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Commit 0606326e authored by Martin Blumenstingl's avatar Martin Blumenstingl Committed by Kevin Hilman
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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: default avatarMartin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: default avatarKevin Hilman <khilman@baylibre.com>
parent 9c52aaf7

arch/arm/include/asm/smp_scu.h

+6 −0
Original line number Diff line number Diff line
@@ -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)

arch/arm/kernel/smp_scu.c

+25 −10
Original line number Diff line number Diff line
@@ -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);

}