[go: nahoru, domu]
1/*
2 * Blackfin On-Chip Watchdog Driver
3 *
4 * Originally based on softdog.c
5 * Copyright 2006-2010 Analog Devices Inc.
6 * Copyright 2006-2007 Michele d'Amico
7 * Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>
8 *
9 * Enter bugs at http://blackfin.uclinux.org/
10 *
11 * Licensed under the GPL-2 or later.
12 */
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/platform_device.h>
17#include <linux/module.h>
18#include <linux/moduleparam.h>
19#include <linux/types.h>
20#include <linux/timer.h>
21#include <linux/miscdevice.h>
22#include <linux/watchdog.h>
23#include <linux/fs.h>
24#include <linux/init.h>
25#include <linux/interrupt.h>
26#include <linux/uaccess.h>
27#include <asm/blackfin.h>
28#include <asm/bfin_watchdog.h>
29
30#define stamp(fmt, args...) \
31	pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
32#define stampit() stamp("here i am")
33
34#define WATCHDOG_NAME "bfin-wdt"
35
36/* The BF561 has two watchdogs (one per core), but since Linux
37 * only runs on core A, we'll just work with that one.
38 */
39#ifdef BF561_FAMILY
40# define bfin_read_WDOG_CTL()    bfin_read_WDOGA_CTL()
41# define bfin_read_WDOG_CNT()    bfin_read_WDOGA_CNT()
42# define bfin_read_WDOG_STAT()   bfin_read_WDOGA_STAT()
43# define bfin_write_WDOG_CTL(x)  bfin_write_WDOGA_CTL(x)
44# define bfin_write_WDOG_CNT(x)  bfin_write_WDOGA_CNT(x)
45# define bfin_write_WDOG_STAT(x) bfin_write_WDOGA_STAT(x)
46#endif
47
48/* some defaults */
49#define WATCHDOG_TIMEOUT 20
50
51static unsigned int timeout = WATCHDOG_TIMEOUT;
52static bool nowayout = WATCHDOG_NOWAYOUT;
53static const struct watchdog_info bfin_wdt_info;
54static unsigned long open_check;
55static char expect_close;
56static DEFINE_SPINLOCK(bfin_wdt_spinlock);
57
58/**
59 *	bfin_wdt_keepalive - Keep the Userspace Watchdog Alive
60 *
61 *	The Userspace watchdog got a KeepAlive: schedule the next timeout.
62 */
63static int bfin_wdt_keepalive(void)
64{
65	stampit();
66	bfin_write_WDOG_STAT(0);
67	return 0;
68}
69
70/**
71 *	bfin_wdt_stop - Stop the Watchdog
72 *
73 *	Stops the on-chip watchdog.
74 */
75static int bfin_wdt_stop(void)
76{
77	stampit();
78	bfin_write_WDOG_CTL(WDEN_DISABLE);
79	return 0;
80}
81
82/**
83 *	bfin_wdt_start - Start the Watchdog
84 *
85 *	Starts the on-chip watchdog.  Automatically loads WDOG_CNT
86 *	into WDOG_STAT for us.
87 */
88static int bfin_wdt_start(void)
89{
90	stampit();
91	bfin_write_WDOG_CTL(WDEN_ENABLE | ICTL_RESET);
92	return 0;
93}
94
95/**
96 *	bfin_wdt_running - Check Watchdog status
97 *
98 *	See if the watchdog is running.
99 */
100static int bfin_wdt_running(void)
101{
102	stampit();
103	return ((bfin_read_WDOG_CTL() & WDEN_MASK) != WDEN_DISABLE);
104}
105
106/**
107 *	bfin_wdt_set_timeout - Set the Userspace Watchdog timeout
108 *	@t: new timeout value (in seconds)
109 *
110 *	Translate the specified timeout in seconds into System Clock
111 *	terms which is what the on-chip Watchdog requires.
112 */
113static int bfin_wdt_set_timeout(unsigned long t)
114{
115	u32 cnt, max_t, sclk;
116	unsigned long flags;
117
118	sclk = get_sclk();
119	max_t = -1 / sclk;
120	cnt = t * sclk;
121	stamp("maxtimeout=%us newtimeout=%lus (cnt=%#x)", max_t, t, cnt);
122
123	if (t > max_t) {
124		pr_warn("timeout value is too large\n");
125		return -EINVAL;
126	}
127
128	spin_lock_irqsave(&bfin_wdt_spinlock, flags);
129	{
130		int run = bfin_wdt_running();
131		bfin_wdt_stop();
132		bfin_write_WDOG_CNT(cnt);
133		if (run)
134			bfin_wdt_start();
135	}
136	spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
137
138	timeout = t;
139
140	return 0;
141}
142
143/**
144 *	bfin_wdt_open - Open the Device
145 *	@inode: inode of device
146 *	@file: file handle of device
147 *
148 *	Watchdog device is opened and started.
149 */
150static int bfin_wdt_open(struct inode *inode, struct file *file)
151{
152	stampit();
153
154	if (test_and_set_bit(0, &open_check))
155		return -EBUSY;
156
157	if (nowayout)
158		__module_get(THIS_MODULE);
159
160	bfin_wdt_keepalive();
161	bfin_wdt_start();
162
163	return nonseekable_open(inode, file);
164}
165
166/**
167 *	bfin_wdt_close - Close the Device
168 *	@inode: inode of device
169 *	@file: file handle of device
170 *
171 *	Watchdog device is closed and stopped.
172 */
173static int bfin_wdt_release(struct inode *inode, struct file *file)
174{
175	stampit();
176
177	if (expect_close == 42)
178		bfin_wdt_stop();
179	else {
180		pr_crit("Unexpected close, not stopping watchdog!\n");
181		bfin_wdt_keepalive();
182	}
183	expect_close = 0;
184	clear_bit(0, &open_check);
185	return 0;
186}
187
188/**
189 *	bfin_wdt_write - Write to Device
190 *	@file: file handle of device
191 *	@buf: buffer to write
192 *	@count: length of buffer
193 *	@ppos: offset
194 *
195 *	Pings the watchdog on write.
196 */
197static ssize_t bfin_wdt_write(struct file *file, const char __user *data,
198						size_t len, loff_t *ppos)
199{
200	stampit();
201
202	if (len) {
203		if (!nowayout) {
204			size_t i;
205
206			/* In case it was set long ago */
207			expect_close = 0;
208
209			for (i = 0; i != len; i++) {
210				char c;
211				if (get_user(c, data + i))
212					return -EFAULT;
213				if (c == 'V')
214					expect_close = 42;
215			}
216		}
217		bfin_wdt_keepalive();
218	}
219
220	return len;
221}
222
223/**
224 *	bfin_wdt_ioctl - Query Device
225 *	@file: file handle of device
226 *	@cmd: watchdog command
227 *	@arg: argument
228 *
229 *	Query basic information from the device or ping it, as outlined by the
230 *	watchdog API.
231 */
232static long bfin_wdt_ioctl(struct file *file,
233				unsigned int cmd, unsigned long arg)
234{
235	void __user *argp = (void __user *)arg;
236	int __user *p = argp;
237
238	stampit();
239
240	switch (cmd) {
241	case WDIOC_GETSUPPORT:
242		if (copy_to_user(argp, &bfin_wdt_info, sizeof(bfin_wdt_info)))
243			return -EFAULT;
244		else
245			return 0;
246	case WDIOC_GETSTATUS:
247	case WDIOC_GETBOOTSTATUS:
248		return put_user(!!(_bfin_swrst & SWRST_RESET_WDOG), p);
249	case WDIOC_SETOPTIONS: {
250		unsigned long flags;
251		int options, ret = -EINVAL;
252
253		if (get_user(options, p))
254			return -EFAULT;
255
256		spin_lock_irqsave(&bfin_wdt_spinlock, flags);
257		if (options & WDIOS_DISABLECARD) {
258			bfin_wdt_stop();
259			ret = 0;
260		}
261		if (options & WDIOS_ENABLECARD) {
262			bfin_wdt_start();
263			ret = 0;
264		}
265		spin_unlock_irqrestore(&bfin_wdt_spinlock, flags);
266		return ret;
267	}
268	case WDIOC_KEEPALIVE:
269		bfin_wdt_keepalive();
270		return 0;
271	case WDIOC_SETTIMEOUT: {
272		int new_timeout;
273
274		if (get_user(new_timeout, p))
275			return -EFAULT;
276		if (bfin_wdt_set_timeout(new_timeout))
277			return -EINVAL;
278	}
279	/* Fall */
280	case WDIOC_GETTIMEOUT:
281		return put_user(timeout, p);
282	default:
283		return -ENOTTY;
284	}
285}
286
287#ifdef CONFIG_PM
288static int state_before_suspend;
289
290/**
291 *	bfin_wdt_suspend - suspend the watchdog
292 *	@pdev: device being suspended
293 *	@state: requested suspend state
294 *
295 *	Remember if the watchdog was running and stop it.
296 *	TODO: is this even right?  Doesn't seem to be any
297 *	      standard in the watchdog world ...
298 */
299static int bfin_wdt_suspend(struct platform_device *pdev, pm_message_t state)
300{
301	stampit();
302
303	state_before_suspend = bfin_wdt_running();
304	bfin_wdt_stop();
305
306	return 0;
307}
308
309/**
310 *	bfin_wdt_resume - resume the watchdog
311 *	@pdev: device being resumed
312 *
313 *	If the watchdog was running, turn it back on.
314 */
315static int bfin_wdt_resume(struct platform_device *pdev)
316{
317	stampit();
318
319	if (state_before_suspend) {
320		bfin_wdt_set_timeout(timeout);
321		bfin_wdt_start();
322	}
323
324	return 0;
325}
326#else
327# define bfin_wdt_suspend NULL
328# define bfin_wdt_resume NULL
329#endif
330
331static const struct file_operations bfin_wdt_fops = {
332	.owner		= THIS_MODULE,
333	.llseek		= no_llseek,
334	.write		= bfin_wdt_write,
335	.unlocked_ioctl	= bfin_wdt_ioctl,
336	.open		= bfin_wdt_open,
337	.release	= bfin_wdt_release,
338};
339
340static struct miscdevice bfin_wdt_miscdev = {
341	.minor    = WATCHDOG_MINOR,
342	.name     = "watchdog",
343	.fops     = &bfin_wdt_fops,
344};
345
346static const struct watchdog_info bfin_wdt_info = {
347	.identity = "Blackfin Watchdog",
348	.options  = WDIOF_SETTIMEOUT |
349		    WDIOF_KEEPALIVEPING |
350		    WDIOF_MAGICCLOSE,
351};
352
353/**
354 *	bfin_wdt_probe - Initialize module
355 *
356 *	Registers the misc device.  Actual device
357 *	initialization is handled by bfin_wdt_open().
358 */
359static int bfin_wdt_probe(struct platform_device *pdev)
360{
361	int ret;
362
363	ret = misc_register(&bfin_wdt_miscdev);
364	if (ret) {
365		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
366		       WATCHDOG_MINOR, ret);
367		return ret;
368	}
369
370	pr_info("initialized: timeout=%d sec (nowayout=%d)\n",
371		timeout, nowayout);
372
373	return 0;
374}
375
376/**
377 *	bfin_wdt_remove - Initialize module
378 *
379 *	Unregisters the misc device.  Actual device
380 *	deinitialization is handled by bfin_wdt_close().
381 */
382static int bfin_wdt_remove(struct platform_device *pdev)
383{
384	misc_deregister(&bfin_wdt_miscdev);
385	return 0;
386}
387
388/**
389 *	bfin_wdt_shutdown - Soft Shutdown Handler
390 *
391 *	Handles the soft shutdown event.
392 */
393static void bfin_wdt_shutdown(struct platform_device *pdev)
394{
395	stampit();
396
397	bfin_wdt_stop();
398}
399
400static struct platform_device *bfin_wdt_device;
401
402static struct platform_driver bfin_wdt_driver = {
403	.probe     = bfin_wdt_probe,
404	.remove    = bfin_wdt_remove,
405	.shutdown  = bfin_wdt_shutdown,
406	.suspend   = bfin_wdt_suspend,
407	.resume    = bfin_wdt_resume,
408	.driver    = {
409		.name  = WATCHDOG_NAME,
410		.owner = THIS_MODULE,
411	},
412};
413
414/**
415 *	bfin_wdt_init - Initialize module
416 *
417 *	Checks the module params and registers the platform device & driver.
418 *	Real work is in the platform probe function.
419 */
420static int __init bfin_wdt_init(void)
421{
422	int ret;
423
424	stampit();
425
426	/* Check that the timeout value is within range */
427	if (bfin_wdt_set_timeout(timeout))
428		return -EINVAL;
429
430	/* Since this is an on-chip device and needs no board-specific
431	 * resources, we'll handle all the platform device stuff here.
432	 */
433	ret = platform_driver_register(&bfin_wdt_driver);
434	if (ret) {
435		pr_err("unable to register driver\n");
436		return ret;
437	}
438
439	bfin_wdt_device = platform_device_register_simple(WATCHDOG_NAME,
440								-1, NULL, 0);
441	if (IS_ERR(bfin_wdt_device)) {
442		pr_err("unable to register device\n");
443		platform_driver_unregister(&bfin_wdt_driver);
444		return PTR_ERR(bfin_wdt_device);
445	}
446
447	return 0;
448}
449
450/**
451 *	bfin_wdt_exit - Deinitialize module
452 *
453 *	Back out the platform device & driver steps.  Real work is in the
454 *	platform remove function.
455 */
456static void __exit bfin_wdt_exit(void)
457{
458	platform_device_unregister(bfin_wdt_device);
459	platform_driver_unregister(&bfin_wdt_driver);
460}
461
462module_init(bfin_wdt_init);
463module_exit(bfin_wdt_exit);
464
465MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>");
466MODULE_DESCRIPTION("Blackfin Watchdog Device Driver");
467MODULE_LICENSE("GPL");
468
469module_param(timeout, uint, 0);
470MODULE_PARM_DESC(timeout,
471	"Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default="
472		__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
473
474module_param(nowayout, bool, 0);
475MODULE_PARM_DESC(nowayout,
476	"Watchdog cannot be stopped once started (default="
477		__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
478