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linux-next/arch/arm/mach-s3c64xx/cpuidle.c
Mark Brown 90ca2979ed ARM: S3C64XX: Reduce residency requirement for cpuidle WFI mode
Entering and leaving WFI is really cheap so there's no reason to have much
of a residency requirement for the state. Lower it to 1ms.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
2012-02-11 08:02:43 +09:00

92 lines
2.1 KiB
C

/* linux/arch/arm/mach-s3c64xx/cpuidle.c
*
* Copyright (c) 2011 Wolfson Microelectronics, plc
* Copyright (c) 2011 Samsung Electronics Co., Ltd.
* http://www.samsung.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
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/cpuidle.h>
#include <linux/io.h>
#include <linux/export.h>
#include <linux/time.h>
#include <asm/proc-fns.h>
#include <mach/map.h>
#include <mach/regs-sys.h>
#include <mach/regs-syscon-power.h>
static int s3c64xx_enter_idle(struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index)
{
struct timeval before, after;
unsigned long tmp;
int idle_time;
local_irq_disable();
do_gettimeofday(&before);
/* Setup PWRCFG to enter idle mode */
tmp = __raw_readl(S3C64XX_PWR_CFG);
tmp &= ~S3C64XX_PWRCFG_CFG_WFI_MASK;
tmp |= S3C64XX_PWRCFG_CFG_WFI_IDLE;
__raw_writel(tmp, S3C64XX_PWR_CFG);
cpu_do_idle();
do_gettimeofday(&after);
local_irq_enable();
idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
(after.tv_usec - before.tv_usec);
dev->last_residency = idle_time;
return index;
}
static struct cpuidle_state s3c64xx_cpuidle_set[] = {
[0] = {
.enter = s3c64xx_enter_idle,
.exit_latency = 1,
.target_residency = 1,
.flags = CPUIDLE_FLAG_TIME_VALID,
.name = "IDLE",
.desc = "System active, ARM gated",
},
};
static struct cpuidle_driver s3c64xx_cpuidle_driver = {
.name = "s3c64xx_cpuidle",
.owner = THIS_MODULE,
.state_count = ARRAY_SIZE(s3c64xx_cpuidle_set),
};
static struct cpuidle_device s3c64xx_cpuidle_device = {
.state_count = ARRAY_SIZE(s3c64xx_cpuidle_set),
};
static int __init s3c64xx_init_cpuidle(void)
{
int ret;
memcpy(s3c64xx_cpuidle_driver.states, s3c64xx_cpuidle_set,
sizeof(s3c64xx_cpuidle_set));
cpuidle_register_driver(&s3c64xx_cpuidle_driver);
ret = cpuidle_register_device(&s3c64xx_cpuidle_device);
if (ret) {
pr_err("Failed to register cpuidle device: %d\n", ret);
return ret;
}
return 0;
}
device_initcall(s3c64xx_init_cpuidle);