2 * Watchdog driver for Atmel AT91SAM9x processors.
4 * Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
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.
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.
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20 #include <linux/errno.h>
22 #include <linux/init.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>
37 #include "at91sam9_wdt.h"
39 #define DRV_NAME "AT91SAM9 Watchdog"
41 #define wdt_read(field) \
42 __raw_readl(at91wdt_private.base + field)
43 #define wdt_write(field, val) \
44 __raw_writel((val), at91wdt_private.base + field)
46 /* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
47 * use this to convert a watchdog
48 * value from/to milliseconds.
50 #define ms_to_ticks(t) (((t << 8) / 1000) - 1)
51 #define ticks_to_ms(t) (((t + 1) * 1000) >> 8)
53 /* Hardware timeout in seconds */
54 #define WDT_HW_TIMEOUT 2
56 /* Timer heartbeat (500ms) */
57 #define WDT_TIMEOUT (HZ/2)
59 /* User land timeout */
60 #define WDT_HEARTBEAT 15
61 static int heartbeat
= WDT_HEARTBEAT
;
62 module_param(heartbeat
, int, 0);
63 MODULE_PARM_DESC(heartbeat
, "Watchdog heartbeats in seconds. "
64 "(default = " __MODULE_STRING(WDT_HEARTBEAT
) ")");
66 static bool nowayout
= WATCHDOG_NOWAYOUT
;
67 module_param(nowayout
, bool, 0);
68 MODULE_PARM_DESC(nowayout
, "Watchdog cannot be stopped once started "
69 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT
) ")");
71 static void at91_ping(unsigned long data
);
75 unsigned long next_heartbeat
; /* the next_heartbeat for the timer */
78 struct timer_list timer
; /* The timer that pings the watchdog */
81 /* ......................................................................... */
85 * Reload the watchdog timer. (ie, pat the watchdog)
87 static inline void at91_wdt_reset(void)
89 wdt_write(AT91_WDT_CR
, AT91_WDT_KEY
| AT91_WDT_WDRSTT
);
95 static void at91_ping(unsigned long data
)
97 if (time_before(jiffies
, at91wdt_private
.next_heartbeat
) ||
98 (!nowayout
&& !at91wdt_private
.open
)) {
100 mod_timer(&at91wdt_private
.timer
, jiffies
+ WDT_TIMEOUT
);
102 pr_crit("I will reset your machine !\n");
106 * Watchdog device is opened, and watchdog starts running.
108 static int at91_wdt_open(struct inode
*inode
, struct file
*file
)
110 if (test_and_set_bit(0, &at91wdt_private
.open
))
113 at91wdt_private
.next_heartbeat
= jiffies
+ heartbeat
* HZ
;
114 mod_timer(&at91wdt_private
.timer
, jiffies
+ WDT_TIMEOUT
);
116 return nonseekable_open(inode
, file
);
120 * Close the watchdog device.
122 static int at91_wdt_close(struct inode
*inode
, struct file
*file
)
124 clear_bit(0, &at91wdt_private
.open
);
126 /* stop internal ping */
127 if (!at91wdt_private
.expect_close
)
128 del_timer(&at91wdt_private
.timer
);
130 at91wdt_private
.expect_close
= 0;
135 * Set the watchdog time interval in 1/256Hz (write-once)
138 static int at91_wdt_settimeout(unsigned int timeout
)
143 /* Check if disabled */
144 mr
= wdt_read(AT91_WDT_MR
);
145 if (mr
& AT91_WDT_WDDIS
) {
146 pr_err("sorry, watchdog is disabled\n");
151 * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
153 * Since WDV is a 12-bit counter, the maximum period is
154 * 4096 / 256 = 16 seconds.
156 reg
= AT91_WDT_WDRSTEN
/* causes watchdog reset */
157 /* | AT91_WDT_WDRPROC causes processor reset only */
158 | AT91_WDT_WDDBGHLT
/* disabled in debug mode */
159 | AT91_WDT_WDD
/* restart at any time */
160 | (timeout
& AT91_WDT_WDV
); /* timer value */
161 wdt_write(AT91_WDT_MR
, reg
);
166 static const struct watchdog_info at91_wdt_info
= {
167 .identity
= DRV_NAME
,
168 .options
= WDIOF_SETTIMEOUT
| WDIOF_KEEPALIVEPING
|
173 * Handle commands from user-space.
175 static long at91_wdt_ioctl(struct file
*file
,
176 unsigned int cmd
, unsigned long arg
)
178 void __user
*argp
= (void __user
*)arg
;
179 int __user
*p
= argp
;
183 case WDIOC_GETSUPPORT
:
184 return copy_to_user(argp
, &at91_wdt_info
,
185 sizeof(at91_wdt_info
)) ? -EFAULT
: 0;
187 case WDIOC_GETSTATUS
:
188 case WDIOC_GETBOOTSTATUS
:
189 return put_user(0, p
);
191 case WDIOC_KEEPALIVE
:
192 at91wdt_private
.next_heartbeat
= jiffies
+ heartbeat
* HZ
;
195 case WDIOC_SETTIMEOUT
:
196 if (get_user(new_value
, p
))
199 heartbeat
= new_value
;
200 at91wdt_private
.next_heartbeat
= jiffies
+ heartbeat
* HZ
;
202 return put_user(new_value
, p
); /* return current value */
204 case WDIOC_GETTIMEOUT
:
205 return put_user(heartbeat
, p
);
211 * Pat the watchdog whenever device is written to.
213 static ssize_t
at91_wdt_write(struct file
*file
, const char *data
, size_t len
,
219 /* Scan for magic character */
223 at91wdt_private
.expect_close
= 0;
225 for (i
= 0; i
< len
; i
++) {
227 if (get_user(c
, data
+ i
))
230 at91wdt_private
.expect_close
= 42;
236 at91wdt_private
.next_heartbeat
= jiffies
+ heartbeat
* HZ
;
241 /* ......................................................................... */
243 static const struct file_operations at91wdt_fops
= {
244 .owner
= THIS_MODULE
,
246 .unlocked_ioctl
= at91_wdt_ioctl
,
247 .open
= at91_wdt_open
,
248 .release
= at91_wdt_close
,
249 .write
= at91_wdt_write
,
252 static struct miscdevice at91wdt_miscdev
= {
253 .minor
= WATCHDOG_MINOR
,
255 .fops
= &at91wdt_fops
,
258 static int __init
at91wdt_probe(struct platform_device
*pdev
)
263 if (at91wdt_miscdev
.parent
)
265 at91wdt_miscdev
.parent
= &pdev
->dev
;
267 r
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
270 at91wdt_private
.base
= ioremap(r
->start
, resource_size(r
));
271 if (!at91wdt_private
.base
) {
272 dev_err(&pdev
->dev
, "failed to map registers, aborting.\n");
277 res
= at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT
* 1000));
281 res
= misc_register(&at91wdt_miscdev
);
285 at91wdt_private
.next_heartbeat
= jiffies
+ heartbeat
* HZ
;
286 setup_timer(&at91wdt_private
.timer
, at91_ping
, 0);
287 mod_timer(&at91wdt_private
.timer
, jiffies
+ WDT_TIMEOUT
);
289 pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n",
290 heartbeat
, nowayout
);
295 static int __exit
at91wdt_remove(struct platform_device
*pdev
)
299 res
= misc_deregister(&at91wdt_miscdev
);
301 at91wdt_miscdev
.parent
= NULL
;
306 #if defined(CONFIG_OF)
307 static const struct of_device_id at91_wdt_dt_ids
[] __initconst
= {
308 { .compatible
= "atmel,at91sam9260-wdt" },
312 MODULE_DEVICE_TABLE(of
, at91_wdt_dt_ids
);
315 static struct platform_driver at91wdt_driver
= {
316 .remove
= __exit_p(at91wdt_remove
),
319 .owner
= THIS_MODULE
,
320 .of_match_table
= of_match_ptr(at91_wdt_dt_ids
),
324 static int __init
at91sam_wdt_init(void)
326 return platform_driver_probe(&at91wdt_driver
, at91wdt_probe
);
329 static void __exit
at91sam_wdt_exit(void)
331 platform_driver_unregister(&at91wdt_driver
);
334 module_init(at91sam_wdt_init
);
335 module_exit(at91sam_wdt_exit
);
337 MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
338 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
339 MODULE_LICENSE("GPL");
340 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR
);