LXR linux/drivers/watchdog/sun4v

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *      sun4v watchdog timer
   4 *      (c) Copyright 2016 Oracle Corporation
   5 *
   6 *      Implement a simple watchdog driver using the built-in sun4v hypervisor
   7 *      watchdog support. If time expires, the hypervisor stops or bounces
   8 *      the guest domain.
   9 */
  10
  11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13#include <linux/errno.h>
  14#include <linux/init.h>
  15#include <linux/kernel.h>
  16#include <linux/module.h>
  17#include <linux/moduleparam.h>
  18#include <linux/watchdog.h>
  19#include <asm/hypervisor.h>
  20#include <asm/mdesc.h>
  21
  22#define WDT_TIMEOUT                     60
  23#define WDT_MAX_TIMEOUT                 31536000
  24#define WDT_MIN_TIMEOUT                 1
  25#define WDT_DEFAULT_RESOLUTION_MS       1000    /* 1 second */
  26
  27static unsigned int timeout;
  28module_param(timeout, uint, 0);
  29MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  30        __MODULE_STRING(WDT_TIMEOUT) ")");
  31
  32static bool nowayout = WATCHDOG_NOWAYOUT;
  33module_param(nowayout, bool, S_IRUGO);
  34MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  35        __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  36
  37static int sun4v_wdt_stop(struct watchdog_device *wdd)
  38{
  39        sun4v_mach_set_watchdog(0, NULL);
  40
  41        return 0;
  42}
  43
  44static int sun4v_wdt_ping(struct watchdog_device *wdd)
  45{
  46        int hverr;
  47
  48        /*
  49         * HV watchdog timer will round up the timeout
  50         * passed in to the nearest multiple of the
  51         * watchdog resolution in milliseconds.
  52         */
  53        hverr = sun4v_mach_set_watchdog(wdd->timeout * 1000, NULL);
  54        if (hverr == HV_EINVAL)
  55                return -EINVAL;
  56
  57        return 0;
  58}
  59
  60static int sun4v_wdt_set_timeout(struct watchdog_device *wdd,
  61                                 unsigned int timeout)
  62{
  63        wdd->timeout = timeout;
  64
  65        return 0;
  66}
  67
  68static const struct watchdog_info sun4v_wdt_ident = {
  69        .options =      WDIOF_SETTIMEOUT |
  70                        WDIOF_MAGICCLOSE |
  71                        WDIOF_KEEPALIVEPING,
  72        .identity =     "sun4v hypervisor watchdog",
  73        .firmware_version = 0,
  74};
  75
  76static const struct watchdog_ops sun4v_wdt_ops = {
  77        .owner =        THIS_MODULE,
  78        .start =        sun4v_wdt_ping,
  79        .stop =         sun4v_wdt_stop,
  80        .ping =         sun4v_wdt_ping,
  81        .set_timeout =  sun4v_wdt_set_timeout,
  82};
  83
  84static struct watchdog_device wdd = {
  85        .info = &sun4v_wdt_ident,
  86        .ops = &sun4v_wdt_ops,
  87        .min_timeout = WDT_MIN_TIMEOUT,
  88        .max_timeout = WDT_MAX_TIMEOUT,
  89        .timeout = WDT_TIMEOUT,
  90};
  91
  92static int __init sun4v_wdt_init(void)
  93{
  94        struct mdesc_handle *handle;
  95        u64 node;
  96        const u64 *value;
  97        int err = 0;
  98        unsigned long major = 1, minor = 1;
  99
 100        /*
 101         * There are 2 properties that can be set from the control
 102         * domain for the watchdog.
 103         * watchdog-resolution
 104         * watchdog-max-timeout
 105         *
 106         * We can expect a handle to be returned otherwise something
 107         * serious is wrong. Correct to return -ENODEV here.
 108         */
 109
 110        handle = mdesc_grab();
 111        if (!handle)
 112                return -ENODEV;
 113
 114        node = mdesc_node_by_name(handle, MDESC_NODE_NULL, "platform");
 115        err = -ENODEV;
 116        if (node == MDESC_NODE_NULL)
 117                goto out_release;
 118
 119        /*
 120         * This is a safe way to validate if we are on the right
 121         * platform.
 122         */
 123        if (sun4v_hvapi_register(HV_GRP_CORE, major, &minor))
 124                goto out_hv_unreg;
 125
 126        /* Allow value of watchdog-resolution up to 1s (default) */
 127        value = mdesc_get_property(handle, node, "watchdog-resolution", NULL);
 128        err = -EINVAL;
 129        if (value) {
 130                if (*value == 0 ||
 131                    *value > WDT_DEFAULT_RESOLUTION_MS)
 132                        goto out_hv_unreg;
 133        }
 134
 135        value = mdesc_get_property(handle, node, "watchdog-max-timeout", NULL);
 136        if (value) {
 137                /*
 138                 * If the property value (in ms) is smaller than
 139                 * min_timeout, return -EINVAL.
 140                 */
 141                if (*value < wdd.min_timeout * 1000)
 142                        goto out_hv_unreg;
 143
 144                /*
 145                 * If the property value is smaller than
 146                 * default max_timeout  then set watchdog max_timeout to
 147                 * the value of the property in seconds.
 148                 */
 149                if (*value < wdd.max_timeout * 1000)
 150                        wdd.max_timeout = *value  / 1000;
 151        }
 152
 153        watchdog_init_timeout(&wdd, timeout, NULL);
 154
 155        watchdog_set_nowayout(&wdd, nowayout);
 156
 157        err = watchdog_register_device(&wdd);
 158        if (err)
 159                goto out_hv_unreg;
 160
 161        pr_info("initialized (timeout=%ds, nowayout=%d)\n",
 162                 wdd.timeout, nowayout);
 163
 164        mdesc_release(handle);
 165
 166        return 0;
 167
 168out_hv_unreg:
 169        sun4v_hvapi_unregister(HV_GRP_CORE);
 170
 171out_release:
 172        mdesc_release(handle);
 173        return err;
 174}
 175
 176static void __exit sun4v_wdt_exit(void)
 177{
 178        sun4v_hvapi_unregister(HV_GRP_CORE);
 179        watchdog_unregister_device(&wdd);
 180}
 181
 182module_init(sun4v_wdt_init);
 183module_exit(sun4v_wdt_exit);
 184
 185MODULE_AUTHOR("Wim Coekaerts <wim.coekaerts@oracle.com>");
 186MODULE_DESCRIPTION("sun4v watchdog driver");
 187MODULE_LICENSE("GPL");
 188