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         dev_info(wdog->dev, "Watchdog timer stopped");
  83         return 0;
  84 }
  85
  86 static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
  87 {
  88         wdog->timeout = t;
  89         return 0;
  90 }
  91
  92 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
  93 {
  94         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  95
  96         uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
  97         return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
  98 }
  99
 100 static struct watchdog_ops bcm2835_wdt_ops = {
 101         .owner =        THIS_MODULE,
 102         .start =        bcm2835_wdt_start,
 103         .stop =         bcm2835_wdt_stop,
 104         .set_timeout =  bcm2835_wdt_set_timeout,
 105         .get_timeleft = bcm2835_wdt_get_timeleft,
 106 };
 107
 108 static struct watchdog_info bcm2835_wdt_info = {
 109         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 110                         WDIOF_KEEPALIVEPING,
 111         .identity =     "Broadcom BCM2835 Watchdog timer",
 112 };
 113
 114 static struct watchdog_device bcm2835_wdt_wdd = {
 115         .info =         &bcm2835_wdt_info,
 116         .ops =          &bcm2835_wdt_ops,
 117         .min_timeout =  1,
 118         .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 119         .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 120 };
 121
 122 static int
 123 bcm2835_restart(struct notifier_block *this, unsigned long mode, void *cmd)
 124 {
 125         struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt,
 126                                                restart_handler);
 127         u32 val;
 128
 129         /* use a timeout of 10 ticks (~150us) */
 130         writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
 131         val = readl_relaxed(wdt->base + PM_RSTC);
 132         val &= PM_RSTC_WRCFG_CLR;
 133         val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
 134         writel_relaxed(val, wdt->base + PM_RSTC);
 135
 136         /* No sleeping, possibly atomic. */
 137         mdelay(1);
 138
 139         return 0;
 140 }
 141
 142 /*
 143  * We can't really power off, but if we do the normal reset scheme, and
 144  * indicate to bootcode.bin not to reboot, then most of the chip will be
 145  * powered off.
 146  */
 147 static void bcm2835_power_off(void)
 148 {
 149         struct device_node *np =
 150                 of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
 151         struct platform_device *pdev = of_find_device_by_node(np);
 152         struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 153         u32 val;
 154
 155         /*
 156          * We set the watchdog hard reset bit here to distinguish this reset
 157          * from the normal (full) reset. bootcode.bin will not reboot after a
 158          * hard reset.
 159          */
 160         val = readl_relaxed(wdt->base + PM_RSTS);
 161         val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
 162         writel_relaxed(val, wdt->base + PM_RSTS);
 163
 164         /* Continue with normal reset mechanism */
 165         bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL);
 166 }
 167
 168 static int bcm2835_wdt_probe(struct platform_device *pdev)
 169 {
 170         struct device *dev = &pdev->dev;
 171         struct device_node *np = dev->of_node;
 172         struct bcm2835_wdt *wdt;
 173         int err;
 174
 175         wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 176         if (!wdt)
 177                 return -ENOMEM;
 178         platform_set_drvdata(pdev, wdt);
 179
 180         spin_lock_init(&wdt->lock);
 181
 182         wdt->base = of_iomap(np, 0);
 183         if (!wdt->base) {
 184                 dev_err(dev, "Failed to remap watchdog regs");
 185                 return -ENODEV;
 186         }
 187
 188         watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 189         watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 190         watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 191         bcm2835_wdt_wdd.parent = &pdev->dev;
 192         err = watchdog_register_device(&bcm2835_wdt_wdd);
 193         if (err) {
 194                 dev_err(dev, "Failed to register watchdog device");
 195                 iounmap(wdt->base);
 196                 return err;
 197         }
 198
 199         wdt->restart_handler.notifier_call = bcm2835_restart;
 200         wdt->restart_handler.priority = 128;
 201         register_restart_handler(&wdt->restart_handler);
 202         if (pm_power_off == NULL)
 203                 pm_power_off = bcm2835_power_off;
 204
 205         dev_info(dev, "Broadcom BCM2835 watchdog timer");
 206         return 0;
 207 }
 208
 209 static int bcm2835_wdt_remove(struct platform_device *pdev)
 210 {
 211         struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 212
 213         unregister_restart_handler(&wdt->restart_handler);
 214         if (pm_power_off == bcm2835_power_off)
 215                 pm_power_off = NULL;
 216         watchdog_unregister_device(&bcm2835_wdt_wdd);
 217         iounmap(wdt->base);
 218
 219         return 0;
 220 }
 221
 222 static void bcm2835_wdt_shutdown(struct platform_device *pdev)
 223 {
 224         bcm2835_wdt_stop(&bcm2835_wdt_wdd);
 225 }
 226
 227 static const struct of_device_id bcm2835_wdt_of_match[] = {
 228         { .compatible = "brcm,bcm2835-pm-wdt", },
 229         {},
 230 };
 231 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
 232
 233 static struct platform_driver bcm2835_wdt_driver = {
 234         .probe          = bcm2835_wdt_probe,
 235         .remove         = bcm2835_wdt_remove,
 236         .shutdown       = bcm2835_wdt_shutdown,
 237         .driver = {
 238                 .name =         "bcm2835-wdt",
 239                 .of_match_table = bcm2835_wdt_of_match,
 240         },
 241 };
 242 module_platform_driver(bcm2835_wdt_driver);
 243
 244 module_param(heartbeat, uint, 0);
 245 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 246
 247 module_param(nowayout, bool, 0);
 248 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 249                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 250
 251 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 252 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 253 MODULE_LICENSE("GPL");