USB: OTG: Take wakelock when VBUS present
Todd Poynor [Sat, 2 Jul 2011 00:19:56 +0000 (17:19 -0700)]
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>

drivers/usb/otg/Kconfig
drivers/usb/otg/Makefile
drivers/usb/otg/otg-wakelock.c [new file with mode: 0644]

index c66481a..cd77719 100644 (file)
@@ -12,6 +12,14 @@ config USB_OTG_UTILS
          Select this to make sure the build includes objects from
          the OTG infrastructure directory.
 
+config USB_OTG_WAKELOCK
+       bool "Hold a wakelock when USB connected"
+       depends on WAKELOCK
+       select USB_OTG_UTILS
+       help
+         Select this to automatically hold a wakelock when USB is
+         connected, preventing suspend.
+
 if USB || USB_GADGET
 
 #
index 566655c..c428207 100644 (file)
@@ -7,6 +7,7 @@ ccflags-$(CONFIG_USB_GADGET_DEBUG)      += -DDEBUG
 
 # infrastructure
 obj-$(CONFIG_USB_OTG_UTILS)    += otg.o
+obj-$(CONFIG_USB_OTG_WAKELOCK) += otg-wakelock.o
 
 # transceiver drivers
 obj-$(CONFIG_USB_GPIO_VBUS)    += gpio_vbus.o
diff --git a/drivers/usb/otg/otg-wakelock.c b/drivers/usb/otg/otg-wakelock.c
new file mode 100644 (file)
index 0000000..9931626
--- /dev/null
@@ -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);