Root/drivers/watchdog/at91sam9_wdt.c

1/*
2 * Watchdog driver for Atmel AT91SAM9x processors.
3 *
4 * Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12/*
13 * The Watchdog Timer Mode Register can be only written to once. If the
14 * timeout need to be set from Linux, be sure that the bootstrap or the
15 * bootloader doesn't write to this register.
16 */
17
18#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19
20#include <linux/errno.h>
21#include <linux/fs.h>
22#include <linux/init.h>
23#include <linux/io.h>
24#include <linux/kernel.h>
25#include <linux/miscdevice.h>
26#include <linux/module.h>
27#include <linux/moduleparam.h>
28#include <linux/platform_device.h>
29#include <linux/types.h>
30#include <linux/watchdog.h>
31#include <linux/jiffies.h>
32#include <linux/timer.h>
33#include <linux/bitops.h>
34#include <linux/uaccess.h>
35
36#include "at91sam9_wdt.h"
37
38#define DRV_NAME "AT91SAM9 Watchdog"
39
40#define wdt_read(field) \
41    __raw_readl(at91wdt_private.base + field)
42#define wdt_write(field, val) \
43    __raw_writel((val), at91wdt_private.base + field)
44
45/* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
46 * use this to convert a watchdog
47 * value from/to milliseconds.
48 */
49#define ms_to_ticks(t) (((t << 8) / 1000) - 1)
50#define ticks_to_ms(t) (((t + 1) * 1000) >> 8)
51
52/* Hardware timeout in seconds */
53#define WDT_HW_TIMEOUT 2
54
55/* Timer heartbeat (500ms) */
56#define WDT_TIMEOUT (HZ/2)
57
58/* User land timeout */
59#define WDT_HEARTBEAT 15
60static int heartbeat = WDT_HEARTBEAT;
61module_param(heartbeat, int, 0);
62MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
63    "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
64
65static bool nowayout = WATCHDOG_NOWAYOUT;
66module_param(nowayout, bool, 0);
67MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
68    "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
69
70static void at91_ping(unsigned long data);
71
72static struct {
73    void __iomem *base;
74    unsigned long next_heartbeat; /* the next_heartbeat for the timer */
75    unsigned long open;
76    char expect_close;
77    struct timer_list timer; /* The timer that pings the watchdog */
78} at91wdt_private;
79
80/* ......................................................................... */
81
82
83/*
84 * Reload the watchdog timer. (ie, pat the watchdog)
85 */
86static inline void at91_wdt_reset(void)
87{
88    wdt_write(AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
89}
90
91/*
92 * Timer tick
93 */
94static void at91_ping(unsigned long data)
95{
96    if (time_before(jiffies, at91wdt_private.next_heartbeat) ||
97            (!nowayout && !at91wdt_private.open)) {
98        at91_wdt_reset();
99        mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
100    } else
101        pr_crit("I will reset your machine !\n");
102}
103
104/*
105 * Watchdog device is opened, and watchdog starts running.
106 */
107static int at91_wdt_open(struct inode *inode, struct file *file)
108{
109    if (test_and_set_bit(0, &at91wdt_private.open))
110        return -EBUSY;
111
112    at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
113    mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
114
115    return nonseekable_open(inode, file);
116}
117
118/*
119 * Close the watchdog device.
120 */
121static int at91_wdt_close(struct inode *inode, struct file *file)
122{
123    clear_bit(0, &at91wdt_private.open);
124
125    /* stop internal ping */
126    if (!at91wdt_private.expect_close)
127        del_timer(&at91wdt_private.timer);
128
129    at91wdt_private.expect_close = 0;
130    return 0;
131}
132
133/*
134 * Set the watchdog time interval in 1/256Hz (write-once)
135 * Counter is 12 bit.
136 */
137static int at91_wdt_settimeout(unsigned int timeout)
138{
139    unsigned int reg;
140    unsigned int mr;
141
142    /* Check if disabled */
143    mr = wdt_read(AT91_WDT_MR);
144    if (mr & AT91_WDT_WDDIS) {
145        pr_err("sorry, watchdog is disabled\n");
146        return -EIO;
147    }
148
149    /*
150     * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
151     *
152     * Since WDV is a 12-bit counter, the maximum period is
153     * 4096 / 256 = 16 seconds.
154     */
155    reg = AT91_WDT_WDRSTEN /* causes watchdog reset */
156        /* | AT91_WDT_WDRPROC causes processor reset only */
157        | AT91_WDT_WDDBGHLT /* disabled in debug mode */
158        | AT91_WDT_WDD /* restart at any time */
159        | (timeout & AT91_WDT_WDV); /* timer value */
160    wdt_write(AT91_WDT_MR, reg);
161
162    return 0;
163}
164
165static const struct watchdog_info at91_wdt_info = {
166    .identity = DRV_NAME,
167    .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
168                        WDIOF_MAGICCLOSE,
169};
170
171/*
172 * Handle commands from user-space.
173 */
174static long at91_wdt_ioctl(struct file *file,
175        unsigned int cmd, unsigned long arg)
176{
177    void __user *argp = (void __user *)arg;
178    int __user *p = argp;
179    int new_value;
180
181    switch (cmd) {
182    case WDIOC_GETSUPPORT:
183        return copy_to_user(argp, &at91_wdt_info,
184                    sizeof(at91_wdt_info)) ? -EFAULT : 0;
185
186    case WDIOC_GETSTATUS:
187    case WDIOC_GETBOOTSTATUS:
188        return put_user(0, p);
189
190    case WDIOC_KEEPALIVE:
191        at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
192        return 0;
193
194    case WDIOC_SETTIMEOUT:
195        if (get_user(new_value, p))
196            return -EFAULT;
197
198        heartbeat = new_value;
199        at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
200
201        return put_user(new_value, p); /* return current value */
202
203    case WDIOC_GETTIMEOUT:
204        return put_user(heartbeat, p);
205    }
206    return -ENOTTY;
207}
208
209/*
210 * Pat the watchdog whenever device is written to.
211 */
212static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len,
213                                loff_t *ppos)
214{
215    if (!len)
216        return 0;
217
218    /* Scan for magic character */
219    if (!nowayout) {
220        size_t i;
221
222        at91wdt_private.expect_close = 0;
223
224        for (i = 0; i < len; i++) {
225            char c;
226            if (get_user(c, data + i))
227                return -EFAULT;
228            if (c == 'V') {
229                at91wdt_private.expect_close = 42;
230                break;
231            }
232        }
233    }
234
235    at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
236
237    return len;
238}
239
240/* ......................................................................... */
241
242static const struct file_operations at91wdt_fops = {
243    .owner = THIS_MODULE,
244    .llseek = no_llseek,
245    .unlocked_ioctl = at91_wdt_ioctl,
246    .open = at91_wdt_open,
247    .release = at91_wdt_close,
248    .write = at91_wdt_write,
249};
250
251static struct miscdevice at91wdt_miscdev = {
252    .minor = WATCHDOG_MINOR,
253    .name = "watchdog",
254    .fops = &at91wdt_fops,
255};
256
257static int __init at91wdt_probe(struct platform_device *pdev)
258{
259    struct resource *r;
260    int res;
261
262    if (at91wdt_miscdev.parent)
263        return -EBUSY;
264    at91wdt_miscdev.parent = &pdev->dev;
265
266    r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
267    if (!r)
268        return -ENODEV;
269    at91wdt_private.base = ioremap(r->start, resource_size(r));
270    if (!at91wdt_private.base) {
271        dev_err(&pdev->dev, "failed to map registers, aborting.\n");
272        return -ENOMEM;
273    }
274
275    /* Set watchdog */
276    res = at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT * 1000));
277    if (res)
278        return res;
279
280    res = misc_register(&at91wdt_miscdev);
281    if (res)
282        return res;
283
284    at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
285    setup_timer(&at91wdt_private.timer, at91_ping, 0);
286    mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
287
288    pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n",
289        heartbeat, nowayout);
290
291    return 0;
292}
293
294static int __exit at91wdt_remove(struct platform_device *pdev)
295{
296    int res;
297
298    res = misc_deregister(&at91wdt_miscdev);
299    if (!res)
300        at91wdt_miscdev.parent = NULL;
301
302    return res;
303}
304
305static struct platform_driver at91wdt_driver = {
306    .remove = __exit_p(at91wdt_remove),
307    .driver = {
308        .name = "at91_wdt",
309        .owner = THIS_MODULE,
310    },
311};
312
313static int __init at91sam_wdt_init(void)
314{
315    return platform_driver_probe(&at91wdt_driver, at91wdt_probe);
316}
317
318static void __exit at91sam_wdt_exit(void)
319{
320    platform_driver_unregister(&at91wdt_driver);
321}
322
323module_init(at91sam_wdt_init);
324module_exit(at91sam_wdt_exit);
325
326MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
327MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
328MODULE_LICENSE("GPL");
329MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
330

Archive Download this file

Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master

Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9



interactive