summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/at91sam9_wdt.c
blob: b111b28acb94829b14509cf12fcd1054463ccf90 (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
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
// SPDX-License-Identifier: GPL-2.0+
/*
 * Watchdog driver for Atmel AT91SAM9x processors.
 *
 * Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
 *
 */

/*
 * The Watchdog Timer Mode Register can be only written to once. If the
 * timeout need to be set from Linux, be sure that the bootstrap or the
 * bootloader doesn't write to this register.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/clk.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/reboot.h>
#include <linux/types.h>
#include <linux/watchdog.h>
#include <linux/jiffies.h>
#include <linux/timer.h>
#include <linux/bitops.h>
#include <linux/uaccess.h>
#include <linux/of.h>
#include <linux/of_irq.h>

#include "at91sam9_wdt.h"

#define DRV_NAME "AT91SAM9 Watchdog"

#define wdt_read(wdt, field) \
	readl_relaxed((wdt)->base + (field))
#define wdt_write(wtd, field, val) \
	writel_relaxed((val), (wdt)->base + (field))

/* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
 * use this to convert a watchdog
 * value from/to milliseconds.
 */
#define ticks_to_hz_rounddown(t)	((((t) + 1) * HZ) >> 8)
#define ticks_to_hz_roundup(t)		(((((t) + 1) * HZ) + 255) >> 8)
#define ticks_to_secs(t)		(((t) + 1) >> 8)
#define secs_to_ticks(s)		((s) ? (((s) << 8) - 1) : 0)

#define WDT_MR_RESET	0x3FFF2FFF

/* Watchdog max counter value in ticks */
#define WDT_COUNTER_MAX_TICKS	0xFFF

/* Watchdog max delta/value in secs */
#define WDT_COUNTER_MAX_SECS	ticks_to_secs(WDT_COUNTER_MAX_TICKS)

/* Hardware timeout in seconds */
#define WDT_HW_TIMEOUT 2

/* Timer heartbeat (500ms) */
#define WDT_TIMEOUT	(HZ/2)

/* User land timeout */
#define WDT_HEARTBEAT 15
static int heartbeat;
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
	"(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");

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

#define to_wdt(wdd) container_of(wdd, struct at91wdt, wdd)
struct at91wdt {
	struct watchdog_device wdd;
	void __iomem *base;
	unsigned long next_heartbeat;	/* the next_heartbeat for the timer */
	struct timer_list timer;	/* The timer that pings the watchdog */
	u32 mr;
	u32 mr_mask;
	unsigned long heartbeat;	/* WDT heartbeat in jiffies */
	bool nowayout;
	unsigned int irq;
	struct clk *sclk;
};

/* ......................................................................... */

static irqreturn_t wdt_interrupt(int irq, void *dev_id)
{
	struct at91wdt *wdt = (struct at91wdt *)dev_id;

	if (wdt_read(wdt, AT91_WDT_SR)) {
		pr_crit("at91sam9 WDT software reset\n");
		emergency_restart();
		pr_crit("Reboot didn't ?????\n");
	}

	return IRQ_HANDLED;
}

/*
 * Reload the watchdog timer.  (ie, pat the watchdog)
 */
static inline void at91_wdt_reset(struct at91wdt *wdt)
{
	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
}

/*
 * Timer tick
 */
static void at91_ping(struct timer_list *t)
{
	struct at91wdt *wdt = from_timer(wdt, t, timer);
	if (time_before(jiffies, wdt->next_heartbeat) ||
	    !watchdog_active(&wdt->wdd)) {
		at91_wdt_reset(wdt);
		mod_timer(&wdt->timer, jiffies + wdt->heartbeat);
	} else {
		pr_crit("I will reset your machine !\n");
	}
}

static int at91_wdt_start(struct watchdog_device *wdd)
{
	struct at91wdt *wdt = to_wdt(wdd);
	/* calculate when the next userspace timeout will be */
	wdt->next_heartbeat = jiffies + wdd->timeout * HZ;
	return 0;
}

static int at91_wdt_stop(struct watchdog_device *wdd)
{
	/* The watchdog timer hardware can not be stopped... */
	return 0;
}

static int at91_wdt_set_timeout(struct watchdog_device *wdd, unsigned int new_timeout)
{
	wdd->timeout = new_timeout;
	return at91_wdt_start(wdd);
}

static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
{
	u32 tmp;
	u32 delta;
	u32 value;
	int err;
	u32 mask = wdt->mr_mask;
	unsigned long min_heartbeat = 1;
	unsigned long max_heartbeat;
	struct device *dev = &pdev->dev;

	tmp = wdt_read(wdt, AT91_WDT_MR);
	if ((tmp & mask) != (wdt->mr & mask)) {
		if (tmp == WDT_MR_RESET) {
			wdt_write(wdt, AT91_WDT_MR, wdt->mr);
			tmp = wdt_read(wdt, AT91_WDT_MR);
		}
	}

	if (tmp & AT91_WDT_WDDIS) {
		if (wdt->mr & AT91_WDT_WDDIS)
			return 0;
		dev_err(dev, "watchdog is disabled\n");
		return -EINVAL;
	}

	value = tmp & AT91_WDT_WDV;
	delta = (tmp & AT91_WDT_WDD) >> 16;

	if (delta < value)
		min_heartbeat = ticks_to_hz_roundup(value - delta);

	max_heartbeat = ticks_to_hz_rounddown(value);
	if (!max_heartbeat) {
		dev_err(dev,
			"heartbeat is too small for the system to handle it correctly\n");
		return -EINVAL;
	}

	/*
	 * Try to reset the watchdog counter 4 or 2 times more often than
	 * actually requested, to avoid spurious watchdog reset.
	 * If this is not possible because of the min_heartbeat value, reset
	 * it at the min_heartbeat period.
	 */
	if ((max_heartbeat / 4) >= min_heartbeat)
		wdt->heartbeat = max_heartbeat / 4;
	else if ((max_heartbeat / 2) >= min_heartbeat)
		wdt->heartbeat = max_heartbeat / 2;
	else
		wdt->heartbeat = min_heartbeat;

	if (max_heartbeat < min_heartbeat + 4)
		dev_warn(dev,
			 "min heartbeat and max heartbeat might be too close for the system to handle it correctly\n");

	if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) {
		err = devm_request_irq(dev, wdt->irq, wdt_interrupt,
				       IRQF_SHARED | IRQF_IRQPOLL | IRQF_NO_SUSPEND,
				       pdev->name, wdt);
		if (err)
			return err;
	}

	if ((tmp & wdt->mr_mask) != (wdt->mr & wdt->mr_mask))
		dev_warn(dev,
			 "watchdog already configured differently (mr = %x expecting %x)\n",
			 tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask);

	timer_setup(&wdt->timer, at91_ping, 0);

	/*
	 * Use min_heartbeat the first time to avoid spurious watchdog reset:
	 * we don't know for how long the watchdog counter is running, and
	 *  - resetting it right now might trigger a watchdog fault reset
	 *  - waiting for heartbeat time might lead to a watchdog timeout
	 *    reset
	 */
	mod_timer(&wdt->timer, jiffies + min_heartbeat);

	/* Try to set timeout from device tree first */
	if (watchdog_init_timeout(&wdt->wdd, 0, dev))
		watchdog_init_timeout(&wdt->wdd, heartbeat, dev);
	watchdog_set_nowayout(&wdt->wdd, wdt->nowayout);
	err = watchdog_register_device(&wdt->wdd);
	if (err)
		goto out_stop_timer;

	wdt->next_heartbeat = jiffies + wdt->wdd.timeout * HZ;

	return 0;

out_stop_timer:
	del_timer(&wdt->timer);
	return err;
}

/* ......................................................................... */

static const struct watchdog_info at91_wdt_info = {
	.identity	= DRV_NAME,
	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
						WDIOF_MAGICCLOSE,
};

static const struct watchdog_ops at91_wdt_ops = {
	.owner =	THIS_MODULE,
	.start =	at91_wdt_start,
	.stop =		at91_wdt_stop,
	.set_timeout =	at91_wdt_set_timeout,
};

#if defined(CONFIG_OF)
static int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
{
	u32 min = 0;
	u32 max = WDT_COUNTER_MAX_SECS;
	const char *tmp;

	/* Get the interrupts property */
	wdt->irq = irq_of_parse_and_map(np, 0);
	if (!wdt->irq)
		dev_warn(wdt->wdd.parent, "failed to get IRQ from DT\n");

	if (!of_property_read_u32_index(np, "atmel,max-heartbeat-sec", 0,
					&max)) {
		if (!max || max > WDT_COUNTER_MAX_SECS)
			max = WDT_COUNTER_MAX_SECS;

		if (!of_property_read_u32_index(np, "atmel,min-heartbeat-sec",
						0, &min)) {
			if (min >= max)
				min = max - 1;
		}
	}

	min = secs_to_ticks(min);
	max = secs_to_ticks(max);

	wdt->mr_mask = 0x3FFFFFFF;
	wdt->mr = 0;
	if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
	    !strcmp(tmp, "software")) {
		wdt->mr |= AT91_WDT_WDFIEN;
		wdt->mr_mask &= ~AT91_WDT_WDRPROC;
	} else {
		wdt->mr |= AT91_WDT_WDRSTEN;
	}

	if (!of_property_read_string(np, "atmel,reset-type", &tmp) &&
	    !strcmp(tmp, "proc"))
		wdt->mr |= AT91_WDT_WDRPROC;

	if (of_property_read_bool(np, "atmel,disable")) {
		wdt->mr |= AT91_WDT_WDDIS;
		wdt->mr_mask &= AT91_WDT_WDDIS;
	}

	if (of_property_read_bool(np, "atmel,idle-halt"))
		wdt->mr |= AT91_WDT_WDIDLEHLT;

	if (of_property_read_bool(np, "atmel,dbg-halt"))
		wdt->mr |= AT91_WDT_WDDBGHLT;

	wdt->mr |= max | ((max - min) << 16);

	return 0;
}
#else
static inline int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
{
	return 0;
}
#endif

static int __init at91wdt_probe(struct platform_device *pdev)
{
	int err;
	struct at91wdt *wdt;

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

	wdt->mr = (WDT_HW_TIMEOUT * 256) | AT91_WDT_WDRSTEN | AT91_WDT_WDD |
		  AT91_WDT_WDDBGHLT | AT91_WDT_WDIDLEHLT;
	wdt->mr_mask = 0x3FFFFFFF;
	wdt->nowayout = nowayout;
	wdt->wdd.parent = &pdev->dev;
	wdt->wdd.info = &at91_wdt_info;
	wdt->wdd.ops = &at91_wdt_ops;
	wdt->wdd.timeout = WDT_HEARTBEAT;
	wdt->wdd.min_timeout = 1;
	wdt->wdd.max_timeout = 0xFFFF;

	wdt->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(wdt->base))
		return PTR_ERR(wdt->base);

	wdt->sclk = devm_clk_get_enabled(&pdev->dev, NULL);
	if (IS_ERR(wdt->sclk)) {
		dev_err(&pdev->dev, "Could not enable slow clock\n");
		return PTR_ERR(wdt->sclk);
	}

	if (pdev->dev.of_node) {
		err = of_at91wdt_init(pdev->dev.of_node, wdt);
		if (err)
			return err;
	}

	err = at91_wdt_init(pdev, wdt);
	if (err)
		return err;

	platform_set_drvdata(pdev, wdt);

	pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n",
		wdt->wdd.timeout, wdt->nowayout);

	return 0;
}

static int __exit at91wdt_remove(struct platform_device *pdev)
{
	struct at91wdt *wdt = platform_get_drvdata(pdev);
	watchdog_unregister_device(&wdt->wdd);

	pr_warn("I quit now, hardware will probably reboot!\n");
	del_timer(&wdt->timer);

	return 0;
}

#if defined(CONFIG_OF)
static const struct of_device_id at91_wdt_dt_ids[] = {
	{ .compatible = "atmel,at91sam9260-wdt" },
	{ /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
#endif

static struct platform_driver at91wdt_driver = {
	.remove		= __exit_p(at91wdt_remove),
	.driver		= {
		.name	= "at91_wdt",
		.of_match_table = of_match_ptr(at91_wdt_dt_ids),
	},
};

module_platform_driver_probe(at91wdt_driver, at91wdt_probe);

MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
MODULE_LICENSE("GPL");