[Linux-ia64] multimedia timer interface

[Jesse Barnes <jbarnes@sgi.com>]

David, we talked awhile back about a generic timer interface that we
could use on SN platforms as a non-drifting replacement for the ITC.
I've taken a look at the Intel multimedia timer spec like you
suggested and came up with the following header file.  I've
implemented it on our system with some glibc changes to the hp timing
routines and things seem to work fine.  I'd like to get people's
comments on the ioctl interface though, because I'd like it to be
useful on other platforms as well.  Also, do you need me to resend the
salinfo patch I posted awhile back or are you just waiting for the SAL
spec to get updated?  I noticed it wasn't in the latest patch.

Thanks,
Jesse

/*
 * Intel Multimedia Timer device interface
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (c) 2001 Silicon Graphics, Inc.  All rights reserved.
 *
 * This file should define an interface compatible with the IA-PC Multimedia 
 * Timers Draft Specification (rev. 0.97) from Intel.  Note that some
 * hardware may not be able to safely export its registers to userspace, 
 * so the ioctl interface should support all necessary functionality.
 *
 * 11/01/01 - jbarnes - initial revision
 */

#ifndef _LINUX_MMTIMER_H

/* name of the device, usually in /dev */
#define MMTIMER_NAME "mmtimer"
#define MMTIMER_FULLNAME "/dev/mmtimer"
#define MMTIMER_DESC "IA-PC Multimedia Timer"
#define MMTIMER_VERSION "1.0"

/*
 * Used by the user to setup an alarm
 */
typedef struct mmtimer_alarm {
	int id;
	unsigned long value;
	int signo;
} mmtimer_alarm_t;

/*
 * Breakdown of the ioctl's available.  An 'optional' next to the command
 * indicates that supporting this command is optional, while 'required'
 * commands must be implemented if conformance is desired.
 *
 * MMTIMER_GETOFFSET - optional
 *   Should return the offset (relative to the start of the page where the 
 *   registers are mapped) for the counter in question.
 *
 * MMTIMER_GETRES - required
 *   The resolution of the clock in fempto (10E-15) seconds
 *
 * MMTIMER_GETFREQ - required
 *   Frequency of the clock in Hz
 *
 * MMTIMER_GETLEGACYIRQ - required
 *   Returns 1 if the device can route IRQs to legacy interrupt controllers
 *
 * MMTIMER_GETBITS - required
 *   Number of bits in the clock's counter
 *
 * MMTIMER_GETNUM - required
 *   Number of comparators available
 *
 * MMTIMER_MMAPAVAIL - required
 *   Returns 1 if the registers can be mmap'd into userspace
 *
 * MMTIMER_SETPERIODIC - required
 *   Sets the comparator in question to the value specified.
 *   The interrupt handler will add the value specified to the
 *   comparator after a match.
 *
 * MMTIMER_SETONESHOT - required
 *   Like the above, but the comparator is not updated after the match.
 *
 * MMTIMER_GETCOUNTER - required
 *   Gets the current value in the counter
 */
#define MMTIMER_IOCTL_BASE 'm'

#define MMTIMER_GETOFFSET _IO(MMTIMER_IOCTL_BASE, 0)
#define MMTIMER_GETRES _IOR(MMTIMER_IOCTL_BASE, 1, unsigned long)
#define MMTIMER_GETFREQ _IOR(MMTIMER_IOCTL_BASE, 2, unsigned long)
#define MMTIMER_GETLEGACYIRQ _IO(MMTIMER_IOCTL_BASE, 3)
#define MMTIMER_GETBITS _IO(MMTIMER_IOCTL_BASE, 4)
#define MMTIMER_GETNUM _IO(MMTIMER_IOCTL_BASE, 5)
#define MMTIMER_MMAPAVAIL _IO(MMTIMER_IOCTL_BASE, 6)
#define MMTIMER_SETPERIODIC _IOW(MMTIMER_IOCTL_BASE, 7, mmtimer_alarm_t)
#define MMTIMER_SETONESHOT _IOW(MMTIMER_IOCTL_BASE, 8, mmtimer_alarm_t)
#define MMTIMER_GETCOUNTER _IOR(MMTIMER_IOCTL_BASE, 9, unsigned long)

/*
 * An mmtimer verification program.  WARNINGs are ok, but ERRORs indicate
 * that the device doesn't fully support the interface defined here.
 */
#ifdef _MMTIMER_TEST_PROGRAM

#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <sys/ioctl.h>

#include "mmtimer.h"

int main(int argc, char *argv[])
{
	int result, fd;
	unsigned long val = 0;
	unsigned long i;

	if((fd = open("/dev/"MMTIMER_NAME, O_RDONLY)) = -1) {
		printf("failed to open /dev/%s", MMTIMER_NAME);
		return 1;
	}

        /*
         * How many comparators are there?
         */
        if((result = ioctl(fd, MMTIMER_GETNUM, 0)) != -ENOSYS)
                printf("comparators available: %d\n", result);
        else
                printf("ERROR: no comparators available\n");

        /*
         * Can we mmap in the counter?
         */
        if((result = ioctl(fd, MMTIMER_MMAPAVAIL, 0)) = 1) {
                printf("mmap available\n");
	        /* ... so try getting the offset for each clock */
	        if((result = ioctl(fd, MMTIMER_GETOFFSET, 0)) != -ENOSYS) 
	                printf("offset: %d\n", result);
	        else
	                printf("WARNING: offset unavailable for clock\n");
	}
        else
                printf("WARNING: mmap unavailable\n");

	/*
	 * Get the resolution in femptoseconds
	 */
        if((result = ioctl(fd, MMTIMER_GETRES, &val)) != -ENOSYS)
                printf("resolution: %ld femptoseconds\n", val);
        else
                printf("ERROR: failed to get resolution\n");

	/*
	 * Get the frequency in Hz
	 */
        if((result = ioctl(fd, MMTIMER_GETFREQ, &val)) != -ENOSYS)
		if(val < 10000000) /* less than 10 MHz? */
			printf("ERROR: frequency only %ld MHz, should be >= 10 MHz\n", val/1000000);
		else
			printf("frequency: %ld MHz\n", val/1000000);
        else
                printf("ERROR: failed to get frequency\n");

	/*
	 * Does this interface have legacy IRQ support?
	 */
        if((result = ioctl(fd, MMTIMER_GETLEGACYIRQ, 0)) = 1)
                printf("legacy IRQ support available\n");
        else
                printf("no legacy IRQ support available\n");

	/*
	 * How many bits in the counter?
	 */
        if((result = ioctl(fd, MMTIMER_GETBITS, 0)) != -ENOSYS)
                printf("bits in counter: %d\n", result);
        else
                printf("ERROR: can't get number of bits in counter\n");

	if((result = ioctl(fd, MMTIMER_GETCOUNTER, &val)) != -ENOSYS)
		printf("counter value: %ld\n", val);
	else
		printf("ERROR: can't get counter value\n");

	return 0;
}

#endif /* _MMTIMER_TEST_PROGRM */

#endif /* _LINUX_MMTIMER_H */