On Sun, Sep 17, 2017 at 06:45:20PM +0200, Martin Blumenstingl wrote:
> 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: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
Acked-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
> ---
> arch/arm/include/asm/smp_scu.h | 6 ++++++
> arch/arm/kernel/smp_scu.c | 18 +++++++++++++++++-
> 2 files changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/include/asm/smp_scu.h b/arch/arm/include/asm/smp_scu.h
> index 4c47bdfd4f61..1529d1ae2f8d 100644
> --- a/arch/arm/include/asm/smp_scu.h
> +++ b/arch/arm/include/asm/smp_scu.h
> @@ -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)
> diff --git a/arch/arm/kernel/smp_scu.c b/arch/arm/kernel/smp_scu.c
> index 1d549c16b5fc..c6b33074c393 100644
> --- a/arch/arm/kernel/smp_scu.c
> +++ b/arch/arm/kernel/smp_scu.c
> @@ -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;
> +}
> --
> 2.14.1
>
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