Commit 66a35939 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
Browse files

USB: core: add helpers to retrieve endpoints 



Many USB drivers iterate over the available endpoints to find required
endpoints of a specific type and direction. Typically the endpoints are
required for proper function and a missing endpoint should abort probe.

To facilitate code reuse, add a helper to retrieve common endpoints
(bulk or interrupt, in or out) and four wrappers to find a single
endpoint.

Note that the helpers are marked as __must_check to serve as a reminder
to always verify that all expected endpoints are indeed present. This
also means that any optional endpoints, typically need to be looked up
through separate calls.

Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 96cfcc9c

drivers/usb/core/usb.c

+83 −0
Original line number Diff line number Diff line
@@ -75,6 +75,89 @@ MODULE_PARM_DESC(autosuspend, "default autosuspend delay"); 
#endif





/**

 * usb_find_common_endpoints() -- look up common endpoint descriptors

 * @alt:	alternate setting to search

 * @bulk_in:	pointer to descriptor pointer, or NULL

 * @bulk_out:	pointer to descriptor pointer, or NULL

 * @int_in:	pointer to descriptor pointer, or NULL

 * @int_out:	pointer to descriptor pointer, or NULL

 *

 * Search the alternate setting's endpoint descriptors for the first bulk-in,

 * bulk-out, interrupt-in and interrupt-out endpoints and return them in the

 * provided pointers (unless they are NULL).

 *

 * If a requested endpoint is not found, the corresponding pointer is set to

 * NULL.

 *

 * Return: Zero if all requested descriptors were found, or -ENXIO otherwise.

 */

int usb_find_common_endpoints(struct usb_host_interface *alt,

		struct usb_endpoint_descriptor **bulk_in,

		struct usb_endpoint_descriptor **bulk_out,

		struct usb_endpoint_descriptor **int_in,

		struct usb_endpoint_descriptor **int_out)

{

	struct usb_endpoint_descriptor *epd;

	int i;



	if (bulk_in)

		*bulk_in = NULL;

	if (bulk_out)

		*bulk_out = NULL;

	if (int_in)

		*int_in = NULL;

	if (int_out)

		*int_out = NULL;



	for (i = 0; i < alt->desc.bNumEndpoints; ++i) {

		epd = &alt->endpoint[i].desc;



		switch (usb_endpoint_type(epd)) {

		case USB_ENDPOINT_XFER_BULK:

			if (usb_endpoint_dir_in(epd)) {

				if (bulk_in && !*bulk_in) {

					*bulk_in = epd;

					break;

				}

			} else {

				if (bulk_out && !*bulk_out) {

					*bulk_out = epd;

					break;

				}

			}



			continue;

		case USB_ENDPOINT_XFER_INT:

			if (usb_endpoint_dir_in(epd)) {

				if (int_in && !*int_in) {

					*int_in = epd;

					break;

				}

			} else {

				if (int_out && !*int_out) {

					*int_out = epd;

					break;

				}

			}



			continue;

		default:

			continue;

		}



		if ((!bulk_in || *bulk_in) &&

				(!bulk_out || *bulk_out) &&

				(!int_in || *int_in) &&

				(!int_out || *int_out)) {

			return 0;

		}

	}



	return -ENXIO;

}

EXPORT_SYMBOL_GPL(usb_find_common_endpoints);



/**

 * usb_find_alt_setting() - Given a configuration, find the alternate setting

 * for the given interface.

include/linux/usb.h

+35 −0
Original line number Diff line number Diff line
@@ -99,6 +99,41 @@ enum usb_interface_condition { 
	USB_INTERFACE_UNBINDING,

};



int __must_check

usb_find_common_endpoints(struct usb_host_interface *alt,

		struct usb_endpoint_descriptor **bulk_in,

		struct usb_endpoint_descriptor **bulk_out,

		struct usb_endpoint_descriptor **int_in,

		struct usb_endpoint_descriptor **int_out);



static inline int __must_check

usb_find_bulk_in_endpoint(struct usb_host_interface *alt,

		struct usb_endpoint_descriptor **bulk_in)

{

	return usb_find_common_endpoints(alt, bulk_in, NULL, NULL, NULL);

}



static inline int __must_check

usb_find_bulk_out_endpoint(struct usb_host_interface *alt,

		struct usb_endpoint_descriptor **bulk_out)

{

	return usb_find_common_endpoints(alt, NULL, bulk_out, NULL, NULL);

}



static inline int __must_check

usb_find_int_in_endpoint(struct usb_host_interface *alt,

		struct usb_endpoint_descriptor **int_in)

{

	return usb_find_common_endpoints(alt, NULL, NULL, int_in, NULL);

}



static inline int __must_check

usb_find_int_out_endpoint(struct usb_host_interface *alt,

		struct usb_endpoint_descriptor **int_out)

{

	return usb_find_common_endpoints(alt, NULL, NULL, NULL, int_out);

}



/**

 * struct usb_interface - what usb device drivers talk to

 * @altsetting: array of interface structures, one for each alternate

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