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 #define PM_RSTS_PARTITION_CLR          0xfffffaaa
  36
  37 #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
  38 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
  39
  40 struct bcm2835_wdt {
  41         void __iomem            *base;
  42         spinlock_t              lock;
  43 };
  44
  45 static struct bcm2835_wdt *bcm2835_power_off_wdt;
  46
  47 static unsigned int heartbeat;
  48 static bool nowayout = WATCHDOG_NOWAYOUT;
  49
  50 static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt)
  51 {
  52         uint32_t cur;
  53
  54         cur = readl(wdt->base + PM_RSTC);
  55
  56         return !!(cur & PM_RSTC_WRCFG_FULL_RESET);
  57 }
  58
  59 static int bcm2835_wdt_start(struct watchdog_device *wdog)
  60 {
  61         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  62         uint32_t cur;
  63         unsigned long flags;
  64
  65         spin_lock_irqsave(&wdt->lock, flags);
  66
  67         writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
  68                                 PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
  69         cur = readl_relaxed(wdt->base + PM_RSTC);
  70         writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
  71                   PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
  72
  73         spin_unlock_irqrestore(&wdt->lock, flags);
  74
  75         return 0;
  76 }
  77
  78 static int bcm2835_wdt_stop(struct watchdog_device *wdog)
  79 {
  80         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  81
  82         writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
  83         return 0;
  84 }
  85
  86 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
  87 {
  88         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
  89
  90         uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
  91         return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
  92 }
  93
  94 /*
  95  * The Raspberry Pi firmware uses the RSTS register to know which partiton
  96  * to boot from. The partiton value is spread into bits 0, 2, 4, 6, 8, 10.
  97  * Partiton 63 is a special partition used by the firmware to indicate halt.
  98  */
  99
 100 static void __bcm2835_restart(struct bcm2835_wdt *wdt, u8 partition)
 101 {
 102         u32 val, rsts;
 103
 104         rsts = (partition & BIT(0)) | ((partition & BIT(1)) << 1) |
 105                ((partition & BIT(2)) << 2) | ((partition & BIT(3)) << 3) |
 106                ((partition & BIT(4)) << 4) | ((partition & BIT(5)) << 5);
 107
 108         val = readl_relaxed(wdt->base + PM_RSTS);
 109         val &= PM_RSTS_PARTITION_CLR;
 110         val |= PM_PASSWORD | rsts;
 111         writel_relaxed(val, wdt->base + PM_RSTS);
 112
 113         /* use a timeout of 10 ticks (~150us) */
 114         writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
 115         val = readl_relaxed(wdt->base + PM_RSTC);
 116         val &= PM_RSTC_WRCFG_CLR;
 117         val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
 118         writel_relaxed(val, wdt->base + PM_RSTC);
 119
 120         /* No sleeping, possibly atomic. */
 121         mdelay(1);
 122 }
 123
 124 static int bcm2835_restart(struct watchdog_device *wdog,
 125                            unsigned long action, void *data)
 126 {
 127         struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
 128
 129         unsigned long long val;
 130         u8 partition = 0;
 131
 132         if (data && !kstrtoull(data, 0, &val) && val <= 63)
 133                 partition = val;
 134
 135         __bcm2835_restart(wdt, partition);
 136
 137         return 0;
 138 }
 139
 140 static const struct watchdog_ops bcm2835_wdt_ops = {
 141         .owner =        THIS_MODULE,
 142         .start =        bcm2835_wdt_start,
 143         .stop =         bcm2835_wdt_stop,
 144         .get_timeleft = bcm2835_wdt_get_timeleft,
 145         .restart =      bcm2835_restart,
 146 };
 147
 148 static const struct watchdog_info bcm2835_wdt_info = {
 149         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
 150                         WDIOF_KEEPALIVEPING,
 151         .identity =     "Broadcom BCM2835 Watchdog timer",
 152 };
 153
 154 static struct watchdog_device bcm2835_wdt_wdd = {
 155         .info =         &bcm2835_wdt_info,
 156         .ops =          &bcm2835_wdt_ops,
 157         .min_timeout =  1,
 158         .max_timeout =  WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 159         .timeout =      WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
 160 };
 161
 162 /*
 163  * We can't really power off, but if we do the normal reset scheme, and
 164  * indicate to bootcode.bin not to reboot, then most of the chip will be
 165  * powered off.
 166  */
 167 static void bcm2835_power_off(void)
 168 {
 169         struct bcm2835_wdt *wdt = bcm2835_power_off_wdt;
 170
 171         /* Partition 63 tells the firmware that this is a halt */
 172         __bcm2835_restart(wdt, 63);
 173 }
 174
 175 static int bcm2835_wdt_probe(struct platform_device *pdev)
 176 {
 177         struct bcm2835_pm *pm = dev_get_drvdata(pdev->dev.parent);
 178         struct device *dev = &pdev->dev;
 179         struct bcm2835_wdt *wdt;
 180         int err;
 181
 182         wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 183         if (!wdt)
 184                 return -ENOMEM;
 185
 186         spin_lock_init(&wdt->lock);
 187
 188         wdt->base = pm->base;
 189
 190         watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 191         watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 192         watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 193         bcm2835_wdt_wdd.parent = dev;
 194         if (bcm2835_wdt_is_running(wdt)) {
 195                 /*
 196                  * The currently active timeout value (set by the
 197                  * bootloader) may be different from the module
 198                  * heartbeat parameter or the value in device
 199                  * tree. But we just need to set WDOG_HW_RUNNING,
 200                  * because then the framework will "immediately" ping
 201                  * the device, updating the timeout.
 202                  */
 203                 set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status);
 204         }
 205
 206         watchdog_set_restart_priority(&bcm2835_wdt_wdd, 128);
 207
 208         watchdog_stop_on_reboot(&bcm2835_wdt_wdd);
 209         err = devm_watchdog_register_device(dev, &bcm2835_wdt_wdd);
 210         if (err)
 211                 return err;
 212
 213         if (of_device_is_system_power_controller(pdev->dev.parent->of_node)) {
 214                 if (!pm_power_off) {
 215                         pm_power_off = bcm2835_power_off;
 216                         bcm2835_power_off_wdt = wdt;
 217                 } else {
 218                         dev_info(dev, "Poweroff handler already present!\n");
 219                 }
 220         }
 221
 222         dev_info(dev, "Broadcom BCM2835 watchdog timer");
 223         return 0;
 224 }
 225
 226 static int bcm2835_wdt_remove(struct platform_device *pdev)
 227 {
 228         if (pm_power_off == bcm2835_power_off)
 229                 pm_power_off = NULL;
 230
 231         return 0;
 232 }
 233
 234 static struct platform_driver bcm2835_wdt_driver = {
 235         .probe          = bcm2835_wdt_probe,
 236         .remove         = bcm2835_wdt_remove,
 237         .driver = {
 238                 .name =         "bcm2835-wdt",
 239         },
 240 };
 241 module_platform_driver(bcm2835_wdt_driver);
 242
 243 module_param(heartbeat, uint, 0);
 244 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 245
 246 module_param(nowayout, bool, 0);
 247 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 248                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 249
 250 MODULE_ALIAS("platform:bcm2835-wdt");
 251 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 252 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 253 MODULE_LICENSE("GPL");