diff options
Diffstat (limited to 'drivers/greybus/svc_watchdog.c')
| -rw-r--r-- | drivers/greybus/svc_watchdog.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/drivers/greybus/svc_watchdog.c b/drivers/greybus/svc_watchdog.c new file mode 100644 index 000000000..b6b1682c1 --- /dev/null +++ b/drivers/greybus/svc_watchdog.c @@ -0,0 +1,197 @@ +// 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; +} |