Merge branch 'master' into tk71

[mv-sheeva.git] / arch / arm / kernel / sched_clock.c

diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c
new file mode 100644 (file)
index 0000000..9a46370
--- /dev/null
+++ b/arch/arm/kernel/sched_clock.c
@@ -0,0 +1,74 @@
+/*
+ * sched_clock.c: support for extending counters to full 64-bit ns counter
+ *
+ * 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/clocksource.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/timer.h>
+
+#include <asm/sched_clock.h>
+
+static void sched_clock_poll(unsigned long wrap_ticks);
+static DEFINE_TIMER(sched_clock_timer, sched_clock_poll, 0, 0);
+static void (*sched_clock_update_fn)(void);
+
+static void sched_clock_poll(unsigned long wrap_ticks)
+{
+       mod_timer(&sched_clock_timer, round_jiffies(jiffies + wrap_ticks));
+       sched_clock_update_fn();
+}
+
+void __init init_sched_clock(struct clock_data *cd, void (*update)(void),
+       unsigned int clock_bits, unsigned long rate)
+{
+       unsigned long r, w;
+       u64 res, wrap;
+       char r_unit;
+
+       sched_clock_update_fn = update;
+
+       /* calculate the mult/shift to convert counter ticks to ns. */
+       clocks_calc_mult_shift(&cd->mult, &cd->shift, rate, NSEC_PER_SEC, 0);
+
+       r = rate;
+       if (r >= 4000000) {
+               r /= 1000000;
+               r_unit = 'M';
+       } else {
+               r /= 1000;
+               r_unit = 'k';
+       }
+
+       /* calculate how many ns until we wrap */
+       wrap = cyc_to_ns((1ULL << clock_bits) - 1, cd->mult, cd->shift);
+       do_div(wrap, NSEC_PER_MSEC);
+       w = wrap;
+
+       /* calculate the ns resolution of this counter */
+       res = cyc_to_ns(1ULL, cd->mult, cd->shift);
+       pr_info("sched_clock: %u bits at %lu%cHz, resolution %lluns, wraps every %lums\n",
+               clock_bits, r, r_unit, res, w);
+
+       /*
+        * Start the timer to keep sched_clock() properly updated and
+        * sets the initial epoch.
+        */
+       sched_clock_timer.data = msecs_to_jiffies(w - (w / 10));
+       update();
+
+       /*
+        * Ensure that sched_clock() starts off at 0ns
+        */
+       cd->epoch_ns = 0;
+}
+
+void __init sched_clock_postinit(void)
+{
+       sched_clock_poll(sched_clock_timer.data);
+}