// SPDX-License-Identifier: GPL-2.0+ /* * Watchdog driver for Broadcom BCM2835 * * "bcm2708_wdog" driver written by Luke Diamand that was obtained from * branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used * as a hardware reference for the Broadcom BCM2835 watchdog timer. * * Copyright (C) 2013 Lubomir Rintel * */ #include #include #include #include #include #include #include #include #include #define PM_RSTC 0x1c #define PM_RSTS 0x20 #define PM_WDOG 0x24 #define PM_PASSWORD 0x5a000000 #define PM_WDOG_TIME_SET 0x000fffff #define PM_RSTC_WRCFG_CLR 0xffffffcf #define PM_RSTS_HADWRH_SET 0x00000040 #define PM_RSTC_WRCFG_SET 0x00000030 #define PM_RSTC_WRCFG_FULL_RESET 0x00000020 #define PM_RSTC_RESET 0x00000102 /* * The Raspberry Pi firmware uses the RSTS register to know which partition * to boot from. The partition value is spread into bits 0, 2, 4, 6, 8, 10. * Partition 63 is a special partition used by the firmware to indicate halt. */ #define PM_RSTS_RASPBERRYPI_HALT 0x555 #define SECS_TO_WDOG_TICKS(x) ((x) << 16) #define WDOG_TICKS_TO_SECS(x) ((x) >> 16) struct bcm2835_wdt { void __iomem *base; spinlock_t lock; }; static struct bcm2835_wdt *bcm2835_power_off_wdt; static unsigned int heartbeat; static bool nowayout = WATCHDOG_NOWAYOUT; static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt) { uint32_t cur; cur = readl(wdt->base + PM_RSTC); return !!(cur & PM_RSTC_WRCFG_FULL_RESET); } static int bcm2835_wdt_start(struct watchdog_device *wdog) { struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); uint32_t cur; unsigned long flags; spin_lock_irqsave(&wdt->lock, flags); writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) & PM_WDOG_TIME_SET), wdt->base + PM_WDOG); cur = readl_relaxed(wdt->base + PM_RSTC); writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) | PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC); spin_unlock_irqrestore(&wdt->lock, flags); return 0; } static int bcm2835_wdt_stop(struct watchdog_device *wdog) { struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC); return 0; } static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog) { struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); uint32_t ret = readl_relaxed(wdt->base + PM_WDOG); return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET); } static void __bcm2835_restart(struct bcm2835_wdt *wdt) { u32 val; /* use a timeout of 10 ticks (~150us) */ writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG); val = readl_relaxed(wdt->base + PM_RSTC); val &= PM_RSTC_WRCFG_CLR; val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET; writel_relaxed(val, wdt->base + PM_RSTC); /* No sleeping, possibly atomic. */ mdelay(1); } static int bcm2835_restart(struct watchdog_device *wdog, unsigned long action, void *data) { struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); __bcm2835_restart(wdt); return 0; } static const struct watchdog_ops bcm2835_wdt_ops = { .owner = THIS_MODULE, .start = bcm2835_wdt_start, .stop = bcm2835_wdt_stop, .get_timeleft = bcm2835_wdt_get_timeleft, .restart = bcm2835_restart, }; static const struct watchdog_info bcm2835_wdt_info = { .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING, .identity = "Broadcom BCM2835 Watchdog timer", }; static struct watchdog_device bcm2835_wdt_wdd = { .info = &bcm2835_wdt_info, .ops = &bcm2835_wdt_ops, .min_timeout = 1, .max_timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), .timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), }; /* * We can't really power off, but if we do the normal reset scheme, and * indicate to bootcode.bin not to reboot, then most of the chip will be * powered off. */ static void bcm2835_power_off(void) { struct bcm2835_wdt *wdt = bcm2835_power_off_wdt; u32 val; /* * We set the watchdog hard reset bit here to distinguish this reset * from the normal (full) reset. bootcode.bin will not reboot after a * hard reset. */ val = readl_relaxed(wdt->base + PM_RSTS); val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT; writel_relaxed(val, wdt->base + PM_RSTS); /* Continue with normal reset mechanism */ __bcm2835_restart(wdt); } static int bcm2835_wdt_probe(struct platform_device *pdev) { struct bcm2835_pm *pm = dev_get_drvdata(pdev->dev.parent); struct device *dev = &pdev->dev; struct bcm2835_wdt *wdt; int err; wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL); if (!wdt) return -ENOMEM; spin_lock_init(&wdt->lock); wdt->base = pm->base; watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt); watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev); watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout); bcm2835_wdt_wdd.parent = dev; if (bcm2835_wdt_is_running(wdt)) { /* * The currently active timeout value (set by the * bootloader) may be different from the module * heartbeat parameter or the value in device * tree. But we just need to set WDOG_HW_RUNNING, * because then the framework will "immediately" ping * the device, updating the timeout. */ set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status); } watchdog_set_restart_priority(&bcm2835_wdt_wdd, 128); watchdog_stop_on_reboot(&bcm2835_wdt_wdd); err = devm_watchdog_register_device(dev, &bcm2835_wdt_wdd); if (err) return err; if (pm_power_off == NULL) { pm_power_off = bcm2835_power_off; bcm2835_power_off_wdt = wdt; } dev_info(dev, "Broadcom BCM2835 watchdog timer"); return 0; } static int bcm2835_wdt_remove(struct platform_device *pdev) { if (pm_power_off == bcm2835_power_off) pm_power_off = NULL; return 0; } static struct platform_driver bcm2835_wdt_driver = { .probe = bcm2835_wdt_probe, .remove = bcm2835_wdt_remove, .driver = { .name = "bcm2835-wdt", }, }; module_platform_driver(bcm2835_wdt_driver); module_param(heartbeat, uint, 0); MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds"); module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); MODULE_ALIAS("platform:bcm2835-wdt"); MODULE_AUTHOR("Lubomir Rintel "); MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer"); MODULE_LICENSE("GPL");