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

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,
};