altera_jtaguart.c revision 3231f075070ac61ab7174a9a82bdc6d7b1de10bb 
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/tty.h>
22#include <linux/tty_flip.h>
23#include <linux/serial.h>
24#include <linux/serial_core.h>
25#include <linux/platform_device.h>
26#include <linux/io.h>
27#include <linux/altera_jtaguart.h>
28
29#define DRV_NAME "altera_jtaguart"
30
31/*
32 * Altera JTAG UART register definitions according to the Altera JTAG UART
33 * datasheet: http://www.altera.com/literature/hb/nios2/n2cpu_nii51009.pdf
34 */
35
36#define ALTERA_JTAGUART_SIZE			8
37
38#define ALTERA_JTAGUART_DATA_REG		0
39
40#define ALTERA_JTAGUART_DATA_DATA_MSK		0x000000FF
41#define ALTERA_JTAGUART_DATA_RVALID_MSK		0x00008000
42#define ALTERA_JTAGUART_DATA_RAVAIL_MSK		0xFFFF0000
43#define ALTERA_JTAGUART_DATA_RAVAIL_OFF		16
44
45#define ALTERA_JTAGUART_CONTROL_REG		4
46
47#define ALTERA_JTAGUART_CONTROL_RE_MSK		0x00000001
48#define ALTERA_JTAGUART_CONTROL_WE_MSK		0x00000002
49#define ALTERA_JTAGUART_CONTROL_RI_MSK		0x00000100
50#define ALTERA_JTAGUART_CONTROL_RI_OFF		8
51#define ALTERA_JTAGUART_CONTROL_WI_MSK		0x00000200
52#define ALTERA_JTAGUART_CONTROL_AC_MSK		0x00000400
53#define ALTERA_JTAGUART_CONTROL_WSPACE_MSK	0xFFFF0000
54#define ALTERA_JTAGUART_CONTROL_WSPACE_OFF	16
55
56/*
57 * Local per-uart structure.
58 */
59struct altera_jtaguart {
60	struct uart_port port;
61	unsigned int sigs;	/* Local copy of line sigs */
62	unsigned long imr;	/* Local IMR mirror */
63};
64
65static unsigned int altera_jtaguart_tx_empty(struct uart_port *port)
66{
67	return (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
68		ALTERA_JTAGUART_CONTROL_WSPACE_MSK) ? TIOCSER_TEMT : 0;
69}
70
71static unsigned int altera_jtaguart_get_mctrl(struct uart_port *port)
72{
73	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
74}
75
76static void altera_jtaguart_set_mctrl(struct uart_port *port, unsigned int sigs)
77{
78}
79
80static void altera_jtaguart_start_tx(struct uart_port *port)
81{
82	struct altera_jtaguart *pp =
83	    container_of(port, struct altera_jtaguart, port);
84
85	pp->imr |= ALTERA_JTAGUART_CONTROL_WE_MSK;
86	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
87}
88
89static void altera_jtaguart_stop_tx(struct uart_port *port)
90{
91	struct altera_jtaguart *pp =
92	    container_of(port, struct altera_jtaguart, port);
93
94	pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
95	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
96}
97
98static void altera_jtaguart_stop_rx(struct uart_port *port)
99{
100	struct altera_jtaguart *pp =
101	    container_of(port, struct altera_jtaguart, port);
102
103	pp->imr &= ~ALTERA_JTAGUART_CONTROL_RE_MSK;
104	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
105}
106
107static void altera_jtaguart_break_ctl(struct uart_port *port, int break_state)
108{
109}
110
111static void altera_jtaguart_enable_ms(struct uart_port *port)
112{
113}
114
115static void altera_jtaguart_set_termios(struct uart_port *port,
116					struct ktermios *termios,
117					struct ktermios *old)
118{
119	/* Just copy the old termios settings back */
120	if (old)
121		tty_termios_copy_hw(termios, old);
122}
123
124static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
125{
126	struct uart_port *port = &pp->port;
127	unsigned char ch, flag;
128	unsigned long status;
129
130	while ((status = readl(port->membase + ALTERA_JTAGUART_DATA_REG)) &
131	       ALTERA_JTAGUART_DATA_RVALID_MSK) {
132		ch = status & ALTERA_JTAGUART_DATA_DATA_MSK;
133		flag = TTY_NORMAL;
134		port->icount.rx++;
135
136		if (uart_handle_sysrq_char(port, ch))
137			continue;
138		uart_insert_char(port, 0, 0, ch, flag);
139	}
140
141	tty_flip_buffer_push(port->state->port.tty);
142}
143
144static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
145{
146	struct uart_port *port = &pp->port;
147	struct circ_buf *xmit = &port->state->xmit;
148	unsigned int pending, count;
149
150	if (port->x_char) {
151		/* Send special char - probably flow control */
152		writel(port->x_char, port->membase + ALTERA_JTAGUART_DATA_REG);
153		port->x_char = 0;
154		port->icount.tx++;
155		return;
156	}
157
158	pending = uart_circ_chars_pending(xmit);
159	if (pending > 0) {
160		count = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
161				ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >>
162			ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
163		if (count > pending)
164			count = pending;
165		if (count > 0) {
166			pending -= count;
167			while (count--) {
168				writel(xmit->buf[xmit->tail],
169				       port->membase + ALTERA_JTAGUART_DATA_REG);
170				xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
171				port->icount.tx++;
172			}
173			if (pending < WAKEUP_CHARS)
174				uart_write_wakeup(port);
175		}
176	}
177
178	if (pending == 0) {
179		pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
180		writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
181	}
182}
183
184static irqreturn_t altera_jtaguart_interrupt(int irq, void *data)
185{
186	struct uart_port *port = data;
187	struct altera_jtaguart *pp =
188	    container_of(port, struct altera_jtaguart, port);
189	unsigned int isr;
190
191	isr = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) >>
192	       ALTERA_JTAGUART_CONTROL_RI_OFF) & pp->imr;
193
194	spin_lock(&port->lock);
195
196	if (isr & ALTERA_JTAGUART_CONTROL_RE_MSK)
197		altera_jtaguart_rx_chars(pp);
198	if (isr & ALTERA_JTAGUART_CONTROL_WE_MSK)
199		altera_jtaguart_tx_chars(pp);
200
201	spin_unlock(&port->lock);
202
203	return IRQ_RETVAL(isr);
204}
205
206static void altera_jtaguart_config_port(struct uart_port *port, int flags)
207{
208	port->type = PORT_ALTERA_JTAGUART;
209
210	/* Clear mask, so no surprise interrupts. */
211	writel(0, port->membase + ALTERA_JTAGUART_CONTROL_REG);
212}
213
214static int altera_jtaguart_startup(struct uart_port *port)
215{
216	struct altera_jtaguart *pp =
217	    container_of(port, struct altera_jtaguart, port);
218	unsigned long flags;
219	int ret;
220
221	ret = request_irq(port->irq, altera_jtaguart_interrupt, IRQF_DISABLED,
222			DRV_NAME, port);
223	if (ret) {
224		pr_err(DRV_NAME ": unable to attach Altera JTAG UART %d "
225		       "interrupt vector=%d\n", port->line, port->irq);
226		return ret;
227	}
228
229	spin_lock_irqsave(&port->lock, flags);
230
231	/* Enable RX interrupts now */
232	pp->imr = ALTERA_JTAGUART_CONTROL_RE_MSK;
233	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
234
235	spin_unlock_irqrestore(&port->lock, flags);
236
237	return 0;
238}
239
240static void altera_jtaguart_shutdown(struct uart_port *port)
241{
242	struct altera_jtaguart *pp =
243	    container_of(port, struct altera_jtaguart, port);
244	unsigned long flags;
245
246	spin_lock_irqsave(&port->lock, flags);
247
248	/* Disable all interrupts now */
249	pp->imr = 0;
250	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
251
252	spin_unlock_irqrestore(&port->lock, flags);
253
254	free_irq(port->irq, port);
255}
256
257static const char *altera_jtaguart_type(struct uart_port *port)
258{
259	return (port->type == PORT_ALTERA_JTAGUART) ? "Altera JTAG UART" : NULL;
260}
261
262static int altera_jtaguart_request_port(struct uart_port *port)
263{
264	/* UARTs always present */
265	return 0;
266}
267
268static void altera_jtaguart_release_port(struct uart_port *port)
269{
270	/* Nothing to release... */
271}
272
273static int altera_jtaguart_verify_port(struct uart_port *port,
274				       struct serial_struct *ser)
275{
276	if (ser->type != PORT_UNKNOWN && ser->type != PORT_ALTERA_JTAGUART)
277		return -EINVAL;
278	return 0;
279}
280
281/*
282 *	Define the basic serial functions we support.
283 */
284static struct uart_ops altera_jtaguart_ops = {
285	.tx_empty	= altera_jtaguart_tx_empty,
286	.get_mctrl	= altera_jtaguart_get_mctrl,
287	.set_mctrl	= altera_jtaguart_set_mctrl,
288	.start_tx	= altera_jtaguart_start_tx,
289	.stop_tx	= altera_jtaguart_stop_tx,
290	.stop_rx	= altera_jtaguart_stop_rx,
291	.enable_ms	= altera_jtaguart_enable_ms,
292	.break_ctl	= altera_jtaguart_break_ctl,
293	.startup	= altera_jtaguart_startup,
294	.shutdown	= altera_jtaguart_shutdown,
295	.set_termios	= altera_jtaguart_set_termios,
296	.type		= altera_jtaguart_type,
297	.request_port	= altera_jtaguart_request_port,
298	.release_port	= altera_jtaguart_release_port,
299	.config_port	= altera_jtaguart_config_port,
300	.verify_port	= altera_jtaguart_verify_port,
301};
302
303#define ALTERA_JTAGUART_MAXPORTS 1
304static struct altera_jtaguart altera_jtaguart_ports[ALTERA_JTAGUART_MAXPORTS];
305
306#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)
307
308#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
309static void altera_jtaguart_console_putc(struct console *co, const char c)
310{
311	struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
312	unsigned long status;
313	unsigned long flags;
314
315	spin_lock_irqsave(&port->lock, flags);
316	while (((status = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG)) &
317		ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
318		if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) {
319			spin_unlock_irqrestore(&port->lock, flags);
320			return;	/* no connection activity */
321		}
322		spin_unlock_irqrestore(&port->lock, flags);
323		cpu_relax();
324		spin_lock_irqsave(&port->lock, flags);
325	}
326	writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
327	spin_unlock_irqrestore(&port->lock, flags);
328}
329#else
330static void altera_jtaguart_console_putc(struct console *co, const char c)
331{
332	struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
333	unsigned long flags;
334
335	spin_lock_irqsave(&port->lock, flags);
336	while ((readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
337		ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
338		spin_unlock_irqrestore(&port->lock, flags);
339		cpu_relax();
340		spin_lock_irqsave(&port->lock, flags);
341	}
342	writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
343	spin_unlock_irqrestore(&port->lock, flags);
344}
345#endif
346
347static void altera_jtaguart_console_write(struct console *co, const char *s,
348					  unsigned int count)
349{
350	for (; count; count--, s++) {
351		altera_jtaguart_console_putc(co, *s);
352		if (*s == '\n')
353			altera_jtaguart_console_putc(co, '\r');
354	}
355}
356
357static int __init altera_jtaguart_console_setup(struct console *co,
358						char *options)
359{
360	struct uart_port *port;
361
362	if (co->index < 0 || co->index >= ALTERA_JTAGUART_MAXPORTS)
363		return -EINVAL;
364	port = &altera_jtaguart_ports[co->index].port;
365	if (port->membase == NULL)
366		return -ENODEV;
367	return 0;
368}
369
370static struct uart_driver altera_jtaguart_driver;
371
372static struct console altera_jtaguart_console = {
373	.name	= "ttyJ",
374	.write	= altera_jtaguart_console_write,
375	.device	= uart_console_device,
376	.setup	= altera_jtaguart_console_setup,
377	.flags	= CON_PRINTBUFFER,
378	.index	= -1,
379	.data	= &altera_jtaguart_driver,
380};
381
382static int __init altera_jtaguart_console_init(void)
383{
384	register_console(&altera_jtaguart_console);
385	return 0;
386}
387
388console_initcall(altera_jtaguart_console_init);
389
390#define	ALTERA_JTAGUART_CONSOLE	(&altera_jtaguart_console)
391
392#else
393
394#define	ALTERA_JTAGUART_CONSOLE	NULL
395
396#endif /* CONFIG_ALTERA_JTAGUART_CONSOLE */
397
398static struct uart_driver altera_jtaguart_driver = {
399	.owner		= THIS_MODULE,
400	.driver_name	= "altera_jtaguart",
401	.dev_name	= "ttyJ",
402	.major		= ALTERA_JTAGUART_MAJOR,
403	.minor		= ALTERA_JTAGUART_MINOR,
404	.nr		= ALTERA_JTAGUART_MAXPORTS,
405	.cons		= ALTERA_JTAGUART_CONSOLE,
406};
407
408static int __devinit altera_jtaguart_probe(struct platform_device *pdev)
409{
410	struct altera_jtaguart_platform_uart *platp = pdev->dev.platform_data;
411	struct uart_port *port;
412	int i;
413
414	for (i = 0; i < ALTERA_JTAGUART_MAXPORTS && platp[i].mapbase; i++) {
415		port = &altera_jtaguart_ports[i].port;
416
417		port->line = i;
418		port->type = PORT_ALTERA_JTAGUART;
419		port->mapbase = platp[i].mapbase;
420		port->membase = ioremap(port->mapbase, ALTERA_JTAGUART_SIZE);
421		port->iotype = SERIAL_IO_MEM;
422		port->irq = platp[i].irq;
423		port->ops = &altera_jtaguart_ops;
424		port->flags = ASYNC_BOOT_AUTOCONF;
425
426		uart_add_one_port(&altera_jtaguart_driver, port);
427	}
428
429	return 0;
430}
431
432static int __devexit altera_jtaguart_remove(struct platform_device *pdev)
433{
434	struct uart_port *port;
435	int i;
436
437	for (i = 0; i < ALTERA_JTAGUART_MAXPORTS; i++) {
438		port = &altera_jtaguart_ports[i].port;
439		if (port)
440			uart_remove_one_port(&altera_jtaguart_driver, port);
441	}
442
443	return 0;
444}
445
446static struct platform_driver altera_jtaguart_platform_driver = {
447	.probe	= altera_jtaguart_probe,
448	.remove	= __devexit_p(altera_jtaguart_remove),
449	.driver	= {
450		.name	= DRV_NAME,
451		.owner	= THIS_MODULE,
452	},
453};
454
455static int __init altera_jtaguart_init(void)
456{
457	int rc;
458
459	rc = uart_register_driver(&altera_jtaguart_driver);
460	if (rc)
461		return rc;
462	rc = platform_driver_register(&altera_jtaguart_platform_driver);
463	if (rc) {
464		uart_unregister_driver(&altera_jtaguart_driver);
465		return rc;
466	}
467	return 0;
468}
469
470static void __exit altera_jtaguart_exit(void)
471{
472	platform_driver_unregister(&altera_jtaguart_platform_driver);
473	uart_unregister_driver(&altera_jtaguart_driver);
474}
475
476module_init(altera_jtaguart_init);
477module_exit(altera_jtaguart_exit);
478
479MODULE_DESCRIPTION("Altera JTAG UART driver");
480MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
481MODULE_LICENSE("GPL");
482MODULE_ALIAS("platform:" DRV_NAME);
483