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
  23#define PM_RSTC                         0x1c
  24#define PM_WDOG                         0x24
  25
  26#define PM_PASSWORD                     0x5a000000
  27
  28#define PM_WDOG_TIME_SET                0x000fffff
  29#define PM_RSTC_WRCFG_CLR               0xffffffcf
  30#define PM_RSTC_WRCFG_SET               0x00000030
  31#define PM_RSTC_WRCFG_FULL_RESET        0x00000020
  32#define PM_RSTC_RESET                   0x00000102
  33
  34#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
  35#define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
  36
  37struct bcm2835_wdt {
  38        void __iomem            *base;
  39        spinlock_t              lock;
  40};
  41
  42static unsigned int heartbeat;
  43static bool nowayout = WATCHDOG_NOWAYOUT;
  44
  45static int bcm2835_wdt_start(struct watchdog_device *wdog)
  46{
  47        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  48        uint32_t cur;
  49        unsigned long flags;
  50
  51        spin_lock_irqsave(&wdt->lock, flags);
  52
  53        writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
  54                                PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
  55        cur = readl_relaxed(wdt->base + PM_RSTC);
  56        writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
  57                  PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
  58
  59        spin_unlock_irqrestore(&wdt->lock, flags);
  60
  61        return 0;
  62}
  63
  64static int bcm2835_wdt_stop(struct watchdog_device *wdog)
  65{
  66        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  67
  68        writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
  69        dev_info(wdog->dev, "Watchdog timer stopped");
  70        return 0;
  71}
  72
  73static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
  74{
  75        wdog->timeout = t;
  76        return 0;
  77}
  78
  79static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
  80{
  81        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  82
  83        uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
  84        return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
  85}
  86
  87static struct watchdog_ops bcm2835_wdt_ops = {
  88        .owner =        THIS_MODULE,
  89        .start =        bcm2835_wdt_start,
  90        .stop =         bcm2835_wdt_stop,
  91        .set_timeout =  bcm2835_wdt_set_timeout,
  92        .get_timeleft = bcm2835_wdt_get_timeleft,
  93};
  94
  95static struct watchdog_info bcm2835_wdt_info = {
  96        .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
  97                        WDIOF_KEEPALIVEPING,
  98        .identity =     "Broadcom BCM2835 Watchdog timer",
  99};
 100
 101static struct watchdog_device bcm2835_wdt_wdd = {
 102        .info =         &bcm2835_wdt_info,
 103        .ops =          &bcm2835_wdt_ops,
 104        .min_timeout =  1,
 105        .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 106        .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 107};
 108
 109static int bcm2835_wdt_probe(struct platform_device *pdev)
 110{
 111        struct device *dev = &pdev->dev;
 112        struct device_node *np = dev->of_node;
 113        struct bcm2835_wdt *wdt;
 114        int err;
 115
 116        wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 117        if (!wdt) {
 118                dev_err(dev, "Failed to allocate memory for watchdog device");
 119                return -ENOMEM;
 120        }
 121        platform_set_drvdata(pdev, wdt);
 122
 123        spin_lock_init(&wdt->lock);
 124
 125        wdt->base = of_iomap(np, 0);
 126        if (!wdt->base) {
 127                dev_err(dev, "Failed to remap watchdog regs");
 128                return -ENODEV;
 129        }
 130
 131        watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 132        watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 133        watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 134        err = watchdog_register_device(&bcm2835_wdt_wdd);
 135        if (err) {
 136                dev_err(dev, "Failed to register watchdog device");
 137                iounmap(wdt->base);
 138                return err;
 139        }
 140
 141        dev_info(dev, "Broadcom BCM2835 watchdog timer");
 142        return 0;
 143}
 144
 145static int bcm2835_wdt_remove(struct platform_device *pdev)
 146{
 147        struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 148
 149        watchdog_unregister_device(&bcm2835_wdt_wdd);
 150        iounmap(wdt->base);
 151
 152        return 0;
 153}
 154
 155static void bcm2835_wdt_shutdown(struct platform_device *pdev)
 156{
 157        bcm2835_wdt_stop(&bcm2835_wdt_wdd);
 158}
 159
 160static const struct of_device_id bcm2835_wdt_of_match[] = {
 161        { .compatible = "brcm,bcm2835-pm-wdt", },
 162        {},
 163};
 164MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
 165
 166static struct platform_driver bcm2835_wdt_driver = {
 167        .probe          = bcm2835_wdt_probe,
 168        .remove         = bcm2835_wdt_remove,
 169        .shutdown       = bcm2835_wdt_shutdown,
 170        .driver = {
 171                .name =         "bcm2835-wdt",
 172                .owner =        THIS_MODULE,
 173                .of_match_table = bcm2835_wdt_of_match,
 174        },
 175};
 176module_platform_driver(bcm2835_wdt_driver);
 177
 178module_param(heartbeat, uint, 0);
 179MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 180
 181module_param(nowayout, bool, 0);
 182MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 183                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 184
 185MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 186MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 187MODULE_LICENSE("GPL");
 188
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