C6X: time management

Original port to early 2.6 kernel using TI COFF toolchain.
Brought up to date by Mark Salter <msalter@redhat.com>

Signed-off-by: Aurelien Jacquiot <a-jacquiot@ti.com>
Signed-off-by: Mark Salter <msalter@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>

arch/c6x/kernel/time.c

@@ -0,0 +1,65 @@
+/*
+ *  Port on Texas Instruments TMS320C6x architecture
+ *
+ *  Copyright (C) 2004, 2009, 2010, 2011 Texas Instruments Incorporated
+ *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/clocksource.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/param.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/timex.h>
+#include <linux/profile.h>
+
+#include <asm/timer64.h>
+
+static u32 sched_clock_multiplier;
+#define SCHED_CLOCK_SHIFT 16
+
+static cycle_t tsc_read(struct clocksource *cs)
+{
+	return get_cycles();
+}
+
+static struct clocksource clocksource_tsc = {
+	.name		= "timestamp",
+	.rating		= 300,
+	.read		= tsc_read,
+	.mask		= CLOCKSOURCE_MASK(64),
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+/*
+ * scheduler clock - returns current time in nanoseconds.
+ */
+u64 sched_clock(void)
+{
+	u64 tsc = get_cycles();
+
+	return (tsc * sched_clock_multiplier) >> SCHED_CLOCK_SHIFT;
+}
+
+void time_init(void)
+{
+	u64 tmp = (u64)NSEC_PER_SEC << SCHED_CLOCK_SHIFT;
+
+	do_div(tmp, c6x_core_freq);
+	sched_clock_multiplier = tmp;
+
+	clocksource_register_hz(&clocksource_tsc, c6x_core_freq);
+
+	/* write anything into TSCL to enable counting */
+	set_creg(TSCL, 0);
+
+	/* probe for timer64 event timer */
+	timer64_init();
+}