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kernel/linux-imx6_3.14.28/drivers/watchdog/bcm2835_wdt.c 4.94 KB
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  /*
   * 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/types.h>
  #include <linux/module.h>
  #include <linux/io.h>
  #include <linux/watchdog.h>
  #include <linux/platform_device.h>
  #include <linux/of_address.h>
  
  #define PM_RSTC				0x1c
  #define PM_WDOG				0x24
  
  #define PM_PASSWORD			0x5a000000
  
  #define PM_WDOG_TIME_SET		0x000fffff
  #define PM_RSTC_WRCFG_CLR		0xffffffcf
  #define PM_RSTC_WRCFG_SET		0x00000030
  #define PM_RSTC_WRCFG_FULL_RESET	0x00000020
  #define PM_RSTC_RESET			0x00000102
  
  #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 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);
  	dev_info(wdog->dev, "Watchdog timer stopped");
  	return 0;
  }
  
  static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
  {
  	wdog->timeout = t;
  	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 struct watchdog_ops bcm2835_wdt_ops = {
  	.owner =	THIS_MODULE,
  	.start =	bcm2835_wdt_start,
  	.stop =		bcm2835_wdt_stop,
  	.set_timeout =	bcm2835_wdt_set_timeout,
  	.get_timeleft =	bcm2835_wdt_get_timeleft,
  };
  
  static 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),
  };
  
  static int bcm2835_wdt_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct device_node *np = dev->of_node;
  	struct bcm2835_wdt *wdt;
  	int err;
  
  	wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
  	if (!wdt) {
  		dev_err(dev, "Failed to allocate memory for watchdog device");
  		return -ENOMEM;
  	}
  	platform_set_drvdata(pdev, wdt);
  
  	spin_lock_init(&wdt->lock);
  
  	wdt->base = of_iomap(np, 0);
  	if (!wdt->base) {
  		dev_err(dev, "Failed to remap watchdog regs");
  		return -ENODEV;
  	}
  
  	watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
  	watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
  	watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
  	err = watchdog_register_device(&bcm2835_wdt_wdd);
  	if (err) {
  		dev_err(dev, "Failed to register watchdog device");
  		iounmap(wdt->base);
  		return err;
  	}
  
  	dev_info(dev, "Broadcom BCM2835 watchdog timer");
  	return 0;
  }
  
  static int bcm2835_wdt_remove(struct platform_device *pdev)
  {
  	struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
  
  	watchdog_unregister_device(&bcm2835_wdt_wdd);
  	iounmap(wdt->base);
  
  	return 0;
  }
  
  static void bcm2835_wdt_shutdown(struct platform_device *pdev)
  {
  	bcm2835_wdt_stop(&bcm2835_wdt_wdd);
  }
  
  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,
  	.shutdown	= bcm2835_wdt_shutdown,
  	.driver = {
  		.name =		"bcm2835-wdt",
  		.owner =	THIS_MODULE,
  		.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");