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
  46 struct bcm2835_wdt {
  47         void __iomem            *base;
  48         spinlock_t              lock;
  49 };
  50
  51 static struct bcm2835_wdt *bcm2835_power_off_wdt;
  52
  53 static unsigned int heartbeat;
  54 static bool nowayout = WATCHDOG_NOWAYOUT;
  55
  56 static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt)
  57 {
  58         uint32_t cur;
  59
  60         cur = readl(wdt->base + PM_RSTC);
  61
  62         return !!(cur & PM_RSTC_WRCFG_FULL_RESET);
  63 }
  64
  65 static int bcm2835_wdt_start(struct watchdog_device *wdog)
  66 {
  67         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  68         uint32_t cur;
  69         unsigned long flags;
  70
  71         spin_lock_irqsave(&wdt->lock, flags);
  72
  73         writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
  74                                 PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
  75         cur = readl_relaxed(wdt->base + PM_RSTC);
  76         writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
  77                   PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
  78
  79         spin_unlock_irqrestore(&wdt->lock, flags);
  80
  81         return 0;
  82 }
  83
  84 static int bcm2835_wdt_stop(struct watchdog_device *wdog)
  85 {
  86         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  87
  88         writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
  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 void __bcm2835_restart(struct bcm2835_wdt *wdt)
 101 {
 102         u32 val;
 103
 104         /* use a timeout of 10 ticks (~150us) */
 105         writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
 106         val = readl_relaxed(wdt->base + PM_RSTC);
 107         val &= PM_RSTC_WRCFG_CLR;
 108         val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
 109         writel_relaxed(val, wdt->base + PM_RSTC);
 110
 111         /* No sleeping, possibly atomic. */
 112         mdelay(1);
 113 }
 114
 115 static int bcm2835_restart(struct watchdog_device *wdog,
 116                            unsigned long action, void *data)
 117 {
 118         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
 119
 120         __bcm2835_restart(wdt);
 121
 122         return 0;
 123 }
 124
 125 static const struct watchdog_ops bcm2835_wdt_ops = {
 126         .owner =        THIS_MODULE,
 127         .start =        bcm2835_wdt_start,
 128         .stop =         bcm2835_wdt_stop,
 129         .get_timeleft = bcm2835_wdt_get_timeleft,
 130         .restart =      bcm2835_restart,
 131 };
 132
 133 static const struct watchdog_info bcm2835_wdt_info = {
 134         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 135                         WDIOF_KEEPALIVEPING,
 136         .identity =     "Broadcom BCM2835 Watchdog timer",
 137 };
 138
 139 static struct watchdog_device bcm2835_wdt_wdd = {
 140         .info =         &bcm2835_wdt_info,
 141         .ops =          &bcm2835_wdt_ops,
 142         .min_timeout =  1,
 143         .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 144         .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 145 };
 146
 147 /*
 148  * We can't really power off, but if we do the normal reset scheme, and
 149  * indicate to bootcode.bin not to reboot, then most of the chip will be
 150  * powered off.
 151  */
 152 static void bcm2835_power_off(void)
 153 {
 154         struct bcm2835_wdt *wdt = bcm2835_power_off_wdt;
 155         u32 val;
 156
 157         /*
 158          * We set the watchdog hard reset bit here to distinguish this reset
 159          * from the normal (full) reset. bootcode.bin will not reboot after a
 160          * hard reset.
 161          */
 162         val = readl_relaxed(wdt->base + PM_RSTS);
 163         val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
 164         writel_relaxed(val, wdt->base + PM_RSTS);
 165
 166         /* Continue with normal reset mechanism */
 167         __bcm2835_restart(wdt);
 168 }
 169
 170 static int bcm2835_wdt_probe(struct platform_device *pdev)
 171 {
 172         struct bcm2835_pm *pm = dev_get_drvdata(pdev->dev.parent);
 173         struct device *dev = &pdev->dev;
 174         struct bcm2835_wdt *wdt;
 175         int err;
 176
 177         wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 178         if (!wdt)
 179                 return -ENOMEM;
 180
 181         spin_lock_init(&wdt->lock);
 182
 183         wdt->base = pm->base;
 184
 185         watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 186         watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 187         watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 188         bcm2835_wdt_wdd.parent = dev;
 189         if (bcm2835_wdt_is_running(wdt)) {
 190                 /*
 191                  * The currently active timeout value (set by the
 192                  * bootloader) may be different from the module
 193                  * heartbeat parameter or the value in device
 194                  * tree. But we just need to set WDOG_HW_RUNNING,
 195                  * because then the framework will "immediately" ping
 196                  * the device, updating the timeout.
 197                  */
 198                 set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status);
 199         }
 200
 201         watchdog_set_restart_priority(&bcm2835_wdt_wdd, 128);
 202
 203         watchdog_stop_on_reboot(&bcm2835_wdt_wdd);
 204         err = devm_watchdog_register_device(dev, &bcm2835_wdt_wdd);
 205         if (err) {
 206                 dev_err(dev, "Failed to register watchdog device");
 207                 return err;
 208         }
 209
 210         if (pm_power_off == NULL) {
 211                 pm_power_off = bcm2835_power_off;
 212                 bcm2835_power_off_wdt = wdt;
 213         }
 214
 215         dev_info(dev, "Broadcom BCM2835 watchdog timer");
 216         return 0;
 217 }
 218
 219 static int bcm2835_wdt_remove(struct platform_device *pdev)
 220 {
 221         if (pm_power_off == bcm2835_power_off)
 222                 pm_power_off = NULL;
 223
 224         return 0;
 225 }
 226
 227 static struct platform_driver bcm2835_wdt_driver = {
 228         .probe          = bcm2835_wdt_probe,
 229         .remove         = bcm2835_wdt_remove,
 230         .driver = {
 231                 .name =         "bcm2835-wdt",
 232         },
 233 };
 234 module_platform_driver(bcm2835_wdt_driver);
 235
 236 module_param(heartbeat, uint, 0);
 237 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 238
 239 module_param(nowayout, bool, 0);
 240 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 241                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 242
 243 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 244 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 245 MODULE_LICENSE("GPL");