Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

To decode a hex IOCTL code:

Most architecures use this generic format, but check
include/ARCH/ioctl.h for specifics, e.g. powerpc
uses 3 bits to encode read/write and 13 bits for size.

 bits    meaning
 31-30  00 - no parameters: uses _IO macro
        10 - read: _IOR
        01 - write: _IOW
        11 - read/write: _IOWR

 29-16  size of arguments

 15-8   ascii character supposedly
        unique to each driver

 7-0    function #


 So for example 0x82187201 is a read with arg length of 0x218,
character 'r' function 1. Grepping the source reveals this is:

#define VFAT_IOCTL_READDIR_BOTH         _IOR('r', 1, struct dirent [2])