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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: Abhilash Kesavan <a.kesavan@samsung.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
This commit is contained in:
Abhilash Kesavan 2014-07-05 05:50:58 +09:00 committed by Kukjin Kim
parent 5f534d10d2
commit 20fe6f98fa
2 changed files with 33 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

66
arch/arm/mach-exynos/mcpm-exynos.c
View File

@ -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);
exynos_cpu_power_up(cpunr);
} 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

2
arch/arm/mach-exynos/regs-pmu.h
View File

@ -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)