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Commit 20fe6f98 authored by Abhilash Kesavan's avatar Abhilash Kesavan Committed by Kukjin Kim
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ARM: EXYNOS: Support cluster power off on exynos5420/5800 



Turning off a cluster when all 4 cores of the cluster are powered off
saves power significantly. Powering off the A15 L2 alone gives around
100mW in savings. Add support for powering off the A15/A7 clusters on
exynos5420/5800.

The patch enables specific register bits which ensure that:
   - cluster L2 will be turned on before the first man is powered up.
   - last man will be turned off before the cluster L2 is turned off.
   - core is powered down before powering it up.

Remove the exynos_cluster_power_control function completely as we can
rely on the above mentioned bits rather than polling the cluster power
status register.

Signed-off-by: default avatarAbhilash Kesavan <a.kesavan@samsung.com>
Acked-by: default avatarNicolas Pitre <nico@linaro.org>
Tested-by: default avatarKevin Hilman <khilman@linaro.org>
Signed-off-by: default avatarKukjin Kim <kgene.kim@samsung.com>
parent 5f534d10

arch/arm/mach-exynos/mcpm-exynos.c

+31 −35
Original line number Diff line number Diff line
@@ -26,6 +26,10 @@ 
#define EXYNOS5420_CPUS_PER_CLUSTER	4

#define EXYNOS5420_NR_CLUSTERS		2



#define EXYNOS5420_ENABLE_AUTOMATIC_CORE_DOWN	BIT(9)

#define EXYNOS5420_USE_ARM_CORE_DOWN_STATE	BIT(29)

#define EXYNOS5420_USE_L2_COMMON_UP_STATE	BIT(30)



/*

 * The common v7_exit_coherency_flush API could not be used because of the

 * Erratum 799270 workaround. This macro is the same as the common one (in
@@ -73,36 +77,9 @@ cpu_use_count[EXYNOS5420_CPUS_PER_CLUSTER][EXYNOS5420_NR_CLUSTERS]; 


#define exynos_cluster_unused(cluster) !exynos_cluster_usecnt(cluster)



static int exynos_cluster_power_control(unsigned int cluster, int enable)

{

	unsigned int tries = 100;

	unsigned int val;



	if (enable) {

		exynos_cluster_power_up(cluster);

		val = S5P_CORE_LOCAL_PWR_EN;

	} else {

		exynos_cluster_power_down(cluster);

		val = 0;

	}



	/* Wait until cluster power control is applied */

	while (tries--) {

		if (exynos_cluster_power_state(cluster) == val)

			return 0;



		cpu_relax();

	}

	pr_debug("timed out waiting for cluster %u to power %s\n", cluster,

		enable ? "on" : "off");



	return -ETIMEDOUT;

}



static int exynos_power_up(unsigned int cpu, unsigned int cluster)

{

	unsigned int cpunr = cpu + (cluster * EXYNOS5420_CPUS_PER_CLUSTER);

	int err = 0;



	pr_debug("%s: cpu %u cluster %u\n", __func__, cpu, cluster);

	if (cpu >= EXYNOS5420_CPUS_PER_CLUSTER ||
@@ -126,12 +103,9 @@ static int exynos_power_up(unsigned int cpu, unsigned int cluster) 
		 * cores.

		 */

		if (was_cluster_down)

			err = exynos_cluster_power_control(cluster, 1);

			exynos_cluster_power_up(cluster);



		if (!err)

		exynos_cpu_power_up(cpunr);

		else

			exynos_cluster_power_control(cluster, 0);

	} else if (cpu_use_count[cpu][cluster] != 2) {

		/*

		 * The only possible values are:
@@ -147,7 +121,7 @@ static int exynos_power_up(unsigned int cpu, unsigned int cluster) 
	arch_spin_unlock(&exynos_mcpm_lock);

	local_irq_enable();



	return err;

	return 0;

}



/*
@@ -178,9 +152,10 @@ static void exynos_power_down(void) 
	if (cpu_use_count[cpu][cluster] == 0) {

		exynos_cpu_power_down(cpunr);



		if (exynos_cluster_unused(cluster))

			/* TODO: Turn off the cluster here to save power. */

		if (exynos_cluster_unused(cluster)) {

			exynos_cluster_power_down(cluster);

			last_man = true;

		}

	} else if (cpu_use_count[cpu][cluster] == 1) {

		/*

		 * A power_up request went ahead of us.
@@ -335,6 +310,7 @@ static int __init exynos_mcpm_init(void) 
{

	struct device_node *node;

	void __iomem *ns_sram_base_addr;

	unsigned int value, i;

	int ret;



	node = of_find_matching_node(NULL, exynos_dt_mcpm_match);
@@ -377,6 +353,26 @@ static int __init exynos_mcpm_init(void) 


	pr_info("Exynos MCPM support installed\n");



	/*

	 * On Exynos5420/5800 for the A15 and A7 clusters:

	 *

	 * EXYNOS5420_ENABLE_AUTOMATIC_CORE_DOWN ensures that all the cores

	 * in a cluster are turned off before turning off the cluster L2.

	 *

	 * EXYNOS5420_USE_ARM_CORE_DOWN_STATE ensures that a cores is powered

	 * off before waking it up.

	 *

	 * EXYNOS5420_USE_L2_COMMON_UP_STATE ensures that cluster L2 will be

	 * turned on before the first man is powered up.

	 */

	for (i = 0; i < EXYNOS5420_NR_CLUSTERS; i++) {

		value = __raw_readl(EXYNOS_COMMON_OPTION(i));

		value |= EXYNOS5420_ENABLE_AUTOMATIC_CORE_DOWN |

			 EXYNOS5420_USE_ARM_CORE_DOWN_STATE    |

			 EXYNOS5420_USE_L2_COMMON_UP_STATE;

		__raw_writel(value, EXYNOS_COMMON_OPTION(i));

	}



	/*

	 * U-Boot SPL is hardcoded to jump to the start of ns_sram_base_addr

	 * as part of secondary_cpu_start().  Let's redirect it to the

arch/arm/mach-exynos/regs-pmu.h

+2 −0
Original line number Diff line number Diff line
@@ -116,6 +116,8 @@ 
			(EXYNOS_ARM_COMMON_CONFIGURATION + (0x80 * (_nr)))

#define EXYNOS_COMMON_STATUS(_nr)		\

			(EXYNOS_COMMON_CONFIGURATION(_nr) + 0x4)

#define EXYNOS_COMMON_OPTION(_nr)		\

			(EXYNOS_COMMON_CONFIGURATION(_nr) + 0x8)



#define S5P_PAD_RET_MAUDIO_OPTION		S5P_PMUREG(0x3028)

#define S5P_PAD_RET_GPIO_OPTION			S5P_PMUREG(0x3108)