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/types.h>
  17 #include <linux/module.h>
  18 #include <linux/io.h>
  19 #include <linux/watchdog.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/of_address.h>
  22 #include <linux/miscdevice.h>
  23
  24 #define PM_RSTC                         0x1c
  25 #define PM_WDOG                         0x24
  26
  27 #define PM_PASSWORD                     0x5a000000
  28
  29 #define PM_WDOG_TIME_SET                0x000fffff
  30 #define PM_RSTC_WRCFG_CLR               0xffffffcf
  31 #define PM_RSTC_WRCFG_SET               0x00000030
  32 #define PM_RSTC_WRCFG_FULL_RESET        0x00000020
  33 #define PM_RSTC_RESET                   0x00000102
  34
  35 #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
  36 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
  37
  38 struct bcm2835_wdt {
  39         void __iomem            *base;
  40         spinlock_t              lock;
  41 };
  42
  43 static unsigned int heartbeat;
  44 static bool nowayout = WATCHDOG_NOWAYOUT;
  45
  46 static int bcm2835_wdt_start(struct watchdog_device *wdog)
  47 {
  48         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  49         uint32_t cur;
  50         unsigned long flags;
  51
  52         spin_lock_irqsave(&wdt->lock, flags);
  53
  54         writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
  55                                 PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
  56         cur = readl_relaxed(wdt->base + PM_RSTC);
  57         writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
  58                   PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
  59
  60         spin_unlock_irqrestore(&wdt->lock, flags);
  61
  62         return 0;
  63 }
  64
  65 static int bcm2835_wdt_stop(struct watchdog_device *wdog)
  66 {
  67         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  68
  69         writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
  70         dev_info(wdog->dev, "Watchdog timer stopped");
  71         return 0;
  72 }
  73
  74 static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
  75 {
  76         wdog->timeout = t;
  77         return 0;
  78 }
  79
  80 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
  81 {
  82         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  83
  84         uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
  85         return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
  86 }
  87
  88 static struct watchdog_ops bcm2835_wdt_ops = {
  89         .owner =        THIS_MODULE,
  90         .start =        bcm2835_wdt_start,
  91         .stop =         bcm2835_wdt_stop,
  92         .set_timeout =  bcm2835_wdt_set_timeout,
  93         .get_timeleft = bcm2835_wdt_get_timeleft,
  94 };
  95
  96 static struct watchdog_info bcm2835_wdt_info = {
  97         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
  98                         WDIOF_KEEPALIVEPING,
  99         .identity =     "Broadcom BCM2835 Watchdog timer",
 100 };
 101
 102 static struct watchdog_device bcm2835_wdt_wdd = {
 103         .info =         &bcm2835_wdt_info,
 104         .ops =          &bcm2835_wdt_ops,
 105         .min_timeout =  1,
 106         .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 107         .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 108 };
 109
 110 static int bcm2835_wdt_probe(struct platform_device *pdev)
 111 {
 112         struct device *dev = &pdev->dev;
 113         struct device_node *np = dev->of_node;
 114         struct bcm2835_wdt *wdt;
 115         int err;
 116
 117         wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 118         if (!wdt) {
 119                 dev_err(dev, "Failed to allocate memory for watchdog device");
 120                 return -ENOMEM;
 121         }
 122         platform_set_drvdata(pdev, wdt);
 123
 124         spin_lock_init(&wdt->lock);
 125
 126         wdt->base = of_iomap(np, 0);
 127         if (!wdt->base) {
 128                 dev_err(dev, "Failed to remap watchdog regs");
 129                 return -ENODEV;
 130         }
 131
 132         watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 133         watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 134         watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 135         err = watchdog_register_device(&bcm2835_wdt_wdd);
 136         if (err) {
 137                 dev_err(dev, "Failed to register watchdog device");
 138                 iounmap(wdt->base);
 139                 return err;
 140         }
 141
 142         dev_info(dev, "Broadcom BCM2835 watchdog timer");
 143         return 0;
 144 }
 145
 146 static int bcm2835_wdt_remove(struct platform_device *pdev)
 147 {
 148         struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 149
 150         watchdog_unregister_device(&bcm2835_wdt_wdd);
 151         iounmap(wdt->base);
 152
 153         return 0;
 154 }
 155
 156 static void bcm2835_wdt_shutdown(struct platform_device *pdev)
 157 {
 158         bcm2835_wdt_stop(&bcm2835_wdt_wdd);
 159 }
 160
 161 static const struct of_device_id bcm2835_wdt_of_match[] = {
 162         { .compatible = "brcm,bcm2835-pm-wdt", },
 163         {},
 164 };
 165 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
 166
 167 static struct platform_driver bcm2835_wdt_driver = {
 168         .probe          = bcm2835_wdt_probe,
 169         .remove         = bcm2835_wdt_remove,
 170         .shutdown       = bcm2835_wdt_shutdown,
 171         .driver = {
 172                 .name =         "bcm2835-wdt",
 173                 .owner =        THIS_MODULE,
 174                 .of_match_table = bcm2835_wdt_of_match,
 175         },
 176 };
 177 module_platform_driver(bcm2835_wdt_driver);
 178
 179 module_param(heartbeat, uint, 0);
 180 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 181
 182 module_param(nowayout, bool, 0);
 183 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 184                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 185
 186 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 187 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 188 MODULE_LICENSE("GPL");
 189 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);