am7xxx-play: don't override return value when there is a usable one
[libam7xxx.git] / examples / am7xxx-modeswitch.c
1 /* am7xxx-modeswitch - a simple usb-modeswitch for am7xxx devices
2  *
3  * Copyright (C) 2012-2014  Antonio Ospite <ao2@ao2.it>
4  *
5  * This program is free software: you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation, either version 3 of the License, or
8  * (at your option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU General Public License for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
17  */
18
19 #include <stdio.h>
20 #include <string.h>
21 #include <errno.h>
22 #include <libusb.h>
23
24 #define AM7XXX_STORAGE_VID           0x1de1
25 #define AM7XXX_STORAGE_PID           0x1101
26 #define AM7XXX_STORAGE_CONFIGURATION 1
27 #define AM7XXX_STORAGE_INTERFACE     0
28 #define AM7XXX_STORAGE_OUT_EP        0x01
29
30 static unsigned char switch_command[] =
31         "\x55\x53\x42\x43\x08\x70\x52\x89\x00\x00\x00\x00\x00\x00"
32         "\x10\xff\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
33
34 int main(void)
35 {
36         int ret;
37         libusb_device_handle *usb_device;
38         int current_configuration;
39         unsigned int len;
40         int transferred;
41
42         ret = libusb_init(NULL);
43         if (ret < 0) {
44                 fprintf(stderr, "libusb_init failed: %s\n",
45                         libusb_error_name(ret));
46                 goto out;
47         }
48
49         libusb_set_debug(NULL, LIBUSB_LOG_LEVEL_INFO);
50
51         usb_device = libusb_open_device_with_vid_pid(NULL,
52                                                      AM7XXX_STORAGE_VID,
53                                                      AM7XXX_STORAGE_PID);
54         if (usb_device == NULL) {
55                 fprintf(stderr, "libusb_open failed: %s\n", strerror(errno));
56                 ret = -errno;
57                 goto out;
58         }
59
60         current_configuration = -1;
61         ret = libusb_get_configuration(usb_device, &current_configuration);
62         if (ret < 0) {
63                 fprintf(stderr, "libusb_get_configuration failed: %s\n",
64                         libusb_error_name(ret));
65                 goto out_libusb_close;
66         }
67
68         if (current_configuration != AM7XXX_STORAGE_CONFIGURATION) {
69                 ret = libusb_set_configuration(usb_device,
70                                                AM7XXX_STORAGE_CONFIGURATION);
71                 if (ret < 0) {
72                         fprintf(stderr, "libusb_set_configuration failed: %s\n",
73                                 libusb_error_name(ret));
74                         fprintf(stderr, "Cannot set configuration %d\n",
75                                 AM7XXX_STORAGE_CONFIGURATION);
76                         goto out_libusb_close;
77                 }
78         }
79
80         libusb_set_auto_detach_kernel_driver(usb_device, 1);
81
82         ret = libusb_claim_interface(usb_device, AM7XXX_STORAGE_INTERFACE);
83         if (ret < 0) {
84                 fprintf(stderr, "libusb_claim_interface failed: %s\n",
85                         libusb_error_name(ret));
86                 fprintf(stderr, "Cannot claim interface %d\n",
87                         AM7XXX_STORAGE_INTERFACE);
88                 goto out_libusb_close;
89         }
90
91         /* 
92          * Checking that the configuration has not changed, as suggested in
93          * http://libusb.sourceforge.net/api-1.0/caveats.html
94          */
95         current_configuration = -1;
96         ret = libusb_get_configuration(usb_device, &current_configuration);
97         if (ret < 0) {
98                 fprintf(stderr, "libusb_get_configuration after claim failed: %s\n",
99                         libusb_error_name(ret));
100                 goto out_libusb_release_interface;
101         }
102
103         if (current_configuration != AM7XXX_STORAGE_CONFIGURATION) {
104                 fprintf(stderr, "libusb configuration changed (expected: %d, current: %d)\n",
105                         AM7XXX_STORAGE_CONFIGURATION, current_configuration);
106                 ret = -EINVAL;
107                 goto out_libusb_release_interface;
108         }
109
110         len = sizeof(switch_command);
111
112         transferred = 0;
113         ret = libusb_bulk_transfer(usb_device, AM7XXX_STORAGE_OUT_EP,
114                                    switch_command, len, &transferred, 0);
115         if (ret != 0 || (unsigned int)transferred != len) {
116                 fprintf(stderr, "ret: %d\ttransferred: %d (expected %u)\n",
117                       ret, transferred, len);
118                 goto out_libusb_release_interface;
119         }
120
121         fprintf(stderr, "OK, command sent!\n");
122
123 out_libusb_release_interface:
124         libusb_release_interface(usb_device, AM7XXX_STORAGE_INTERFACE);
125 out_libusb_close:
126         libusb_close(usb_device);
127         usb_device = NULL;
128 out:
129         libusb_exit(NULL);
130         return ret;
131 }