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 bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt)
  59{
  60        uint32_t cur;
  61
  62        cur = readl(wdt->base + PM_RSTC);
  63
  64        return !!(cur & PM_RSTC_WRCFG_FULL_RESET);
  65}
  66
  67static int bcm2835_wdt_start(struct watchdog_device *wdog)
  68{
  69        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  70        uint32_t cur;
  71        unsigned long flags;
  72
  73        spin_lock_irqsave(&wdt->lock, flags);
  74
  75        writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
  76                                PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
  77        cur = readl_relaxed(wdt->base + PM_RSTC);
  78        writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
  79                  PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
  80
  81        spin_unlock_irqrestore(&wdt->lock, flags);
  82
  83        return 0;
  84}
  85
  86static int bcm2835_wdt_stop(struct watchdog_device *wdog)
  87{
  88        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  89
  90        writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
  91        return 0;
  92}
  93
  94static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
  95{
  96        struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  97
  98        uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
  99        return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
 100}
 101
 102static const struct watchdog_ops bcm2835_wdt_ops = {
 103        .owner =        THIS_MODULE,
 104        .start =        bcm2835_wdt_start,
 105        .stop =         bcm2835_wdt_stop,
 106        .get_timeleft = bcm2835_wdt_get_timeleft,
 107};
 108
 109static const struct watchdog_info bcm2835_wdt_info = {
 110        .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 111                        WDIOF_KEEPALIVEPING,
 112        .identity =     "Broadcom BCM2835 Watchdog timer",
 113};
 114
 115static struct watchdog_device bcm2835_wdt_wdd = {
 116        .info =         &bcm2835_wdt_info,
 117        .ops =          &bcm2835_wdt_ops,
 118        .min_timeout =  1,
 119        .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 120        .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 121};
 122
 123static int
 124bcm2835_restart(struct notifier_block *this, unsigned long mode, void *cmd)
 125{
 126        struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt,
 127                                               restart_handler);
 128        u32 val;
 129
 130        /* use a timeout of 10 ticks (~150us) */
 131        writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
 132        val = readl_relaxed(wdt->base + PM_RSTC);
 133        val &= PM_RSTC_WRCFG_CLR;
 134        val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
 135        writel_relaxed(val, wdt->base + PM_RSTC);
 136
 137        /* No sleeping, possibly atomic. */
 138        mdelay(1);
 139
 140        return 0;
 141}
 142
 143/*
 144 * We can't really power off, but if we do the normal reset scheme, and
 145 * indicate to bootcode.bin not to reboot, then most of the chip will be
 146 * powered off.
 147 */
 148static void bcm2835_power_off(void)
 149{
 150        struct device_node *np =
 151                of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
 152        struct platform_device *pdev = of_find_device_by_node(np);
 153        struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 154        u32 val;
 155
 156        /*
 157         * We set the watchdog hard reset bit here to distinguish this reset
 158         * from the normal (full) reset. bootcode.bin will not reboot after a
 159         * hard reset.
 160         */
 161        val = readl_relaxed(wdt->base + PM_RSTS);
 162        val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
 163        writel_relaxed(val, wdt->base + PM_RSTS);
 164
 165        /* Continue with normal reset mechanism */
 166        bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL);
 167}
 168
 169static int bcm2835_wdt_probe(struct platform_device *pdev)
 170{
 171        struct device *dev = &pdev->dev;
 172        struct device_node *np = dev->of_node;
 173        struct bcm2835_wdt *wdt;
 174        int err;
 175
 176        wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 177        if (!wdt)
 178                return -ENOMEM;
 179        platform_set_drvdata(pdev, wdt);
 180
 181        spin_lock_init(&wdt->lock);
 182
 183        wdt->base = of_iomap(np, 0);
 184        if (!wdt->base) {
 185                dev_err(dev, "Failed to remap watchdog regs");
 186                return -ENODEV;
 187        }
 188
 189        watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 190        watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 191        watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 192        bcm2835_wdt_wdd.parent = &pdev->dev;
 193        if (bcm2835_wdt_is_running(wdt)) {
 194                /*
 195                 * The currently active timeout value (set by the
 196                 * bootloader) may be different from the module
 197                 * heartbeat parameter or the value in device
 198                 * tree. But we just need to set WDOG_HW_RUNNING,
 199                 * because then the framework will "immediately" ping
 200                 * the device, updating the timeout.
 201                 */
 202                set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status);
 203        }
 204        err = watchdog_register_device(&bcm2835_wdt_wdd);
 205        if (err) {
 206                dev_err(dev, "Failed to register watchdog device");
 207                iounmap(wdt->base);
 208                return err;
 209        }
 210
 211        wdt->restart_handler.notifier_call = bcm2835_restart;
 212        wdt->restart_handler.priority = 128;
 213        register_restart_handler(&wdt->restart_handler);
 214        if (pm_power_off == NULL)
 215                pm_power_off = bcm2835_power_off;
 216
 217        dev_info(dev, "Broadcom BCM2835 watchdog timer");
 218        return 0;
 219}
 220
 221static int bcm2835_wdt_remove(struct platform_device *pdev)
 222{
 223        struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 224
 225        unregister_restart_handler(&wdt->restart_handler);
 226        if (pm_power_off == bcm2835_power_off)
 227                pm_power_off = NULL;
 228        watchdog_unregister_device(&bcm2835_wdt_wdd);
 229        iounmap(wdt->base);
 230
 231        return 0;
 232}
 233
 234static void bcm2835_wdt_shutdown(struct platform_device *pdev)
 235{
 236        bcm2835_wdt_stop(&bcm2835_wdt_wdd);
 237}
 238
 239static const struct of_device_id bcm2835_wdt_of_match[] = {
 240        { .compatible = "brcm,bcm2835-pm-wdt", },
 241        {},
 242};
 243MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
 244
 245static struct platform_driver bcm2835_wdt_driver = {
 246        .probe          = bcm2835_wdt_probe,
 247        .remove         = bcm2835_wdt_remove,
 248        .shutdown       = bcm2835_wdt_shutdown,
 249        .driver = {
 250                .name =         "bcm2835-wdt",
 251                .of_match_table = bcm2835_wdt_of_match,
 252        },
 253};
 254module_platform_driver(bcm2835_wdt_driver);
 255
 256module_param(heartbeat, uint, 0);
 257MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 258
 259module_param(nowayout, bool, 0);
 260MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 261                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 262
 263MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 264MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 265MODULE_LICENSE("GPL");
 266
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