drivers/watchdog/sun4v_wdt.c

   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
  31 static unsigned int timeout;
  32 module_param(timeout, uint, 0);
  33 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
  34         __MODULE_STRING(WDT_TIMEOUT) ")");
  35
  36 static bool nowayout = WATCHDOG_NOWAYOUT;
  37 module_param(nowayout, bool, S_IRUGO);
  38 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  39         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  40
  41 static int sun4v_wdt_stop(struct watchdog_device *wdd)
  42 {
  43         sun4v_mach_set_watchdog(0, NULL);
  44
  45         return 0;
  46 }
  47
  48 static 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
  64 static int sun4v_wdt_set_timeout(struct watchdog_device *wdd,
  65                                  unsigned int timeout)
  66 {
  67         wdd->timeout = timeout;
  68
  69         return 0;
  70 }
  71
  72 static 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
  80 static 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
  88 static 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
  96 static 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
 172 out_hv_unreg:
 173         sun4v_hvapi_unregister(HV_GRP_CORE);
 174
 175 out_release:
 176         mdesc_release(handle);
 177         return err;
 178 }
 179
 180 static void __exit sun4v_wdt_exit(void)
 181 {
 182         sun4v_hvapi_unregister(HV_GRP_CORE);
 183         watchdog_unregister_device(&wdd);
 184 }
 185
 186 module_init(sun4v_wdt_init);
 187 module_exit(sun4v_wdt_exit);
 188
 189 MODULE_AUTHOR("Wim Coekaerts <wim.coekaerts@oracle.com>");
 190 MODULE_DESCRIPTION("sun4v watchdog driver");
 191 MODULE_LICENSE("GPL");