Tegra2: Add microsecond timer function

These functions provide access to the high resolution microsecond timer
and tidy up a global variable in the code.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/arm/cpu/armv7/tegra2/timer.c

@@ -38,13 +38,12 @@
 #include <common.h>
 #include <asm/io.h>
 #include <asm/arch/tegra2.h>
+#include <asm/arch/timer.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
-struct timerus *timer_base = (struct timerus *)NV_PA_TMRUS_BASE;
-
 /* counter runs at 1MHz */
-#define TIMER_CLK	(1000000)
+#define TIMER_CLK	1000000
 #define TIMER_LOAD_VAL	0xffffffff
 
 /* timer without interrupts */
@@ -57,10 +56,10 @@ ulong get_timer(ulong base)
 void __udelay(unsigned long usec)
 {
 	long tmo = usec * (TIMER_CLK / 1000) / 1000;
-	unsigned long now, last = readl(&timer_base->cntr_1us);
+	unsigned long now, last = timer_get_us();
 
 	while (tmo > 0) {
-		now = readl(&timer_base->cntr_1us);
+		now = timer_get_us();
 		if (last > now) /* count up timer overflow */
 			tmo -= TIMER_LOAD_VAL - last + now;
 		else
@@ -74,7 +73,7 @@ ulong get_timer_masked(void)
 	ulong now;
 
 	/* current tick value */
-	now = readl(&timer_base->cntr_1us) / (TIMER_CLK / CONFIG_SYS_HZ);
+	now = timer_get_us() / (TIMER_CLK / CONFIG_SYS_HZ);
 
 	if (now >= gd->lastinc)	/* normal mode (non roll) */
 		/* move stamp forward with absolute diff ticks */
@@ -103,3 +102,10 @@ ulong get_tbclk(void)
 {
 	return CONFIG_SYS_HZ;
 }
+
+unsigned long timer_get_us(void)
+{
+	struct timerus *timer_base = (struct timerus *)NV_PA_TMRUS_BASE;
+
+	return readl(&timer_base->cntr_1us);
+}

arch/arm/include/asm/arch-tegra2/timer.h

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2011 The Chromium OS Authors.
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * 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., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+/* Tegra2 timer functions */
+
+#ifndef _TEGRA2_TIMER_H
+#define _TEGRA2_TIMER_H
+
+/* returns the current monotonic timer value in microseconds */
+unsigned long timer_get_us(void);
+
+#endif