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/types.h>
18 #include <linux/module.h>
20 #include <linux/watchdog.h>
21 #include <linux/platform_device.h>
22 #include <linux/of_address.h>
23 #include <linux/of_platform.h>
29 #define PM_PASSWORD 0x5a000000
31 #define PM_WDOG_TIME_SET 0x000fffff
32 #define PM_RSTC_WRCFG_CLR 0xffffffcf
33 #define PM_RSTS_HADWRH_SET 0x00000040
34 #define PM_RSTC_WRCFG_SET 0x00000030
35 #define PM_RSTC_WRCFG_FULL_RESET 0x00000020
36 #define PM_RSTC_RESET 0x00000102
37 #define PM_RSTS_PARTITION_CLR 0xfffffaaa
39 #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
40 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
47 static unsigned int heartbeat
;
48 static bool nowayout
= WATCHDOG_NOWAYOUT
;
50 static bool bcm2835_wdt_is_running(struct bcm2835_wdt
*wdt
)
54 cur
= readl(wdt
->base
+ PM_RSTC
);
56 return !!(cur
& PM_RSTC_WRCFG_FULL_RESET
);
59 static int bcm2835_wdt_start(struct watchdog_device
*wdog
)
61 struct bcm2835_wdt
*wdt
= watchdog_get_drvdata(wdog
);
65 spin_lock_irqsave(&wdt
->lock
, flags
);
67 writel_relaxed(PM_PASSWORD
| (SECS_TO_WDOG_TICKS(wdog
->timeout
) &
68 PM_WDOG_TIME_SET
), wdt
->base
+ PM_WDOG
);
69 cur
= readl_relaxed(wdt
->base
+ PM_RSTC
);
70 writel_relaxed(PM_PASSWORD
| (cur
& PM_RSTC_WRCFG_CLR
) |
71 PM_RSTC_WRCFG_FULL_RESET
, wdt
->base
+ PM_RSTC
);
73 spin_unlock_irqrestore(&wdt
->lock
, flags
);
78 static int bcm2835_wdt_stop(struct watchdog_device
*wdog
)
80 struct bcm2835_wdt
*wdt
= watchdog_get_drvdata(wdog
);
82 writel_relaxed(PM_PASSWORD
| PM_RSTC_RESET
, wdt
->base
+ PM_RSTC
);
86 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device
*wdog
)
88 struct bcm2835_wdt
*wdt
= watchdog_get_drvdata(wdog
);
90 uint32_t ret
= readl_relaxed(wdt
->base
+ PM_WDOG
);
91 return WDOG_TICKS_TO_SECS(ret
& PM_WDOG_TIME_SET
);
95 * The Raspberry Pi firmware uses the RSTS register to know which partiton
96 * to boot from. The partiton value is spread into bits 0, 2, 4, 6, 8, 10.
97 * Partiton 63 is a special partition used by the firmware to indicate halt.
100 static void __bcm2835_restart(struct bcm2835_wdt
*wdt
, u8 partition
)
104 rsts
= (partition
& BIT(0)) | ((partition
& BIT(1)) << 1) |
105 ((partition
& BIT(2)) << 2) | ((partition
& BIT(3)) << 3) |
106 ((partition
& BIT(4)) << 4) | ((partition
& BIT(5)) << 5);
108 val
= readl_relaxed(wdt
->base
+ PM_RSTS
);
109 val
&= PM_RSTS_PARTITION_CLR
;
110 val
|= PM_PASSWORD
| rsts
;
111 writel_relaxed(val
, wdt
->base
+ PM_RSTS
);
113 /* use a timeout of 10 ticks (~150us) */
114 writel_relaxed(10 | PM_PASSWORD
, wdt
->base
+ PM_WDOG
);
115 val
= readl_relaxed(wdt
->base
+ PM_RSTC
);
116 val
&= PM_RSTC_WRCFG_CLR
;
117 val
|= PM_PASSWORD
| PM_RSTC_WRCFG_FULL_RESET
;
118 writel_relaxed(val
, wdt
->base
+ PM_RSTC
);
120 /* No sleeping, possibly atomic. */
124 static int bcm2835_restart(struct watchdog_device
*wdog
,
125 unsigned long action
, void *data
)
127 struct bcm2835_wdt
*wdt
= watchdog_get_drvdata(wdog
);
129 unsigned long long val
;
132 if (data
&& !kstrtoull(data
, 0, &val
) && val
<= 63)
135 __bcm2835_restart(wdt
, partition
);
140 static const struct watchdog_ops bcm2835_wdt_ops
= {
141 .owner
= THIS_MODULE
,
142 .start
= bcm2835_wdt_start
,
143 .stop
= bcm2835_wdt_stop
,
144 .get_timeleft
= bcm2835_wdt_get_timeleft
,
145 .restart
= bcm2835_restart
,
148 static const struct watchdog_info bcm2835_wdt_info
= {
149 .options
= WDIOF_SETTIMEOUT
| WDIOF_MAGICCLOSE
|
151 .identity
= "Broadcom BCM2835 Watchdog timer",
154 static struct watchdog_device bcm2835_wdt_wdd
= {
155 .info
= &bcm2835_wdt_info
,
156 .ops
= &bcm2835_wdt_ops
,
158 .max_timeout
= WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET
),
159 .timeout
= WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET
),
163 * We can't really power off, but if we do the normal reset scheme, and
164 * indicate to bootcode.bin not to reboot, then most of the chip will be
167 static void bcm2835_power_off(void)
169 struct device_node
*np
=
170 of_find_compatible_node(NULL
, NULL
, "brcm,bcm2835-pm-wdt");
171 struct platform_device
*pdev
= of_find_device_by_node(np
);
172 struct bcm2835_wdt
*wdt
= platform_get_drvdata(pdev
);
174 /* Partition 63 tells the firmware that this is a halt */
175 __bcm2835_restart(wdt
, 63);
178 static int bcm2835_wdt_probe(struct platform_device
*pdev
)
180 struct resource
*res
;
181 struct device
*dev
= &pdev
->dev
;
182 struct bcm2835_wdt
*wdt
;
185 wdt
= devm_kzalloc(dev
, sizeof(struct bcm2835_wdt
), GFP_KERNEL
);
188 platform_set_drvdata(pdev
, wdt
);
190 spin_lock_init(&wdt
->lock
);
192 res
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
193 wdt
->base
= devm_ioremap_resource(dev
, res
);
194 if (IS_ERR(wdt
->base
))
195 return PTR_ERR(wdt
->base
);
197 watchdog_set_drvdata(&bcm2835_wdt_wdd
, wdt
);
198 watchdog_init_timeout(&bcm2835_wdt_wdd
, heartbeat
, dev
);
199 watchdog_set_nowayout(&bcm2835_wdt_wdd
, nowayout
);
200 bcm2835_wdt_wdd
.parent
= dev
;
201 if (bcm2835_wdt_is_running(wdt
)) {
203 * The currently active timeout value (set by the
204 * bootloader) may be different from the module
205 * heartbeat parameter or the value in device
206 * tree. But we just need to set WDOG_HW_RUNNING,
207 * because then the framework will "immediately" ping
208 * the device, updating the timeout.
210 set_bit(WDOG_HW_RUNNING
, &bcm2835_wdt_wdd
.status
);
213 watchdog_set_restart_priority(&bcm2835_wdt_wdd
, 128);
215 watchdog_stop_on_reboot(&bcm2835_wdt_wdd
);
216 err
= devm_watchdog_register_device(dev
, &bcm2835_wdt_wdd
);
218 dev_err(dev
, "Failed to register watchdog device");
222 if (pm_power_off
== NULL
)
223 pm_power_off
= bcm2835_power_off
;
225 dev_info(dev
, "Broadcom BCM2835 watchdog timer");
229 static int bcm2835_wdt_remove(struct platform_device
*pdev
)
231 if (pm_power_off
== bcm2835_power_off
)
237 static const struct of_device_id bcm2835_wdt_of_match
[] = {
238 { .compatible
= "brcm,bcm2835-pm-wdt", },
241 MODULE_DEVICE_TABLE(of
, bcm2835_wdt_of_match
);
243 static struct platform_driver bcm2835_wdt_driver
= {
244 .probe
= bcm2835_wdt_probe
,
245 .remove
= bcm2835_wdt_remove
,
247 .name
= "bcm2835-wdt",
248 .of_match_table
= bcm2835_wdt_of_match
,
251 module_platform_driver(bcm2835_wdt_driver
);
253 module_param(heartbeat
, uint
, 0);
254 MODULE_PARM_DESC(heartbeat
, "Initial watchdog heartbeat in seconds");
256 module_param(nowayout
, bool, 0);
257 MODULE_PARM_DESC(nowayout
, "Watchdog cannot be stopped once started (default="
258 __MODULE_STRING(WATCHDOG_NOWAYOUT
) ")");
260 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
261 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
262 MODULE_LICENSE("GPL");