drivers/staging/greybus/svc_watchdog.c

   1 /*
   2  * SVC Greybus "watchdog" driver.
   3  *
   4  * Copyright 2016 Google Inc.
   5  *
   6  * Released under the GPLv2 only.
   7  */
   8
   9 #include <linux/delay.h>
  10 #include <linux/suspend.h>
  11 #include <linux/workqueue.h>
  12 #include "greybus.h"
  13
  14 #define SVC_WATCHDOG_PERIOD     (2*HZ)
  15
  16 struct gb_svc_watchdog {
  17         struct delayed_work     work;
  18         struct gb_svc           *svc;
  19         bool                    enabled;
  20         struct notifier_block pm_notifier;
  21 };
  22
  23 static struct delayed_work reset_work;
  24
  25 static int svc_watchdog_pm_notifier(struct notifier_block *notifier,
  26                                     unsigned long pm_event, void *unused)
  27 {
  28         struct gb_svc_watchdog *watchdog =
  29                 container_of(notifier, struct gb_svc_watchdog, pm_notifier);
  30
  31         switch (pm_event) {
  32         case PM_SUSPEND_PREPARE:
  33                 gb_svc_watchdog_disable(watchdog->svc);
  34                 break;
  35         case PM_POST_SUSPEND:
  36                 gb_svc_watchdog_enable(watchdog->svc);
  37                 break;
  38         default:
  39                 break;
  40         }
  41
  42         return NOTIFY_DONE;
  43 }
  44
  45 static void greybus_reset(struct work_struct *work)
  46 {
  47         static char start_path[256] = "/system/bin/start";
  48         static char *envp[] = {
  49                 "HOME=/",
  50                 "PATH=/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin",
  51                 NULL,
  52         };
  53         static char *argv[] = {
  54                 start_path,
  55                 "unipro_reset",
  56                 NULL,
  57         };
  58
  59         printk(KERN_ERR "svc_watchdog: calling \"%s %s\" to reset greybus network!\n",
  60                argv[0], argv[1]);
  61         call_usermodehelper(start_path, argv, envp, UMH_WAIT_EXEC);
  62 }
  63
  64 static void do_work(struct work_struct *work)
  65 {
  66         struct gb_svc_watchdog *watchdog;
  67         struct gb_svc *svc;
  68         int retval;
  69
  70         watchdog = container_of(work, struct gb_svc_watchdog, work.work);
  71         svc = watchdog->svc;
  72
  73         dev_dbg(&svc->dev, "%s: ping.\n", __func__);
  74         retval = gb_svc_ping(svc);
  75         if (retval) {
  76                 /*
  77                  * Something went really wrong, let's warn userspace and then
  78                  * pull the plug and reset the whole greybus network.
  79                  * We need to do this outside of this workqueue as we will be
  80                  * tearing down the svc device itself.  So queue up
  81                  * yet-another-callback to do that.
  82                  */
  83                 dev_err(&svc->dev,
  84                         "SVC ping has returned %d, something is wrong!!!\n",
  85                         retval);
  86
  87                 if (svc->action == GB_SVC_WATCHDOG_BITE_PANIC_KERNEL) {
  88                         panic("SVC is not responding\n");
  89                 } else if (svc->action == GB_SVC_WATCHDOG_BITE_RESET_UNIPRO) {
  90                         dev_err(&svc->dev, "Resetting the greybus network, watch out!!!\n");
  91
  92                         INIT_DELAYED_WORK(&reset_work, greybus_reset);
  93                         schedule_delayed_work(&reset_work, HZ / 2);
  94
  95                         /*
  96                          * Disable ourselves, we don't want to trip again unless
  97                          * userspace wants us to.
  98                          */
  99                         watchdog->enabled = false;
 100                 }
 101         }
 102
 103         /* resubmit our work to happen again, if we are still "alive" */
 104         if (watchdog->enabled)
 105                 schedule_delayed_work(&watchdog->work, SVC_WATCHDOG_PERIOD);
 106 }
 107
 108 int gb_svc_watchdog_create(struct gb_svc *svc)
 109 {
 110         struct gb_svc_watchdog *watchdog;
 111         int retval;
 112
 113         if (svc->watchdog)
 114                 return 0;
 115
 116         watchdog = kmalloc(sizeof(*watchdog), GFP_KERNEL);
 117         if (!watchdog)
 118                 return -ENOMEM;
 119
 120         watchdog->enabled = false;
 121         watchdog->svc = svc;
 122         INIT_DELAYED_WORK(&watchdog->work, do_work);
 123         svc->watchdog = watchdog;
 124
 125         watchdog->pm_notifier.notifier_call = svc_watchdog_pm_notifier;
 126         retval = register_pm_notifier(&watchdog->pm_notifier);
 127         if (retval) {
 128                 dev_err(&svc->dev, "error registering pm notifier(%d)\n",
 129                         retval);
 130                 goto svc_watchdog_create_err;
 131         }
 132
 133         retval = gb_svc_watchdog_enable(svc);
 134         if (retval) {
 135                 dev_err(&svc->dev, "error enabling watchdog (%d)\n", retval);
 136                 unregister_pm_notifier(&watchdog->pm_notifier);
 137                 goto svc_watchdog_create_err;
 138         }
 139         return retval;
 140
 141 svc_watchdog_create_err:
 142         svc->watchdog = NULL;
 143         kfree(watchdog);
 144
 145         return retval;
 146 }
 147
 148 void gb_svc_watchdog_destroy(struct gb_svc *svc)
 149 {
 150         struct gb_svc_watchdog *watchdog = svc->watchdog;
 151
 152         if (!watchdog)
 153                 return;
 154
 155         unregister_pm_notifier(&watchdog->pm_notifier);
 156         gb_svc_watchdog_disable(svc);
 157         svc->watchdog = NULL;
 158         kfree(watchdog);
 159 }
 160
 161 bool gb_svc_watchdog_enabled(struct gb_svc *svc)
 162 {
 163         if (!svc || !svc->watchdog)
 164                 return false;
 165         return svc->watchdog->enabled;
 166 }
 167
 168 int gb_svc_watchdog_enable(struct gb_svc *svc)
 169 {
 170         struct gb_svc_watchdog *watchdog;
 171
 172         if (!svc->watchdog)
 173                 return -ENODEV;
 174
 175         watchdog = svc->watchdog;
 176         if (watchdog->enabled)
 177                 return 0;
 178
 179         watchdog->enabled = true;
 180         schedule_delayed_work(&watchdog->work, SVC_WATCHDOG_PERIOD);
 181         return 0;
 182 }
 183
 184 int gb_svc_watchdog_disable(struct gb_svc *svc)
 185 {
 186         struct gb_svc_watchdog *watchdog;
 187
 188         if (!svc->watchdog)
 189                 return -ENODEV;
 190
 191         watchdog = svc->watchdog;
 192         if (!watchdog->enabled)
 193                 return 0;
 194
 195         watchdog->enabled = false;
 196         cancel_delayed_work_sync(&watchdog->work);
 197         return 0;
 198 }