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/delay.h>
  17#include <linux/reboot.h>
  18#include <linux/types.h>
  19#include <linux/module.h>
  20#include <linux/io.h>
  21#include <linux/watchdog.h>
  22#include <linux/platform_device.h>
  23#include <linux/of_address.h>
  24#include <linux/of_platform.h>
  25
  26#define PM_RSTC                         0x1c
  27#define PM_RSTS                         0x20
  28#define PM_WDOG                         0x24
  29
  30#define PM_PASSWORD                     0x5a000000
  31
  32#define PM_WDOG_TIME_SET                0x000fffff
  33#define PM_RSTC_WRCFG_CLR               0xffffffcf
  34#define PM_RSTS_HADWRH_SET              0x00000040
  35#define PM_RSTC_WRCFG_SET               0x00000030
  36#define PM_RSTC_WRCFG_FULL_RESET        0x00000020
  37#define PM_RSTC_RESET                   0x00000102
  38
  39/*
  40 * The Raspberry Pi firmware uses the RSTS register to know which partiton
  41 * to boot from. The partiton value is spread into bits 0, 2, 4, 6, 8, 10.
  42 * Partiton 63 is a special partition used by the firmware to indicate halt.
  43 */
  44#define PM_RSTS_RASPBERRYPI_HALT        0x555
  45
  46#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
  47#define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
  48
  49struct bcm2835_wdt {
  50        void __iomem            *base;
  51        spinlock_t              lock;
  52        struct notifier_block   restart_handler;
  53};
  54
  55static unsigned int heartbeat;
  56static bool nowayout = WATCHDOG_NOWAYOUT;
  57
  58static int bcm2835_wdt_start(struct watchdog_device *wdog)
  59{
  60        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  61        uint32_t cur;
  62        unsigned long flags;
  63
  64        spin_lock_irqsave(&wdt->lock, flags);
  65
  66        writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
  67                                PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
  68        cur = readl_relaxed(wdt->base + PM_RSTC);
  69        writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
  70                  PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
  71
  72        spin_unlock_irqrestore(&wdt->lock, flags);
  73
  74        return 0;
  75}
  76
  77static int bcm2835_wdt_stop(struct watchdog_device *wdog)
  78{
  79        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  80
  81        writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
  82        return 0;
  83}
  84
  85static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
  86{
  87        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  88
  89        uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
  90        return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
  91}
  92
  93static const struct watchdog_ops bcm2835_wdt_ops = {
  94        .owner =        THIS_MODULE,
  95        .start =        bcm2835_wdt_start,
  96        .stop =         bcm2835_wdt_stop,
  97        .get_timeleft = bcm2835_wdt_get_timeleft,
  98};
  99
 100static const struct watchdog_info bcm2835_wdt_info = {
 101        .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 102                        WDIOF_KEEPALIVEPING,
 103        .identity =     "Broadcom BCM2835 Watchdog timer",
 104};
 105
 106static struct watchdog_device bcm2835_wdt_wdd = {
 107        .info =         &bcm2835_wdt_info,
 108        .ops =          &bcm2835_wdt_ops,
 109        .min_timeout =  1,
 110        .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 111        .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 112};
 113
 114static int
 115bcm2835_restart(struct notifier_block *this, unsigned long mode, void *cmd)
 116{
 117        struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt,
 118                                               restart_handler);
 119        u32 val;
 120
 121        /* use a timeout of 10 ticks (~150us) */
 122        writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
 123        val = readl_relaxed(wdt->base + PM_RSTC);
 124        val &= PM_RSTC_WRCFG_CLR;
 125        val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
 126        writel_relaxed(val, wdt->base + PM_RSTC);
 127
 128        /* No sleeping, possibly atomic. */
 129        mdelay(1);
 130
 131        return 0;
 132}
 133
 134/*
 135 * We can't really power off, but if we do the normal reset scheme, and
 136 * indicate to bootcode.bin not to reboot, then most of the chip will be
 137 * powered off.
 138 */
 139static void bcm2835_power_off(void)
 140{
 141        struct device_node *np =
 142                of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
 143        struct platform_device *pdev = of_find_device_by_node(np);
 144        struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 145        u32 val;
 146
 147        /*
 148         * We set the watchdog hard reset bit here to distinguish this reset
 149         * from the normal (full) reset. bootcode.bin will not reboot after a
 150         * hard reset.
 151         */
 152        val = readl_relaxed(wdt->base + PM_RSTS);
 153        val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
 154        writel_relaxed(val, wdt->base + PM_RSTS);
 155
 156        /* Continue with normal reset mechanism */
 157        bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL);
 158}
 159
 160static int bcm2835_wdt_probe(struct platform_device *pdev)
 161{
 162        struct device *dev = &pdev->dev;
 163        struct device_node *np = dev->of_node;
 164        struct bcm2835_wdt *wdt;
 165        int err;
 166
 167        wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 168        if (!wdt)
 169                return -ENOMEM;
 170        platform_set_drvdata(pdev, wdt);
 171
 172        spin_lock_init(&wdt->lock);
 173
 174        wdt->base = of_iomap(np, 0);
 175        if (!wdt->base) {
 176                dev_err(dev, "Failed to remap watchdog regs");
 177                return -ENODEV;
 178        }
 179
 180        watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 181        watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 182        watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 183        bcm2835_wdt_wdd.parent = &pdev->dev;
 184        err = watchdog_register_device(&bcm2835_wdt_wdd);
 185        if (err) {
 186                dev_err(dev, "Failed to register watchdog device");
 187                iounmap(wdt->base);
 188                return err;
 189        }
 190
 191        wdt->restart_handler.notifier_call = bcm2835_restart;
 192        wdt->restart_handler.priority = 128;
 193        register_restart_handler(&wdt->restart_handler);
 194        if (pm_power_off == NULL)
 195                pm_power_off = bcm2835_power_off;
 196
 197        dev_info(dev, "Broadcom BCM2835 watchdog timer");
 198        return 0;
 199}
 200
 201static int bcm2835_wdt_remove(struct platform_device *pdev)
 202{
 203        struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 204
 205        unregister_restart_handler(&wdt->restart_handler);
 206        if (pm_power_off == bcm2835_power_off)
 207                pm_power_off = NULL;
 208        watchdog_unregister_device(&bcm2835_wdt_wdd);
 209        iounmap(wdt->base);
 210
 211        return 0;
 212}
 213
 214static void bcm2835_wdt_shutdown(struct platform_device *pdev)
 215{
 216        bcm2835_wdt_stop(&bcm2835_wdt_wdd);
 217}
 218
 219static const struct of_device_id bcm2835_wdt_of_match[] = {
 220        { .compatible = "brcm,bcm2835-pm-wdt", },
 221        {},
 222};
 223MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
 224
 225static struct platform_driver bcm2835_wdt_driver = {
 226        .probe          = bcm2835_wdt_probe,
 227        .remove         = bcm2835_wdt_remove,
 228        .shutdown       = bcm2835_wdt_shutdown,
 229        .driver = {
 230                .name =         "bcm2835-wdt",
 231                .of_match_table = bcm2835_wdt_of_match,
 232        },
 233};
 234module_platform_driver(bcm2835_wdt_driver);
 235
 236module_param(heartbeat, uint, 0);
 237MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 238
 239module_param(nowayout, bool, 0);
 240MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 241                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 242
 243MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 244MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 245MODULE_LICENSE("GPL");
 246
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