drivers/watchdog/bcm2835_wdt.c

   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 #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
  40 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
  41
  42 struct bcm2835_wdt {
  43         void __iomem            *base;
  44         spinlock_t              lock;
  45         struct notifier_block   restart_handler;
  46 };
  47
  48 static unsigned int heartbeat;
  49 static bool nowayout = WATCHDOG_NOWAYOUT;
  50
  51 static int bcm2835_wdt_start(struct watchdog_device *wdog)
  52 {
  53         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  54         uint32_t cur;
  55         unsigned long flags;
  56
  57         spin_lock_irqsave(&wdt->lock, flags);
  58
  59         writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
  60                                 PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
  61         cur = readl_relaxed(wdt->base + PM_RSTC);
  62         writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
  63                   PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
  64
  65         spin_unlock_irqrestore(&wdt->lock, flags);
  66
  67         return 0;
  68 }
  69
  70 static int bcm2835_wdt_stop(struct watchdog_device *wdog)
  71 {
  72         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  73
  74         writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
  75         dev_info(wdog->dev, "Watchdog timer stopped");
  76         return 0;
  77 }
  78
  79 static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
  80 {
  81         wdog->timeout = t;
  82         return 0;
  83 }
  84
  85 static 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
  93 static struct watchdog_ops bcm2835_wdt_ops = {
  94         .owner =        THIS_MODULE,
  95         .start =        bcm2835_wdt_start,
  96         .stop =         bcm2835_wdt_stop,
  97         .set_timeout =  bcm2835_wdt_set_timeout,
  98         .get_timeleft = bcm2835_wdt_get_timeleft,
  99 };
 100
 101 static struct watchdog_info bcm2835_wdt_info = {
 102         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 103                         WDIOF_KEEPALIVEPING,
 104         .identity =     "Broadcom BCM2835 Watchdog timer",
 105 };
 106
 107 static struct watchdog_device bcm2835_wdt_wdd = {
 108         .info =         &bcm2835_wdt_info,
 109         .ops =          &bcm2835_wdt_ops,
 110         .min_timeout =  1,
 111         .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 112         .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 113 };
 114
 115 static int
 116 bcm2835_restart(struct notifier_block *this, unsigned long mode, void *cmd)
 117 {
 118         struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt,
 119                                                restart_handler);
 120         u32 val;
 121
 122         /* use a timeout of 10 ticks (~150us) */
 123         writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
 124         val = readl_relaxed(wdt->base + PM_RSTC);
 125         val &= PM_RSTC_WRCFG_CLR;
 126         val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
 127         writel_relaxed(val, wdt->base + PM_RSTC);
 128
 129         /* No sleeping, possibly atomic. */
 130         mdelay(1);
 131
 132         return 0;
 133 }
 134
 135 /*
 136  * We can't really power off, but if we do the normal reset scheme, and
 137  * indicate to bootcode.bin not to reboot, then most of the chip will be
 138  * powered off.
 139  */
 140 static void bcm2835_power_off(void)
 141 {
 142         struct device_node *np =
 143                 of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
 144         struct platform_device *pdev = of_find_device_by_node(np);
 145         struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 146         u32 val;
 147
 148         /*
 149          * We set the watchdog hard reset bit here to distinguish this reset
 150          * from the normal (full) reset. bootcode.bin will not reboot after a
 151          * hard reset.
 152          */
 153         val = readl_relaxed(wdt->base + PM_RSTS);
 154         val &= PM_RSTC_WRCFG_CLR;
 155         val |= PM_PASSWORD | PM_RSTS_HADWRH_SET;
 156         writel_relaxed(val, wdt->base + PM_RSTS);
 157
 158         /* Continue with normal reset mechanism */
 159         bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL);
 160 }
 161
 162 static int bcm2835_wdt_probe(struct platform_device *pdev)
 163 {
 164         struct device *dev = &pdev->dev;
 165         struct device_node *np = dev->of_node;
 166         struct bcm2835_wdt *wdt;
 167         int err;
 168
 169         wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 170         if (!wdt)
 171                 return -ENOMEM;
 172         platform_set_drvdata(pdev, wdt);
 173
 174         spin_lock_init(&wdt->lock);
 175
 176         wdt->base = of_iomap(np, 0);
 177         if (!wdt->base) {
 178                 dev_err(dev, "Failed to remap watchdog regs");
 179                 return -ENODEV;
 180         }
 181
 182         watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 183         watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 184         watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 185         err = watchdog_register_device(&bcm2835_wdt_wdd);
 186         if (err) {
 187                 dev_err(dev, "Failed to register watchdog device");
 188                 iounmap(wdt->base);
 189                 return err;
 190         }
 191
 192         wdt->restart_handler.notifier_call = bcm2835_restart;
 193         wdt->restart_handler.priority = 128;
 194         register_restart_handler(&wdt->restart_handler);
 195         if (pm_power_off == NULL)
 196                 pm_power_off = bcm2835_power_off;
 197
 198         dev_info(dev, "Broadcom BCM2835 watchdog timer");
 199         return 0;
 200 }
 201
 202 static int bcm2835_wdt_remove(struct platform_device *pdev)
 203 {
 204         struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 205
 206         unregister_restart_handler(&wdt->restart_handler);
 207         if (pm_power_off == bcm2835_power_off)
 208                 pm_power_off = NULL;
 209         watchdog_unregister_device(&bcm2835_wdt_wdd);
 210         iounmap(wdt->base);
 211
 212         return 0;
 213 }
 214
 215 static void bcm2835_wdt_shutdown(struct platform_device *pdev)
 216 {
 217         bcm2835_wdt_stop(&bcm2835_wdt_wdd);
 218 }
 219
 220 static const struct of_device_id bcm2835_wdt_of_match[] = {
 221         { .compatible = "brcm,bcm2835-pm-wdt", },
 222         {},
 223 };
 224 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
 225
 226 static struct platform_driver bcm2835_wdt_driver = {
 227         .probe          = bcm2835_wdt_probe,
 228         .remove         = bcm2835_wdt_remove,
 229         .shutdown       = bcm2835_wdt_shutdown,
 230         .driver = {
 231                 .name =         "bcm2835-wdt",
 232                 .of_match_table = bcm2835_wdt_of_match,
 233         },
 234 };
 235 module_platform_driver(bcm2835_wdt_driver);
 236
 237 module_param(heartbeat, uint, 0);
 238 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 239
 240 module_param(nowayout, bool, 0);
 241 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 242                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 243
 244 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 245 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 246 MODULE_LICENSE("GPL");