2 * Watchdog driver for Broadcom BCM2835
4 * "bcm2708_wdog" driver written by Luke Diamand that was obtained from
5 * branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used
6 * as a hardware reference for the Broadcom BCM2835 watchdog timer.
8 * Copyright (C) 2013 Lubomir Rintel <lkundrak@v3.sk>
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the
12 * Free Software Foundation; either version 2 of the License, or (at your
13 * option) any later version.
16 #include <linux/delay.h>
17 #include <linux/reboot.h>
18 #include <linux/types.h>
19 #include <linux/module.h>
21 #include <linux/watchdog.h>
22 #include <linux/platform_device.h>
23 #include <linux/of_address.h>
24 #include <linux/of_platform.h>
30 #define PM_PASSWORD 0x5a000000
32 #define PM_WDOG_TIME_SET 0x000fffff
33 #define PM_RSTC_WRCFG_CLR 0xffffffcf
34 #define PM_RSTS_HADWRH_SET 0x00000040
35 #define PM_RSTC_WRCFG_SET 0x00000030
36 #define PM_RSTC_WRCFG_FULL_RESET 0x00000020
37 #define PM_RSTC_RESET 0x00000102
39 #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
40 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
45 struct notifier_block restart_handler
;
48 static unsigned int heartbeat
;
49 static bool nowayout
= WATCHDOG_NOWAYOUT
;
51 static int bcm2835_wdt_start(struct watchdog_device
*wdog
)
53 struct bcm2835_wdt
*wdt
= watchdog_get_drvdata(wdog
);
57 spin_lock_irqsave(&wdt
->lock
, flags
);
59 writel_relaxed(PM_PASSWORD
| (SECS_TO_WDOG_TICKS(wdog
->timeout
) &
60 PM_WDOG_TIME_SET
), wdt
->base
+ PM_WDOG
);
61 cur
= readl_relaxed(wdt
->base
+ PM_RSTC
);
62 writel_relaxed(PM_PASSWORD
| (cur
& PM_RSTC_WRCFG_CLR
) |
63 PM_RSTC_WRCFG_FULL_RESET
, wdt
->base
+ PM_RSTC
);
65 spin_unlock_irqrestore(&wdt
->lock
, flags
);
70 static int bcm2835_wdt_stop(struct watchdog_device
*wdog
)
72 struct bcm2835_wdt
*wdt
= watchdog_get_drvdata(wdog
);
74 writel_relaxed(PM_PASSWORD
| PM_RSTC_RESET
, wdt
->base
+ PM_RSTC
);
75 dev_info(wdog
->dev
, "Watchdog timer stopped");
79 static int bcm2835_wdt_set_timeout(struct watchdog_device
*wdog
, unsigned int t
)
85 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device
*wdog
)
87 struct bcm2835_wdt
*wdt
= watchdog_get_drvdata(wdog
);
89 uint32_t ret
= readl_relaxed(wdt
->base
+ PM_WDOG
);
90 return WDOG_TICKS_TO_SECS(ret
& PM_WDOG_TIME_SET
);
93 static struct watchdog_ops bcm2835_wdt_ops
= {
95 .start
= bcm2835_wdt_start
,
96 .stop
= bcm2835_wdt_stop
,
97 .set_timeout
= bcm2835_wdt_set_timeout
,
98 .get_timeleft
= bcm2835_wdt_get_timeleft
,
101 static struct watchdog_info bcm2835_wdt_info
= {
102 .options
= WDIOF_SETTIMEOUT
| WDIOF_MAGICCLOSE
|
104 .identity
= "Broadcom BCM2835 Watchdog timer",
107 static struct watchdog_device bcm2835_wdt_wdd
= {
108 .info
= &bcm2835_wdt_info
,
109 .ops
= &bcm2835_wdt_ops
,
111 .max_timeout
= WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET
),
112 .timeout
= WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET
),
116 bcm2835_restart(struct notifier_block
*this, unsigned long mode
, void *cmd
)
118 struct bcm2835_wdt
*wdt
= container_of(this, struct bcm2835_wdt
,
122 /* use a timeout of 10 ticks (~150us) */
123 writel_relaxed(10 | PM_PASSWORD
, wdt
->base
+ PM_WDOG
);
124 val
= readl_relaxed(wdt
->base
+ PM_RSTC
);
125 val
&= PM_RSTC_WRCFG_CLR
;
126 val
|= PM_PASSWORD
| PM_RSTC_WRCFG_FULL_RESET
;
127 writel_relaxed(val
, wdt
->base
+ PM_RSTC
);
129 /* No sleeping, possibly atomic. */
136 * We can't really power off, but if we do the normal reset scheme, and
137 * indicate to bootcode.bin not to reboot, then most of the chip will be
140 static void bcm2835_power_off(void)
142 struct device_node
*np
=
143 of_find_compatible_node(NULL
, NULL
, "brcm,bcm2835-pm-wdt");
144 struct platform_device
*pdev
= of_find_device_by_node(np
);
145 struct bcm2835_wdt
*wdt
= platform_get_drvdata(pdev
);
149 * We set the watchdog hard reset bit here to distinguish this reset
150 * from the normal (full) reset. bootcode.bin will not reboot after a
153 val
= readl_relaxed(wdt
->base
+ PM_RSTS
);
154 val
&= PM_RSTC_WRCFG_CLR
;
155 val
|= PM_PASSWORD
| PM_RSTS_HADWRH_SET
;
156 writel_relaxed(val
, wdt
->base
+ PM_RSTS
);
158 /* Continue with normal reset mechanism */
159 bcm2835_restart(&wdt
->restart_handler
, REBOOT_HARD
, NULL
);
162 static int bcm2835_wdt_probe(struct platform_device
*pdev
)
164 struct device
*dev
= &pdev
->dev
;
165 struct device_node
*np
= dev
->of_node
;
166 struct bcm2835_wdt
*wdt
;
169 wdt
= devm_kzalloc(dev
, sizeof(struct bcm2835_wdt
), GFP_KERNEL
);
172 platform_set_drvdata(pdev
, wdt
);
174 spin_lock_init(&wdt
->lock
);
176 wdt
->base
= of_iomap(np
, 0);
178 dev_err(dev
, "Failed to remap watchdog regs");
182 watchdog_set_drvdata(&bcm2835_wdt_wdd
, wdt
);
183 watchdog_init_timeout(&bcm2835_wdt_wdd
, heartbeat
, dev
);
184 watchdog_set_nowayout(&bcm2835_wdt_wdd
, nowayout
);
185 err
= watchdog_register_device(&bcm2835_wdt_wdd
);
187 dev_err(dev
, "Failed to register watchdog device");
192 wdt
->restart_handler
.notifier_call
= bcm2835_restart
;
193 wdt
->restart_handler
.priority
= 128;
194 register_restart_handler(&wdt
->restart_handler
);
195 if (pm_power_off
== NULL
)
196 pm_power_off
= bcm2835_power_off
;
198 dev_info(dev
, "Broadcom BCM2835 watchdog timer");
202 static int bcm2835_wdt_remove(struct platform_device
*pdev
)
204 struct bcm2835_wdt
*wdt
= platform_get_drvdata(pdev
);
206 unregister_restart_handler(&wdt
->restart_handler
);
207 if (pm_power_off
== bcm2835_power_off
)
209 watchdog_unregister_device(&bcm2835_wdt_wdd
);
215 static void bcm2835_wdt_shutdown(struct platform_device
*pdev
)
217 bcm2835_wdt_stop(&bcm2835_wdt_wdd
);
220 static const struct of_device_id bcm2835_wdt_of_match
[] = {
221 { .compatible
= "brcm,bcm2835-pm-wdt", },
224 MODULE_DEVICE_TABLE(of
, bcm2835_wdt_of_match
);
226 static struct platform_driver bcm2835_wdt_driver
= {
227 .probe
= bcm2835_wdt_probe
,
228 .remove
= bcm2835_wdt_remove
,
229 .shutdown
= bcm2835_wdt_shutdown
,
231 .name
= "bcm2835-wdt",
232 .of_match_table
= bcm2835_wdt_of_match
,
235 module_platform_driver(bcm2835_wdt_driver
);
237 module_param(heartbeat
, uint
, 0);
238 MODULE_PARM_DESC(heartbeat
, "Initial watchdog heartbeat in seconds");
240 module_param(nowayout
, bool, 0);
241 MODULE_PARM_DESC(nowayout
, "Watchdog cannot be stopped once started (default="
242 __MODULE_STRING(WATCHDOG_NOWAYOUT
) ")");
244 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
245 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
246 MODULE_LICENSE("GPL");