LXR linux/drivers/watchdog/sun4v

   1/*
   2 *      sun4v watchdog timer
   3 *      (c) Copyright 2016 Oracle Corporation
   4 *
   5 *      Implement a simple watchdog driver using the built-in sun4v hypervisor
   6 *      watchdog support. If time expires, the hypervisor stops or bounces
   7 *      the guest domain.
   8 *
   9 *      This program is free software; you can redistribute it and/or
  10 *      modify it under the terms of the GNU General Public License
  11 *      as published by the Free Software Foundation; either version
  12 *      2 of the License, or (at your option) any later version.
  13 */
  14
  15#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  16
  17#include <linux/errno.h>
  18#include <linux/init.h>
  19#include <linux/kernel.h>
  20#include <linux/module.h>
  21#include <linux/moduleparam.h>
  22#include <linux/watchdog.h>
  23#include <asm/hypervisor.h>
  24#include <asm/mdesc.h>
  25
  26#define WDT_TIMEOUT                     60
  27#define WDT_MAX_TIMEOUT                 31536000
  28#define WDT_MIN_TIMEOUT                 1
  29#define WDT_DEFAULT_RESOLUTION_MS       1000    /* 1 second */
  30
  31static unsigned int timeout;
  32module_param(timeout, uint, 0);
  33MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  34        __MODULE_STRING(WDT_TIMEOUT) ")");
  35
  36static bool nowayout = WATCHDOG_NOWAYOUT;
  37module_param(nowayout, bool, S_IRUGO);
  38MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  39        __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  40
  41static int sun4v_wdt_stop(struct watchdog_device *wdd)
  42{
  43        sun4v_mach_set_watchdog(0, NULL);
  44
  45        return 0;
  46}
  47
  48static int sun4v_wdt_ping(struct watchdog_device *wdd)
  49{
  50        int hverr;
  51
  52        /*
  53         * HV watchdog timer will round up the timeout
  54         * passed in to the nearest multiple of the
  55         * watchdog resolution in milliseconds.
  56         */
  57        hverr = sun4v_mach_set_watchdog(wdd->timeout * 1000, NULL);
  58        if (hverr == HV_EINVAL)
  59                return -EINVAL;
  60
  61        return 0;
  62}
  63
  64static int sun4v_wdt_set_timeout(struct watchdog_device *wdd,
  65                                 unsigned int timeout)
  66{
  67        wdd->timeout = timeout;
  68
  69        return 0;
  70}
  71
  72static const struct watchdog_info sun4v_wdt_ident = {
  73        .options =      WDIOF_SETTIMEOUT |
  74                        WDIOF_MAGICCLOSE |
  75                        WDIOF_KEEPALIVEPING,
  76        .identity =     "sun4v hypervisor watchdog",
  77        .firmware_version = 0,
  78};
  79
  80static const struct watchdog_ops sun4v_wdt_ops = {
  81        .owner =        THIS_MODULE,
  82        .start =        sun4v_wdt_ping,
  83        .stop =         sun4v_wdt_stop,
  84        .ping =         sun4v_wdt_ping,
  85        .set_timeout =  sun4v_wdt_set_timeout,
  86};
  87
  88static struct watchdog_device wdd = {
  89        .info = &sun4v_wdt_ident,
  90        .ops = &sun4v_wdt_ops,
  91        .min_timeout = WDT_MIN_TIMEOUT,
  92        .max_timeout = WDT_MAX_TIMEOUT,
  93        .timeout = WDT_TIMEOUT,
  94};
  95
  96static int __init sun4v_wdt_init(void)
  97{
  98        struct mdesc_handle *handle;
  99        u64 node;
 100        const u64 *value;
 101        int err = 0;
 102        unsigned long major = 1, minor = 1;
 103
 104        /*
 105         * There are 2 properties that can be set from the control
 106         * domain for the watchdog.
 107         * watchdog-resolution
 108         * watchdog-max-timeout
 109         *
 110         * We can expect a handle to be returned otherwise something
 111         * serious is wrong. Correct to return -ENODEV here.
 112         */
 113
 114        handle = mdesc_grab();
 115        if (!handle)
 116                return -ENODEV;
 117
 118        node = mdesc_node_by_name(handle, MDESC_NODE_NULL, "platform");
 119        err = -ENODEV;
 120        if (node == MDESC_NODE_NULL)
 121                goto out_release;
 122
 123        /*
 124         * This is a safe way to validate if we are on the right
 125         * platform.
 126         */
 127        if (sun4v_hvapi_register(HV_GRP_CORE, major, &minor))
 128                goto out_hv_unreg;
 129
 130        /* Allow value of watchdog-resolution up to 1s (default) */
 131        value = mdesc_get_property(handle, node, "watchdog-resolution", NULL);
 132        err = -EINVAL;
 133        if (value) {
 134                if (*value == 0 ||
 135                    *value > WDT_DEFAULT_RESOLUTION_MS)
 136                        goto out_hv_unreg;
 137        }
 138
 139        value = mdesc_get_property(handle, node, "watchdog-max-timeout", NULL);
 140        if (value) {
 141                /*
 142                 * If the property value (in ms) is smaller than
 143                 * min_timeout, return -EINVAL.
 144                 */
 145                if (*value < wdd.min_timeout * 1000)
 146                        goto out_hv_unreg;
 147
 148                /*
 149                 * If the property value is smaller than
 150                 * default max_timeout  then set watchdog max_timeout to
 151                 * the value of the property in seconds.
 152                 */
 153                if (*value < wdd.max_timeout * 1000)
 154                        wdd.max_timeout = *value  / 1000;
 155        }
 156
 157        watchdog_init_timeout(&wdd, timeout, NULL);
 158
 159        watchdog_set_nowayout(&wdd, nowayout);
 160
 161        err = watchdog_register_device(&wdd);
 162        if (err)
 163                goto out_hv_unreg;
 164
 165        pr_info("initialized (timeout=%ds, nowayout=%d)\n",
 166                 wdd.timeout, nowayout);
 167
 168        mdesc_release(handle);
 169
 170        return 0;
 171
 172out_hv_unreg:
 173        sun4v_hvapi_unregister(HV_GRP_CORE);
 174
 175out_release:
 176        mdesc_release(handle);
 177        return err;
 178}
 179
 180static void __exit sun4v_wdt_exit(void)
 181{
 182        sun4v_hvapi_unregister(HV_GRP_CORE);
 183        watchdog_unregister_device(&wdd);
 184}
 185
 186module_init(sun4v_wdt_init);
 187module_exit(sun4v_wdt_exit);
 188
 189MODULE_AUTHOR("Wim Coekaerts <wim.coekaerts@oracle.com>");
 190MODULE_DESCRIPTION("sun4v watchdog driver");
 191MODULE_LICENSE("GPL");
 192