aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/max63xx_wdt.c
blob: 7a82ce5a6337e3948adc1d9e42eab5c72aecf654 (plain) (blame)
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
/*
 * drivers/char/watchdog/max63xx_wdt.c
 *
 * Driver for max63{69,70,71,72,73,74} watchdog timers
 *
 * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 *
 * This driver assumes the watchdog pins are memory mapped (as it is
 * the case for the Arcom Zeus). Should it be connected over GPIOs or
 * another interface, some abstraction will have to be introduced.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/init.h>
#include <linux/bitops.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/device.h>
#include <linux/slab.h>

#define DEFAULT_HEARTBEAT 60
#define MAX_HEARTBEAT     60

static int heartbeat = DEFAULT_HEARTBEAT;
static int nowayout  = WATCHDOG_NOWAYOUT;

/*
 * Memory mapping: a single byte, 3 first lower bits to select bit 3
 * to ping the watchdog.
 */
#define MAX6369_WDSET	(7 << 0)
#define MAX6369_WDI	(1 << 3)

static DEFINE_SPINLOCK(io_lock);

static unsigned long wdt_status;
#define WDT_IN_USE	0
#define WDT_RUNNING	1
#define WDT_OK_TO_CLOSE 2

static int nodelay;
static struct resource	*wdt_mem;
static void __iomem	*wdt_base;
static struct platform_device *max63xx_pdev;

/*
 * The timeout values used are actually the absolute minimum the chip
 * offers. Typical values on my board are slightly over twice as long
 * (10s setting ends up with a 25s timeout), and can be up to 3 times
 * the nominal setting (according to the datasheet). So please take
 * these values with a grain of salt. Same goes for the initial delay
 * "feature". Only max6373/74 have a few settings without this initial
 * delay (selected with the "nodelay" parameter).
 *
 * I also decided to remove from the tables any timeout smaller than a
 * second, as it looked completly overkill...
 */

/* Timeouts in second */
struct max63xx_timeout {
	u8 wdset;
	u8 tdelay;
	u8 twd;
};

static struct max63xx_timeout max6369_table[] = {
	{ 5,  1,  1 },
	{ 6, 10, 10 },
	{ 7, 60, 60 },
	{ },
};

static struct max63xx_timeout max6371_table[] = {
	{ 6, 60,  3 },
	{ 7, 60, 60 },
	{ },
};

static struct max63xx_timeout max6373_table[] = {
	{ 2, 60,  1 },
	{ 5,  0,  1 },
	{ 1,  3,  3 },
	{ 7, 60, 10 },
	{ 6,  0, 10 },
	{ },
};

static struct max63xx_timeout *current_timeout;

static struct max63xx_timeout *
max63xx_select_timeout(struct max63xx_timeout *table, int value)
{
	while (table->twd) {
		if (value <= table->twd) {
			if (nodelay && table->tdelay == 0)
				return table;

			if (!nodelay)
				return table;
		}

		table++;
	}

	return NULL;
}

static void max63xx_wdt_ping(void)
{
	u8 val;

	spin_lock(&io_lock);

	val = __raw_readb(wdt_base);

	__raw_writeb(val | MAX6369_WDI, wdt_base);
	__raw_writeb(val & ~MAX6369_WDI, wdt_base);

	spin_unlock(&io_lock);
}

static void max63xx_wdt_enable(struct max63xx_timeout *entry)
{
	u8 val;

	if (test_and_set_bit(WDT_RUNNING, &wdt_status))
		return;

	spin_lock(&io_lock);

	val = __raw_readb(wdt_base);
	val &= ~MAX6369_WDSET;
	val |= entry->wdset;
	__raw_writeb(val, wdt_base);

	spin_unlock(&io_lock);

	/* check for a edge triggered startup */
	if (entry->tdelay == 0)
		max63xx_wdt_ping();
}

static void max63xx_wdt_disable(void)
{
	u8 val;

	spin_lock(&io_lock);

	val = __raw_readb(wdt_base);
	val &= ~MAX6369_WDSET;
	val |= 3;
	__raw_writeb(val, wdt_base);

	spin_unlock(&io_lock);

	clear_bit(WDT_RUNNING, &wdt_status);
}

static int max63xx_wdt_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
		return -EBUSY;

	max63xx_wdt_enable(current_timeout);
	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);

	return nonseekable_open(inode, file);
}

static ssize_t max63xx_wdt_write(struct file *file, const char *data,
				 size_t len, loff_t *ppos)
{
	if (len) {
		if (!nowayout) {
			size_t i;

			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
			for (i = 0; i != len; i++) {
				char c;

				if (get_user(c, data + i))
					return -EFAULT;

				if (c == 'V')
					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
			}
		}

		max63xx_wdt_ping();
	}

	return len;
}

static const struct watchdog_info ident = {
	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
	.identity = "max63xx Watchdog",
};

static long max63xx_wdt_ioctl(struct file *file, unsigned int cmd,
			      unsigned long arg)
{
	int ret = -ENOTTY;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		ret = copy_to_user((struct watchdog_info *)arg, &ident,
				   sizeof(ident)) ? -EFAULT : 0;
		break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		ret = put_user(0, (int *)arg);
		break;

	case WDIOC_KEEPALIVE:
		max63xx_wdt_ping();
		ret = 0;
		break;

	case WDIOC_GETTIMEOUT:
		ret = put_user(heartbeat, (int *)arg);
		break;
	}
	return ret;
}

static int max63xx_wdt_release(struct inode *inode, struct file *file)
{
	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
		max63xx_wdt_disable();
	else
		dev_crit(&max63xx_pdev->dev,
			 "device closed unexpectedly - timer will not stop\n");

	clear_bit(WDT_IN_USE, &wdt_status);
	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);

	return 0;
}

static const struct file_operations max63xx_wdt_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= max63xx_wdt_write,
	.unlocked_ioctl	= max63xx_wdt_ioctl,
	.open		= max63xx_wdt_open,
	.release	= max63xx_wdt_release,
};

static struct miscdevice max63xx_wdt_miscdev = {
	.minor	= WATCHDOG_MINOR,
	.name	= "watchdog",
	.fops	= &max63xx_wdt_fops,
};

static int __devinit max63xx_wdt_probe(struct platform_device *pdev)
{
	int ret = 0;
	int size;
	struct resource *res;
	struct device *dev = &pdev->dev;
	struct max63xx_timeout *table;

	table = (struct max63xx_timeout *)pdev->id_entry->driver_data;

	if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
		heartbeat = DEFAULT_HEARTBEAT;

	dev_info(dev, "requesting %ds heartbeat\n", heartbeat);
	current_timeout = max63xx_select_timeout(table, heartbeat);

	if (!current_timeout) {
		dev_err(dev, "unable to satisfy heartbeat request\n");
		return -EINVAL;
	}

	dev_info(dev, "using %ds heartbeat with %ds initial delay\n",
		 current_timeout->twd, current_timeout->tdelay);

	heartbeat = current_timeout->twd;

	max63xx_pdev = pdev;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (res == NULL) {
		dev_err(dev, "failed to get memory region resource\n");
		return -ENOENT;
	}

	size = resource_size(res);
	wdt_mem = request_mem_region(res->start, size, pdev->name);

	if (wdt_mem == NULL) {
		dev_err(dev, "failed to get memory region\n");
		return -ENOENT;
	}

	wdt_base = ioremap(res->start, size);
	if (!wdt_base) {
		dev_err(dev, "failed to map memory region\n");
		ret = -ENOMEM;
		goto out_request;
	}

	ret = misc_register(&max63xx_wdt_miscdev);
	if (ret < 0) {
		dev_err(dev, "cannot register misc device\n");
		goto out_unmap;
	}

	return 0;

out_unmap:
	iounmap(wdt_base);
out_request:
	release_resource(wdt_mem);
	kfree(wdt_mem);

	return ret;
}

static int __devexit max63xx_wdt_remove(struct platform_device *pdev)
{
	misc_deregister(&max63xx_wdt_miscdev);
	if (wdt_mem) {
		release_resource(wdt_mem);
		kfree(wdt_mem);
		wdt_mem = NULL;
	}

	if (wdt_base)
		iounmap(wdt_base);

	return 0;
}

static struct platform_device_id max63xx_id_table[] = {
	{ "max6369_wdt", (kernel_ulong_t)max6369_table, },
	{ "max6370_wdt", (kernel_ulong_t)max6369_table, },
	{ "max6371_wdt", (kernel_ulong_t)max6371_table, },
	{ "max6372_wdt", (kernel_ulong_t)max6371_table, },
	{ "max6373_wdt", (kernel_ulong_t)max6373_table, },
	{ "max6374_wdt", (kernel_ulong_t)max6373_table, },
	{ },
};
MODULE_DEVICE_TABLE(platform, max63xx_id_table);

static struct platform_driver max63xx_wdt_driver = {
	.probe		= max63xx_wdt_probe,
	.remove		= __devexit_p(max63xx_wdt_remove),
	.id_table	= max63xx_id_table,
	.driver		= {
		.name	= "max63xx_wdt",
		.owner	= THIS_MODULE,
	},
};

static int __init max63xx_wdt_init(void)
{
	return platform_driver_register(&max63xx_wdt_driver);
}

static void __exit max63xx_wdt_exit(void)
{
	platform_driver_unregister(&max63xx_wdt_driver);
}

module_init(max63xx_wdt_init);
module_exit(max63xx_wdt_exit);

MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
MODULE_DESCRIPTION("max63xx Watchdog Driver");

module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat,
		 "Watchdog heartbeat period in seconds from 1 to "
		 __MODULE_STRING(MAX_HEARTBEAT) ", default "
		 __MODULE_STRING(DEFAULT_HEARTBEAT));

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

module_param(nodelay, int, 0);
MODULE_PARM_DESC(nodelay,
		 "Force selection of a timeout setting without initial delay "
		 "(max6373/74 only, default=0)");

MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);