[ARM] 3949/2: AT91: SAM9 timer driver

Add support for the timer on the Atmel AT91SAM9261 and AT91SAM9260
processors.
Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-at91rm9200/Makefile

@@ -11,8 +11,8 @@ obj-$(CONFIG_PM)		+= pm.o
 
 # CPU-specific support
 obj-$(CONFIG_ARCH_AT91RM9200)	+= at91rm9200.o at91rm9200_time.o at91rm9200_devices.c
-obj-$(CONFIG_ARCH_AT91SAM9260)	+= at91sam9260.o
-obj-$(CONFIG_ARCH_AT91SAM9261)	+= at91sam9261.o
+obj-$(CONFIG_ARCH_AT91SAM9260)	+= at91sam9260.o at91sam926x_time.o
+obj-$(CONFIG_ARCH_AT91SAM9261)	+= at91sam9261.o at91sam926x_time.o
 
 # AT91RM9200 board-specific support
 obj-$(CONFIG_MACH_ONEARM)	+= board-1arm.o

arch/arm/mach-at91rm9200/at91sam926x_time.c

+/*
+ * linux/arch/arm/mach-at91rm9200/at91sam926x_time.c
+ *
+ * Copyright (C) 2005-2006 M. Amine SAYA, ATMEL Rousset, France
+ * Revision	 2005 M. Nicolas Diremdjian, ATMEL Rousset, France
+ *
+ * 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/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/mach/time.h>
+
+#include <asm/arch/at91_pit.h>
+
+
+#define PIT_CPIV(x)	((x) & AT91_PIT_CPIV)
+#define PIT_PICNT(x)	(((x) & AT91_PIT_PICNT) >> 20)
+
+/*
+ * Returns number of microseconds since last timer interrupt.  Note that interrupts
+ * will have been disabled by do_gettimeofday()
+ *  'LATCH' is hwclock ticks (see CLOCK_TICK_RATE in timex.h) per jiffy.
+ *  'tick' is usecs per jiffy (linux/timex.h).
+ */
+static unsigned long at91sam926x_gettimeoffset(void)
+{
+	unsigned long elapsed;
+	unsigned long t = at91_sys_read(AT91_PIT_PIIR);
+
+	elapsed = (PIT_PICNT(t) * LATCH) + PIT_CPIV(t);		/* hardware clock cycles */
+
+	return (unsigned long)(elapsed * 1000000) / LATCH;
+}
+
+/*
+ * IRQ handler for the timer.
+ */
+static irqreturn_t at91sam926x_timer_interrupt(int irq, void *dev_id)
+{
+	volatile long nr_ticks;
+
+	if (at91_sys_read(AT91_PIT_SR) & AT91_PIT_PITS) {	/* This is a shared interrupt */
+		write_seqlock(&xtime_lock);
+
+		/* Get number to ticks performed before interrupt and clear PIT interrupt */
+		nr_ticks = PIT_PICNT(at91_sys_read(AT91_PIT_PIVR));
+		do {
+			timer_tick();
+			nr_ticks--;
+		} while (nr_ticks);
+
+		write_sequnlock(&xtime_lock);
+		return IRQ_HANDLED;
+	} else
+		return IRQ_NONE;		/* not handled */
+}
+
+static struct irqaction at91sam926x_timer_irq = {
+	.name		= "at91_tick",
+	.flags		= IRQF_SHARED | IRQF_DISABLED | IRQF_TIMER,
+	.handler	= at91sam926x_timer_interrupt
+};
+
+void at91sam926x_timer_reset(void)
+{
+	/* Disable timer */
+	at91_sys_write(AT91_PIT_MR, 0);
+
+	/* Clear any pending interrupts */
+	(void) at91_sys_read(AT91_PIT_PIVR);
+
+	/* Set Period Interval timer and enable its interrupt */
+	at91_sys_write(AT91_PIT_MR, (LATCH & AT91_PIT_PIV) | AT91_PIT_PITIEN | AT91_PIT_PITEN);
+}
+
+/*
+ * Set up timer interrupt.
+ */
+void __init at91sam926x_timer_init(void)
+{
+	/* Initialize and enable the timer */
+	at91sam926x_timer_reset();
+
+	/* Make IRQs happen for the system timer. */
+	setup_irq(AT91_ID_SYS, &at91sam926x_timer_irq);
+}
+
+#ifdef CONFIG_PM
+static void at91sam926x_timer_suspend(void)
+{
+	/* Disable timer */
+	at91_sys_write(AT91_PIT_MR, 0);
+}
+#else
+#define at91sam926x_timer_suspend	NULL
+#endif
+
+struct sys_timer at91sam926x_timer = {
+	.init		= at91sam926x_timer_init,
+	.offset		= at91sam926x_gettimeoffset,
+	.suspend	= at91sam926x_timer_suspend,
+	.resume		= at91sam926x_timer_reset,
+};
+

include/asm-arm/arch-at91rm9200/at91_pit.h

+/*
+ * include/asm-arm/arch-at91rm9200/at91_pit.h
+ *
+ * Periodic Interval Timer (PIT) - System peripherals regsters.
+ * Based on AT91SAM9261 datasheet revision D.
+ *
+ * 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.
+ */
+
+#ifndef AT91_PIT_H
+#define AT91_PIT_H
+
+#define AT91_PIT_MR		(AT91_PIT + 0x00)	/* Mode Register */
+#define		AT91_PIT_PITIEN		(1 << 25)		/* Timer Interrupt Enable */
+#define		AT91_PIT_PITEN		(1 << 24)		/* Timer Enabled */
+#define		AT91_PIT_PIV		(0xfffff)		/* Periodic Interval Value */
+
+#define AT91_PIT_SR		(AT91_PIT + 0x04)	/* Status Register */
+#define		AT91_PIT_PITS		(1 << 0)		/* Timer Status */
+
+#define AT91_PIT_PIVR		(AT91_PIT + 0x08)	/* Periodic Interval Value Register */
+#define AT91_PIT_PIIR		(AT91_PIT + 0x0c)	/* Periodic Interval Image Register */
+#define		AT91_PIT_PICNT		(0xfff << 20)		/* Interval Counter */
+#define		AT91_PIT_CPIV		(0xfffff)		/* Inverval Value */
+
+#endif