aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/sp805_wdt.c
blob: cc2cfbe33b30d441a2ef6449d2babe0b1eb43a3d (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
/*
 * drivers/char/watchdog/sp805-wdt.c
 *
 * Watchdog driver for ARM SP805 watchdog module
 *
 * Copyright (C) 2010 ST Microelectronics
 * Viresh Kumar<viresh.kumar@st.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2 or later. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/device.h>
#include <linux/resource.h>
#include <linux/amba/bus.h>
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/watchdog.h>

/* default timeout in seconds */
#define DEFAULT_TIMEOUT		60

#define MODULE_NAME		"sp805-wdt"

/* watchdog register offsets and masks */
#define WDTLOAD			0x000
	#define LOAD_MIN	0x00000001
	#define LOAD_MAX	0xFFFFFFFF
#define WDTVALUE		0x004
#define WDTCONTROL		0x008
	/* control register masks */
	#define	INT_ENABLE	(1 << 0)
	#define	RESET_ENABLE	(1 << 1)
#define WDTINTCLR		0x00C
#define WDTRIS			0x010
#define WDTMIS			0x014
	#define INT_MASK	(1 << 0)
#define WDTLOCK			0xC00
	#define	UNLOCK		0x1ACCE551
	#define	LOCK		0x00000001

/**
 * struct sp805_wdt: sp805 wdt device structure
 *
 * lock: spin lock protecting dev structure and io access
 * base: base address of wdt
 * clk: clock structure of wdt
 * dev: amba device structure of wdt
 * status: current status of wdt
 * load_val: load value to be set for current timeout
 * timeout: current programmed timeout
 */
struct sp805_wdt {
	spinlock_t			lock;
	void __iomem			*base;
	struct clk			*clk;
	struct amba_device		*adev;
	unsigned long			status;
	#define WDT_BUSY		0
	#define WDT_CAN_BE_CLOSED	1
	unsigned int			load_val;
	unsigned int			timeout;
};

/* local variables */
static struct sp805_wdt *wdt;
static int nowayout = WATCHDOG_NOWAYOUT;

/* This routine finds load value that will reset system in required timout */
static void wdt_setload(unsigned int timeout)
{
	u64 load, rate;

	rate = clk_get_rate(wdt->clk);

	/*
	 * sp805 runs counter with given value twice, after the end of first
	 * counter it gives an interrupt and then starts counter again. If
	 * interrupt already occurred then it resets the system. This is why
	 * load is half of what should be required.
	 */
	load = div_u64(rate, 2) * timeout - 1;

	load = (load > LOAD_MAX) ? LOAD_MAX : load;
	load = (load < LOAD_MIN) ? LOAD_MIN : load;

	spin_lock(&wdt->lock);
	wdt->load_val = load;
	/* roundup timeout to closest positive integer value */
	wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
	spin_unlock(&wdt->lock);
}

/* returns number of seconds left for reset to occur */
static u32 wdt_timeleft(void)
{
	u64 load, rate;

	rate = clk_get_rate(wdt->clk);

	spin_lock(&wdt->lock);
	load = readl(wdt->base + WDTVALUE);

	/*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
	if (!(readl(wdt->base + WDTRIS) & INT_MASK))
		load += wdt->load_val + 1;
	spin_unlock(&wdt->lock);

	return div_u64(load, rate);
}

/* enables watchdog timers reset */
static void wdt_enable(void)
{
	spin_lock(&wdt->lock);

	writel(UNLOCK, wdt->base + WDTLOCK);
	writel(wdt->load_val, wdt->base + WDTLOAD);
	writel(INT_MASK, wdt->base + WDTINTCLR);
	writel(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
	writel(LOCK, wdt->base + WDTLOCK);

	/* Flush posted writes. */
	readl(wdt->base + WDTLOCK);
	spin_unlock(&wdt->lock);
}

/* disables watchdog timers reset */
static void wdt_disable(void)
{
	spin_lock(&wdt->lock);

	writel(UNLOCK, wdt->base + WDTLOCK);
	writel(0, wdt->base + WDTCONTROL);
	writel(LOCK, wdt->base + WDTLOCK);

	/* Flush posted writes. */
	readl(wdt->base + WDTLOCK);
	spin_unlock(&wdt->lock);
}

static ssize_t sp805_wdt_write(struct file *file, const char *data,
		size_t len, loff_t *ppos)
{
	if (len) {
		if (!nowayout) {
			size_t i;

			clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);

			for (i = 0; i != len; i++) {
				char c;

				if (get_user(c, data + i))
					return -EFAULT;
				/* Check for Magic Close character */
				if (c == 'V') {
					set_bit(WDT_CAN_BE_CLOSED,
							&wdt->status);
					break;
				}
			}
		}
		wdt_enable();
	}
	return len;
}

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

static long sp805_wdt_ioctl(struct file *file, unsigned int cmd,
		unsigned long arg)
{
	int ret = -ENOTTY;
	unsigned int timeout;

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

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

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

	case WDIOC_SETTIMEOUT:
		ret = get_user(timeout, (unsigned int *)arg);
		if (ret)
			break;

		wdt_setload(timeout);

		wdt_enable();
		/* Fall through */

	case WDIOC_GETTIMEOUT:
		ret = put_user(wdt->timeout, (unsigned int *)arg);
		break;
	case WDIOC_GETTIMELEFT:
		ret = put_user(wdt_timeleft(), (unsigned int *)arg);
		break;
	}
	return ret;
}

static int sp805_wdt_open(struct inode *inode, struct file *file)
{
	int ret = 0;

	if (test_and_set_bit(WDT_BUSY, &wdt->status))
		return -EBUSY;

	ret = clk_enable(wdt->clk);
	if (ret) {
		dev_err(&wdt->adev->dev, "clock enable fail");
		goto err;
	}

	wdt_enable();

	/* can not be closed, once enabled */
	clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
	return nonseekable_open(inode, file);

err:
	clear_bit(WDT_BUSY, &wdt->status);
	return ret;
}

static int sp805_wdt_release(struct inode *inode, struct file *file)
{
	if (!test_bit(WDT_CAN_BE_CLOSED, &wdt->status)) {
		clear_bit(WDT_BUSY, &wdt->status);
		dev_warn(&wdt->adev->dev, "Device closed unexpectedly\n");
		return 0;
	}

	wdt_disable();
	clk_disable(wdt->clk);
	clear_bit(WDT_BUSY, &wdt->status);

	return 0;
}

static const struct file_operations sp805_wdt_fops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.write = sp805_wdt_write,
	.unlocked_ioctl = sp805_wdt_ioctl,
	.open = sp805_wdt_open,
	.release = sp805_wdt_release,
};

static struct miscdevice sp805_wdt_miscdev = {
	.minor = WATCHDOG_MINOR,
	.name = "watchdog",
	.fops = &sp805_wdt_fops,
};

static int __devinit
sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
{
	int ret = 0;

	if (!request_mem_region(adev->res.start, resource_size(&adev->res),
				"sp805_wdt")) {
		dev_warn(&adev->dev, "Failed to get memory region resource\n");
		ret = -ENOENT;
		goto err;
	}

	wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
	if (!wdt) {
		dev_warn(&adev->dev, "Kzalloc failed\n");
		ret = -ENOMEM;
		goto err_kzalloc;
	}

	wdt->clk = clk_get(&adev->dev, NULL);
	if (IS_ERR(wdt->clk)) {
		dev_warn(&adev->dev, "Clock not found\n");
		ret = PTR_ERR(wdt->clk);
		goto err_clk_get;
	}

	wdt->base = ioremap(adev->res.start, resource_size(&adev->res));
	if (!wdt->base) {
		ret = -ENOMEM;
		dev_warn(&adev->dev, "ioremap fail\n");
		goto err_ioremap;
	}

	wdt->adev = adev;
	spin_lock_init(&wdt->lock);
	wdt_setload(DEFAULT_TIMEOUT);

	ret = misc_register(&sp805_wdt_miscdev);
	if (ret < 0) {
		dev_warn(&adev->dev, "cannot register misc device\n");
		goto err_misc_register;
	}

	dev_info(&adev->dev, "registration successful\n");
	return 0;

err_misc_register:
	iounmap(wdt->base);
err_ioremap:
	clk_put(wdt->clk);
err_clk_get:
	kfree(wdt);
	wdt = NULL;
err_kzalloc:
	release_mem_region(adev->res.start, resource_size(&adev->res));
err:
	dev_err(&adev->dev, "Probe Failed!!!\n");
	return ret;
}

static int __devexit sp805_wdt_remove(struct amba_device *adev)
{
	misc_deregister(&sp805_wdt_miscdev);
	iounmap(wdt->base);
	clk_put(wdt->clk);
	kfree(wdt);
	release_mem_region(adev->res.start, resource_size(&adev->res));

	return 0;
}

static struct amba_id sp805_wdt_ids[] __initdata = {
	{
		.id	= 0x00141805,
		.mask	= 0x00ffffff,
	},
	{ 0, 0 },
};

static struct amba_driver sp805_wdt_driver = {
	.drv = {
		.name	= MODULE_NAME,
	},
	.id_table	= sp805_wdt_ids,
	.probe		= sp805_wdt_probe,
	.remove = __devexit_p(sp805_wdt_remove),
};

static int __init sp805_wdt_init(void)
{
	return amba_driver_register(&sp805_wdt_driver);
}
module_init(sp805_wdt_init);

static void __exit sp805_wdt_exit(void)
{
	amba_driver_unregister(&sp805_wdt_driver);
}
module_exit(sp805_wdt_exit);

module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout,
		"Set to 1 to keep watchdog running after device release");

MODULE_AUTHOR("Viresh Kumar <viresh.kumar@st.com>");
MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);