256 lines
6.8 KiB
C
256 lines
6.8 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Watchdog driver for Broadcom BCM2835
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*
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* "bcm2708_wdog" driver written by Luke Diamand that was obtained from
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* branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used
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* as a hardware reference for the Broadcom BCM2835 watchdog timer.
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*
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* Copyright (C) 2013 Lubomir Rintel <lkundrak@v3.sk>
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*
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*/
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#include <linux/delay.h>
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#include <linux/types.h>
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#include <linux/module.h>
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#include <linux/io.h>
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#include <linux/watchdog.h>
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#include <linux/platform_device.h>
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#include <linux/of_address.h>
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#include <linux/of_platform.h>
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#define PM_RSTC 0x1c
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#define PM_RSTS 0x20
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#define PM_WDOG 0x24
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#define PM_PASSWORD 0x5a000000
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#define PM_WDOG_TIME_SET 0x000fffff
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#define PM_RSTC_WRCFG_CLR 0xffffffcf
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#define PM_RSTS_HADWRH_SET 0x00000040
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#define PM_RSTC_WRCFG_SET 0x00000030
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#define PM_RSTC_WRCFG_FULL_RESET 0x00000020
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#define PM_RSTC_RESET 0x00000102
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/*
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* The Raspberry Pi firmware uses the RSTS register to know which partition
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* to boot from. The partition value is spread into bits 0, 2, 4, 6, 8, 10.
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* Partition 63 is a special partition used by the firmware to indicate halt.
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*/
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#define PM_RSTS_RASPBERRYPI_HALT 0x555
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#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
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#define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
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struct bcm2835_wdt {
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void __iomem *base;
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spinlock_t lock;
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};
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static unsigned int heartbeat;
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static bool nowayout = WATCHDOG_NOWAYOUT;
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static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt)
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{
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uint32_t cur;
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cur = readl(wdt->base + PM_RSTC);
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return !!(cur & PM_RSTC_WRCFG_FULL_RESET);
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}
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static int bcm2835_wdt_start(struct watchdog_device *wdog)
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{
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struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
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uint32_t cur;
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unsigned long flags;
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spin_lock_irqsave(&wdt->lock, flags);
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writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
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PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
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cur = readl_relaxed(wdt->base + PM_RSTC);
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writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
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PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
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spin_unlock_irqrestore(&wdt->lock, flags);
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return 0;
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}
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static int bcm2835_wdt_stop(struct watchdog_device *wdog)
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{
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struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
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writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
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return 0;
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}
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static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
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{
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struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
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uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
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return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
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}
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static void __bcm2835_restart(struct bcm2835_wdt *wdt)
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{
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u32 val;
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/* use a timeout of 10 ticks (~150us) */
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writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
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val = readl_relaxed(wdt->base + PM_RSTC);
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val &= PM_RSTC_WRCFG_CLR;
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val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
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writel_relaxed(val, wdt->base + PM_RSTC);
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/* No sleeping, possibly atomic. */
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mdelay(1);
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}
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static int bcm2835_restart(struct watchdog_device *wdog,
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unsigned long action, void *data)
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{
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struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
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__bcm2835_restart(wdt);
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return 0;
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}
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static const struct watchdog_ops bcm2835_wdt_ops = {
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.owner = THIS_MODULE,
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.start = bcm2835_wdt_start,
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.stop = bcm2835_wdt_stop,
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.get_timeleft = bcm2835_wdt_get_timeleft,
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.restart = bcm2835_restart,
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};
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static const struct watchdog_info bcm2835_wdt_info = {
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.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
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WDIOF_KEEPALIVEPING,
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.identity = "Broadcom BCM2835 Watchdog timer",
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};
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static struct watchdog_device bcm2835_wdt_wdd = {
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.info = &bcm2835_wdt_info,
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.ops = &bcm2835_wdt_ops,
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.min_timeout = 1,
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.max_timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
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.timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
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};
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/*
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* We can't really power off, but if we do the normal reset scheme, and
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* indicate to bootcode.bin not to reboot, then most of the chip will be
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* powered off.
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*/
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static void bcm2835_power_off(void)
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{
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struct device_node *np =
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of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
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struct platform_device *pdev = of_find_device_by_node(np);
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struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
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u32 val;
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/*
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* We set the watchdog hard reset bit here to distinguish this reset
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* from the normal (full) reset. bootcode.bin will not reboot after a
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* hard reset.
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*/
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val = readl_relaxed(wdt->base + PM_RSTS);
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val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
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writel_relaxed(val, wdt->base + PM_RSTS);
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/* Continue with normal reset mechanism */
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__bcm2835_restart(wdt);
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}
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static int bcm2835_wdt_probe(struct platform_device *pdev)
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{
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struct resource *res;
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struct device *dev = &pdev->dev;
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struct bcm2835_wdt *wdt;
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int err;
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wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
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if (!wdt)
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return -ENOMEM;
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platform_set_drvdata(pdev, wdt);
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spin_lock_init(&wdt->lock);
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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wdt->base = devm_ioremap_resource(dev, res);
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if (IS_ERR(wdt->base))
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return PTR_ERR(wdt->base);
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watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
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watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
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watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
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bcm2835_wdt_wdd.parent = dev;
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if (bcm2835_wdt_is_running(wdt)) {
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/*
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* The currently active timeout value (set by the
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* bootloader) may be different from the module
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* heartbeat parameter or the value in device
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* tree. But we just need to set WDOG_HW_RUNNING,
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* because then the framework will "immediately" ping
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* the device, updating the timeout.
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*/
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set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status);
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}
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watchdog_set_restart_priority(&bcm2835_wdt_wdd, 128);
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watchdog_stop_on_reboot(&bcm2835_wdt_wdd);
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err = devm_watchdog_register_device(dev, &bcm2835_wdt_wdd);
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if (err) {
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dev_err(dev, "Failed to register watchdog device");
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return err;
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}
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if (pm_power_off == NULL)
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pm_power_off = bcm2835_power_off;
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dev_info(dev, "Broadcom BCM2835 watchdog timer");
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return 0;
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}
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static int bcm2835_wdt_remove(struct platform_device *pdev)
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{
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if (pm_power_off == bcm2835_power_off)
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pm_power_off = NULL;
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return 0;
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}
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static const struct of_device_id bcm2835_wdt_of_match[] = {
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{ .compatible = "brcm,bcm2835-pm-wdt", },
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{},
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};
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MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
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static struct platform_driver bcm2835_wdt_driver = {
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.probe = bcm2835_wdt_probe,
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.remove = bcm2835_wdt_remove,
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.driver = {
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.name = "bcm2835-wdt",
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.of_match_table = bcm2835_wdt_of_match,
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},
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};
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module_platform_driver(bcm2835_wdt_driver);
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module_param(heartbeat, uint, 0);
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MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
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module_param(nowayout, bool, 0);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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MODULE_ALIAS("platform:bcm2835-wdt");
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MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
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MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
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MODULE_LICENSE("GPL");
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