diff options
Diffstat (limited to 'drivers/usb/otg/otg-wakelock.c')
| -rw-r--r-- | drivers/usb/otg/otg-wakelock.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/drivers/usb/otg/otg-wakelock.c b/drivers/usb/otg/otg-wakelock.c new file mode 100644 index 00000000000..479376bfa48 --- /dev/null +++ b/drivers/usb/otg/otg-wakelock.c @@ -0,0 +1,173 @@ +/* + * 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/err.h> +#include <linux/module.h> +#include <linux/notifier.h> +#include <linux/wakelock.h> +#include <linux/spinlock.h> +#include <linux/usb/otg.h> + +#define TEMPORARY_HOLD_TIME 2000 + +static bool enabled = true; +static struct usb_phy *otgwl_xceiv; +static struct notifier_block otgwl_nb; + +/* + * otgwl_spinlock is held while the VBUS lock is grabbed or dropped and the + * held 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 held; +}; + +/* + * VBUS present lock. Also used as a timed lock on charger + * connect/disconnect and USB host disconnect, to allow the system + * to react to the change in power. + */ + +static struct otgwl_lock vbus_lock; + +static void otgwl_hold(struct otgwl_lock *lock) +{ + if (!lock->held) { + wake_lock(&lock->wakelock); + lock->held = true; + } +} + +static void otgwl_temporary_hold(struct otgwl_lock *lock) +{ + wake_lock_timeout(&lock->wakelock, + msecs_to_jiffies(TEMPORARY_HOLD_TIME)); + lock->held = false; +} + +static void otgwl_drop(struct otgwl_lock *lock) +{ + if (lock->held) { + wake_unlock(&lock->wakelock); + lock->held = false; + } +} + +static void otgwl_handle_event(unsigned long event) +{ + unsigned long irqflags; + + spin_lock_irqsave(&otgwl_spinlock, irqflags); + + if (!enabled) { + otgwl_drop(&vbus_lock); + spin_unlock_irqrestore(&otgwl_spinlock, irqflags); + return; + } + + switch (event) { + case USB_EVENT_VBUS: + case USB_EVENT_ENUMERATED: + otgwl_hold(&vbus_lock); + break; + + case USB_EVENT_NONE: + case USB_EVENT_ID: + case USB_EVENT_CHARGER: + otgwl_temporary_hold(&vbus_lock); + break; + + default: + break; + } + + spin_unlock_irqrestore(&otgwl_spinlock, irqflags); +} + +static int otgwl_otg_notifications(struct notifier_block *nb, + unsigned long event, void *unused) +{ + otgwl_handle_event(event); + return NOTIFY_OK; +} + +static int set_enabled(const char *val, const struct kernel_param *kp) +{ + int rv = param_set_bool(val, kp); + + if (rv) + return rv; + + if (otgwl_xceiv) + otgwl_handle_event(otgwl_xceiv->last_event); + + 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) +{ + int ret; + struct usb_phy *phy; + + phy = usb_get_phy(USB_PHY_TYPE_USB2); + + if (IS_ERR(phy)) { + pr_err("%s: No USB transceiver found\n", __func__); + return PTR_ERR(phy); + } + otgwl_xceiv = phy; + + 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); + + otgwl_nb.notifier_call = otgwl_otg_notifications; + ret = usb_register_notifier(otgwl_xceiv, &otgwl_nb); + + if (ret) { + pr_err("%s: usb_register_notifier on transceiver %s" + " failed\n", __func__, + dev_name(otgwl_xceiv->dev)); + otgwl_xceiv = NULL; + wake_lock_destroy(&vbus_lock.wakelock); + return ret; + } + + otgwl_handle_event(otgwl_xceiv->last_event); + return ret; +} + +late_initcall(otg_wakelock_init); |