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[ARM] 4811/1: RealView: clocksource support for the RealView platforms

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The patch updates the RealView platform code to use the generic
clocksource infrastructure for basic time keeping. Based on the
Versatile implementation by Kevin Hilman.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Catalin Marinas 2008-02-04 17:24:54 +01:00 committed by Russell King
parent ae9458d6a0
commit 85802afeb0
2 changed files with 32 additions and 42 deletions
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1
arch/arm/Kconfig
View file

@ -168,6 +168,7 @@ config ARCH_REALVIEW
bool "ARM Ltd. RealView family"
select ARM_AMBA
select ICST307
select GENERIC_TIME
help
This enables support for ARM Ltd RealView boards.

73
arch/arm/mach-realview/core.c
View file

@ -25,6 +25,7 @@
#include <linux/interrupt.h>
#include <linux/amba/bus.h>
#include <linux/amba/clcd.h>
#include <linux/clocksource.h>
#include <asm/system.h>
#include <asm/hardware.h>
@ -484,47 +485,6 @@ void realview_leds_event(led_event_t ledevt)
#define TICKS2USECS(x) ((x) / TICKS_PER_uSEC)
#endif
/*
* Returns number of ms since last clock interrupt. Note that interrupts
* will have been disabled by do_gettimeoffset()
*/
static unsigned long realview_gettimeoffset(void)
{
unsigned long ticks1, ticks2, status;
/*
* Get the current number of ticks. Note that there is a race
* condition between us reading the timer and checking for
* an interrupt. We get around this by ensuring that the
* counter has not reloaded between our two reads.
*/
ticks2 = readl(TIMER0_VA_BASE + TIMER_VALUE) & 0xffff;
do {
ticks1 = ticks2;
status = __raw_readl(__io_address(REALVIEW_GIC_DIST_BASE + GIC_DIST_PENDING_SET)
+ ((IRQ_TIMERINT0_1 >> 5) << 2));
ticks2 = readl(TIMER0_VA_BASE + TIMER_VALUE) & 0xffff;
} while (ticks2 > ticks1);
/*
* Number of ticks since last interrupt.
*/
ticks1 = TIMER_RELOAD - ticks2;
/*
* Interrupt pending? If so, we've reloaded once already.
*
* FIXME: Need to check this is effectively timer 0 that expires
*/
if (status & IRQMASK_TIMERINT0_1)
ticks1 += TIMER_RELOAD;
/*
* Convert the ticks to usecs
*/
return TICKS2USECS(ticks1);
}
/*
* IRQ handler for the timer
*/
@ -549,6 +509,34 @@ static struct irqaction realview_timer_irq = {
.handler = realview_timer_interrupt,
};
static cycle_t realview_get_cycles(void)
{
return ~readl(TIMER3_VA_BASE + TIMER_VALUE);
}
static struct clocksource clocksource_realview = {
.name = "timer3",
.rating = 200,
.read = realview_get_cycles,
.mask = CLOCKSOURCE_MASK(32),
.shift = 20,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static void __init realview_clocksource_init(void)
{
/* setup timer 0 as free-running clocksource */
writel(0, TIMER3_VA_BASE + TIMER_CTRL);
writel(0xffffffff, TIMER3_VA_BASE + TIMER_LOAD);
writel(0xffffffff, TIMER3_VA_BASE + TIMER_VALUE);
writel(TIMER_CTRL_32BIT | TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC,
TIMER3_VA_BASE + TIMER_CTRL);
clocksource_realview.mult =
clocksource_khz2mult(1000, clocksource_realview.shift);
clocksource_register(&clocksource_realview);
}
/*
* Set up timer interrupt, and return the current time in seconds.
*/
@ -585,9 +573,10 @@ static void __init realview_timer_init(void)
* Make irqs happen for the system timer
*/
setup_irq(IRQ_TIMERINT0_1, &realview_timer_irq);
realview_clocksource_init();
}
struct sys_timer realview_timer = {
.init = realview_timer_init,
.offset = realview_gettimeoffset,
};