[PATCH] device driver for the SGI system clock, mmtimer

SGI has been using this driver under Linux since 2001 but it was
never included in the upstream kernel. SuSE did include the patch for mmtimer
in SLES 9. The driver has been widely used for applications on the Altix
platform.

The timer hardware was designed around the multimedia timer specification by
Intel but to my knowledge only SGI has implemented that standard. The driver
was written by Jesse Barnes.

The second revision has interrupt support removed and was somewhat simplified
by removing one include file.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 140 insertions, 0 deletions

diff --git a/include/linux/mmtimer.h b/include/linux/mmtimer.h
new file mode 100644
index 000000000000..6b5855016a4e
--- /dev/null
+++ b/include/linux/mmtimer.h
@@ -0,0 +1,140 @@
+/*
+ * 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) 2001-2003 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
+ * 9/10/04 - Christoph Lameter - remove interrupt support
+ */
+
+#ifndef _LINUX_MMTIMER_H
+#define _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"
+
+/*
+ * 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 femto (10^-15) seconds
+ *
+ * MMTIMER_GETFREQ - required
+ *   Frequency of the clock in Hz
+ *
+ * MMTIMER_GETBITS - required
+ *   Number of bits in the clock's counter
+ *
+ * MMTIMER_MMAPAVAIL - required
+ *   Returns nonzero if the registers can be mmap'd into userspace, 0 otherwise
+ *
+ * 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_GETBITS _IO(MMTIMER_IOCTL_BASE, 4)
+#define MMTIMER_MMAPAVAIL _IO(MMTIMER_IOCTL_BASE, 6)
+#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;
+	}
+
+        /*
+         * 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 femtoseconds
+	 */
+        if((result = ioctl(fd, MMTIMER_GETRES, &val)) != -ENOSYS)
+                printf("resolution: %ld femtoseconds\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");
+
+	/*
+	 * 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 */