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- // SPDX-License-Identifier: GPL-2.0
- /*
- * SVC Greybus "watchdog" driver.
- *
- * Copyright 2016 Google Inc.
- */
- #include <linux/delay.h>
- #include <linux/suspend.h>
- #include <linux/workqueue.h>
- #include <linux/greybus.h>
- #define SVC_WATCHDOG_PERIOD (2 * HZ)
- struct gb_svc_watchdog {
- struct delayed_work work;
- struct gb_svc *svc;
- bool enabled;
- struct notifier_block pm_notifier;
- };
- static struct delayed_work reset_work;
- static int svc_watchdog_pm_notifier(struct notifier_block *notifier,
- unsigned long pm_event, void *unused)
- {
- struct gb_svc_watchdog *watchdog =
- container_of(notifier, struct gb_svc_watchdog, pm_notifier);
- switch (pm_event) {
- case PM_SUSPEND_PREPARE:
- gb_svc_watchdog_disable(watchdog->svc);
- break;
- case PM_POST_SUSPEND:
- gb_svc_watchdog_enable(watchdog->svc);
- break;
- default:
- break;
- }
- return NOTIFY_DONE;
- }
- static void greybus_reset(struct work_struct *work)
- {
- static char const start_path[] = "/system/bin/start";
- static char *envp[] = {
- "HOME=/",
- "PATH=/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin",
- NULL,
- };
- static char *argv[] = {
- (char *)start_path,
- "unipro_reset",
- NULL,
- };
- pr_err("svc_watchdog: calling \"%s %s\" to reset greybus network!\n",
- argv[0], argv[1]);
- call_usermodehelper(start_path, argv, envp, UMH_WAIT_EXEC);
- }
- static void do_work(struct work_struct *work)
- {
- struct gb_svc_watchdog *watchdog;
- struct gb_svc *svc;
- int retval;
- watchdog = container_of(work, struct gb_svc_watchdog, work.work);
- svc = watchdog->svc;
- dev_dbg(&svc->dev, "%s: ping.\n", __func__);
- retval = gb_svc_ping(svc);
- if (retval) {
- /*
- * Something went really wrong, let's warn userspace and then
- * pull the plug and reset the whole greybus network.
- * We need to do this outside of this workqueue as we will be
- * tearing down the svc device itself. So queue up
- * yet-another-callback to do that.
- */
- dev_err(&svc->dev,
- "SVC ping has returned %d, something is wrong!!!\n",
- retval);
- if (svc->action == GB_SVC_WATCHDOG_BITE_PANIC_KERNEL) {
- panic("SVC is not responding\n");
- } else if (svc->action == GB_SVC_WATCHDOG_BITE_RESET_UNIPRO) {
- dev_err(&svc->dev, "Resetting the greybus network, watch out!!!\n");
- INIT_DELAYED_WORK(&reset_work, greybus_reset);
- schedule_delayed_work(&reset_work, HZ / 2);
- /*
- * Disable ourselves, we don't want to trip again unless
- * userspace wants us to.
- */
- watchdog->enabled = false;
- }
- }
- /* resubmit our work to happen again, if we are still "alive" */
- if (watchdog->enabled)
- schedule_delayed_work(&watchdog->work, SVC_WATCHDOG_PERIOD);
- }
- int gb_svc_watchdog_create(struct gb_svc *svc)
- {
- struct gb_svc_watchdog *watchdog;
- int retval;
- if (svc->watchdog)
- return 0;
- watchdog = kmalloc(sizeof(*watchdog), GFP_KERNEL);
- if (!watchdog)
- return -ENOMEM;
- watchdog->enabled = false;
- watchdog->svc = svc;
- INIT_DELAYED_WORK(&watchdog->work, do_work);
- svc->watchdog = watchdog;
- watchdog->pm_notifier.notifier_call = svc_watchdog_pm_notifier;
- retval = register_pm_notifier(&watchdog->pm_notifier);
- if (retval) {
- dev_err(&svc->dev, "error registering pm notifier(%d)\n",
- retval);
- goto svc_watchdog_create_err;
- }
- retval = gb_svc_watchdog_enable(svc);
- if (retval) {
- dev_err(&svc->dev, "error enabling watchdog (%d)\n", retval);
- unregister_pm_notifier(&watchdog->pm_notifier);
- goto svc_watchdog_create_err;
- }
- return retval;
- svc_watchdog_create_err:
- svc->watchdog = NULL;
- kfree(watchdog);
- return retval;
- }
- void gb_svc_watchdog_destroy(struct gb_svc *svc)
- {
- struct gb_svc_watchdog *watchdog = svc->watchdog;
- if (!watchdog)
- return;
- unregister_pm_notifier(&watchdog->pm_notifier);
- gb_svc_watchdog_disable(svc);
- svc->watchdog = NULL;
- kfree(watchdog);
- }
- bool gb_svc_watchdog_enabled(struct gb_svc *svc)
- {
- if (!svc || !svc->watchdog)
- return false;
- return svc->watchdog->enabled;
- }
- int gb_svc_watchdog_enable(struct gb_svc *svc)
- {
- struct gb_svc_watchdog *watchdog;
- if (!svc->watchdog)
- return -ENODEV;
- watchdog = svc->watchdog;
- if (watchdog->enabled)
- return 0;
- watchdog->enabled = true;
- schedule_delayed_work(&watchdog->work, SVC_WATCHDOG_PERIOD);
- return 0;
- }
- int gb_svc_watchdog_disable(struct gb_svc *svc)
- {
- struct gb_svc_watchdog *watchdog;
- if (!svc->watchdog)
- return -ENODEV;
- watchdog = svc->watchdog;
- if (!watchdog->enabled)
- return 0;
- watchdog->enabled = false;
- cancel_delayed_work_sync(&watchdog->work);
- return 0;
- }
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