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ARM: smp_scu: add a helper for powering on a specific CPU 

To boot the secondary CPUs on the Amlogic Meson8/Meson8m2 (Cortex-A9)
and Meson8b (Cortex-A5) SoCs we have to enable SCU mode SCU_PM_NORMAL,
otherwise the secondary cores will not start.
This patch adds a scu_cpu_power_enable() function which can be used to
enable SCU_PM_NORMAL for a specific (logical) CPU. An internal helper
function is also created, to avoid code duplication with
scu_power_mode().

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
hifive-unleashed-5.1
Martin Blumenstingl 2017-09-17 18:45:19 +02:00 committed by Kevin Hilman
parent 9c52aaf756
commit 0606326eff
2 changed files with 31 additions and 10 deletions
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6
arch/arm/include/asm/smp_scu.h
View File

@ -27,6 +27,7 @@ static inline unsigned long scu_a9_get_base(void)
#ifdef CONFIG_HAVE_ARM_SCU
unsigned int scu_get_core_count(void __iomem *);
int scu_power_mode(void __iomem *, unsigned int);
int scu_cpu_power_enable(void __iomem *, unsigned int);
#else
static inline unsigned int scu_get_core_count(void __iomem *scu_base)
{
@ -36,6 +37,11 @@ static inline int scu_power_mode(void __iomem *scu_base, unsigned int mode)
{
return -EINVAL;
}
static inline int scu_cpu_power_enable(void __iomem *scu_base,
unsigned int mode)
{
return -EINVAL;
}
#endif
#if defined(CONFIG_SMP) && defined(CONFIG_HAVE_ARM_SCU)

35
arch/arm/kernel/smp_scu.c
View File

@ -72,18 +72,12 @@ void scu_enable(void __iomem *scu_base)
}
#endif
/*
* Set the executing CPUs power mode as defined. This will be in
* preparation for it executing a WFI instruction.
*
* This function must be called with preemption disabled, and as it
* has the side effect of disabling coherency, caches must have been
* flushed. Interrupts must also have been disabled.
*/
int scu_power_mode(void __iomem *scu_base, unsigned int mode)
static int scu_set_power_mode_internal(void __iomem *scu_base,
unsigned int logical_cpu,
unsigned int mode)
{
unsigned int val;
int cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(smp_processor_id()), 0);
int cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(logical_cpu), 0);
if (mode > 3 || mode == 1 || cpu > 3)
return -EINVAL;
@ -94,3 +88,24 @@ int scu_power_mode(void __iomem *scu_base, unsigned int mode)
return 0;
}
/*
* Set the executing CPUs power mode as defined. This will be in
* preparation for it executing a WFI instruction.
*
* This function must be called with preemption disabled, and as it
* has the side effect of disabling coherency, caches must have been
* flushed. Interrupts must also have been disabled.
*/
int scu_power_mode(void __iomem *scu_base, unsigned int mode)
{
return scu_set_power_mode_internal(scu_base, smp_processor_id(), mode);
}
/*
* Set the given (logical) CPU's power mode to SCU_PM_NORMAL.
*/
int scu_cpu_power_enable(void __iomem *scu_base, unsigned int cpu)
{
return scu_set_power_mode_internal(scu_base, cpu, SCU_PM_NORMAL);
}