ANDROID: USB: OTG: Take wakelock when VBUS present
Enabled by default, can disable with:
echo N > /sys/module/otg_wakelock/parameters/enabled
Change-Id: I34974624c52ae23490852b44c270d2f326cf6116
Signed-off-by: Todd Poynor <toddpoynor@google.com>
diff --git a/drivers/usb/phy/otg-wakelock.c b/drivers/usb/phy/otg-wakelock.c
new file mode 100644
index 0000000..9931626
--- /dev/null
+++ b/drivers/usb/phy/otg-wakelock.c
@@ -0,0 +1,190 @@
+/*
+ * 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);