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Date: Thu, 10 Jan 2008 17:42:25 +1000
From: Greg Ungerer <gerg@...pgear.com>
To: linux-kernel@...r.kernel.org
Cc: gerg@...inux.org
Subject: [M68KNOMMU]: use GENERIC_TIME for ColdFire PIT timer
A first attempt at switching the m68knommu/ColdFire PIT timer to
use GENERIC_TIME.
Signed-of-by: Greg Ungerer <gerg@...inux.org>
--- arch/m68knommu/platform/5307/pit.c 10 Oct 2007 06:46:56 -0000 1.11
+++ arch/m68knommu/platform/5307/pit.c 10 Jan 2008 07:17:34 -0000
@@ -3,9 +3,10 @@
/*
* pit.c -- Freescale ColdFire PIT timer. Currently this type of
* hardware timer only exists in the Freescale ColdFire
- * 5270/5271, 5282 and other CPUs.
+ * 5270/5271, 5282 and 5208 CPUs. No doubt newer ColdFire
+ * family members will probably use it too.
*
- * Copyright (C) 1999-2007, Greg Ungerer (gerg@...pgear.com)
+ * Copyright (C) 1999-2008, Greg Ungerer (gerg@...pgear.com)
* Copyright (C) 2001-2004, SnapGear Inc. (www.snapgear.com)
*/
@@ -17,6 +18,7 @@
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
+#include <linux/clocksource.h>
#include <asm/machdep.h>
#include <asm/io.h>
#include <asm/coldfire.h>
@@ -28,35 +30,69 @@
/*
* By default use timer1 as the system clock timer.
*/
+#define FREQ ((MCF_CLK / 2) / 64)
#define TA(a) (MCF_IPSBAR + MCFPIT_BASE1 + (a))
#define INTC0 (MCF_IPSBAR + MCFICM_INTC0)
+static u32 pit_cycles_per_jiffy;
+static u32 pit_cnt;
+
/***************************************************************************/
-static irqreturn_t hw_tick(int irq, void *dummy)
+static irqreturn_t pit_tick(int irq, void *dummy)
{
- unsigned short pcsr;
+ u16 pcsr;
/* Reset the ColdFire timer */
pcsr = __raw_readw(TA(MCFPIT_PCSR));
__raw_writew(pcsr | MCFPIT_PCSR_PIF, TA(MCFPIT_PCSR));
+ pit_cnt += pit_cycles_per_jiffy;
return arch_timer_interrupt(irq, dummy);
}
/***************************************************************************/
-static struct irqaction coldfire_pit_irq = {
+static struct irqaction pit_irq = {
.name = "timer",
.flags = IRQF_DISABLED | IRQF_TIMER,
- .handler = hw_tick,
+ .handler = pit_tick,
};
+/***************************************************************************/
+
+static cycle_t pit_read_clk(void)
+{
+ unsigned long flags;
+ u32 pmr, pcntr, cycles;
+
+ local_irq_save(flags);
+ pmr = __raw_readw(TA(MCFPIT_PMR));
+ pcntr = __raw_readw(TA(MCFPIT_PCNTR));
+ cycles = pit_cnt;
+ local_irq_restore(flags);
+
+ return cycles + pmr - pcntr;
+}
+
+/***************************************************************************/
+
+static struct clocksource pit_clk = {
+ .name = "pit",
+ .rating = 250,
+ .read = pit_read_clk,
+ .shift = 20,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+/***************************************************************************/
+
void hw_timer_init(void)
{
u32 imr;
- setup_irq(MCFINT_VECBASE + MCFINT_PIT1, &coldfire_pit_irq);
+ setup_irq(MCFINT_VECBASE + MCFINT_PIT1, &pit_irq);
__raw_writeb(ICR_INTRCONF, INTC0 + MCFINTC_ICR0 + MCFINT_PIT1);
imr = __raw_readl(INTC0 + MCFPIT_IMR);
@@ -64,32 +100,14 @@
__raw_writel(imr, INTC0 + MCFPIT_IMR);
/* Set up PIT timer 1 as poll clock */
+ pit_cycles_per_jiffy = FREQ / HZ;
__raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
- __raw_writew(((MCF_CLK / 2) / 64) / HZ, TA(MCFPIT_PMR));
+ __raw_writew(pit_cycles_per_jiffy, TA(MCFPIT_PMR));
__raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE | MCFPIT_PCSR_OVW |
MCFPIT_PCSR_RLD | MCFPIT_PCSR_CLK64, TA(MCFPIT_PCSR));
-}
-
-/***************************************************************************/
-
-unsigned long hw_timer_offset(void)
-{
- volatile unsigned long *ipr;
- unsigned long pmr, pcntr, offset;
-
- ipr = (volatile unsigned long *) (MCF_IPSBAR + MCFICM_INTC0 + MCFPIT_IMR);
-
- pmr = __raw_readw(TA(MCFPIT_PMR));
- pcntr = __raw_readw(TA(MCFPIT_PCNTR));
- /*
- * If we are still in the first half of the upcount and a
- * timer interupt is pending, then add on a ticks worth of time.
- */
- offset = ((pmr - pcntr) * (1000000 / HZ)) / pmr;
- if ((offset < (1000000 / HZ / 2)) && (*ipr & MCFPIT_IMR_IBIT))
- offset += 1000000 / HZ;
- return offset;
+ pit_clk.mult = clocksource_hz2mult(FREQ, pit_clk.shift);
+ clocksource_register(&pit_clk);
}
/***************************************************************************/
--
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