usb: gadget: udc-core: Add extcon hanling to reduce power use

Extcon driver provides information about what kind of cable has been
inserted in the device's USB port. Power use can be reduced if UDC is
switched off while no suitable cable is present.

Signed-off-by: Kamil Debski <k.debski@samsung.com>

diff --git a/drivers/usb/gadget/udc-core.c b/drivers/usb/gadget/udc-core.c
index 817a26c..07d025a 100644 (file)
--- a/drivers/usb/gadget/udc-core.c
+++ b/drivers/usb/gadget/udc-core.c
@@ -27,6 +27,11 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 
+#include <linux/of.h>
+#include <linux/extcon.h>
+#include <linux/extcon/of_extcon.h>
+#include <linux/workqueue.h>
+
 /**
  * struct usb_udc - describes one usb device controller
  * @driver - the gadget driver pointer. For use by the class code
@@ -42,6 +47,12 @@ struct usb_udc {
        struct usb_gadget               *gadget;
        struct device                   dev;
        struct list_head                list;
+       struct extcon_specific_cable_nb extcon_usb_dev;
+       struct notifier_block           extcon_nb;
+       struct workqueue_struct         *pwr_workqueue;
+       struct work_struct              pwr_work;
+       char                            cable_state;
+       char                            enabled;
 };
 
 static struct class *udc_class;
@@ -266,6 +277,10 @@ static void usb_gadget_remove_driver(struct usb_udc *udc)
        dev_dbg(&udc->dev, "unregistering UDC driver [%s]\n",
                        udc->gadget->name);
 
+       if (udc->extcon_usb_dev.edev)
+               extcon_unregister_notifier(udc->extcon_usb_dev.edev,
+                                                       &udc->extcon_nb);
+
        kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
 
        usb_gadget_disconnect(udc->gadget);
@@ -314,10 +329,44 @@ found:
 }
 EXPORT_SYMBOL_GPL(usb_del_gadget_udc);
 
+static void udc_pwr_worker(struct work_struct * work)
+{
+       struct usb_udc *udc = container_of(work, struct usb_udc, pwr_work);
+
+       dev_dbg(&udc->dev, "UDC power worker, cable_state=%d, enabled=%d\n",
+                                               udc->cable_state, udc->enabled);
+
+       if (udc->cable_state && !udc->enabled) {
+               usb_gadget_udc_start(udc->gadget, udc->driver);
+               usb_gadget_connect(udc->gadget);
+               udc->enabled = 1;
+       } else if (!udc->cable_state && udc->enabled) {
+               usb_gadget_disconnect(udc->gadget);
+               usb_gadget_udc_stop(udc->gadget, udc->driver);
+               udc->enabled = 0;
+       }
+}
+
+static int udc_extcon_notifier(struct notifier_block *nb, unsigned long event,
+                                                               void *ptr)
+{
+       struct usb_udc *udc = container_of(nb, struct usb_udc, extcon_nb);
+
+       dev_dbg(&udc->dev, "extcon notifier, cable state=%lu\n", event);
+       udc->cable_state = event;
+
+       queue_work(udc->pwr_workqueue, &udc->pwr_work);
+
+       return NOTIFY_OK;
+}
+
+
 /* ------------------------------------------------------------------------- */
 
 static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *driver)
 {
+       const struct device_node *node;
+       struct extcon_dev *edev = 0;
        int ret;
 
        dev_dbg(&udc->dev, "registering UDC driver [%s]\n",
@@ -327,18 +376,54 @@ static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *dri
        udc->dev.driver = &driver->driver;
        udc->gadget->dev.driver = &driver->driver;
 
+       node = udc->gadget->dev.of_node;
+       /* Check if we have an extcon associated with the UDC driver */
+       if (node && of_property_read_bool(node, "extcon")) {
+               edev = of_extcon_get_extcon_dev(&udc->gadget->dev, 0);
+
+               if(IS_ERR(edev)) {
+                       dev_dbg(&udc->dev, "couldn't get extcon device\n");
+                       ret = -EINVAL;
+                       goto err1;
+               }
+
+               udc->pwr_workqueue = create_singlethread_workqueue("udc");
+               INIT_WORK(&udc->pwr_work, udc_pwr_worker);
+               udc->extcon_nb.notifier_call = udc_extcon_notifier;
+               ret = extcon_register_interest(&udc->extcon_usb_dev, edev->name,
+                                                       "USB", &udc->extcon_nb);
+
+               if (ret) {
+                       dev_err(&udc->dev, "failed to register notifier for USB\n");
+                       goto err1;
+               }
+
+       }
+
        ret = driver->bind(udc->gadget, driver);
        if (ret)
-               goto err1;
+               goto err2;
        ret = usb_gadget_udc_start(udc->gadget, driver);
        if (ret) {
                driver->unbind(udc->gadget);
-               goto err1;
+               goto err2;
        }
+
        usb_gadget_connect(udc->gadget);
 
+       if (udc->extcon_usb_dev.edev) {
+               udc->enabled = 1;
+               udc->cable_state = extcon_get_cable_state_(
+                                       udc->extcon_usb_dev.edev,
+                                       udc->extcon_usb_dev.cable_index);
+               queue_work(udc->pwr_workqueue, &udc->pwr_work);
+       }
+
        kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
        return 0;
+err2:
+       if (udc->extcon_usb_dev.edev)
+               extcon_unregister_notifier(edev, &udc->extcon_nb);
 err1:
        dev_err(&udc->dev, "failed to start %s: %d\n",
                        udc->driver->function, ret);
@@ -556,6 +641,7 @@ static int __init usb_udc_init(void)
        }
 
        udc_class->dev_uevent = usb_udc_uevent;
+
        return 0;
 }
 subsys_initcall(usb_udc_init);