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Commit 1ea60cf7 authored by Albin Tonnerre's avatar Albin Tonnerre Committed by Russell King
Browse files

ARM: 5778/1: AT91: Add cpuidle support 



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: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: default avatarAlbin Tonnerre <albin.tonnerre@free-electrons.com>
Acked-by: default avatarAndrew Victor <linux@maxim.org.za>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent cd3abf98

arch/arm/mach-at91/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/arm/mach-at91/cpuidle.c

0 → 100644
+94 −0
Original line number Diff line number Diff line 
/*

 * 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);

arch/arm/mach-at91/pm.c

+4 −58
Original line number Diff line number Diff line
@@ -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:

arch/arm/mach-at91/pm.h

0 → 100644
+67 −0
Original line number Diff line number Diff line 
#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