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ARM: 5778/1: AT91: Add cpuidle support

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This patch adds the support for cpuidle on AT91 SoCs, taken from the
cpuidle support in mach-kirkwood.
cpuidle needs sdram_selfrefresh_enable and _disable, so move their
definition to a separate header file instead of duplicating the code
already used in pm.c.

Tested-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Acked-by: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Albin Tonnerre 2009-11-01 18:40:50 +01:00 committed by Russell King
parent cd3abf98ae
commit 1ea60cf706
4 changed files with 166 additions and 58 deletions
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1
arch/arm/mach-at91/Makefile
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@ -77,6 +77,7 @@ obj-y += leds.o
# Power Management
obj-$(CONFIG_PM) += pm.o
obj-$(CONFIG_AT91_SLOW_CLOCK) += pm_slowclock.o
obj-$(CONFIG_CPU_IDLE) += cpuidle.o
ifeq ($(CONFIG_PM_DEBUG),y)
CFLAGS_pm.o += -DDEBUG

94
arch/arm/mach-at91/cpuidle.c Normal file
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@ -0,0 +1,94 @@
/*
* based on arch/arm/mach-kirkwood/cpuidle.c
*
* CPU idle support for AT91 SoC
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*
* The cpu idle uses wait-for-interrupt and RAM self refresh in order
* to implement two idle states -
* #1 wait-for-interrupt
* #2 wait-for-interrupt and RAM self refresh
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/cpuidle.h>
#include <asm/proc-fns.h>
#include <linux/io.h>
#include "pm.h"
#define AT91_MAX_STATES 2
static DEFINE_PER_CPU(struct cpuidle_device, at91_cpuidle_device);
static struct cpuidle_driver at91_idle_driver = {
.name = "at91_idle",
.owner = THIS_MODULE,
};
/* Actual code that puts the SoC in different idle states */
static int at91_enter_idle(struct cpuidle_device *dev,
struct cpuidle_state *state)
{
struct timeval before, after;
int idle_time;
u32 saved_lpr;
local_irq_disable();
do_gettimeofday(&before);
if (state == &dev->states[0])
/* Wait for interrupt state */
cpu_do_idle();
else if (state == &dev->states[1]) {
asm("b 1f; .align 5; 1:");
asm("mcr p15, 0, r0, c7, c10, 4"); /* drain write buffer */
saved_lpr = sdram_selfrefresh_enable();
cpu_do_idle();
sdram_selfrefresh_disable(saved_lpr);
}
do_gettimeofday(&after);
local_irq_enable();
idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
(after.tv_usec - before.tv_usec);
return idle_time;
}
/* Initialize CPU idle by registering the idle states */
static int at91_init_cpuidle(void)
{
struct cpuidle_device *device;
cpuidle_register_driver(&at91_idle_driver);
device = &per_cpu(at91_cpuidle_device, smp_processor_id());
device->state_count = AT91_MAX_STATES;
/* Wait for interrupt state */
device->states[0].enter = at91_enter_idle;
device->states[0].exit_latency = 1;
device->states[0].target_residency = 10000;
device->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
strcpy(device->states[0].name, "WFI");
strcpy(device->states[0].desc, "Wait for interrupt");
/* Wait for interrupt and RAM self refresh state */
device->states[1].enter = at91_enter_idle;
device->states[1].exit_latency = 10;
device->states[1].target_residency = 10000;
device->states[1].flags = CPUIDLE_FLAG_TIME_VALID;
strcpy(device->states[1].name, "RAM_SR");
strcpy(device->states[1].desc, "WFI and RAM Self Refresh");
if (cpuidle_register_device(device)) {
printk(KERN_ERR "at91_init_cpuidle: Failed registering\n");
return -EIO;
}
return 0;
}
device_initcall(at91_init_cpuidle);

62
arch/arm/mach-at91/pm.c
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@ -29,62 +29,7 @@
#include <mach/cpu.h>
#include "generic.h"
#ifdef CONFIG_ARCH_AT91RM9200
#include <mach/at91rm9200_mc.h>
/*
* The AT91RM9200 goes into self-refresh mode with this command, and will
* terminate self-refresh automatically on the next SDRAM access.
*/
#define sdram_selfrefresh_enable() at91_sys_write(AT91_SDRAMC_SRR, 1)
#define sdram_selfrefresh_disable() do {} while (0)
#elif defined(CONFIG_ARCH_AT91CAP9)
#include <mach/at91cap9_ddrsdr.h>
static u32 saved_lpr;
static inline void sdram_selfrefresh_enable(void)
{
u32 lpr;
saved_lpr = at91_sys_read(AT91_DDRSDRC_LPR);
lpr = saved_lpr & ~AT91_DDRSDRC_LPCB;
at91_sys_write(AT91_DDRSDRC_LPR, lpr | AT91_DDRSDRC_LPCB_SELF_REFRESH);
}
#define sdram_selfrefresh_disable() at91_sys_write(AT91_DDRSDRC_LPR, saved_lpr)
#else
#include <mach/at91sam9_sdramc.h>
#ifdef CONFIG_ARCH_AT91SAM9263
/*
* FIXME either or both the SDRAM controllers (EB0, EB1) might be in use;
* handle those cases both here and in the Suspend-To-RAM support.
*/
#define AT91_SDRAMC AT91_SDRAMC0
#warning Assuming EB1 SDRAM controller is *NOT* used
#endif
static u32 saved_lpr;
static inline void sdram_selfrefresh_enable(void)
{
u32 lpr;
saved_lpr = at91_sys_read(AT91_SDRAMC_LPR);
lpr = saved_lpr & ~AT91_SDRAMC_LPCB;
at91_sys_write(AT91_SDRAMC_LPR, lpr | AT91_SDRAMC_LPCB_SELF_REFRESH);
}
#define sdram_selfrefresh_disable() at91_sys_write(AT91_SDRAMC_LPR, saved_lpr)
#endif
#include "pm.h"
/*
* Show the reason for the previous system reset.
@ -260,6 +205,7 @@ extern u32 at91_slow_clock_sz;
static int at91_pm_enter(suspend_state_t state)
{
u32 saved_lpr;
at91_gpio_suspend();
at91_irq_suspend();
@ -315,9 +261,9 @@ static int at91_pm_enter(suspend_state_t state)
*/
asm("b 1f; .align 5; 1:");
asm("mcr p15, 0, r0, c7, c10, 4"); /* drain write buffer */
sdram_selfrefresh_enable();
saved_lpr = sdram_selfrefresh_enable();
asm("mcr p15, 0, r0, c7, c0, 4"); /* wait for interrupt */
sdram_selfrefresh_disable();
sdram_selfrefresh_disable(saved_lpr);
break;
case PM_SUSPEND_ON:

67
arch/arm/mach-at91/pm.h Normal file
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@ -0,0 +1,67 @@
#ifdef CONFIG_ARCH_AT91RM9200
#include <mach/at91rm9200_mc.h>
/*
* The AT91RM9200 goes into self-refresh mode with this command, and will
* terminate self-refresh automatically on the next SDRAM access.
*
* Self-refresh mode is exited as soon as a memory access is made, but we don't
* know for sure when that happens. However, we need to restore the low-power
* mode if it was enabled before going idle. Restoring low-power mode while
* still in self-refresh is "not recommended", but seems to work.
*/
static inline u32 sdram_selfrefresh_enable(void)
{
u32 saved_lpr = at91_sys_read(AT91_SDRAMC_LPR);
at91_sys_write(AT91_SDRAMC_LPR, 0);
at91_sys_write(AT91_SDRAMC_SRR, 1);
return saved_lpr;
}
#define sdram_selfrefresh_disable(saved_lpr) at91_sys_write(AT91_SDRAMC_LPR, saved_lpr)
#elif defined(CONFIG_ARCH_AT91CAP9)
#include <mach/at91cap9_ddrsdr.h>
static inline u32 sdram_selfrefresh_enable(void)
{
u32 saved_lpr, lpr;
saved_lpr = at91_sys_read(AT91_DDRSDRC_LPR);
lpr = saved_lpr & ~AT91_DDRSDRC_LPCB;
at91_sys_write(AT91_DDRSDRC_LPR, lpr | AT91_DDRSDRC_LPCB_SELF_REFRESH);
return saved_lpr;
}
#define sdram_selfrefresh_disable(saved_lpr) at91_sys_write(AT91_DDRSDRC_LPR, saved_lpr)
#else
#include <mach/at91sam9_sdramc.h>
#ifdef CONFIG_ARCH_AT91SAM9263
/*
* FIXME either or both the SDRAM controllers (EB0, EB1) might be in use;
* handle those cases both here and in the Suspend-To-RAM support.
*/
#define AT91_SDRAMC AT91_SDRAMC0
#warning Assuming EB1 SDRAM controller is *NOT* used
#endif
static inline u32 sdram_selfrefresh_enable(void)
{
u32 saved_lpr, lpr;
saved_lpr = at91_sys_read(AT91_SDRAMC_LPR);
lpr = saved_lpr & ~AT91_SDRAMC_LPCB;
at91_sys_write(AT91_SDRAMC_LPR, lpr | AT91_SDRAMC_LPCB_SELF_REFRESH);
return saved_lpr;
}
#define sdram_selfrefresh_disable(saved_lpr) at91_sys_write(AT91_SDRAMC_LPR, saved_lpr)
#endif