dw_wdt.c
9.49 KB
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
/*
* Copyright 2010-2011 Picochip Ltd., Jamie Iles
* http://www.picochip.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; either version
* 2 of the License, or (at your option) any later version.
*
* This file implements a driver for the Synopsys DesignWare watchdog device
* in the many subsystems. The watchdog has 16 different timeout periods
* and these are a function of the input clock frequency.
*
* The DesignWare watchdog cannot be stopped once it has been started so we
* use a software timer to implement a ping that will keep the watchdog alive.
* If we receive an expected close for the watchdog then we keep the timer
* running, otherwise the timer is stopped and the watchdog will expire.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/notifier.h>
#include <linux/of.h>
#include <linux/pm.h>
#include <linux/platform_device.h>
#include <linux/reboot.h>
#include <linux/timer.h>
#include <linux/uaccess.h>
#include <linux/watchdog.h>
#define WDOG_CONTROL_REG_OFFSET 0x00
#define WDOG_CONTROL_REG_WDT_EN_MASK 0x01
#define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04
#define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT 4
#define WDOG_CURRENT_COUNT_REG_OFFSET 0x08
#define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c
#define WDOG_COUNTER_RESTART_KICK_VALUE 0x76
/* The maximum TOP (timeout period) value that can be set in the watchdog. */
#define DW_WDT_MAX_TOP 15
#define DW_WDT_DEFAULT_SECONDS 30
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 WDT_TIMEOUT (HZ / 2)
static struct {
void __iomem *regs;
struct clk *clk;
unsigned long in_use;
unsigned long next_heartbeat;
struct timer_list timer;
int expect_close;
struct notifier_block restart_handler;
} dw_wdt;
static inline int dw_wdt_is_enabled(void)
{
return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
WDOG_CONTROL_REG_WDT_EN_MASK;
}
static inline int dw_wdt_top_in_seconds(unsigned top)
{
/*
* There are 16 possible timeout values in 0..15 where the number of
* cycles is 2 ^ (16 + i) and the watchdog counts down.
*/
return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk);
}
static int dw_wdt_get_top(void)
{
int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
return dw_wdt_top_in_seconds(top);
}
static inline void dw_wdt_set_next_heartbeat(void)
{
dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
}
static void dw_wdt_keepalive(void)
{
writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
WDOG_COUNTER_RESTART_REG_OFFSET);
}
static int dw_wdt_set_top(unsigned top_s)
{
int i, top_val = DW_WDT_MAX_TOP;
/*
* Iterate over the timeout values until we find the closest match. We
* always look for >=.
*/
for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
if (dw_wdt_top_in_seconds(i) >= top_s) {
top_val = i;
break;
}
/*
* Set the new value in the watchdog. Some versions of dw_wdt
* have have TOPINIT in the TIMEOUT_RANGE register (as per
* CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1). On those we
* effectively get a pat of the watchdog right here.
*/
writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
/*
* Add an explicit pat to handle versions of the watchdog that
* don't have TOPINIT. This won't hurt on versions that have
* it.
*/
dw_wdt_keepalive();
dw_wdt_set_next_heartbeat();
return dw_wdt_top_in_seconds(top_val);
}
static int dw_wdt_restart_handle(struct notifier_block *this,
unsigned long mode, void *cmd)
{
u32 val;
writel(0, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
val = readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
if (val & WDOG_CONTROL_REG_WDT_EN_MASK)
writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
WDOG_COUNTER_RESTART_REG_OFFSET);
else
writel(WDOG_CONTROL_REG_WDT_EN_MASK,
dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
/* wait for reset to assert... */
mdelay(500);
return NOTIFY_DONE;
}
static void dw_wdt_ping(unsigned long data)
{
if (time_before(jiffies, dw_wdt.next_heartbeat) ||
(!nowayout && !dw_wdt.in_use)) {
dw_wdt_keepalive();
mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
} else
pr_crit("keepalive missed, machine will reset\n");
}
static int dw_wdt_open(struct inode *inode, struct file *filp)
{
if (test_and_set_bit(0, &dw_wdt.in_use))
return -EBUSY;
/* Make sure we don't get unloaded. */
__module_get(THIS_MODULE);
if (!dw_wdt_is_enabled()) {
/*
* The watchdog is not currently enabled. Set the timeout to
* something reasonable and then start it.
*/
dw_wdt_set_top(DW_WDT_DEFAULT_SECONDS);
writel(WDOG_CONTROL_REG_WDT_EN_MASK,
dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
}
dw_wdt_set_next_heartbeat();
return nonseekable_open(inode, filp);
}
static ssize_t dw_wdt_write(struct file *filp, const char __user *buf,
size_t len, loff_t *offset)
{
if (!len)
return 0;
if (!nowayout) {
size_t i;
dw_wdt.expect_close = 0;
for (i = 0; i < len; ++i) {
char c;
if (get_user(c, buf + i))
return -EFAULT;
if (c == 'V') {
dw_wdt.expect_close = 1;
break;
}
}
}
dw_wdt_set_next_heartbeat();
dw_wdt_keepalive();
mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
return len;
}
static u32 dw_wdt_time_left(void)
{
return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
clk_get_rate(dw_wdt.clk);
}
static const struct watchdog_info dw_wdt_ident = {
.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
WDIOF_MAGICCLOSE,
.identity = "Synopsys DesignWare Watchdog",
};
static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
unsigned long val;
int timeout;
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user((void __user *)arg, &dw_wdt_ident,
sizeof(dw_wdt_ident)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, (int __user *)arg);
case WDIOC_KEEPALIVE:
dw_wdt_set_next_heartbeat();
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(val, (int __user *)arg))
return -EFAULT;
timeout = dw_wdt_set_top(val);
return put_user(timeout , (int __user *)arg);
case WDIOC_GETTIMEOUT:
return put_user(dw_wdt_get_top(), (int __user *)arg);
case WDIOC_GETTIMELEFT:
/* Get the time left until expiry. */
if (get_user(val, (int __user *)arg))
return -EFAULT;
return put_user(dw_wdt_time_left(), (int __user *)arg);
default:
return -ENOTTY;
}
}
static int dw_wdt_release(struct inode *inode, struct file *filp)
{
clear_bit(0, &dw_wdt.in_use);
if (!dw_wdt.expect_close) {
del_timer(&dw_wdt.timer);
if (!nowayout)
pr_crit("unexpected close, system will reboot soon\n");
else
pr_crit("watchdog cannot be disabled, system will reboot soon\n");
}
dw_wdt.expect_close = 0;
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int dw_wdt_suspend(struct device *dev)
{
clk_disable_unprepare(dw_wdt.clk);
return 0;
}
static int dw_wdt_resume(struct device *dev)
{
int err = clk_prepare_enable(dw_wdt.clk);
if (err)
return err;
dw_wdt_keepalive();
return 0;
}
#endif /* CONFIG_PM_SLEEP */
static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
static const struct file_operations wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.open = dw_wdt_open,
.write = dw_wdt_write,
.unlocked_ioctl = dw_wdt_ioctl,
.release = dw_wdt_release
};
static struct miscdevice dw_wdt_miscdev = {
.fops = &wdt_fops,
.name = "watchdog",
.minor = WATCHDOG_MINOR,
};
static int dw_wdt_drv_probe(struct platform_device *pdev)
{
int ret;
struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
dw_wdt.regs = devm_ioremap_resource(&pdev->dev, mem);
if (IS_ERR(dw_wdt.regs))
return PTR_ERR(dw_wdt.regs);
dw_wdt.clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(dw_wdt.clk))
return PTR_ERR(dw_wdt.clk);
ret = clk_prepare_enable(dw_wdt.clk);
if (ret)
return ret;
ret = misc_register(&dw_wdt_miscdev);
if (ret)
goto out_disable_clk;
dw_wdt.restart_handler.notifier_call = dw_wdt_restart_handle;
dw_wdt.restart_handler.priority = 128;
ret = register_restart_handler(&dw_wdt.restart_handler);
if (ret)
pr_warn("cannot register restart handler\n");
dw_wdt_set_next_heartbeat();
setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
return 0;
out_disable_clk:
clk_disable_unprepare(dw_wdt.clk);
return ret;
}
static int dw_wdt_drv_remove(struct platform_device *pdev)
{
unregister_restart_handler(&dw_wdt.restart_handler);
misc_deregister(&dw_wdt_miscdev);
clk_disable_unprepare(dw_wdt.clk);
return 0;
}
#ifdef CONFIG_OF
static const struct of_device_id dw_wdt_of_match[] = {
{ .compatible = "snps,dw-wdt", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
#endif
static struct platform_driver dw_wdt_driver = {
.probe = dw_wdt_drv_probe,
.remove = dw_wdt_drv_remove,
.driver = {
.name = "dw_wdt",
.of_match_table = of_match_ptr(dw_wdt_of_match),
.pm = &dw_wdt_pm_ops,
},
};
module_platform_driver(dw_wdt_driver);
MODULE_AUTHOR("Jamie Iles");
MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
MODULE_LICENSE("GPL");