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 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
  77 static 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
  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 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
 100 static const struct watchdog_info bcm2835_wdt_info = {
 101         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 102                         WDIOF_KEEPALIVEPING,
 103         .identity =     "Broadcom BCM2835 Watchdog timer",
 104 };
 105
 106 static 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
 114 static int
 115 bcm2835_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  */
 139 static 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
 160 static 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
 201 static 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
 214 static void bcm2835_wdt_shutdown(struct platform_device *pdev)
 215 {
 216         bcm2835_wdt_stop(&bcm2835_wdt_wdd);
 217 }
 218
 219 static const struct of_device_id bcm2835_wdt_of_match[] = {
 220         { .compatible = "brcm,bcm2835-pm-wdt", },
 221         {},
 222 };
 223 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
 224
 225 static 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 };
 234 module_platform_driver(bcm2835_wdt_driver);
 235
 236 module_param(heartbeat, uint, 0);
 237 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 238
 239 module_param(nowayout, bool, 0);
 240 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 241                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 242
 243 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 244 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 245 MODULE_LICENSE("GPL");