exynos5250: monotonic timer implementation (using MCT)

This implements the new monotonic timer API using the global
multi-core timer (MCT).

Change-Id: Id56249ff5d3e0f85808f5754954c83c0bc75f1c1
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: http://review.coreboot.org/3175
Reviewed-by: Aaron Durbin <adurbin@google.com>
Tested-by: build bot (Jenkins)

src/cpu/samsung/exynos5250/clk.h

@@ -585,4 +585,6 @@ int clock_get_mem_selection(enum ddr_mode *mem_type,
 		unsigned *frequency_mhz, unsigned *arm_freq,
 		enum mem_manuf *mem_manuf);
 
+uint64_t mct_raw_value(void);
+
 #endif

src/cpu/samsung/exynos5250/mct.c

@@ -88,7 +88,7 @@ static int enabled = 0;
 static struct mct_regs *const mct =
 	(struct mct_regs *)MCT_ADDRESS;
 
-static uint64_t timer_raw_value(void)
+uint64_t mct_raw_value(void)
 {
 	if (!enabled) {
 		writel(readl(&mct->g_tcon) | (0x1 << 8), &mct->g_tcon);
@@ -109,9 +109,8 @@ void timer_start(void)
 
 u32 timer_us(void)
 {
-	uint64_t raw = timer_raw_value();
+	uint64_t raw = mct_raw_value();
 	static uint32_t ticks_per_microsecond = MCT_HZ/1000000;
 	uint32_t usec = raw / ticks_per_microsecond;
 	return usec;
 }
-

src/cpu/samsung/exynos5250/monotonic_timer.c

@@ -0,0 +1,58 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2013 Google, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <stdint.h>
+#include <delay.h>
+#include <timer.h>
+#include <time.h>	/* TODO: deprecate in favor of monotonic timer stuff */
+
+#include "clk.h"
+
+static struct monotonic_counter {
+	int initialized;
+	struct mono_time time;
+	uint64_t last_value;
+} mono_counter;
+
+static const uint32_t clocks_per_usec = MCT_HZ/1000000;
+
+void timer_monotonic_get(struct mono_time *mt)
+{
+	uint64_t current_tick;
+	uint64_t usecs_elapsed;
+
+	if (!mono_counter.initialized) {
+		init_timer();
+		mono_counter.last_value = mct_raw_value();
+		mono_counter.initialized = 1;
+	}
+
+	current_tick = mct_raw_value();
+	usecs_elapsed = (current_tick - mono_counter.last_value) /
+							clocks_per_usec;
+
+	/* Update current time and tick values only if a full tick occurred. */
+	if (usecs_elapsed) {
+		mono_time_add_usecs(&mono_counter.time, usecs_elapsed);
+		mono_counter.last_value = current_tick;
+	}
+
+	/* Save result. */
+	*mt = mono_counter.time;
+}