drivers/watchdog/bcm2835_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Watchdog driver for Broadcom BCM2835
   4  *
   5  * "bcm2708_wdog" driver written by Luke Diamand that was obtained from
   6  * branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used
   7  * as a hardware reference for the Broadcom BCM2835 watchdog timer.
   8  *
   9  * Copyright (C) 2013 Lubomir Rintel <lkundrak@v3.sk>
  10  *
  11  */
  12
  13 #include <linux/delay.h>
  14 #include <linux/types.h>
  15 #include <linux/mfd/bcm2835-pm.h>
  16 #include <linux/module.h>
  17 #include <linux/io.h>
  18 #include <linux/watchdog.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/of_address.h>
  21 #include <linux/of_platform.h>
  22
  23 #define PM_RSTC                         0x1c
  24 #define PM_RSTS                         0x20
  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_RSTS_HADWRH_SET              0x00000040
  32 #define PM_RSTC_WRCFG_SET               0x00000030
  33 #define PM_RSTC_WRCFG_FULL_RESET        0x00000020
  34 #define PM_RSTC_RESET                   0x00000102
  35
  36 /*
  37  * The Raspberry Pi firmware uses the RSTS register to know which partition
  38  * to boot from. The partition value is spread into bits 0, 2, 4, 6, 8, 10.
  39  * Partition 63 is a special partition used by the firmware to indicate halt.
  40  */
  41 #define PM_RSTS_RASPBERRYPI_HALT        0x555
  42
  43 #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
  44 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
  45 #define WDOG_TICKS_TO_MSECS(x) ((x) * 1000 >> 16)
  46
  47 struct bcm2835_wdt {
  48         void __iomem            *base;
  49         spinlock_t              lock;
  50 };
  51
  52 static struct bcm2835_wdt *bcm2835_power_off_wdt;
  53
  54 static unsigned int heartbeat;
  55 static bool nowayout = WATCHDOG_NOWAYOUT;
  56
  57 static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt)
  58 {
  59         uint32_t cur;
  60
  61         cur = readl(wdt->base + PM_RSTC);
  62
  63         return !!(cur & PM_RSTC_WRCFG_FULL_RESET);
  64 }
  65
  66 static int bcm2835_wdt_start(struct watchdog_device *wdog)
  67 {
  68         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  69         uint32_t cur;
  70         unsigned long flags;
  71
  72         spin_lock_irqsave(&wdt->lock, flags);
  73
  74         writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
  75                                 PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
  76         cur = readl_relaxed(wdt->base + PM_RSTC);
  77         writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
  78                   PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
  79
  80         spin_unlock_irqrestore(&wdt->lock, flags);
  81
  82         return 0;
  83 }
  84
  85 static int bcm2835_wdt_stop(struct watchdog_device *wdog)
  86 {
  87         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  88
  89         writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
  90         return 0;
  91 }
  92
  93 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
  94 {
  95         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  96
  97         uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
  98         return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
  99 }
 100
 101 static void __bcm2835_restart(struct bcm2835_wdt *wdt)
 102 {
 103         u32 val;
 104
 105         /* use a timeout of 10 ticks (~150us) */
 106         writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
 107         val = readl_relaxed(wdt->base + PM_RSTC);
 108         val &= PM_RSTC_WRCFG_CLR;
 109         val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
 110         writel_relaxed(val, wdt->base + PM_RSTC);
 111
 112         /* No sleeping, possibly atomic. */
 113         mdelay(1);
 114 }
 115
 116 static int bcm2835_restart(struct watchdog_device *wdog,
 117                            unsigned long action, void *data)
 118 {
 119         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
 120
 121         __bcm2835_restart(wdt);
 122
 123         return 0;
 124 }
 125
 126 static const struct watchdog_ops bcm2835_wdt_ops = {
 127         .owner =        THIS_MODULE,
 128         .start =        bcm2835_wdt_start,
 129         .stop =         bcm2835_wdt_stop,
 130         .get_timeleft = bcm2835_wdt_get_timeleft,
 131         .restart =      bcm2835_restart,
 132 };
 133
 134 static const struct watchdog_info bcm2835_wdt_info = {
 135         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 136                         WDIOF_KEEPALIVEPING,
 137         .identity =     "Broadcom BCM2835 Watchdog timer",
 138 };
 139
 140 static struct watchdog_device bcm2835_wdt_wdd = {
 141         .info =         &bcm2835_wdt_info,
 142         .ops =          &bcm2835_wdt_ops,
 143         .min_timeout =  1,
 144         .max_hw_heartbeat_ms =  WDOG_TICKS_TO_MSECS(PM_WDOG_TIME_SET),
 145         .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 146 };
 147
 148 /*
 149  * We can't really power off, but if we do the normal reset scheme, and
 150  * indicate to bootcode.bin not to reboot, then most of the chip will be
 151  * powered off.
 152  */
 153 static void bcm2835_power_off(void)
 154 {
 155         struct bcm2835_wdt *wdt = bcm2835_power_off_wdt;
 156         u32 val;
 157
 158         /*
 159          * We set the watchdog hard reset bit here to distinguish this reset
 160          * from the normal (full) reset. bootcode.bin will not reboot after a
 161          * hard reset.
 162          */
 163         val = readl_relaxed(wdt->base + PM_RSTS);
 164         val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
 165         writel_relaxed(val, wdt->base + PM_RSTS);
 166
 167         /* Continue with normal reset mechanism */
 168         __bcm2835_restart(wdt);
 169 }
 170
 171 static int bcm2835_wdt_probe(struct platform_device *pdev)
 172 {
 173         struct bcm2835_pm *pm = dev_get_drvdata(pdev->dev.parent);
 174         struct device *dev = &pdev->dev;
 175         struct bcm2835_wdt *wdt;
 176         int err;
 177
 178         wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 179         if (!wdt)
 180                 return -ENOMEM;
 181
 182         spin_lock_init(&wdt->lock);
 183
 184         wdt->base = pm->base;
 185
 186         watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 187         watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 188         watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 189         bcm2835_wdt_wdd.parent = dev;
 190         if (bcm2835_wdt_is_running(wdt)) {
 191                 /*
 192                  * The currently active timeout value (set by the
 193                  * bootloader) may be different from the module
 194                  * heartbeat parameter or the value in device
 195                  * tree. But we just need to set WDOG_HW_RUNNING,
 196                  * because then the framework will "immediately" ping
 197                  * the device, updating the timeout.
 198                  */
 199                 set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status);
 200         }
 201
 202         watchdog_set_restart_priority(&bcm2835_wdt_wdd, 128);
 203
 204         watchdog_stop_on_reboot(&bcm2835_wdt_wdd);
 205         err = devm_watchdog_register_device(dev, &bcm2835_wdt_wdd);
 206         if (err)
 207                 return err;
 208
 209         if (pm_power_off == NULL) {
 210                 pm_power_off = bcm2835_power_off;
 211                 bcm2835_power_off_wdt = wdt;
 212         }
 213
 214         dev_info(dev, "Broadcom BCM2835 watchdog timer");
 215         return 0;
 216 }
 217
 218 static int bcm2835_wdt_remove(struct platform_device *pdev)
 219 {
 220         if (pm_power_off == bcm2835_power_off)
 221                 pm_power_off = NULL;
 222
 223         return 0;
 224 }
 225
 226 static struct platform_driver bcm2835_wdt_driver = {
 227         .probe          = bcm2835_wdt_probe,
 228         .remove         = bcm2835_wdt_remove,
 229         .driver = {
 230                 .name =         "bcm2835-wdt",
 231         },
 232 };
 233 module_platform_driver(bcm2835_wdt_driver);
 234
 235 module_param(heartbeat, uint, 0);
 236 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 237
 238 module_param(nowayout, bool, 0);
 239 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 240                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 241
 242 MODULE_ALIAS("platform:bcm2835-wdt");
 243 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 244 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 245 MODULE_LICENSE("GPL");