173 lines
3.7 KiB
C
173 lines
3.7 KiB
C
/*
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* otg-wakelock.c
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*
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* Copyright (C) 2011 Google, Inc.
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*
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* This software is licensed under the terms of the GNU General Public
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* License version 2, as published by the Free Software Foundation, and
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* may be copied, distributed, and modified under those terms.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/module.h>
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#include <linux/notifier.h>
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#include <linux/wakelock.h>
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#include <linux/spinlock.h>
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#include <linux/usb/otg.h>
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#define TEMPORARY_HOLD_TIME 2000
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static bool enabled = true;
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static struct usb_phy *otgwl_xceiv;
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static struct notifier_block otgwl_nb;
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/*
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* otgwl_spinlock is held while the VBUS lock is grabbed or dropped and the
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* held field is updated to match.
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*/
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static DEFINE_SPINLOCK(otgwl_spinlock);
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/*
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* Only one lock, but since these 3 fields are associated with each other...
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*/
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struct otgwl_lock {
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char name[40];
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struct wake_lock wakelock;
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bool held;
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};
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/*
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* VBUS present lock. Also used as a timed lock on charger
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* connect/disconnect and USB host disconnect, to allow the system
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* to react to the change in power.
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*/
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static struct otgwl_lock vbus_lock;
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static void otgwl_hold(struct otgwl_lock *lock)
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{
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if (!lock->held) {
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wake_lock(&lock->wakelock);
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lock->held = true;
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}
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}
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static void otgwl_temporary_hold(struct otgwl_lock *lock)
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{
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wake_lock_timeout(&lock->wakelock,
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msecs_to_jiffies(TEMPORARY_HOLD_TIME));
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lock->held = false;
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}
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static void otgwl_drop(struct otgwl_lock *lock)
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{
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if (lock->held) {
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wake_unlock(&lock->wakelock);
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lock->held = false;
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}
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}
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static void otgwl_handle_event(unsigned long event)
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{
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unsigned long irqflags;
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spin_lock_irqsave(&otgwl_spinlock, irqflags);
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if (!enabled) {
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otgwl_drop(&vbus_lock);
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spin_unlock_irqrestore(&otgwl_spinlock, irqflags);
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return;
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}
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switch (event) {
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case USB_EVENT_VBUS:
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case USB_EVENT_ENUMERATED:
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otgwl_hold(&vbus_lock);
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break;
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case USB_EVENT_NONE:
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case USB_EVENT_ID:
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case USB_EVENT_CHARGER:
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otgwl_temporary_hold(&vbus_lock);
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break;
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default:
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break;
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}
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spin_unlock_irqrestore(&otgwl_spinlock, irqflags);
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}
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static int otgwl_otg_notifications(struct notifier_block *nb,
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unsigned long event, void *unused)
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{
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otgwl_handle_event(event);
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return NOTIFY_OK;
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}
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static int set_enabled(const char *val, const struct kernel_param *kp)
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{
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int rv = param_set_bool(val, kp);
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if (rv)
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return rv;
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if (otgwl_xceiv)
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otgwl_handle_event(otgwl_xceiv->last_event);
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return 0;
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}
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static struct kernel_param_ops enabled_param_ops = {
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.set = set_enabled,
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.get = param_get_bool,
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};
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module_param_cb(enabled, &enabled_param_ops, &enabled, 0644);
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MODULE_PARM_DESC(enabled, "enable wakelock when VBUS present");
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static int __init otg_wakelock_init(void)
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{
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int ret;
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struct usb_phy *phy;
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phy = usb_get_phy(USB_PHY_TYPE_USB2);
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if (IS_ERR(phy)) {
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pr_err("%s: No USB transceiver found\n", __func__);
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return PTR_ERR(phy);
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}
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otgwl_xceiv = phy;
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snprintf(vbus_lock.name, sizeof(vbus_lock.name), "vbus-%s",
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dev_name(otgwl_xceiv->dev));
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wake_lock_init(&vbus_lock.wakelock, WAKE_LOCK_SUSPEND,
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vbus_lock.name);
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otgwl_nb.notifier_call = otgwl_otg_notifications;
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ret = usb_register_notifier(otgwl_xceiv, &otgwl_nb);
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if (ret) {
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pr_err("%s: usb_register_notifier on transceiver %s"
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" failed\n", __func__,
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dev_name(otgwl_xceiv->dev));
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otgwl_xceiv = NULL;
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wake_lock_destroy(&vbus_lock.wakelock);
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return ret;
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}
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otgwl_handle_event(otgwl_xceiv->last_event);
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return ret;
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}
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late_initcall(otg_wakelock_init);
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