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    Subject[PATCH v3 09/11] usb: gadget: udc: adapt to OTG core
    Date
    The OTG state machine needs a mechanism to start and
    stop the gadget controller. Add usb_gadget_start()
    and usb_gadget_stop().

    Register with OTG core when gadget function driver
    is available and unregister when function driver is unbound.

    We need to unlock the usb_lock mutexbefore calling
    usb_otg_register_gadget() in udc_bind_to_driver() and
    usb_gadget_remove_driver() else it will cause a circular
    locking dependency.

    Ignore softconnect sysfs control when we're in OTG
    mode as OTG FSM takes care of gadget softconnect using
    the b_bus_req mechanism.

    Signed-off-by: Roger Quadros <rogerq@ti.com>
    ---
    drivers/usb/gadget/udc/udc-core.c | 124 +++++++++++++++++++++++++++++++++++---
    1 file changed, 114 insertions(+), 10 deletions(-)

    diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
    index d69c355..3380d03 100644
    --- a/drivers/usb/gadget/udc/udc-core.c
    +++ b/drivers/usb/gadget/udc/udc-core.c
    @@ -28,6 +28,7 @@
    #include <linux/usb/ch9.h>
    #include <linux/usb/gadget.h>
    #include <linux/usb.h>
    +#include <linux/usb/otg.h>

    /**
    * struct usb_udc - describes one usb device controller
    @@ -37,6 +38,7 @@
    * @list - for use by the udc class driver
    * @vbus - for udcs who care about vbus status, this value is real vbus status;
    * for udcs who do not care about vbus status, this value is always true
    + * @is_otg - we're registered with OTG core and it takes care of UDC start/stop
    *
    * This represents the internal data structure which is used by the UDC-class
    * to hold information about udc driver and gadget together.
    @@ -47,6 +49,7 @@ struct usb_udc {
    struct device dev;
    struct list_head list;
    bool vbus;
    + bool is_otg;
    };

    static struct class *udc_class;
    @@ -208,6 +211,7 @@ EXPORT_SYMBOL_GPL(usb_gadget_udc_reset);
    */
    static inline int usb_gadget_udc_start(struct usb_udc *udc)
    {
    + dev_dbg(&udc->dev, "%s\n", __func__);
    return udc->gadget->ops->udc_start(udc->gadget, udc->driver);
    }

    @@ -225,10 +229,81 @@ static inline int usb_gadget_udc_start(struct usb_udc *udc)
    */
    static inline void usb_gadget_udc_stop(struct usb_udc *udc)
    {
    + dev_dbg(&udc->dev, "%s\n", __func__);
    udc->gadget->ops->udc_stop(udc->gadget);
    }

    /**
    + * usb_gadget_start - start the usb gadget controller and connect to bus
    + * @gadget: the gadget device to start
    + *
    + * This is external API for use by OTG core.
    + *
    + * Start the usb device controller and connect to bus (enable pull).
    + */
    +static int usb_gadget_start(struct usb_gadget *gadget)
    +{
    + int ret;
    + struct usb_udc *udc = NULL;
    +
    + dev_dbg(&gadget->dev, "%s\n", __func__);
    + mutex_lock(&udc_lock);
    + list_for_each_entry(udc, &udc_list, list)
    + if (udc->gadget == gadget)
    + goto found;
    +
    + dev_err(gadget->dev.parent, "%s: gadget not registered.\n",
    + __func__);
    + mutex_unlock(&udc_lock);
    + return -EINVAL;
    +
    +found:
    + ret = usb_gadget_udc_start(udc);
    + if (ret)
    + dev_err(&udc->dev, "USB Device Controller didn't start: %d\n",
    + ret);
    + else
    + usb_udc_connect_control(udc);
    +
    + mutex_unlock(&udc_lock);
    +
    + return ret;
    +}
    +
    +/**
    + * usb_gadget_stop - disconnect from bus and stop the usb gadget
    + * @gadget: The gadget device we want to stop
    + *
    + * This is external API for use by OTG core.
    + *
    + * Disconnect from the bus (disable pull) and stop the
    + * gadget controller.
    + */
    +static int usb_gadget_stop(struct usb_gadget *gadget)
    +{
    + struct usb_udc *udc = NULL;
    +
    + dev_dbg(&gadget->dev, "%s\n", __func__);
    + mutex_lock(&udc_lock);
    + list_for_each_entry(udc, &udc_list, list)
    + if (udc->gadget == gadget)
    + goto found;
    +
    + dev_err(gadget->dev.parent, "%s: gadget not registered.\n",
    + __func__);
    + mutex_unlock(&udc_lock);
    + return -EINVAL;
    +
    +found:
    + usb_gadget_disconnect(udc->gadget);
    + udc->driver->disconnect(udc->gadget);
    + usb_gadget_udc_stop(udc);
    + mutex_unlock(&udc_lock);
    +
    + return 0;
    +}
    +
    +/**
    * usb_udc_release - release the usb_udc struct
    * @dev: the dev member within usb_udc
    *
    @@ -345,6 +420,7 @@ int usb_add_gadget_udc(struct device *parent, struct usb_gadget *gadget)
    }
    EXPORT_SYMBOL_GPL(usb_add_gadget_udc);

    +/* udc_lock must be held */
    static void usb_gadget_remove_driver(struct usb_udc *udc)
    {
    dev_dbg(&udc->dev, "unregistering UDC driver [%s]\n",
    @@ -352,10 +428,18 @@ static void usb_gadget_remove_driver(struct usb_udc *udc)

    kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);

    - usb_gadget_disconnect(udc->gadget);
    - udc->driver->disconnect(udc->gadget);
    + /* If OTG, the otg core ensures UDC is stopped on unregister */
    + if (udc->is_otg) {
    + mutex_unlock(&udc_lock);
    + usb_otg_unregister_gadget(udc->gadget);
    + mutex_lock(&udc_lock);
    + } else {
    + usb_gadget_disconnect(udc->gadget);
    + udc->driver->disconnect(udc->gadget);
    + usb_gadget_udc_stop(udc);
    + }
    +
    udc->driver->unbind(udc->gadget);
    - usb_gadget_udc_stop(udc);

    udc->driver = NULL;
    udc->dev.driver = NULL;
    @@ -380,11 +464,12 @@ void usb_del_gadget_udc(struct usb_gadget *gadget)

    mutex_lock(&udc_lock);
    list_del(&udc->list);
    - mutex_unlock(&udc_lock);

    if (udc->driver)
    usb_gadget_remove_driver(udc);

    + mutex_unlock(&udc_lock);
    +
    kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
    flush_work(&gadget->work);
    device_unregister(&udc->dev);
    @@ -394,6 +479,12 @@ EXPORT_SYMBOL_GPL(usb_del_gadget_udc);

    /* ------------------------------------------------------------------------- */

    +struct otg_gadget_ops otg_gadget_intf = {
    + .start = usb_gadget_start,
    + .stop = usb_gadget_stop,
    +};
    +
    +/* udc_lock must be held */
    static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *driver)
    {
    int ret;
    @@ -408,12 +499,19 @@ static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *dri
    ret = driver->bind(udc->gadget, driver);
    if (ret)
    goto err1;
    - ret = usb_gadget_udc_start(udc);
    - if (ret) {
    - driver->unbind(udc->gadget);
    - goto err1;
    +
    + /* If OTG, the otg core starts the UDC when needed */
    + mutex_unlock(&udc_lock);
    + udc->is_otg = !usb_otg_register_gadget(udc->gadget, &otg_gadget_intf);
    + mutex_lock(&udc_lock);
    + if (!udc->is_otg) {
    + ret = usb_gadget_udc_start(udc);
    + if (ret) {
    + driver->unbind(udc->gadget);
    + goto err1;
    + }
    + usb_udc_connect_control(udc);
    }
    - usb_udc_connect_control(udc);

    kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
    return 0;
    @@ -525,9 +623,15 @@ static ssize_t usb_udc_softconn_store(struct device *dev,
    return -EOPNOTSUPP;
    }

    + /* In OTG mode we don't support softconnect, but b_bus_req */
    + if (udc->is_otg) {
    + dev_err(dev, "soft-connect not supported in OTG mode\n");
    + return -EOPNOTSUPP;
    + }
    +
    if (sysfs_streq(buf, "connect")) {
    usb_gadget_udc_start(udc);
    - usb_gadget_connect(udc->gadget);
    + usb_udc_connect_control(udc);
    } else if (sysfs_streq(buf, "disconnect")) {
    usb_gadget_disconnect(udc->gadget);
    udc->driver->disconnect(udc->gadget);
    --
    2.1.4


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