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