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 #define PM_RSTS_PARTITION_CLR           0xfffffaaa
  39
  40 #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
  41 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
  42
  43 struct bcm2835_wdt {
  44         void __iomem            *base;
  45         spinlock_t              lock;
  46         struct notifier_block   restart_handler;
  47 };
  48
  49 static unsigned int heartbeat;
  50 static bool nowayout = WATCHDOG_NOWAYOUT;
  51
  52 static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt)
  53 {
  54         uint32_t cur;
  55
  56         cur = readl(wdt->base + PM_RSTC);
  57
  58         return !!(cur & PM_RSTC_WRCFG_FULL_RESET);
  59 }
  60
  61 static int bcm2835_wdt_start(struct watchdog_device *wdog)
  62 {
  63         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  64         uint32_t cur;
  65         unsigned long flags;
  66
  67         spin_lock_irqsave(&wdt->lock, flags);
  68
  69         writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
  70                                 PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
  71         cur = readl_relaxed(wdt->base + PM_RSTC);
  72         writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
  73                   PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
  74
  75         spin_unlock_irqrestore(&wdt->lock, flags);
  76
  77         return 0;
  78 }
  79
  80 static int bcm2835_wdt_stop(struct watchdog_device *wdog)
  81 {
  82         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  83
  84         writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
  85         return 0;
  86 }
  87
  88 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
  89 {
  90         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  91
  92         uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
  93         return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
  94 }
  95
  96 static const struct watchdog_ops bcm2835_wdt_ops = {
  97         .owner =        THIS_MODULE,
  98         .start =        bcm2835_wdt_start,
  99         .stop =         bcm2835_wdt_stop,
 100         .get_timeleft = bcm2835_wdt_get_timeleft,
 101 };
 102
 103 static const struct watchdog_info bcm2835_wdt_info = {
 104         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 105                         WDIOF_KEEPALIVEPING,
 106         .identity =     "Broadcom BCM2835 Watchdog timer",
 107 };
 108
 109 static struct watchdog_device bcm2835_wdt_wdd = {
 110         .info =         &bcm2835_wdt_info,
 111         .ops =          &bcm2835_wdt_ops,
 112         .min_timeout =  1,
 113         .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 114         .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 115 };
 116
 117 /*
 118  * The Raspberry Pi firmware uses the RSTS register to know which partiton
 119  * to boot from. The partiton value is spread into bits 0, 2, 4, 6, 8, 10.
 120  * Partiton 63 is a special partition used by the firmware to indicate halt.
 121  */
 122
 123 static void bcm2835_restart(struct bcm2835_wdt *wdt, u8 partition)
 124 {
 125         u32 val, rsts;
 126
 127         rsts = (partition & BIT(0)) | ((partition & BIT(1)) << 1) |
 128                ((partition & BIT(2)) << 2) | ((partition & BIT(3)) << 3) |
 129                ((partition & BIT(4)) << 4) | ((partition & BIT(5)) << 5);
 130
 131         val = readl_relaxed(wdt->base + PM_RSTS);
 132         val &= PM_RSTS_PARTITION_CLR;
 133         val |= PM_PASSWORD | rsts;
 134         writel_relaxed(val, wdt->base + PM_RSTS);
 135
 136         /* use a timeout of 10 ticks (~150us) */
 137         writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
 138
 139         val = readl_relaxed(wdt->base + PM_RSTC);
 140         val &= PM_RSTC_WRCFG_CLR;
 141         val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
 142         writel_relaxed(val, wdt->base + PM_RSTC);
 143
 144         /* No sleeping, possibly atomic. */
 145         mdelay(1);
 146 }
 147
 148 static int bcm2835_restart_notifier_call(struct notifier_block *this,
 149                                          unsigned long mode, void *cmd)
 150 {
 151         struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt,
 152                                                restart_handler);
 153         unsigned long long val;
 154         u8 partition = 0;
 155
 156         if (cmd && !kstrtoull(cmd, 0, &val) && val <= 63)
 157                 partition = val;
 158
 159         bcm2835_restart(wdt, partition);
 160
 161         return 0;
 162 }
 163
 164 /*
 165  * We can't really power off, but if we do the normal reset scheme, and
 166  * indicate to bootcode.bin not to reboot, then most of the chip will be
 167  * powered off.
 168  */
 169 static void bcm2835_power_off(void)
 170 {
 171         struct device_node *np =
 172                 of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
 173         struct platform_device *pdev = of_find_device_by_node(np);
 174         struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 175
 176         /* Partition 63 tells the firmware that this is a halt */
 177         bcm2835_restart(wdt, 63);
 178 }
 179
 180 static int bcm2835_wdt_probe(struct platform_device *pdev)
 181 {
 182         struct device *dev = &pdev->dev;
 183         struct device_node *np = dev->of_node;
 184         struct bcm2835_wdt *wdt;
 185         int err;
 186
 187         wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 188         if (!wdt)
 189                 return -ENOMEM;
 190         platform_set_drvdata(pdev, wdt);
 191
 192         spin_lock_init(&wdt->lock);
 193
 194         wdt->base = of_iomap(np, 0);
 195         if (!wdt->base) {
 196                 dev_err(dev, "Failed to remap watchdog regs");
 197                 return -ENODEV;
 198         }
 199
 200         watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 201         watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 202         watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 203         bcm2835_wdt_wdd.parent = &pdev->dev;
 204         if (bcm2835_wdt_is_running(wdt)) {
 205                 /*
 206                  * The currently active timeout value (set by the
 207                  * bootloader) may be different from the module
 208                  * heartbeat parameter or the value in device
 209                  * tree. But we just need to set WDOG_HW_RUNNING,
 210                  * because then the framework will "immediately" ping
 211                  * the device, updating the timeout.
 212                  */
 213                 set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status);
 214         }
 215         err = watchdog_register_device(&bcm2835_wdt_wdd);
 216         if (err) {
 217                 dev_err(dev, "Failed to register watchdog device");
 218                 iounmap(wdt->base);
 219                 return err;
 220         }
 221
 222         wdt->restart_handler.notifier_call = bcm2835_restart_notifier_call;
 223         wdt->restart_handler.priority = 128;
 224         register_restart_handler(&wdt->restart_handler);
 225         if (pm_power_off == NULL)
 226                 pm_power_off = bcm2835_power_off;
 227
 228         dev_info(dev, "Broadcom BCM2835 watchdog timer");
 229         return 0;
 230 }
 231
 232 static int bcm2835_wdt_remove(struct platform_device *pdev)
 233 {
 234         struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 235
 236         unregister_restart_handler(&wdt->restart_handler);
 237         if (pm_power_off == bcm2835_power_off)
 238                 pm_power_off = NULL;
 239         watchdog_unregister_device(&bcm2835_wdt_wdd);
 240         iounmap(wdt->base);
 241
 242         return 0;
 243 }
 244
 245 static void bcm2835_wdt_shutdown(struct platform_device *pdev)
 246 {
 247         bcm2835_wdt_stop(&bcm2835_wdt_wdd);
 248 }
 249
 250 static const struct of_device_id bcm2835_wdt_of_match[] = {
 251         { .compatible = "brcm,bcm2835-pm-wdt", },
 252         {},
 253 };
 254 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
 255
 256 static struct platform_driver bcm2835_wdt_driver = {
 257         .probe          = bcm2835_wdt_probe,
 258         .remove         = bcm2835_wdt_remove,
 259         .shutdown       = bcm2835_wdt_shutdown,
 260         .driver = {
 261                 .name =         "bcm2835-wdt",
 262                 .of_match_table = bcm2835_wdt_of_match,
 263         },
 264 };
 265 module_platform_driver(bcm2835_wdt_driver);
 266
 267 module_param(heartbeat, uint, 0);
 268 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 269
 270 module_param(nowayout, bool, 0);
 271 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 272                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 273
 274 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 275 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 276 MODULE_LICENSE("GPL");