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/types.h>
  18 #include <linux/module.h>
  19 #include <linux/io.h>
  20 #include <linux/watchdog.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/of_address.h>
  23 #include <linux/of_platform.h>
  24
  25 #define PM_RSTC                         0x1c
  26 #define PM_RSTS                         0x20
  27 #define PM_WDOG                         0x24
  28
  29 #define PM_PASSWORD                     0x5a000000
  30
  31 #define PM_WDOG_TIME_SET                0x000fffff
  32 #define PM_RSTC_WRCFG_CLR               0xffffffcf
  33 #define PM_RSTS_HADWRH_SET              0x00000040
  34 #define PM_RSTC_WRCFG_SET               0x00000030
  35 #define PM_RSTC_WRCFG_FULL_RESET        0x00000020
  36 #define PM_RSTC_RESET                   0x00000102
  37
  38 /*
  39  * The Raspberry Pi firmware uses the RSTS register to know which partition
  40  * to boot from. The partition value is spread into bits 0, 2, 4, 6, 8, 10.
  41  * Partition 63 is a special partition used by the firmware to indicate halt.
  42  */
  43 #define PM_RSTS_RASPBERRYPI_HALT        0x555
  44
  45 #define SECS_TO_WDOG_TICKS(x) ((x) << 16)
  46 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
  47
  48 struct bcm2835_wdt {
  49         void __iomem            *base;
  50         spinlock_t              lock;
  51 };
  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 device_node *np =
 155                 of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
 156         struct platform_device *pdev = of_find_device_by_node(np);
 157         struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
 158         u32 val;
 159
 160         /*
 161          * We set the watchdog hard reset bit here to distinguish this reset
 162          * from the normal (full) reset. bootcode.bin will not reboot after a
 163          * hard reset.
 164          */
 165         val = readl_relaxed(wdt->base + PM_RSTS);
 166         val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
 167         writel_relaxed(val, wdt->base + PM_RSTS);
 168
 169         /* Continue with normal reset mechanism */
 170         __bcm2835_restart(wdt);
 171 }
 172
 173 static int bcm2835_wdt_probe(struct platform_device *pdev)
 174 {
 175         struct resource *res;
 176         struct device *dev = &pdev->dev;
 177         struct bcm2835_wdt *wdt;
 178         int err;
 179
 180         wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
 181         if (!wdt)
 182                 return -ENOMEM;
 183         platform_set_drvdata(pdev, wdt);
 184
 185         spin_lock_init(&wdt->lock);
 186
 187         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 188         wdt->base = devm_ioremap_resource(dev, res);
 189         if (IS_ERR(wdt->base))
 190                 return PTR_ERR(wdt->base);
 191
 192         watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
 193         watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
 194         watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
 195         bcm2835_wdt_wdd.parent = dev;
 196         if (bcm2835_wdt_is_running(wdt)) {
 197                 /*
 198                  * The currently active timeout value (set by the
 199                  * bootloader) may be different from the module
 200                  * heartbeat parameter or the value in device
 201                  * tree. But we just need to set WDOG_HW_RUNNING,
 202                  * because then the framework will "immediately" ping
 203                  * the device, updating the timeout.
 204                  */
 205                 set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status);
 206         }
 207
 208         watchdog_set_restart_priority(&bcm2835_wdt_wdd, 128);
 209
 210         watchdog_stop_on_reboot(&bcm2835_wdt_wdd);
 211         err = devm_watchdog_register_device(dev, &bcm2835_wdt_wdd);
 212         if (err) {
 213                 dev_err(dev, "Failed to register watchdog device");
 214                 return err;
 215         }
 216
 217         if (pm_power_off == NULL)
 218                 pm_power_off = bcm2835_power_off;
 219
 220         dev_info(dev, "Broadcom BCM2835 watchdog timer");
 221         return 0;
 222 }
 223
 224 static int bcm2835_wdt_remove(struct platform_device *pdev)
 225 {
 226         if (pm_power_off == bcm2835_power_off)
 227                 pm_power_off = NULL;
 228
 229         return 0;
 230 }
 231
 232 static const struct of_device_id bcm2835_wdt_of_match[] = {
 233         { .compatible = "brcm,bcm2835-pm-wdt", },
 234         {},
 235 };
 236 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
 237
 238 static struct platform_driver bcm2835_wdt_driver = {
 239         .probe          = bcm2835_wdt_probe,
 240         .remove         = bcm2835_wdt_remove,
 241         .driver = {
 242                 .name =         "bcm2835-wdt",
 243                 .of_match_table = bcm2835_wdt_of_match,
 244         },
 245 };
 246 module_platform_driver(bcm2835_wdt_driver);
 247
 248 module_param(heartbeat, uint, 0);
 249 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
 250
 251 module_param(nowayout, bool, 0);
 252 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 253                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 254
 255 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
 256 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
 257 MODULE_LICENSE("GPL");