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 /*
  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
  49 struct bcm2835_wdt {
  50         void __iomem            *base;
  51         spinlock_t              lock;
  52         struct notifier_block   restart_handler;
  53 };
  54
  55 static unsigned int heartbeat;
  56 static bool nowayout = WATCHDOG_NOWAYOUT;
  57
  58 static 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
  67 static 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
  86 static 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
  94 static 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
 102 static 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
 109 static const struct watchdog_info bcm2835_wdt_info = {
 110         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 111                         WDIOF_KEEPALIVEPING,
 112         .identity =     "Broadcom BCM2835 Watchdog timer",
 113 };
 114
 115 static 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
 123 static int
 124 bcm2835_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  */
 148 static 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
 169 static 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
 221 static 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
 234 static void bcm2835_wdt_shutdown(struct platform_device *pdev)
 235 {
 236         bcm2835_wdt_stop(&bcm2835_wdt_wdd);
 237 }
 238
 239 static const struct of_device_id bcm2835_wdt_of_match[] = {
 240         { .compatible = "brcm,bcm2835-pm-wdt", },
 241         {},
 242 };
 243 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
 244
 245 static 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 };
 254 module_platform_driver(bcm2835_wdt_driver);
 255
 256 module_param(heartbeat, uint, 0);
 257 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 258
 259 module_param(nowayout, bool, 0);
 260 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 261                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 262
 263 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 264 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 265 MODULE_LICENSE("GPL");