source: mainline/uspace/lib/usbdev/src/altiface.c@ a6a5b25

/*
 * Copyright (c) 2011 Vojtech Horky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup libusbdev
 * @{
 */
/** @file
 * Handling alternate interface settings.
 */

#include <usb/dev/alternate_ifaces.h>
#include <usb/dev/dp.h>
#include <malloc.h>
#include <errno.h>
#include <assert.h>

/** Count number of alternate settings of a interface.
 *
 * @param config_descr Full configuration descriptor.
 * @param config_descr_size Size of @p config_descr in bytes.
 * @param interface_no Interface number.
 * @return Number of alternate interfaces for @p interface_no interface.
 */
size_t usb_interface_count_alternates(const uint8_t *config_descr,
    size_t config_descr_size, uint8_t interface_no)
{
        assert(config_descr != NULL);
        assert(config_descr_size > 0);

        const usb_dp_parser_t dp_parser = {
                .nesting = usb_dp_standard_descriptor_nesting
        };
        const usb_dp_parser_data_t dp_data = {
                .data = config_descr,
                .size = config_descr_size,
                .arg = NULL
        };

        size_t alternate_count = 0;

        const void *iface_ptr =
            usb_dp_get_nested_descriptor(&dp_parser, &dp_data, config_descr);
        while (iface_ptr != NULL) {
                const usb_standard_interface_descriptor_t *iface = iface_ptr;
                if (iface->descriptor_type == USB_DESCTYPE_INTERFACE
                    && iface->interface_number == interface_no) {
                        ++alternate_count;
                }
                iface_ptr = usb_dp_get_sibling_descriptor(&dp_parser, &dp_data,
                    config_descr, iface_ptr);
        }

        return alternate_count;
}

/** Initialize alternate interface representation structure.
 *
 * @param[in] alternates Pointer to allocated structure.
 * @param[in] config_descr Configuration descriptor.
 * @param[in] config_descr_size Size of configuration descriptor.
 * @param[in] interface_number Interface number.
 * @return Error code.
 */
int usb_alternate_interfaces_init(usb_alternate_interfaces_t *alternates,
    const uint8_t *config_descr, size_t config_descr_size, int interface_number)
{
        assert(alternates != NULL);
        assert(config_descr != NULL);
        assert(config_descr_size > 0);

        alternates->alternatives = NULL;
        alternates->alternative_count = 0;
        alternates->current = 0;

        /* No interfaces. */
        if (interface_number < 0) {
                return EOK;
        }

        const size_t alt_count =usb_interface_count_alternates(config_descr,
            config_descr_size, interface_number);

        if (alt_count == 0) {
                return ENOENT;
        }

        usb_alternate_interface_descriptors_t *alts = calloc(alt_count,
            sizeof(usb_alternate_interface_descriptors_t));
        if (alts == NULL) {
                return ENOMEM;
        }

        const usb_dp_parser_t dp_parser = {
                .nesting = usb_dp_standard_descriptor_nesting
        };
        const usb_dp_parser_data_t dp_data = {
                .data = config_descr,
                .size = config_descr_size,
                .arg = NULL
        };


        const void *iface_ptr =
            usb_dp_get_nested_descriptor(&dp_parser, &dp_data, dp_data.data);

        usb_alternate_interface_descriptors_t *iterator = alts;
        for (; iface_ptr != NULL && iterator < &alts[alt_count]; ++iterator) {
                const usb_standard_interface_descriptor_t *iface = iface_ptr;

                if ((iface->descriptor_type != USB_DESCTYPE_INTERFACE)
                    || (iface->interface_number != interface_number)) {
                        /* This is not a valid alternate interface descriptor
                         * for interface with number == interface_number. */
                        iface_ptr = usb_dp_get_sibling_descriptor(&dp_parser,
                            &dp_data, dp_data.data, iface_ptr);
                        continue;
                }

                iterator->interface = iface;
                iterator->nested_descriptors = iface_ptr + sizeof(*iface);

                /* Find next interface to count size of nested descriptors. */
                iface_ptr = usb_dp_get_sibling_descriptor(&dp_parser, &dp_data,
                    dp_data.data, iface_ptr);

                const uint8_t *next = (iface_ptr == NULL) ?
                    dp_data.data + dp_data.size : iface_ptr;

                iterator->nested_descriptors_size =
                    next - iterator->nested_descriptors;
        }

        alternates->alternatives = alts;
        alternates->alternative_count = alt_count;

        return EOK;
}

/** Clean initialized structure.
 * @param instance structure do deinitialize.
 */
void usb_alternate_interfaces_deinit(usb_alternate_interfaces_t *instance)
{
        if (!instance)
                return;
        free(instance->alternatives);
        instance->alternatives = NULL;
}
/**
 * @}
 */