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[ARM] 4374/3: i.MX/MX1 clock event source

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Support clock event source based on i.MX general purpose
timer in free running timer mode.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Pavel Pisa 2007-05-13 17:37:33 +01:00 committed by Russell King
parent b3e6a508ed
commit 89bba43514
2 changed files with 109 additions and 14 deletions
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2
arch/arm/Kconfig
View file

@ -242,6 +242,8 @@ config ARCH_H720X
config ARCH_IMX
bool "IMX"
select GENERIC_GPIO
select GENERIC_TIME
select GENERIC_CLOCKEVENTS
help
Support for Motorola's i.MX family of processors (MX1, MXL).

121
arch/arm/mach-imx/time.c
View file

@ -3,6 +3,7 @@
*
* Copyright (C) 2000-2001 Deep Blue Solutions
* Copyright (C) 2002 Shane Nay (shane@minirl.com)
* Copyright (C) 2006-2007 Pavel Pisa (ppisa@pikron.com)
*
* 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
@ -15,6 +16,7 @@
#include <linux/irq.h>
#include <linux/time.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <asm/hardware.h>
#include <asm/io.h>
@ -25,7 +27,8 @@
/* Use timer 1 as system timer */
#define TIMER_BASE IMX_TIM1_BASE
static unsigned long evt_diff;
static struct clock_event_device clockevent_imx;
static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED;
/*
* IRQ handler for the timer
@ -33,25 +36,20 @@ static unsigned long evt_diff;
static irqreturn_t
imx_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &clockevent_imx;
uint32_t tstat;
irqreturn_t ret = IRQ_NONE;
/* clear the interrupt */
tstat = IMX_TSTAT(TIMER_BASE);
IMX_TSTAT(TIMER_BASE) = 0;
if (tstat & TSTAT_COMP) {
do {
write_seqlock(&xtime_lock);
timer_tick();
write_sequnlock(&xtime_lock);
IMX_TCMP(TIMER_BASE) += evt_diff;
} while (unlikely((int32_t)(IMX_TCMP(TIMER_BASE)
- IMX_TCN(TIMER_BASE)) < 0));
evt->event_handler(evt);
ret = IRQ_HANDLED;
}
return IRQ_HANDLED;
return ret;
}
static struct irqaction imx_timer_irq = {
@ -70,10 +68,8 @@ static void __init imx_timer_hardware_init(void)
*/
IMX_TCTL(TIMER_BASE) = 0;
IMX_TPRER(TIMER_BASE) = 0;
IMX_TCMP(TIMER_BASE) = LATCH - 1;
IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_IRQEN | TCTL_TEN;
evt_diff = LATCH;
IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_TEN;
}
cycle_t imx_get_cycles(void)
@ -99,11 +95,108 @@ static int __init imx_clocksource_init(void)
return 0;
}
static int imx_set_next_event(unsigned long evt,
struct clock_event_device *unused)
{
unsigned long tcmp;
tcmp = IMX_TCN(TIMER_BASE) + evt;
IMX_TCMP(TIMER_BASE) = tcmp;
return (int32_t)(tcmp - IMX_TCN(TIMER_BASE)) < 0 ? -ETIME : 0;
}
#ifdef DEBUG
static const char *clock_event_mode_label[]={
[CLOCK_EVT_MODE_PERIODIC] = "CLOCK_EVT_MODE_PERIODIC",
[CLOCK_EVT_MODE_ONESHOT] = "CLOCK_EVT_MODE_ONESHOT",
[CLOCK_EVT_MODE_SHUTDOWN] = "CLOCK_EVT_MODE_SHUTDOWN",
[CLOCK_EVT_MODE_UNUSED] = "CLOCK_EVT_MODE_UNUSED"
};
#endif /*DEBUG*/
static void imx_set_mode(enum clock_event_mode mode, struct clock_event_device *evt)
{
unsigned long flags;
/*
* The timer interrupt generation is disabled at least
* for enough time to call imx_set_next_event()
*/
local_irq_save(flags);
/* Disable interrupt in GPT module */
IMX_TCTL(TIMER_BASE) &= ~TCTL_IRQEN;
if (mode != clockevent_mode) {
/* Set event time into far-far future */
IMX_TCMP(TIMER_BASE) = IMX_TCN(TIMER_BASE) - 3;
/* Clear pending interrupt */
IMX_TSTAT(TIMER_BASE) &= ~TSTAT_COMP;
}
#ifdef DEBUG
printk(KERN_INFO "imx_set_mode: changing mode from %s to %s\n",
clock_event_mode_label[clockevent_mode], clock_event_mode_label[mode]);
#endif /*DEBUG*/
/* Remember timer mode */
clockevent_mode = mode;
local_irq_restore(flags);
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
printk(KERN_ERR "imx_set_mode: Periodic mode is not supported for i.MX\n");
break;
case CLOCK_EVT_MODE_ONESHOT:
/*
* Do not put overhead of interrupt enable/disable into
* imx_set_next_event(), the core has about 4 minutes
* to call imx_set_next_event() or shutdown clock after
* mode switching
*/
local_irq_save(flags);
IMX_TCTL(TIMER_BASE) |= TCTL_IRQEN;
local_irq_restore(flags);
break;
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_UNUSED:
/* Left event sources disabled, no more interrupts appears */
break;
}
}
static struct clock_event_device clockevent_imx = {
.name = "imx_timer1",
.features = CLOCK_EVT_FEAT_ONESHOT,
.shift = 32,
.set_mode = imx_set_mode,
.set_next_event = imx_set_next_event,
.rating = 200,
};
static int __init imx_clockevent_init(void)
{
clockevent_imx.mult = div_sc(imx_get_perclk1(), NSEC_PER_SEC,
clockevent_imx.shift);
clockevent_imx.max_delta_ns =
clockevent_delta2ns(0xfffffffe, &clockevent_imx);
clockevent_imx.min_delta_ns =
clockevent_delta2ns(0xf, &clockevent_imx);
clockevent_imx.cpumask = cpumask_of_cpu(0);
clockevents_register_device(&clockevent_imx);
return 0;
}
static void __init imx_timer_init(void)
{
imx_timer_hardware_init();
imx_clocksource_init();
imx_clockevent_init();
/*
* Make irqs happen for the system timer
*/