPORTS)
359		return -EINVAL;
360	port = &altera_jtaguart_ports[co->index].port;
361	if (port->membase == NULL)
362		return -ENODEV;
363	return 0;
364}
365
366static struct uart_driver altera_jtaguart_driver;
367
368static struct console altera_jtaguart_console = {
369	.name	= "ttyJ",
370	.write	= altera_jtaguart_console_write,
371	.device	= uart_console_device,
372	.setup	= altera_jtaguart_console_setup,
373	.flags	= CON_PRINTBUFFER,
374	.index	= -1,
375	.data	= &altera_jtaguart_driver,
376};
377
378static int __init altera_jtaguart_console_init(void)
379{
380	register_console(&altera_jtaguart_console);
381	return 0;
382}
383
384console_initcall(altera_jtaguart_console_init);
385
386#define	ALTERA_JTAGUART_CONSOLE	(&altera_jtaguart_console)
387
388#else
389
390#define	ALTERA_JTAGUART_CONSOLE	NULL
391
392#endif /* CONFIG_ALTERA_JTAGUART_CONSOLE */
393
394static struct uart_driver altera_jtaguart_driver = {
395	.owner		= THIS_MODULE,
396	.driver_name	= "altera_jtaguart",
397	.dev_name	= "ttyJ",
398	.major		= ALTERA_JTAGUART_MAJOR,
399	.minor		= ALTERA_JTAGUART_MINOR,
400	.nr		= ALTERA_JTAGUART_MAXPORTS,
401	.cons		= ALTERA_JTAGUART_CONSOLE,
402};
403
404static int altera_jtaguart_probe(struct platform_device *pdev)
405{
406	struct altera_jtaguart_platform_uart *platp =
407			dev_get_platdata(&pdev->dev);
408	struct uart_port *port;
409	struct resource *res_irq, *res_mem;
410	int i = pdev->id;
411
412	/* -1 emphasizes that the platform must have one port, no .N suffix */
413	if (i == -1)
414		i = 0;
415
416	if (i >= ALTERA_JTAGUART_MAXPORTS)
417		return -EINVAL;
418
419	port = &altera_jtaguart_ports[i].port;
420
421	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
422	if (res_mem)
423		port->mapbase = res_mem->start;
424	else if (platp)
425		port->mapbase = platp->mapbase;
426	else
427		return -ENODEV;
428
429	res_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
430	if (res_irq)
431		port->irq = res_irq->start;
432	else if (platp)
433		port->irq = platp->irq;
434	else
435		return -ENODEV;
436
437	port->membase = ioremap(port->mapbase, ALTERA_JTAGUART_SIZE);
438	if (!port->membase)
439		return -ENOMEM;
440
441	port->line = i;
442	port->type = PORT_ALTERA_JTAGUART;
443	port->iotype = SERIAL_IO_MEM;
444	port->ops = &altera_jtaguart_ops;
445	port->flags = UPF_BOOT_AUTOCONF;
446
447	uart_add_one_port(&altera_jtaguart_driver, port);
448
449	return 0;
450}
451
452static int altera_jtaguart_remove(struct platform_device *pdev)
453{
454	struct uart_port *port;
455	int i = pdev->id;
456
457	if (i == -1)
458		i = 0;
459
460	port = &altera_jtaguart_ports[i].port;
461	uart_remove_one_port(&altera_jtaguart_driver, port);
462
463	return 0;
464}
465
466#ifdef CONFIG_OF
467static struct of_device_id altera_jtaguart_match[] = {
468	{ .compatible = "ALTR,juart-1.0", },
469	{ .compatible = "altr,juart-1.0", },
470	{},
471};
472MODULE_DEVICE_TABLE(of, altera_jtaguart_match);
473#endif /* CONFIG_OF */
474
475static struct platform_driver altera_jtaguart_platform_driver = {
476	.probe	= altera_jtaguart_probe,
477	.remove	= altera_jtaguart_remove,
478	.driver	= {
479		.name		= DRV_NAME,
480		.owner		= THIS_MODULE,
481		.of_match_table	= of_match_ptr(altera_jtaguart_match),
482	},
483};
484
485static int __init altera_jtaguart_init(void)
486{
487	int rc;
488
489	rc = uart_register_driver(&altera_jtaguart_driver);
490	if (rc)
491		return rc;
492	rc = platform_driver_register(&altera_jtaguart_platform_driver);
493	if (rc)
494		uart_unregister_driver(&altera_jtaguart_driver);
495	return rc;
496}
497
498static void __exit altera_jtaguart_exit(void)
499{
500	platform_driver_unregister(&altera_jtaguart_platform_driver);
501	uart_unregister_driver(&altera_jtaguart_driver);
502}
503
504module_init(altera_jtaguart_init);
505module_exit(altera_jtaguart_exit);
506
507MODULE_DESCRIPTION("Altera JTAG UART driver");
508MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
509MODULE_LICENSE("GPL");
510MODULE_ALIAS("platform:" DRV_NAME);
511