summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/shwdt.c
blob: 9c57af943b87e250fad13815130fb8f24261a4c1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
/*
 * drivers/watchdog/shwdt.c
 *
 * Watchdog driver for integrated watchdog in the SuperH processors.
 *
 * Copyright (C) 2001 - 2012  Paul Mundt <lethal@linux-sh.org>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
 *     Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
 *
 * 19-Apr-2002 Rob Radez <rob@osinvestor.com>
 *     Added expect close support, made emulated timeout runtime changeable
 *     general cleanups, add some ioctls
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/pm_runtime.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <asm/watchdog.h>

#define DRV_NAME "sh-wdt"

/*
 * Default clock division ratio is 5.25 msecs. For an additional table of
 * values, consult the asm-sh/watchdog.h. Overload this at module load
 * time.
 *
 * In order for this to work reliably we need to have HZ set to 1000 or
 * something quite higher than 100 (or we need a proper high-res timer
 * implementation that will deal with this properly), otherwise the 10ms
 * resolution of a jiffy is enough to trigger the overflow. For things like
 * the SH-4 and SH-5, this isn't necessarily that big of a problem, though
 * for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely
 * necssary.
 *
 * As a result of this timing problem, the only modes that are particularly
 * feasible are the 4096 and the 2048 divisors, which yield 5.25 and 2.62ms
 * overflow periods respectively.
 *
 * Also, since we can't really expect userspace to be responsive enough
 * before the overflow happens, we maintain two separate timers .. One in
 * the kernel for clearing out WOVF every 2ms or so (again, this depends on
 * HZ == 1000), and another for monitoring userspace writes to the WDT device.
 *
 * As such, we currently use a configurable heartbeat interval which defaults
 * to 30s. In this case, the userspace daemon is only responsible for periodic
 * writes to the device before the next heartbeat is scheduled. If the daemon
 * misses its deadline, the kernel timer will allow the WDT to overflow.
 */
static int clock_division_ratio = WTCSR_CKS_4096;
#define next_ping_period(cks)	(jiffies + msecs_to_jiffies(cks - 4))

#define WATCHDOG_HEARTBEAT 30			/* 30 sec default heartbeat */
static int heartbeat = WATCHDOG_HEARTBEAT;	/* in seconds */
static bool nowayout = WATCHDOG_NOWAYOUT;
static unsigned long next_heartbeat;

struct sh_wdt {
	void __iomem		*base;
	struct device		*dev;
	struct clk		*clk;
	spinlock_t		lock;

	struct timer_list	timer;
};

static int sh_wdt_start(struct watchdog_device *wdt_dev)
{
	struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
	unsigned long flags;
	u8 csr;

	pm_runtime_get_sync(wdt->dev);
	clk_enable(wdt->clk);

	spin_lock_irqsave(&wdt->lock, flags);

	next_heartbeat = jiffies + (heartbeat * HZ);
	mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));

	csr = sh_wdt_read_csr();
	csr |= WTCSR_WT | clock_division_ratio;
	sh_wdt_write_csr(csr);

	sh_wdt_write_cnt(0);

	/*
	 * These processors have a bit of an inconsistent initialization
	 * process.. starting with SH-3, RSTS was moved to WTCSR, and the
	 * RSTCSR register was removed.
	 *
	 * On the SH-2 however, in addition with bits being in different
	 * locations, we must deal with RSTCSR outright..
	 */
	csr = sh_wdt_read_csr();
	csr |= WTCSR_TME;
	csr &= ~WTCSR_RSTS;
	sh_wdt_write_csr(csr);

#ifdef CONFIG_CPU_SH2
	csr = sh_wdt_read_rstcsr();
	csr &= ~RSTCSR_RSTS;
	sh_wdt_write_rstcsr(csr);
#endif
	spin_unlock_irqrestore(&wdt->lock, flags);

	return 0;
}

static int sh_wdt_stop(struct watchdog_device *wdt_dev)
{
	struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
	unsigned long flags;
	u8 csr;

	spin_lock_irqsave(&wdt->lock, flags);

	del_timer(&wdt->timer);

	csr = sh_wdt_read_csr();
	csr &= ~WTCSR_TME;
	sh_wdt_write_csr(csr);

	spin_unlock_irqrestore(&wdt->lock, flags);

	clk_disable(wdt->clk);
	pm_runtime_put_sync(wdt->dev);

	return 0;
}

static int sh_wdt_keepalive(struct watchdog_device *wdt_dev)
{
	struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
	unsigned long flags;

	spin_lock_irqsave(&wdt->lock, flags);
	next_heartbeat = jiffies + (heartbeat * HZ);
	spin_unlock_irqrestore(&wdt->lock, flags);

	return 0;
}

static int sh_wdt_set_heartbeat(struct watchdog_device *wdt_dev, unsigned t)
{
	struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
	unsigned long flags;

	if (unlikely(t < 1 || t > 3600)) /* arbitrary upper limit */
		return -EINVAL;

	spin_lock_irqsave(&wdt->lock, flags);
	heartbeat = t;
	wdt_dev->timeout = t;
	spin_unlock_irqrestore(&wdt->lock, flags);

	return 0;
}

static void sh_wdt_ping(unsigned long data)
{
	struct sh_wdt *wdt = (struct sh_wdt *)data;
	unsigned long flags;

	spin_lock_irqsave(&wdt->lock, flags);
	if (time_before(jiffies, next_heartbeat)) {
		u8 csr;

		csr = sh_wdt_read_csr();
		csr &= ~WTCSR_IOVF;
		sh_wdt_write_csr(csr);

		sh_wdt_write_cnt(0);

		mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));
	} else
		dev_warn(wdt->dev, "Heartbeat lost! Will not ping "
		         "the watchdog\n");
	spin_unlock_irqrestore(&wdt->lock, flags);
}

static const struct watchdog_info sh_wdt_info = {
	.options		= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
				  WDIOF_MAGICCLOSE,
	.firmware_version	= 1,
	.identity		= "SH WDT",
};

static const struct watchdog_ops sh_wdt_ops = {
	.owner		= THIS_MODULE,
	.start		= sh_wdt_start,
	.stop		= sh_wdt_stop,
	.ping		= sh_wdt_keepalive,
	.set_timeout	= sh_wdt_set_heartbeat,
};

static struct watchdog_device sh_wdt_dev = {
	.info	= &sh_wdt_info,
	.ops	= &sh_wdt_ops,
};

static int sh_wdt_probe(struct platform_device *pdev)
{
	struct sh_wdt *wdt;
	struct resource *res;
	int rc;

	/*
	 * As this driver only covers the global watchdog case, reject
	 * any attempts to register per-CPU watchdogs.
	 */
	if (pdev->id != -1)
		return -EINVAL;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (unlikely(!res))
		return -EINVAL;

	wdt = devm_kzalloc(&pdev->dev, sizeof(struct sh_wdt), GFP_KERNEL);
	if (unlikely(!wdt))
		return -ENOMEM;

	wdt->dev = &pdev->dev;

	wdt->clk = clk_get(&pdev->dev, NULL);
	if (IS_ERR(wdt->clk)) {
		/*
		 * Clock framework support is optional, continue on
		 * anyways if we don't find a matching clock.
		 */
		wdt->clk = NULL;
	}

	wdt->base = devm_request_and_ioremap(wdt->dev, res);
	if (unlikely(!wdt->base)) {
		rc = -EADDRNOTAVAIL;
		goto err;
	}

	watchdog_set_nowayout(&sh_wdt_dev, nowayout);
	watchdog_set_drvdata(&sh_wdt_dev, wdt);

	spin_lock_init(&wdt->lock);

	rc = sh_wdt_set_heartbeat(&sh_wdt_dev, heartbeat);
	if (unlikely(rc)) {
		/* Default timeout if invalid */
		sh_wdt_set_heartbeat(&sh_wdt_dev, WATCHDOG_HEARTBEAT);

		dev_warn(&pdev->dev,
			 "heartbeat value must be 1<=x<=3600, using %d\n",
			 sh_wdt_dev.timeout);
	}

	dev_info(&pdev->dev, "configured with heartbeat=%d sec (nowayout=%d)\n",
		 sh_wdt_dev.timeout, nowayout);

	rc = watchdog_register_device(&sh_wdt_dev);
	if (unlikely(rc)) {
		dev_err(&pdev->dev, "Can't register watchdog (err=%d)\n", rc);
		goto err;
	}

	init_timer(&wdt->timer);
	wdt->timer.function	= sh_wdt_ping;
	wdt->timer.data		= (unsigned long)wdt;
	wdt->timer.expires	= next_ping_period(clock_division_ratio);

	platform_set_drvdata(pdev, wdt);

	dev_info(&pdev->dev, "initialized.\n");

	pm_runtime_enable(&pdev->dev);

	return 0;

err:
	clk_put(wdt->clk);

	return rc;
}

static int __devexit sh_wdt_remove(struct platform_device *pdev)
{
	struct sh_wdt *wdt = platform_get_drvdata(pdev);

	platform_set_drvdata(pdev, NULL);

	watchdog_unregister_device(&sh_wdt_dev);

	pm_runtime_disable(&pdev->dev);
	clk_put(wdt->clk);

	return 0;
}

static void sh_wdt_shutdown(struct platform_device *pdev)
{
	sh_wdt_stop(&sh_wdt_dev);
}

static struct platform_driver sh_wdt_driver = {
	.driver		= {
		.name	= DRV_NAME,
		.owner	= THIS_MODULE,
	},

	.probe		= sh_wdt_probe,
	.remove		= sh_wdt_remove,
	.shutdown	= sh_wdt_shutdown,
};

static int __init sh_wdt_init(void)
{
	if (unlikely(clock_division_ratio < 0x5 ||
		     clock_division_ratio > 0x7)) {
		clock_division_ratio = WTCSR_CKS_4096;

		pr_info("divisor must be 0x5<=x<=0x7, using %d\n",
			clock_division_ratio);
	}

	return platform_driver_register(&sh_wdt_driver);
}

static void __exit sh_wdt_exit(void)
{
	platform_driver_unregister(&sh_wdt_driver);
}
module_init(sh_wdt_init);
module_exit(sh_wdt_exit);

MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
MODULE_DESCRIPTION("SuperH watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

module_param(clock_division_ratio, int, 0);
MODULE_PARM_DESC(clock_division_ratio,
	"Clock division ratio. Valid ranges are from 0x5 (1.31ms) "
	"to 0x7 (5.25ms). (default=" __MODULE_STRING(WTCSR_CKS_4096) ")");

module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat,
	"Watchdog heartbeat in seconds. (1 <= heartbeat <= 3600, default="
				__MODULE_STRING(WATCHDOG_HEARTBEAT) ")");

module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
	"Watchdog cannot be stopped once started (default="
				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
OpenPOWER on IntegriCloud