1 files changed, 134 insertions, 0 deletions
diff --git a/arch/arm/cpu/arm920t/ep93xx/timer.c b/arch/arm/cpu/arm920t/ep93xx/timer.c
new file mode 100644
index 0000000..a3990a7
--- /dev/null
+++ b/arch/arm/cpu/arm920t/ep93xx/timer.c
@@ -0,0 +1,134 @@
+/*
+ * Cirrus Logic EP93xx timer support.
+ *
+ * Copyright (C) 2009, 2010 Matthias Kaehlcke <matthias@kaehlcke.net>
+ *
+ * Copyright (C) 2004, 2005
+ * Cory T. Tusar, Videon Central, Inc., <ctusar@videon-central.com>
+ *
+ * Based on the original intr.c Cirrus Logic EP93xx Rev D. interrupt support,
+ * author unknown.
+ *
+ * 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.,
+ * 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <common.h>
+#include <linux/types.h>
+#include <asm/arch/ep93xx.h>
+#include <asm/io.h>
+#include <div64.h>
+
+#define TIMER_CLKSEL	(1 << 3)
+#define TIMER_ENABLE	(1 << 7)
+
+#define TIMER_FREQ			508469		/* ticks / second */
+#define TIMER_MAX_VAL			0xFFFFFFFF
+
+static struct ep93xx_timer
+{
+	unsigned long long ticks;
+	unsigned long last_read;
+} timer;
+
+static inline unsigned long long usecs_to_ticks(unsigned long usecs)
+{
+	unsigned long long ticks = (unsigned long long)usecs * TIMER_FREQ;
+	do_div(ticks, 1000 * 1000);
+
+	return ticks;
+}
+
+static inline void read_timer(void)
+{
+	struct timer_regs *timer_regs = (struct timer_regs *)TIMER_BASE;
+	const unsigned long now = TIMER_MAX_VAL - readl(&timer_regs->timer3.value);
+
+	if (now >= timer.last_read)
+		timer.ticks += now - timer.last_read;
+	else
+		/* an overflow occurred */
+		timer.ticks += TIMER_MAX_VAL - timer.last_read + now;
+
+	timer.last_read = now;
+}
+
+/*
+ * Get the number of ticks (in CONFIG_SYS_HZ resolution)
+ */
+unsigned long long get_ticks(void)
+{
+	unsigned long long sys_ticks;
+
+	read_timer();
+
+	sys_ticks = timer.ticks * CONFIG_SYS_HZ;
+	do_div(sys_ticks, TIMER_FREQ);
+
+	return sys_ticks;
+}
+
+unsigned long get_timer_masked(void)
+{
+	return get_ticks();
+}
+
+unsigned long get_timer(unsigned long base)
+{
+	return get_timer_masked() - base;
+}
+
+void __udelay(unsigned long usec)
+{
+	unsigned long long target;
+
+	read_timer();
+
+	target = timer.ticks + usecs_to_ticks(usec);
+
+	while (timer.ticks < target)
+		read_timer();
+}
+
+int timer_init(void)
+{
+	struct timer_regs *timer_regs = (struct timer_regs *)TIMER_BASE;
+
+	/* use timer 3 with 508KHz and free running, not enabled now */
+	writel(TIMER_CLKSEL, &timer_regs->timer3.control);
+
+	/* set initial timer value */
+	writel(TIMER_MAX_VAL, &timer_regs->timer3.load);
+
+	/* Enable the timer */
+	writel(TIMER_ENABLE | TIMER_CLKSEL,
+		&timer_regs->timer3.control);
+
+	/* Reset the timer */
+	read_timer();
+	timer.ticks = 0;
+
+	return 0;
+}
+
+/*
+ * This function is derived from PowerPC code (timebase clock frequency).
+ * On ARM it returns the number of timer ticks per second.
+ */
+unsigned long get_tbclk(void)
+{
+	return CONFIG_SYS_HZ;
+}