package/usbreset/src/usbreset.c

   1 /* usbreset -- send a USB port reset to a USB device */
   2
   3 /*
   4
   5 http://marc.info/?l=linux-usb-users&m=116827193506484&w=2
   6
   7 and needs mounted usbfs filesystem
   8
   9         sudo mount -t usbfs none /proc/bus/usb
  10
  11 There is a way to suspend a USB device.  In order to use it,
  12 you must have a kernel with CONFIG_PM_SYSFS_DEPRECATED turned on.  To
  13 suspend a device, do (as root):
  14
  15         echo -n 2 >/sys/bus/usb/devices/.../power/state
  16
  17 where the "..." is the ID for your device.  To unsuspend, do the same
  18 thing but with a "0" instead of the "2" above.
  19
  20 Note that this mechanism is slated to be removed from the kernel within
  21 the next year.  Hopefully some other mechanism will take its place.
  22
  23 > To reset a
  24 > device?
  25
  26 Here's a program to do it.  You invoke it as either
  27
  28         usbreset /proc/bus/usb/BBB/DDD
  29 or
  30         usbreset /dev/usbB.D
  31
  32 depending on how your system is set up, where BBB and DDD are the bus and
  33 device address numbers.
  34
  35 Alan Stern
  36
  37 */
  38
  39 #include <stdio.h>
  40 #include <unistd.h>
  41 #include <fcntl.h>
  42 #include <errno.h>
  43 #include <sys/ioctl.h>
  44
  45 #include <linux/usbdevice_fs.h>
  46
  47
  48 int main(int argc, char **argv)
  49 {
  50         const char *filename;
  51         int fd;
  52         int rc;
  53
  54         if (argc != 2) {
  55                 fprintf(stderr, "Usage: usbreset device-filename\n");
  56                 return 1;
  57         }
  58         filename = argv[1];
  59
  60         fd = open(filename, O_WRONLY);
  61         if (fd < 0) {
  62                 perror("Error opening output file");
  63                 return 1;
  64         }
  65
  66         printf("Resetting USB device %s\n", filename);
  67         rc = ioctl(fd, USBDEVFS_RESET, 0);
  68         if (rc < 0) {
  69                 perror("Error in ioctl");
  70                 return 1;
  71         }
  72         printf("Reset successful\n");
  73
  74         close(fd);
  75         return 0;
  76 }