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Commit 936a4174 authored by Martin Blumenstingl's avatar Martin Blumenstingl Committed by Kevin Hilman
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ARM: smp_scu: allow the platform code to read the SCU CPU status 



On Amlogic Meson8 / Meson8m2 (both Cortex-A9) and Meson8b (Cortex-A5)
the CPU hotplug code needs to wait until the SCU status of the CPU that
is being taken offline is SCU_PM_POWEROFF.
Provide a utility function (which can be invoked for example from
.cpu_kill()) which allows reading the SCU status of a CPU.

While here, replace the magic number 0x3 with a preprocessor macro
(SCU_CPU_STATUS_MASK) so we don't have to duplicate this magic number in
the new function.

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 0606326e

arch/arm/include/asm/smp_scu.h

+6 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ static inline unsigned long scu_a9_get_base(void) 
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);

int scu_get_cpu_power_mode(void __iomem *scu_base, unsigned int logical_cpu);

#else

static inline unsigned int scu_get_core_count(void __iomem *scu_base)

{
@@ -42,6 +43,11 @@ static inline int scu_cpu_power_enable(void __iomem *scu_base, 
{

	return -EINVAL;

}

static inline int scu_get_cpu_power_mode(void __iomem *scu_base,

					 unsigned int logical_cpu)

{

	return -EINVAL;

}

#endif



#if defined(CONFIG_SMP) && defined(CONFIG_HAVE_ARM_SCU)

arch/arm/kernel/smp_scu.c

+17 −1
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#define SCU_STANDBY_ENABLE	(1 << 5)

#define SCU_CONFIG		0x04

#define SCU_CPU_STATUS		0x08

#define SCU_CPU_STATUS_MASK	GENMASK(1, 0)

#define SCU_INVALIDATE		0x0c

#define SCU_FPGA_REVISION	0x10
@@ -82,7 +83,8 @@ static int scu_set_power_mode_internal(void __iomem *scu_base, 
	if (mode > 3 || mode == 1 || cpu > 3)

		return -EINVAL;



	val = readb_relaxed(scu_base + SCU_CPU_STATUS + cpu) & ~0x03;

	val = readb_relaxed(scu_base + SCU_CPU_STATUS + cpu);

	val &= ~SCU_CPU_STATUS_MASK;

	val |= mode;

	writeb_relaxed(val, scu_base + SCU_CPU_STATUS + cpu);
@@ -109,3 +111,17 @@ int scu_cpu_power_enable(void __iomem *scu_base, unsigned int cpu) 
{

	return scu_set_power_mode_internal(scu_base, cpu, SCU_PM_NORMAL);

}



int scu_get_cpu_power_mode(void __iomem *scu_base, unsigned int logical_cpu)

{

	unsigned int val;

	int cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(logical_cpu), 0);



	if (cpu > 3)

		return -EINVAL;



	val = readb_relaxed(scu_base + SCU_CPU_STATUS + cpu);

	val &= SCU_CPU_STATUS_MASK;



	return val;

}