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 int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
  86{
  87        wdog->timeout = t;
  88        return 0;
  89}
  90
  91static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
  92{
  93        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  94
  95        uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
  96        return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
  97}
  98
  99static struct watchdog_ops bcm2835_wdt_ops = {
 100        .owner =        THIS_MODULE,
 101        .start =        bcm2835_wdt_start,
 102        .stop =         bcm2835_wdt_stop,
 103        .set_timeout =  bcm2835_wdt_set_timeout,
 104        .get_timeleft = bcm2835_wdt_get_timeleft,
 105};
 106
 107static struct watchdog_info bcm2835_wdt_info = {
 108        .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 109                        WDIOF_KEEPALIVEPING,
 110        .identity =     "Broadcom BCM2835 Watchdog timer",
 111};
 112
 113static struct watchdog_device bcm2835_wdt_wdd = {
 114        .info =         &bcm2835_wdt_info,
 115        .ops =          &bcm2835_wdt_ops,
 116        .min_timeout =  1,
 117        .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 118        .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 119};
 120
 121static int
 122bcm2835_restart(struct notifier_block *this, unsigned long mode, void *cmd)
 123{
 124        struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt,
 125                                               restart_handler);
 126        u32 val;
 127
 128        /* use a timeout of 10 ticks (~150us) */
 129        writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
 130        val = readl_relaxed(wdt->base + PM_RSTC);
 131        val &= PM_RSTC_WRCFG_CLR;
 132        val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
 133        writel_relaxed(val, wdt->base + PM_RSTC);
 134
 135        /* No sleeping, possibly atomic. */
 136        mdelay(1);
 137
 138        return 0;
 139}
 140
 141/*
 142 * We can't really power off, but if we do the normal reset scheme, and
 143 * indicate to bootcode.bin not to reboot, then most of the chip will be
 144 * powered off.
 145 */
 146static void bcm2835_power_off(void)
 147{
 148        struct device_node *np =
 149                of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
 150        struct platform_device *pdev = of_find_device_by_node(np);
 151        struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 152        u32 val;
 153
 154        /*
 155         * We set the watchdog hard reset bit here to distinguish this reset
 156         * from the normal (full) reset. bootcode.bin will not reboot after a
 157         * hard reset.
 158         */
 159        val = readl_relaxed(wdt->base + PM_RSTS);
 160        val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
 161        writel_relaxed(val, wdt->base + PM_RSTS);
 162
 163        /* Continue with normal reset mechanism */
 164        bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL);
 165}
 166
 167static int bcm2835_wdt_probe(struct platform_device *pdev)
 168{
 169        struct device *dev = &pdev->dev;
 170        struct device_node *np = dev->of_node;
 171        struct bcm2835_wdt *wdt;
 172        int err;
 173
 174        wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 175        if (!wdt)
 176                return -ENOMEM;
 177        platform_set_drvdata(pdev, wdt);
 178
 179        spin_lock_init(&wdt->lock);
 180
 181        wdt->base = of_iomap(np, 0);
 182        if (!wdt->base) {
 183                dev_err(dev, "Failed to remap watchdog regs");
 184                return -ENODEV;
 185        }
 186
 187        watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 188        watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 189        watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 190        bcm2835_wdt_wdd.parent = &pdev->dev;
 191        err = watchdog_register_device(&bcm2835_wdt_wdd);
 192        if (err) {
 193                dev_err(dev, "Failed to register watchdog device");
 194                iounmap(wdt->base);
 195                return err;
 196        }
 197
 198        wdt->restart_handler.notifier_call = bcm2835_restart;
 199        wdt->restart_handler.priority = 128;
 200        register_restart_handler(&wdt->restart_handler);
 201        if (pm_power_off == NULL)
 202                pm_power_off = bcm2835_power_off;
 203
 204        dev_info(dev, "Broadcom BCM2835 watchdog timer");
 205        return 0;
 206}
 207
 208static int bcm2835_wdt_remove(struct platform_device *pdev)
 209{
 210        struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 211
 212        unregister_restart_handler(&wdt->restart_handler);
 213        if (pm_power_off == bcm2835_power_off)
 214                pm_power_off = NULL;
 215        watchdog_unregister_device(&bcm2835_wdt_wdd);
 216        iounmap(wdt->base);
 217
 218        return 0;
 219}
 220
 221static void bcm2835_wdt_shutdown(struct platform_device *pdev)
 222{
 223        bcm2835_wdt_stop(&bcm2835_wdt_wdd);
 224}
 225
 226static const struct of_device_id bcm2835_wdt_of_match[] = {
 227        { .compatible = "brcm,bcm2835-pm-wdt", },
 228        {},
 229};
 230MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
 231
 232static struct platform_driver bcm2835_wdt_driver = {
 233        .probe          = bcm2835_wdt_probe,
 234        .remove         = bcm2835_wdt_remove,
 235        .shutdown       = bcm2835_wdt_shutdown,
 236        .driver = {
 237                .name =         "bcm2835-wdt",
 238                .of_match_table = bcm2835_wdt_of_match,
 239        },
 240};
 241module_platform_driver(bcm2835_wdt_driver);
 242
 243module_param(heartbeat, uint, 0);
 244MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 245
 246module_param(nowayout, bool, 0);
 247MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 248                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 249
 250MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 251MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 252MODULE_LICENSE("GPL");
 253
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