int mmtimer_ioctl (struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg);
Executes the command specified by cmd. Returns 0 for success, < 0 for failure.
MMTIMER_GETOFFSET - Should return the offset (relative to the start of the page where the registers are mapped) for the counter in question.
MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15) seconds
MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address specified by arg
MMTIMER_GETBITS - Returns the number of bits in the clock's counter
MMTIMER_MMAPAVAIL - Returns 1 if the registers can be mmap'd into userspace
MMTIMER_GETCOUNTER - Gets the current value in the counter and places it in the address specified by arg.