Hi,
On Mon, May 20, 2013 at 3:33 PM, Sanjay Singh Rawat <sanjay.ra...@linaro.org
> wrote:
> Add function which prepare arm processors to enter the low power for
> hotplug
> functionality and handle the return path.
>
> Signed-off-by: Sanjay Singh Rawat <sanjay.ra...@linaro.org>
> ---
> arch/arm/include/asm/hotplug.h | 24 +++++++++++++++
> arch/arm/kernel/Makefile | 1 +
> arch/arm/kernel/cpuhotplug.c | 64
> ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 89 insertions(+)
> create mode 100644 arch/arm/include/asm/hotplug.h
> create mode 100644 arch/arm/kernel/cpuhotplug.c
>
> diff --git a/arch/arm/include/asm/hotplug.h
> b/arch/arm/include/asm/hotplug.h
> new file mode 100644
> index 0000000..ae80f0e
> --- /dev/null
> +++ b/arch/arm/include/asm/hotplug.h
> @@ -0,0 +1,24 @@
> +/*
> + * arch/arm/include/asm/hotplug.h
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#ifdef CONFIG_HOTPLUG_CPU
> +
> +extern inline void cpu_enter_lowpower(void);
> +extern inline void cpu_leave_lowpower(void);
> +
> +#else
> +static inline void cpu_enter_lowpower(void)
> +{
> + return -ENODEV;
> +}
> +static inline void cpu_leave_lowpower(void)
> +{
> + return -ENODEV;
> +}
> +
> +#endif
> diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
> index 5f3338e..9bd370b 100644
> --- a/arch/arm/kernel/Makefile
> +++ b/arch/arm/kernel/Makefile
> @@ -33,6 +33,7 @@ obj-$(CONFIG_ISA_DMA) += dma-isa.o
> obj-$(CONFIG_PCI) += bios32.o isa.o
> obj-$(CONFIG_ARM_CPU_SUSPEND) += sleep.o suspend.o
> obj-$(CONFIG_SMP) += smp.o smp_tlb.o
> +obj-$(CONFIG_HOTPLUG_CPU) += cpuhotplug.o
> obj-$(CONFIG_HAVE_ARM_SCU) += smp_scu.o
> obj-$(CONFIG_HAVE_ARM_TWD) += smp_twd.o
> obj-$(CONFIG_ARM_ARCH_TIMER) += arch_timer.o
> diff --git a/arch/arm/kernel/cpuhotplug.c b/arch/arm/kernel/cpuhotplug.c
> new file mode 100644
> index 0000000..8651b96
> --- /dev/null
> +++ b/arch/arm/kernel/cpuhotplug.c
> @@ -0,0 +1,64 @@
> +/*
> + * Copyright (C) 2002 ARM Ltd.
> + * All Rights Reserved
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/kernel.h>
> +#include <asm/cp15.h>
> +
> +/*
> + * For Cortex-A9 processor
> + */
> +static inline void ca9_enter_lowpower(void)
> +{
> + unsigned int v;
> +
> + asm volatile(
> + " mcr p15, 0, %1, c7, c5, 0\n"
> + " mcr p15, 0, %1, c7, c10, 4\n"
> + /*
> + * Turn off coherency
> + */
> + " mrc p15, 0, %0, c1, c0, 1\n"
> + " bic %0, %0, %3\n"
> + " mcr p15, 0, %0, c1, c0, 1\n"
> + " mrc p15, 0, %0, c1, c0, 0\n"
> + " bic %0, %0, %2\n"
> + " mcr p15, 0, %0, c1, c0, 0\n"
> + : "=&r" (v)
> + : "r" (0), "Ir" (CR_C), "Ir" (0x40)
> + : "cc");
> +}
> +
> +inline void cpu_leave_lowpower(void)
> +{
> + unsigned int v;
> +
> + asm volatile(
> + "mrc p15, 0, %0, c1, c0, 0\n"
> + " orr %0, %0, %1\n"
> + " mcr p15, 0, %0, c1, c0, 0\n"
> + " mrc p15, 0, %0, c1, c0, 1\n"
> + " orr %0, %0, %2\n"
> + " mcr p15, 0, %0, c1, c0, 1\n"
> + : "=&r" (v)
> + : "Ir" (CR_C), "Ir" (0x40)
> + : "cc");
> +}
> +
> +void cpu_enter_lowpower(void)
> +{
> + int id = 0;
> +
> + /* check the cpuid */
> + asm("mrc p15, 0, %0, c0, c0, 0" : "=r"(id) : : "cc");
>
do you want to call it every time? doesn't better to run it once and use
the variable? or make function pointer and use it.
> +
> + if ((id & 0xffffffff) == 0x411fc090)
> + ca9_enter_lowpower();
> + else
> + pr_warn(KERN_WARNING "Unknown CPU type\n");
> +}
>
Thank you,
Kyungmin Park
> --
> 1.7.9.5
>
>
> _______________________________________________
> linaro-dev mailing list
> linaro-dev@lists.linaro.org
> http://lists.linaro.org/mailman/listinfo/linaro-dev
>
_______________________________________________
linaro-dev mailing list
linaro-dev@lists.linaro.org
http://lists.linaro.org/mailman/listinfo/linaro-dev
