UM0851 datasheet(75/245 Pages) STMICROELECTRONICS

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UM0851

Communication device drivers

Doc ID 16604 Rev 2

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USBD control

You can use the following APIs to configure and program the USB Device.

USBD driver usage

As explained above, there can be various user defined functions over the Linux gadget

framework. Each of the functions (gadgets) exposes its own interface. For example, the USB

Ethernet function exposes a netdev interface, the USB serial gadget exposes a tty interface

and so on. This makes the usage of the USB gadgets very easy. You can use standard tools

for standard interfaces provided by these gadgets. You can find such example usage in:

●

linux/Documentation/gadget_printer.txt for usb printer device

●

linux/Documentation/gadget_serial.txt for usb serial device

SPEAr LSP provides a test gadget driver, "zero gadget", to test the USB Device controller.

This gadget does not have any user interface. It just provides two configurations, "source &

sink" and "loop back" to support several test cases which can be executed from the USB

Host side.

On USB Host corresponding to the zero gadget we have a "usbtest" driver which supports

several test cases to validate USB through ioctls. A standard application "testusb" is

void usb_ep_free_request(struct usb_ep *ep,

struct usb_request *req)

Frees the allocated request

int usb_ep_disable(struct usb_ep *ep)

Disables the endpoint ep, so that it is not usable

int usb_ep_queue(struct usb_ep *ep,

struct usb_request *req, gfp_t gfp_flags)

Submist a transfer request on this endpoint (ep)

int usb_ep_set_halt(struct usb_ep *ep)

Halts a particular endpoint (ep)

Table 23.

USB device control APIs

API

Description

int usb_gadget_frame_number(struct

usb_gadget *gadget)

Returns the current Start of Frame number

int usb_gadget_wakeup(struct usb_gadget

*gadget)

Enables the remote wakeup feature of USB

Device

int usb_gadget_set_selfpowered(struct

usb_gadget *gadget)

USB Device is self powered

int usb_gadget_clear_selfpowered(struct

usb_gadget *gadget)

USB Device is not self powered but bus powered

int usb_gadget_ioctl(struct usb_gadget *,

unsigned code, unsigned long param)

Configures USB device on configuration change.

This API is SPEAr-specific and is mandatory to

call on SET CONFIGURATION as it programs the

controller accordingly. param points to the

function descriptors.

Please refer hardware User Manual, USB_CSR

(of USBD) register for details.

Table 22.

Linux gadget endpoint APIs (continued)

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