drivers/watchdog/bcm2835_wdt.c - arm/linux - Git at Google

 /*
  * 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 <lkundrak@v3.sk>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
  * Free Software Foundation; either version 2 of the License, or (at your
  * option) any later version.
  */

 #include <linux/delay.h>
 #include <linux/types.h>
 #include <linux/module.h>
 #include <linux/io.h>
 #include <linux/watchdog.h>
 #include <linux/platform_device.h>
 #include <linux/of_address.h>
 #include <linux/of_platform.h>

 #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 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 device_node *np =
 		of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
 	struct platform_device *pdev = of_find_device_by_node(np);
 	struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 	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 resource *res;
 	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;
 	platform_set_drvdata(pdev, wdt);

 	spin_lock_init(&wdt->lock);

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	wdt->base = devm_ioremap_resource(dev, res);
 	if (IS_ERR(wdt->base))
 		return PTR_ERR(wdt->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) {
 		dev_err(dev, "Failed to register watchdog device");
 		return err;
 	}

 	if (pm_power_off == NULL)
 		pm_power_off = bcm2835_power_off;

 	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 const struct of_device_id bcm2835_wdt_of_match[] = {
 	{ .compatible = "brcm,bcm2835-pm-wdt", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);

 static struct platform_driver bcm2835_wdt_driver = {
 	.probe		= bcm2835_wdt_probe,
 	.remove		= bcm2835_wdt_remove,
 	.driver = {
 		.name =		"bcm2835-wdt",
 		.of_match_table = bcm2835_wdt_of_match,
 	},
 };
 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_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 MODULE_LICENSE("GPL");
	/*
	* 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 <lkundrak@v3.sk>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License as published by the
	* Free Software Foundation; either version 2 of the License, or (at your
	* option) any later version.
	*/

	#include <linux/delay.h>
	#include <linux/types.h>
	#include <linux/module.h>
	#include <linux/io.h>
	#include <linux/watchdog.h>
	#include <linux/platform_device.h>
	#include <linux/of_address.h>
	#include <linux/of_platform.h>

	#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 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 device_node *np =
	of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
	struct platform_device *pdev = of_find_device_by_node(np);
	struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
	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 resource *res;
	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;
	platform_set_drvdata(pdev, wdt);

	spin_lock_init(&wdt->lock);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	wdt->base = devm_ioremap_resource(dev, res);
	if (IS_ERR(wdt->base))
	return PTR_ERR(wdt->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) {
	dev_err(dev, "Failed to register watchdog device");
	return err;
	}

	if (pm_power_off == NULL)
	pm_power_off = bcm2835_power_off;

	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 const struct of_device_id bcm2835_wdt_of_match[] = {
	{ .compatible = "brcm,bcm2835-pm-wdt", },
	{},
	};
	MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);

	static struct platform_driver bcm2835_wdt_driver = {
	.probe = bcm2835_wdt_probe,
	.remove = bcm2835_wdt_remove,
	.driver = {
	.name = "bcm2835-wdt",
	.of_match_table = bcm2835_wdt_of_match,
	},
	};
	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_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
	MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
	MODULE_LICENSE("GPL");