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Message-Id: <200802010740.m117eLFQ022781@goober>
Date: Fri, 1 Feb 2008 17:40:21 +1000
From: Greg Ungerer <gerg@...pgear.com>
To: torvalds@...ux-foundation.org
Cc: gerg@...inux.org, linux-kernel@...r.kernel.org
Subject: [M68KNOMMU 02/07]: switch ColdFire PIT timer to use GENERIC_TIME
Switch the ColdFire PIT timer to using GENERIC_TIME.
Signed-off-by: Greg Ungerer <gerg@...inux.org>
---
diff -Naurp linux-2.6.24.1/arch/m68knommu/platform/coldfire/pit.c linux-2.6.24.2/arch/m68knommu/platform/coldfire/pit.c
--- linux-2.6.24.1/arch/m68knommu/platform/coldfire/pit.c 2008-01-25 08:58:37.000000000 +1000
+++ linux-2.6.24.2/arch/m68knommu/platform/coldfire/pit.c 2008-02-01 16:29:26.000000000 +1000
@@ -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>
@@ -28,70 +30,84 @@
/*
* 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,
};
-void hw_timer_init(void)
+/***************************************************************************/
+
+static cycle_t pit_read_clk(void)
{
- volatile unsigned char *icrp;
- volatile unsigned long *imrp;
+ unsigned long flags;
+ u32 cycles;
+ u16 pcntr;
- setup_irq(MCFINT_VECBASE + MCFINT_PIT1, &coldfire_pit_irq);
+ local_irq_save(flags);
+ pcntr = __raw_readw(TA(MCFPIT_PCNTR));
+ cycles = pit_cnt;
+ local_irq_restore(flags);
- icrp = (volatile unsigned char *) (MCF_IPSBAR + MCFICM_INTC0 +
- MCFINTC_ICR0 + MCFINT_PIT1);
- *icrp = ICR_INTRCONF;
+ return cycles + pit_cycles_per_jiffy - pcntr;
+}
- imrp = (volatile unsigned long *) (MCF_IPSBAR + MCFICM_INTC0 + MCFPIT_IMR);
- *imrp &= ~MCFPIT_IMR_IBIT;
+/***************************************************************************/
- /* Set up PIT timer 1 as poll clock */
- __raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
- __raw_writew(((MCF_CLK / 2) / 64) / HZ, TA(MCFPIT_PMR));
- __raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE | MCFPIT_PCSR_OVW |
- MCFPIT_PCSR_RLD | MCFPIT_PCSR_CLK64, TA(MCFPIT_PCSR));
-}
+static struct clocksource pit_clk = {
+ .name = "pit",
+ .rating = 250,
+ .read = pit_read_clk,
+ .shift = 20,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
/***************************************************************************/
-unsigned long hw_timer_offset(void)
+void hw_timer_init(void)
{
- volatile unsigned long *ipr;
- unsigned long pmr, pcntr, offset;
+ u32 imr;
- ipr = (volatile unsigned long *) (MCF_IPSBAR + MCFICM_INTC0 + MCFPIT_IMR);
+ setup_irq(MCFINT_VECBASE + MCFINT_PIT1, &pit_irq);
- pmr = __raw_readw(TA(MCFPIT_PMR));
- pcntr = __raw_readw(TA(MCFPIT_PCNTR));
+ __raw_writeb(ICR_INTRCONF, INTC0 + MCFINTC_ICR0 + MCFINT_PIT1);
+ imr = __raw_readl(INTC0 + MCFPIT_IMR);
+ imr &= ~MCFPIT_IMR_IBIT;
+ __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(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));
- /*
- * If we are still in the first half of the upcount and a
- * timer interrupt 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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