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1// SPDX-License-Identifier: GPL-2.02/*3 * SVC Greybus "watchdog" driver.4 *5 * Copyright 2016 Google Inc.6 */7 8#include <linux/delay.h>9#include <linux/suspend.h>10#include <linux/workqueue.h>11#include <linux/greybus.h>12 13#define SVC_WATCHDOG_PERIOD (2 * HZ)14 15struct gb_svc_watchdog {16 struct delayed_work work;17 struct gb_svc *svc;18 bool enabled;19 struct notifier_block pm_notifier;20};21 22static struct delayed_work reset_work;23 24static int svc_watchdog_pm_notifier(struct notifier_block *notifier,25 unsigned long pm_event, void *unused)26{27 struct gb_svc_watchdog *watchdog =28 container_of(notifier, struct gb_svc_watchdog, pm_notifier);29 30 switch (pm_event) {31 case PM_SUSPEND_PREPARE:32 gb_svc_watchdog_disable(watchdog->svc);33 break;34 case PM_POST_SUSPEND:35 gb_svc_watchdog_enable(watchdog->svc);36 break;37 default:38 break;39 }40 41 return NOTIFY_DONE;42}43 44static void greybus_reset(struct work_struct *work)45{46 static char const start_path[] = "/system/bin/start";47 static char *envp[] = {48 "HOME=/",49 "PATH=/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin",50 NULL,51 };52 static char *argv[] = {53 (char *)start_path,54 "unipro_reset",55 NULL,56 };57 58 pr_err("svc_watchdog: calling \"%s %s\" to reset greybus network!\n",59 argv[0], argv[1]);60 call_usermodehelper(start_path, argv, envp, UMH_WAIT_EXEC);61}62 63static void do_work(struct work_struct *work)64{65 struct gb_svc_watchdog *watchdog;66 struct gb_svc *svc;67 int retval;68 69 watchdog = container_of(work, struct gb_svc_watchdog, work.work);70 svc = watchdog->svc;71 72 dev_dbg(&svc->dev, "%s: ping.\n", __func__);73 retval = gb_svc_ping(svc);74 if (retval) {75 /*76 * Something went really wrong, let's warn userspace and then77 * pull the plug and reset the whole greybus network.78 * We need to do this outside of this workqueue as we will be79 * tearing down the svc device itself. So queue up80 * yet-another-callback to do that.81 */82 dev_err(&svc->dev,83 "SVC ping has returned %d, something is wrong!!!\n",84 retval);85 86 if (svc->action == GB_SVC_WATCHDOG_BITE_PANIC_KERNEL) {87 panic("SVC is not responding\n");88 } else if (svc->action == GB_SVC_WATCHDOG_BITE_RESET_UNIPRO) {89 dev_err(&svc->dev, "Resetting the greybus network, watch out!!!\n");90 91 INIT_DELAYED_WORK(&reset_work, greybus_reset);92 schedule_delayed_work(&reset_work, HZ / 2);93 94 /*95 * Disable ourselves, we don't want to trip again unless96 * userspace wants us to.97 */98 watchdog->enabled = false;99 }100 }101 102 /* resubmit our work to happen again, if we are still "alive" */103 if (watchdog->enabled)104 schedule_delayed_work(&watchdog->work, SVC_WATCHDOG_PERIOD);105}106 107int gb_svc_watchdog_create(struct gb_svc *svc)108{109 struct gb_svc_watchdog *watchdog;110 int retval;111 112 if (svc->watchdog)113 return 0;114 115 watchdog = kmalloc(sizeof(*watchdog), GFP_KERNEL);116 if (!watchdog)117 return -ENOMEM;118 119 watchdog->enabled = false;120 watchdog->svc = svc;121 INIT_DELAYED_WORK(&watchdog->work, do_work);122 svc->watchdog = watchdog;123 124 watchdog->pm_notifier.notifier_call = svc_watchdog_pm_notifier;125 retval = register_pm_notifier(&watchdog->pm_notifier);126 if (retval) {127 dev_err(&svc->dev, "error registering pm notifier(%d)\n",128 retval);129 goto svc_watchdog_create_err;130 }131 132 retval = gb_svc_watchdog_enable(svc);133 if (retval) {134 dev_err(&svc->dev, "error enabling watchdog (%d)\n", retval);135 unregister_pm_notifier(&watchdog->pm_notifier);136 goto svc_watchdog_create_err;137 }138 return retval;139 140svc_watchdog_create_err:141 svc->watchdog = NULL;142 kfree(watchdog);143 144 return retval;145}146 147void gb_svc_watchdog_destroy(struct gb_svc *svc)148{149 struct gb_svc_watchdog *watchdog = svc->watchdog;150 151 if (!watchdog)152 return;153 154 unregister_pm_notifier(&watchdog->pm_notifier);155 gb_svc_watchdog_disable(svc);156 svc->watchdog = NULL;157 kfree(watchdog);158}159 160bool gb_svc_watchdog_enabled(struct gb_svc *svc)161{162 if (!svc || !svc->watchdog)163 return false;164 return svc->watchdog->enabled;165}166 167int gb_svc_watchdog_enable(struct gb_svc *svc)168{169 struct gb_svc_watchdog *watchdog;170 171 if (!svc->watchdog)172 return -ENODEV;173 174 watchdog = svc->watchdog;175 if (watchdog->enabled)176 return 0;177 178 watchdog->enabled = true;179 schedule_delayed_work(&watchdog->work, SVC_WATCHDOG_PERIOD);180 return 0;181}182 183int gb_svc_watchdog_disable(struct gb_svc *svc)184{185 struct gb_svc_watchdog *watchdog;186 187 if (!svc->watchdog)188 return -ENODEV;189 190 watchdog = svc->watchdog;191 if (!watchdog->enabled)192 return 0;193 194 watchdog->enabled = false;195 cancel_delayed_work_sync(&watchdog->work);196 return 0;197}198