am7xxx-modeswitch.c

/* am7xxx-modeswitch - a simple usb-modeswitch for am7xxx devices
 *
 * Copyright (C) 2012-2014  Antonio Ospite <ao2@ao2.it>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <libusb.h>

#define AM7XXX_STORAGE_VID           0x1de1
#define AM7XXX_STORAGE_PID           0x1101
#define AM7XXX_STORAGE_CONFIGURATION 1
#define AM7XXX_STORAGE_INTERFACE     0
#define AM7XXX_STORAGE_OUT_EP        0x01

static unsigned char switch_command[] =
        "\x55\x53\x42\x43\x08\x70\x52\x89\x00\x00\x00\x00\x00\x00"
        "\x10\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";

int main(void)
{
        int ret;
        libusb_device_handle *usb_device;
        int current_configuration;
        unsigned int len;
        int transferred;

        ret = libusb_init(NULL);
        if (ret < 0) {
                fprintf(stderr, "libusb_init failed: %s\n",
                        libusb_error_name(ret));
                goto out;
        }

        libusb_set_debug(NULL, LIBUSB_LOG_LEVEL_INFO);

        usb_device = libusb_open_device_with_vid_pid(NULL,
                                                     AM7XXX_STORAGE_VID,
                                                     AM7XXX_STORAGE_PID);
        if (usb_device == NULL) {
                fprintf(stderr, "libusb_open failed: %s\n", strerror(errno));
                ret = -errno;
                goto out;
        }

        current_configuration = -1;
        ret = libusb_get_configuration(usb_device, &current_configuration);
        if (ret < 0) {
                fprintf(stderr, "libusb_get_configuration failed: %s\n",
                        libusb_error_name(ret));
                goto out_libusb_close;
        }

        if (current_configuration != AM7XXX_STORAGE_CONFIGURATION) {
                ret = libusb_set_configuration(usb_device,
                                               AM7XXX_STORAGE_CONFIGURATION);
                if (ret < 0) {
                        fprintf(stderr, "libusb_set_configuration failed: %s\n",
                                libusb_error_name(ret));
                        fprintf(stderr, "Cannot set configuration %d\n",
                                AM7XXX_STORAGE_CONFIGURATION);
                        goto out_libusb_close;
                }
        }

        libusb_set_auto_detach_kernel_driver(usb_device, 1);

        ret = libusb_claim_interface(usb_device, AM7XXX_STORAGE_INTERFACE);
        if (ret < 0) {
                fprintf(stderr, "libusb_claim_interface failed: %s\n",
                        libusb_error_name(ret));
                fprintf(stderr, "Cannot claim interface %d\n",
                        AM7XXX_STORAGE_INTERFACE);
                goto out_libusb_close;
        }

        /* Checking that the configuration has not changed, as suggested in
         * http://libusb.sourceforge.net/api-1.0/caveats.html
         */
        current_configuration = -1;
        ret = libusb_get_configuration(usb_device, &current_configuration);
        if (ret < 0) {
                fprintf(stderr, "libusb_get_configuration after claim failed: %s\n",
                        libusb_error_name(ret));
                goto out_libusb_release_interface;
        }

        if (current_configuration != AM7XXX_STORAGE_CONFIGURATION) {
                fprintf(stderr, "libusb configuration changed (expected: %d, current: %d\n",
                        AM7XXX_STORAGE_CONFIGURATION, current_configuration);
                ret = -EINVAL;
                goto out_libusb_release_interface;
        }

        len = sizeof(switch_command);

        transferred = 0;
        ret = libusb_bulk_transfer(usb_device, AM7XXX_STORAGE_OUT_EP,
                                   switch_command, len, &transferred, 0);
        if (ret != 0 || (unsigned int)transferred != len) {
                fprintf(stderr, "ret: %d\ttransferred: %d (expected %u)\n",
                      ret, transferred, len);
                goto out_libusb_release_interface;
        }

        fprintf(stderr, "OK, command sent!\n");

out_libusb_release_interface:
        libusb_release_interface(usb_device, AM7XXX_STORAGE_INTERFACE);
out_libusb_close:
        libusb_close(usb_device);
        usb_device = NULL;
out:
        libusb_exit(NULL);
        return ret;
}