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.rawat@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"); + + if ((id & 0xffffffff) == 0x411fc090) + ca9_enter_lowpower(); + else + pr_warn(KERN_WARNING "Unknown CPU type\n"); +}