patch-2.4.19 linux-2.4.19/include/asm-ia64/sn/hires_clock.h

• Lines: 53
• Date: Fri Aug 2 17:39:45 2002
• Orig file: linux-2.4.18/include/asm-ia64/sn/hires_clock.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.18/include/asm-ia64/sn/hires_clock.h linux-2.4.19/include/asm-ia64/sn/hires_clock.h
@@ -0,0 +1,52 @@
+/*
+ * 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.
+ *
+ * SGI Hi Resolution Clock
+ *
+ * SGI SN platforms provide a high resolution clock that is
+ * synchronized across all nodes. The clock can be memory mapped
+ * and directly read from user space.
+ *
+ * Access to the clock is thru the following:
+ *       (error checking not shown)
+ *
+ * (Note: should library routines be provided to encapsulate this??)
+ *
+ *	int		fd:
+ *	volatile long	*clk;
+ *
+ *	fd = open (HIRES_FULLNAME, O_RDONLY);
+ *	clk = mmap(0, getpagesize(), PROT_READ, MAP_SHARED, fd, 0);
+ *	clk += ioctl(fd, HIRES_IOCQGETOFFSET, 0);
+ *
+ * At this point, clk is a pointer to the high resolution clock.
+ *
+ * The clock period can be obtained via:
+ *
+ *	long	picosec_per_tick;
+ *	picosec_per_tick = ioctl(fd, HIRES_IOCQGETPICOSEC, 0);
+ */
+
+#ifndef _ASM_IA64_SN_HIRES_CLOCK_H
+#define _ASM_IA64_SN_HIRES_CLOCK_H
+
+
+#define HIRES_BASENAME	"sgi_hires_clock"
+#define HIRES_FULLNAME  "/dev/sgi_hires_clock"
+#define HIRES_IOC_BASE	's'
+
+
+/* Get page offset of hires timer */
+#define HIRES_IOCQGETOFFSET	_IO( HIRES_IOC_BASE, 0 )
+
+/* get clock period in picoseconds per tick */
+#define HIRES_IOCQGETPICOSEC	_IO( HIRES_IOC_BASE, 1 )
+
+/* get number of significant bits in clock counter */
+#define HIRES_IOCQGETCLOCKBITS	_IO( HIRES_IOC_BASE, 2 )
+
+#endif /* _ASM_IA64_SN_HIRES_CLOCK_H */