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/*
* SVC Greybus "watchdog" driver.
*
* Copyright 2016 Google Inc.
*
* Released under the GPLv2 only.
*/
#include <linux/delay.h>
#include <linux/workqueue.h>
#include "greybus.h"
#define SVC_WATCHDOG_PERIOD (2*HZ)
struct gb_svc_watchdog {
struct delayed_work work;
struct gb_svc *svc;
bool enabled;
};
static struct delayed_work reset_work;
static void greybus_reset(struct work_struct *work)
{
static char start_path[256] = "/system/bin/start";
static char *envp[] = {
"HOME=/",
"PATH=/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin",
NULL,
};
static char *argv[] = {
start_path,
"unipro_reset",
NULL,
};
printk(KERN_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);
dev_err(&svc->dev, "Resetting the greybus network, watch out!!!\n");
INIT_DELAYED_WORK(&reset_work, greybus_reset);
queue_delayed_work(system_wq, &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)
queue_delayed_work(system_wq, &watchdog->work,
SVC_WATCHDOG_PERIOD);
}
int gb_svc_watchdog_create(struct gb_svc *svc)
{
struct gb_svc_watchdog *watchdog;
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;
return gb_svc_watchdog_enable(svc);
}
void gb_svc_watchdog_destroy(struct gb_svc *svc)
{
struct gb_svc_watchdog *watchdog = svc->watchdog;
if (!watchdog)
return;
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;
queue_delayed_work(system_wq, &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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