linux/drivers/watchdog/bcm2835_wdt.c
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   1/*
   2 * Watchdog driver for Broadcom BCM2835
   3 *
   4 * "bcm2708_wdog" driver written by Luke Diamand that was obtained from
   5 * branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used
   6 * as a hardware reference for the Broadcom BCM2835 watchdog timer.
   7 *
   8 * Copyright (C) 2013 Lubomir Rintel <lkundrak@v3.sk>
   9 *
  10 * This program is free software; you can redistribute it and/or modify it
  11 * under the terms of the GNU General Public License as published by the
  12 * Free Software Foundation; either version 2 of the License, or (at your
  13 * option) any later version.
  14 */
  15
  16#include <linux/types.h>
  17#include <linux/module.h>
  18#include <linux/io.h>
  19#include <linux/watchdog.h>
  20#include <linux/platform_device.h>
  21#include <linux/of_address.h>
  22#include <linux/miscdevice.h>
  23
  24#define PM_RSTC                         0x1c
  25#define PM_WDOG                         0x24
  26
  27#define PM_PASSWORD                     0x5a000000
  28
  29#define PM_WDOG_TIME_SET                0x000fffff
  30#define PM_RSTC_WRCFG_CLR               0xffffffcf
  31#define PM_RSTC_WRCFG_SET               0x00000030
  32#define PM_RSTC_WRCFG_FULL_RESET        0x00000020
  33#define PM_RSTC_RESET                   0x00000102
  34
  35#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
  36#define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
  37
  38struct bcm2835_wdt {
  39        void __iomem            *base;
  40        spinlock_t              lock;
  41};
  42
  43static unsigned int heartbeat;
  44static bool nowayout = WATCHDOG_NOWAYOUT;
  45
  46static int bcm2835_wdt_start(struct watchdog_device *wdog)
  47{
  48        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  49        uint32_t cur;
  50        unsigned long flags;
  51
  52        spin_lock_irqsave(&wdt->lock, flags);
  53
  54        writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
  55                                PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
  56        cur = readl_relaxed(wdt->base + PM_RSTC);
  57        writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
  58                  PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
  59
  60        spin_unlock_irqrestore(&wdt->lock, flags);
  61
  62        return 0;
  63}
  64
  65static int bcm2835_wdt_stop(struct watchdog_device *wdog)
  66{
  67        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  68
  69        writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
  70        dev_info(wdog->dev, "Watchdog timer stopped");
  71        return 0;
  72}
  73
  74static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
  75{
  76        wdog->timeout = t;
  77        return 0;
  78}
  79
  80static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
  81{
  82        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  83
  84        uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
  85        return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
  86}
  87
  88static struct watchdog_ops bcm2835_wdt_ops = {
  89        .owner =        THIS_MODULE,
  90        .start =        bcm2835_wdt_start,
  91        .stop =         bcm2835_wdt_stop,
  92        .set_timeout =  bcm2835_wdt_set_timeout,
  93        .get_timeleft = bcm2835_wdt_get_timeleft,
  94};
  95
  96static struct watchdog_info bcm2835_wdt_info = {
  97        .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
  98                        WDIOF_KEEPALIVEPING,
  99        .identity =     "Broadcom BCM2835 Watchdog timer",
 100};
 101
 102static struct watchdog_device bcm2835_wdt_wdd = {
 103        .info =         &bcm2835_wdt_info,
 104        .ops =          &bcm2835_wdt_ops,
 105        .min_timeout =  1,
 106        .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 107        .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 108};
 109
 110static int bcm2835_wdt_probe(struct platform_device *pdev)
 111{
 112        struct device *dev = &pdev->dev;
 113        struct device_node *np = dev->of_node;
 114        struct bcm2835_wdt *wdt;
 115        int err;
 116
 117        wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 118        if (!wdt) {
 119                dev_err(dev, "Failed to allocate memory for watchdog device");
 120                return -ENOMEM;
 121        }
 122        platform_set_drvdata(pdev, wdt);
 123
 124        spin_lock_init(&wdt->lock);
 125
 126        wdt->base = of_iomap(np, 0);
 127        if (!wdt->base) {
 128                dev_err(dev, "Failed to remap watchdog regs");
 129                return -ENODEV;
 130        }
 131
 132        watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 133        watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 134        watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 135        err = watchdog_register_device(&bcm2835_wdt_wdd);
 136        if (err) {
 137                dev_err(dev, "Failed to register watchdog device");
 138                iounmap(wdt->base);
 139                return err;
 140        }
 141
 142        dev_info(dev, "Broadcom BCM2835 watchdog timer");
 143        return 0;
 144}
 145
 146static int bcm2835_wdt_remove(struct platform_device *pdev)
 147{
 148        struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 149
 150        watchdog_unregister_device(&bcm2835_wdt_wdd);
 151        iounmap(wdt->base);
 152
 153        return 0;
 154}
 155
 156static void bcm2835_wdt_shutdown(struct platform_device *pdev)
 157{
 158        bcm2835_wdt_stop(&bcm2835_wdt_wdd);
 159}
 160
 161static const struct of_device_id bcm2835_wdt_of_match[] = {
 162        { .compatible = "brcm,bcm2835-pm-wdt", },
 163        {},
 164};
 165MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
 166
 167static struct platform_driver bcm2835_wdt_driver = {
 168        .probe          = bcm2835_wdt_probe,
 169        .remove         = bcm2835_wdt_remove,
 170        .shutdown       = bcm2835_wdt_shutdown,
 171        .driver = {
 172                .name =         "bcm2835-wdt",
 173                .owner =        THIS_MODULE,
 174                .of_match_table = bcm2835_wdt_of_match,
 175        },
 176};
 177module_platform_driver(bcm2835_wdt_driver);
 178
 179module_param(heartbeat, uint, 0);
 180MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 181
 182module_param(nowayout, bool, 0);
 183MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 184                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 185
 186MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 187MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 188MODULE_LICENSE("GPL");
 189MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 190
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