1 // SPDX-License-Identifier: GPL-2.0+
3 * Watchdog driver for Broadcom BCM2835
5 * "bcm2708_wdog" driver written by Luke Diamand that was obtained from
6 * branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used
7 * as a hardware reference for the Broadcom BCM2835 watchdog timer.
9 * Copyright (C) 2013 Lubomir Rintel <lkundrak@v3.sk>
13 #include <linux/delay.h>
14 #include <linux/types.h>
15 #include <linux/mfd/bcm2835-pm.h>
16 #include <linux/module.h>
18 #include <linux/watchdog.h>
19 #include <linux/platform_device.h>
20 #include <linux/of_address.h>
21 #include <linux/of_platform.h>
27 #define PM_PASSWORD 0x5a000000
29 #define PM_WDOG_TIME_SET 0x000fffff
30 #define PM_RSTC_WRCFG_CLR 0xffffffcf
31 #define PM_RSTS_HADWRH_SET 0x00000040
32 #define PM_RSTC_WRCFG_SET 0x00000030
33 #define PM_RSTC_WRCFG_FULL_RESET 0x00000020
34 #define PM_RSTC_RESET 0x00000102
35 #define PM_RSTS_PARTITION_CLR 0xfffffaaa
37 #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
38 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
45 static struct bcm2835_wdt *bcm2835_power_off_wdt;
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 bcm2835_wdt *wdt = bcm2835_power_off_wdt;
171 /* Partition 63 tells the firmware that this is a halt */
172 __bcm2835_restart(wdt, 63);
175 static int bcm2835_wdt_probe(struct platform_device *pdev)
177 struct bcm2835_pm *pm = dev_get_drvdata(pdev->dev.parent);
178 struct device *dev = &pdev->dev;
179 struct bcm2835_wdt *wdt;
182 wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
186 spin_lock_init(&wdt->lock);
188 wdt->base = pm->base;
190 watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
191 watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
192 watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
193 bcm2835_wdt_wdd.parent = dev;
194 if (bcm2835_wdt_is_running(wdt)) {
196 * The currently active timeout value (set by the
197 * bootloader) may be different from the module
198 * heartbeat parameter or the value in device
199 * tree. But we just need to set WDOG_HW_RUNNING,
200 * because then the framework will "immediately" ping
201 * the device, updating the timeout.
203 set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status);
206 watchdog_set_restart_priority(&bcm2835_wdt_wdd, 128);
208 watchdog_stop_on_reboot(&bcm2835_wdt_wdd);
209 err = devm_watchdog_register_device(dev, &bcm2835_wdt_wdd);
213 if (of_device_is_system_power_controller(pdev->dev.parent->of_node)) {
215 pm_power_off = bcm2835_power_off;
216 bcm2835_power_off_wdt = wdt;
218 dev_info(dev, "Poweroff handler already present!\n");
222 dev_info(dev, "Broadcom BCM2835 watchdog timer");
226 static int bcm2835_wdt_remove(struct platform_device *pdev)
228 if (pm_power_off == bcm2835_power_off)
234 static struct platform_driver bcm2835_wdt_driver = {
235 .probe = bcm2835_wdt_probe,
236 .remove = bcm2835_wdt_remove,
238 .name = "bcm2835-wdt",
241 module_platform_driver(bcm2835_wdt_driver);
243 module_param(heartbeat, uint, 0);
244 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
246 module_param(nowayout, bool, 0);
247 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
248 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
250 MODULE_ALIAS("platform:bcm2835-wdt");
251 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
252 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
253 MODULE_LICENSE("GPL");