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/*
* otg-wakelock.c
*
* Copyright (C) 2011 Google, Inc.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/notifier.h>
#include <linux/wakelock.h>
#include <linux/spinlock.h>
#include <linux/usb/otg.h>
static bool enabled = true;
static struct otg_transceiver *otgwl_xceiv;
static struct notifier_block otgwl_nb;
/*
* otgwl_spinlock is held while the VBUS lock is grabbed or dropped and the
* locked field is updated to match.
*/
static DEFINE_SPINLOCK(otgwl_spinlock);
/*
* Only one lock, but since these 3 fields are associated with each other...
*/
struct otgwl_lock {
char name[40];
struct wake_lock wakelock;
bool locked;
};
/*
* VBUS present lock.
*/
static struct otgwl_lock vbus_lock;
static void otgwl_grab(struct otgwl_lock *lock)
{
if (!lock->locked) {
wake_lock(&lock->wakelock);
lock->locked = true;
}
}
static void otgwl_drop(struct otgwl_lock *lock)
{
if (lock->locked) {
wake_unlock(&lock->wakelock);
lock->locked = false;
}
}
static int otgwl_otg_notifications(struct notifier_block *nb,
unsigned long event, void *unused)
{
unsigned long irqflags;
if (!enabled)
return NOTIFY_OK;
spin_lock_irqsave(&otgwl_spinlock, irqflags);
switch (event) {
case USB_EVENT_VBUS:
case USB_EVENT_ENUMERATED:
otgwl_grab(&vbus_lock);
break;
case USB_EVENT_NONE:
case USB_EVENT_ID:
case USB_EVENT_CHARGER:
otgwl_drop(&vbus_lock);
break;
default:
break;
}
spin_unlock_irqrestore(&otgwl_spinlock, irqflags);
return NOTIFY_OK;
}
static void sync_with_xceiv_state(void)
{
if ((otgwl_xceiv->last_event == USB_EVENT_VBUS) ||
(otgwl_xceiv->last_event == USB_EVENT_ENUMERATED))
otgwl_grab(&vbus_lock);
else
otgwl_drop(&vbus_lock);
}
static int init_for_xceiv(void)
{
int rv;
if (!otgwl_xceiv) {
otgwl_xceiv = otg_get_transceiver();
if (!otgwl_xceiv) {
pr_err("%s: No OTG transceiver found\n", __func__);
return -ENODEV;
}
snprintf(vbus_lock.name, sizeof(vbus_lock.name), "vbus-%s",
dev_name(otgwl_xceiv->dev));
wake_lock_init(&vbus_lock.wakelock, WAKE_LOCK_SUSPEND,
vbus_lock.name);
rv = otg_register_notifier(otgwl_xceiv, &otgwl_nb);
if (rv) {
pr_err("%s: otg_register_notifier on transceiver %s"
" failed\n", __func__,
dev_name(otgwl_xceiv->dev));
otgwl_xceiv = NULL;
wake_lock_destroy(&vbus_lock.wakelock);
return rv;
}
}
return 0;
}
static int set_enabled(const char *val, const struct kernel_param *kp)
{
unsigned long irqflags;
int rv = param_set_bool(val, kp);
if (rv)
return rv;
rv = init_for_xceiv();
if (rv)
return rv;
spin_lock_irqsave(&otgwl_spinlock, irqflags);
if (enabled)
sync_with_xceiv_state();
else
otgwl_drop(&vbus_lock);
spin_unlock_irqrestore(&otgwl_spinlock, irqflags);
return 0;
}
static struct kernel_param_ops enabled_param_ops = {
.set = set_enabled,
.get = param_get_bool,
};
module_param_cb(enabled, &enabled_param_ops, &enabled, 0644);
MODULE_PARM_DESC(enabled, "enable wakelock when VBUS present");
static int __init otg_wakelock_init(void)
{
unsigned long irqflags;
otgwl_nb.notifier_call = otgwl_otg_notifications;
if (!init_for_xceiv()) {
spin_lock_irqsave(&otgwl_spinlock, irqflags);
if (enabled)
sync_with_xceiv_state();
spin_unlock_irqrestore(&otgwl_spinlock, irqflags);
} else {
enabled = false;
}
return 0;
}
late_initcall(otg_wakelock_init);
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