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    Subject[RFC][PATCH 2/9] usb: gadget: add usb_gadget_start/stop()
    Date
    The OTG state machine needs a mechanism to start and
    stop the gadget controller. Add usb_gadget_start()
    and usb_gadget_stop().

    Signed-off-by: Roger Quadros <rogerq@ti.com>
    ---
    drivers/usb/gadget/udc/udc-core.c | 166 +++++++++++++++++++++++++++++++++++---
    include/linux/usb/gadget.h | 3 +
    2 files changed, 158 insertions(+), 11 deletions(-)

    diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
    index 5a81cb0..69b4123 100644
    --- a/drivers/usb/gadget/udc/udc-core.c
    +++ b/drivers/usb/gadget/udc/udc-core.c
    @@ -35,6 +35,8 @@
    * @dev - the child device to the actual controller
    * @gadget - the gadget. For use by the class code
    * @list - for use by the udc class driver
    + * @running - udc is running
    + * @softconnect - sysfs softconnect says OK to connect
    *
    * This represents the internal data structure which is used by the UDC-class
    * to hold information about udc driver and gadget together.
    @@ -44,6 +46,8 @@ struct usb_udc {
    struct usb_gadget *gadget;
    struct device dev;
    struct list_head list;
    + bool running;
    + bool softconnect;
    };

    static struct class *udc_class;
    @@ -187,7 +191,14 @@ EXPORT_SYMBOL_GPL(usb_gadget_udc_reset);
    */
    static inline int usb_gadget_udc_start(struct usb_udc *udc)
    {
    - return udc->gadget->ops->udc_start(udc->gadget, udc->driver);
    + int ret;
    +
    + dev_dbg(&udc->dev, "%s\n", __func__);
    + ret = udc->gadget->ops->udc_start(udc->gadget, udc->driver);
    + if (!ret)
    + udc->running = 1;
    +
    + return ret;
    }

    /**
    @@ -204,10 +215,140 @@ 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);
    + udc->running = 0;
    }

    /**
    + * usb_udc_start - Start the usb device controller only if conditions met
    + * @udc: The UDC to be started
    + *
    + * Start the UDC and connect to bus (enable pull) only if the
    + * following conditions are met
    + * - UDC is not already running
    + * - gadget function driver is loaded
    + * - userspace softconnect says OK to connect
    + *
    + * NOTE: udc_lock must be held by caller.
    + *
    + * Returs 0 on success or not ready to start, else negative errno.
    + */
    +static int usb_udc_start(struct usb_udc *udc)
    +{
    + int ret;
    +
    + if (udc->running) {
    + dev_err(&udc->dev, "%s: not starting as already running\n",
    + __func__);
    + return -EBUSY;
    + }
    +
    + if (udc->driver && udc->softconnect) {
    + ret = usb_gadget_udc_start(udc);
    + if (ret)
    + return ret;
    +
    + usb_gadget_connect(udc->gadget);
    + }
    +
    + return 0;
    +}
    +
    +/**
    + * usb_udc_stop - Stop the usb device controller
    + * @udc: The UDC to be stopped
    + *
    + * Disconnect from bus (disable pull) and stop the UDC.
    + *
    + * NOTE: udc_lock must be held by caller.
    + *
    + * Returs 0 on success, else negative errno.
    + */
    +static int usb_udc_stop(struct usb_udc *udc)
    +{
    + if (!udc->running) {
    + dev_err(&udc->dev, "%s: not stopping as already halted\n",
    + __func__);
    + return -EBUSY;
    + }
    +
    + usb_gadget_disconnect(udc->gadget);
    + udc->driver->disconnect(udc->gadget);
    + usb_gadget_udc_stop(udc);
    +
    + return 0;
    +}
    +
    +/**
    + * usb_gadget_start - start the usb gadget controller
    + * @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).
    + * There is no guarantee that the controller is started
    + * as we might be missing some dependencies
    + * i.e. gadget function driver not loaded or softconnect disabled.
    + */
    +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_udc_start(udc);
    + mutex_unlock(&udc_lock);
    +
    + return ret;
    +}
    +EXPORT_SYMBOL_GPL(usb_gadget_start);
    +
    +/**
    + * usb_gadget_stop - 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.
    + */
    +int usb_gadget_stop(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_udc_stop(udc);
    + mutex_unlock(&udc_lock);
    +
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(usb_gadget_stop);
    +
    +/**
    * usb_udc_release - release the usb_udc struct
    * @dev: the dev member within usb_udc
    *
    @@ -278,6 +419,7 @@ int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
    goto err3;

    udc->gadget = gadget;
    + udc->softconnect = 1; /* connect by default */

    mutex_lock(&udc_lock);
    list_add_tail(&udc->list, &udc_list);
    @@ -329,10 +471,8 @@ 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);
    + usb_udc_stop(udc);
    udc->driver->unbind(udc->gadget);
    - usb_gadget_udc_stop(udc);

    udc->driver = NULL;
    udc->dev.driver = NULL;
    @@ -378,6 +518,7 @@ EXPORT_SYMBOL_GPL(usb_del_gadget_udc);

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

    +/* udc_lock must be held */
    static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *driver)
    {
    int ret;
    @@ -392,12 +533,12 @@ 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);
    +
    + ret = usb_udc_start(udc);
    if (ret) {
    driver->unbind(udc->gadget);
    goto err1;
    }
    - usb_gadget_connect(udc->gadget);

    kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
    return 0;
    @@ -510,12 +651,15 @@ static ssize_t usb_udc_softconn_store(struct device *dev,
    }

    if (sysfs_streq(buf, "connect")) {
    - usb_gadget_udc_start(udc);
    - usb_gadget_connect(udc->gadget);
    + mutex_lock(&udc_lock);
    + udc->softconnect = 1;
    + usb_udc_start(udc);
    + mutex_unlock(&udc_lock);
    } else if (sysfs_streq(buf, "disconnect")) {
    - usb_gadget_disconnect(udc->gadget);
    - udc->driver->disconnect(udc->gadget);
    - usb_gadget_udc_stop(udc);
    + mutex_lock(&udc_lock);
    + udc->softconnect = 0;
    + usb_udc_stop(udc);
    + mutex_unlock(&udc_lock);
    } else {
    dev_err(dev, "unsupported command '%s'\n", buf);
    return -EINVAL;
    diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
    index e2f00fd..7ada7e6 100644
    --- a/include/linux/usb/gadget.h
    +++ b/include/linux/usb/gadget.h
    @@ -922,6 +922,9 @@ int usb_gadget_probe_driver(struct usb_gadget_driver *driver);
    */
    int usb_gadget_unregister_driver(struct usb_gadget_driver *driver);

    +int usb_gadget_start(struct usb_gadget *gadget);
    +int usb_gadget_stop(struct usb_gadget *gadget);
    +
    extern int usb_add_gadget_udc_release(struct device *parent,
    struct usb_gadget *gadget, void (*release)(struct device *dev));
    extern int usb_add_gadget_udc(struct device *parent, struct usb_gadget *gadget);
    --
    2.1.0


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