aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/nuc900_wdt.c
blob: 04c45a10299254586729e1125a255179ec5ef66a (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
/*
 * Copyright (c) 2009 Nuvoton technology corporation.
 *
 * Wan ZongShun <mcuos.com@gmail.com>
 *
 * 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;version 2 of the License.
 *
 */

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

#define REG_WTCR		0x1c
#define WTCLK			(0x01 << 10)
#define WTE			(0x01 << 7)	/*wdt enable*/
#define WTIS			(0x03 << 4)
#define WTIF			(0x01 << 3)
#define WTRF			(0x01 << 2)
#define WTRE			(0x01 << 1)
#define WTR			(0x01 << 0)
/*
 * The watchdog time interval can be calculated via following formula:
 * WTIS		real time interval (formula)
 * 0x00		((2^ 14 ) * ((external crystal freq) / 256))seconds
 * 0x01		((2^ 16 ) * ((external crystal freq) / 256))seconds
 * 0x02		((2^ 18 ) * ((external crystal freq) / 256))seconds
 * 0x03		((2^ 20 ) * ((external crystal freq) / 256))seconds
 *
 * The external crystal freq is 15Mhz in the nuc900 evaluation board.
 * So 0x00 = +-0.28 seconds, 0x01 = +-1.12 seconds, 0x02 = +-4.48 seconds,
 * 0x03 = +- 16.92 seconds..
 */
#define WDT_HW_TIMEOUT		0x02
#define WDT_TIMEOUT		(HZ/2)
#define WDT_HEARTBEAT		15

static int heartbeat = WDT_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) ")");

struct nuc900_wdt {
	struct resource  *res;
	struct clk	 *wdt_clock;
	struct platform_device *pdev;
	void __iomem	 *wdt_base;
	char		 expect_close;
	struct timer_list timer;
	spinlock_t       wdt_lock;
	unsigned long next_heartbeat;
};

static unsigned long nuc900wdt_busy;
static struct nuc900_wdt *nuc900_wdt;

static inline void nuc900_wdt_keepalive(void)
{
	unsigned int val;

	spin_lock(&nuc900_wdt->wdt_lock);

	val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
	val |= (WTR | WTIF);
	__raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);

	spin_unlock(&nuc900_wdt->wdt_lock);
}

static inline void nuc900_wdt_start(void)
{
	unsigned int val;

	spin_lock(&nuc900_wdt->wdt_lock);

	val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
	val |= (WTRE | WTE | WTR | WTCLK | WTIF);
	val &= ~WTIS;
	val |= (WDT_HW_TIMEOUT << 0x04);
	__raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);

	spin_unlock(&nuc900_wdt->wdt_lock);

	nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
	mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
}

static inline void nuc900_wdt_stop(void)
{
	unsigned int val;

	del_timer(&nuc900_wdt->timer);

	spin_lock(&nuc900_wdt->wdt_lock);

	val = __raw_readl(nuc900_wdt->wdt_base + REG_WTCR);
	val &= ~WTE;
	__raw_writel(val, nuc900_wdt->wdt_base + REG_WTCR);

	spin_unlock(&nuc900_wdt->wdt_lock);
}

static inline void nuc900_wdt_ping(void)
{
	nuc900_wdt->next_heartbeat = jiffies + heartbeat * HZ;
}

static int nuc900_wdt_open(struct inode *inode, struct file *file)
{

	if (test_and_set_bit(0, &nuc900wdt_busy))
		return -EBUSY;

	nuc900_wdt_start();

	return nonseekable_open(inode, file);
}

static int nuc900_wdt_close(struct inode *inode, struct file *file)
{
	if (nuc900_wdt->expect_close == 42)
		nuc900_wdt_stop();
	else {
		dev_crit(&nuc900_wdt->pdev->dev,
			"Unexpected close, not stopping watchdog!\n");
		nuc900_wdt_ping();
	}

	nuc900_wdt->expect_close = 0;
	clear_bit(0, &nuc900wdt_busy);
	return 0;
}

static const struct watchdog_info nuc900_wdt_info = {
	.identity	= "nuc900 watchdog",
	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
						WDIOF_MAGICCLOSE,
};

static long nuc900_wdt_ioctl(struct file *file,
					unsigned int cmd, unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	int new_value;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		return copy_to_user(argp, &nuc900_wdt_info,
				sizeof(nuc900_wdt_info)) ? -EFAULT : 0;
	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		return put_user(0, p);

	case WDIOC_KEEPALIVE:
		nuc900_wdt_ping();
		return 0;

	case WDIOC_SETTIMEOUT:
		if (get_user(new_value, p))
			return -EFAULT;

		heartbeat = new_value;
		nuc900_wdt_ping();

		return put_user(new_value, p);
	case WDIOC_GETTIMEOUT:
		return put_user(heartbeat, p);
	default:
		return -ENOTTY;
	}
}

static ssize_t nuc900_wdt_write(struct file *file, const char __user *data,
						size_t len, loff_t *ppos)
{
	if (!len)
		return 0;

	/* Scan for magic character */
	if (!nowayout) {
		size_t i;

		nuc900_wdt->expect_close = 0;

		for (i = 0; i < len; i++) {
			char c;
			if (get_user(c, data + i))
				return -EFAULT;
			if (c == 'V') {
				nuc900_wdt->expect_close = 42;
				break;
			}
		}
	}

	nuc900_wdt_ping();
	return len;
}

static void nuc900_wdt_timer_ping(unsigned long data)
{
	if (time_before(jiffies, nuc900_wdt->next_heartbeat)) {
		nuc900_wdt_keepalive();
		mod_timer(&nuc900_wdt->timer, jiffies + WDT_TIMEOUT);
	} else
		dev_warn(&nuc900_wdt->pdev->dev, "Will reset the machine !\n");
}

static const struct file_operations nuc900wdt_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.unlocked_ioctl	= nuc900_wdt_ioctl,
	.open		= nuc900_wdt_open,
	.release	= nuc900_wdt_close,
	.write		= nuc900_wdt_write,
};

static struct miscdevice nuc900wdt_miscdev = {
	.minor		= WATCHDOG_MINOR,
	.name		= "watchdog",
	.fops		= &nuc900wdt_fops,
};

static int nuc900wdt_probe(struct platform_device *pdev)
{
	int ret = 0;

	nuc900_wdt = kzalloc(sizeof(struct nuc900_wdt), GFP_KERNEL);
	if (!nuc900_wdt)
		return -ENOMEM;

	nuc900_wdt->pdev = pdev;

	spin_lock_init(&nuc900_wdt->wdt_lock);

	nuc900_wdt->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (nuc900_wdt->res == NULL) {
		dev_err(&pdev->dev, "no memory resource specified\n");
		ret = -ENOENT;
		goto err_get;
	}

	if (!request_mem_region(nuc900_wdt->res->start,
				resource_size(nuc900_wdt->res), pdev->name)) {
		dev_err(&pdev->dev, "failed to get memory region\n");
		ret = -ENOENT;
		goto err_get;
	}

	nuc900_wdt->wdt_base = ioremap(nuc900_wdt->res->start,
					resource_size(nuc900_wdt->res));
	if (nuc900_wdt->wdt_base == NULL) {
		dev_err(&pdev->dev, "failed to ioremap() region\n");
		ret = -EINVAL;
		goto err_req;
	}

	nuc900_wdt->wdt_clock = clk_get(&pdev->dev, NULL);
	if (IS_ERR(nuc900_wdt->wdt_clock)) {
		dev_err(&pdev->dev, "failed to find watchdog clock source\n");
		ret = PTR_ERR(nuc900_wdt->wdt_clock);
		goto err_map;
	}

	clk_enable(nuc900_wdt->wdt_clock);

	setup_timer(&nuc900_wdt->timer, nuc900_wdt_timer_ping, 0);

	ret = misc_register(&nuc900wdt_miscdev);
	if (ret) {
		dev_err(&pdev->dev, "err register miscdev on minor=%d (%d)\n",
			WATCHDOG_MINOR, ret);
		goto err_clk;
	}

	return 0;

err_clk:
	clk_disable(nuc900_wdt->wdt_clock);
	clk_put(nuc900_wdt->wdt_clock);
err_map:
	iounmap(nuc900_wdt->wdt_base);
err_req:
	release_mem_region(nuc900_wdt->res->start,
					resource_size(nuc900_wdt->res));
err_get:
	kfree(nuc900_wdt);
	return ret;
}

static int nuc900wdt_remove(struct platform_device *pdev)
{
	misc_deregister(&nuc900wdt_miscdev);

	clk_disable(nuc900_wdt->wdt_clock);
	clk_put(nuc900_wdt->wdt_clock);

	iounmap(nuc900_wdt->wdt_base);

	release_mem_region(nuc900_wdt->res->start,
					resource_size(nuc900_wdt->res));

	kfree(nuc900_wdt);

	return 0;
}

static struct platform_driver nuc900wdt_driver = {
	.probe		= nuc900wdt_probe,
	.remove		= nuc900wdt_remove,
	.driver		= {
		.name	= "nuc900-wdt",
		.owner	= THIS_MODULE,
	},
};

module_platform_driver(nuc900wdt_driver);

MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
MODULE_DESCRIPTION("Watchdog driver for NUC900");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:nuc900-wdt");