This patch extracts the common code of the cpu hotplug feature across arm platforms. The goal is to only keep the specific stuff of the platform in the sub-architecture. I have created a hotplug.c file in the arm/common directory after studying the cpu hotplug code of omap2, realview, s5pv310, ux500 and tegra. I have extracted 3 main platform dependent functions: -platform_enter_lowpower which prepares the platform for low power. -platform_do_lowpower on which the cpu will loop until it becomes really plugged (spurious wake up). This function must returned the cpu Id in order to leave the unplug state. -platform_leave_lowpower which restore the platform context.

An ux500 patch is available which uses the common/hotplug.c code. This patch is quite short because the idle / power down functions are not yet upstreamed

Signed-off-by: Vincent Guittot vincent.guittot@linaro.org --- arch/arm/common/Kconfig | 4 ++ arch/arm/common/Makefile | 1 + arch/arm/common/hotplug.c | 85 ++++++++++++++++++++++++++++++++++++++++ arch/arm/include/asm/hotplug.h | 8 ++++ 4 files changed, 98 insertions(+), 0 deletions(-) create mode 100644 arch/arm/common/hotplug.c create mode 100644 arch/arm/include/asm/hotplug.h

diff --git a/arch/arm/common/Kconfig b/arch/arm/common/Kconfig index 0a34c81..b1c5f6b 100644 --- a/arch/arm/common/Kconfig +++ b/arch/arm/common/Kconfig @@ -41,3 +41,7 @@ config SHARP_SCOOP config COMMON_CLKDEV bool select HAVE_CLK + +config USE_COMMON_ARM_HOTPLUG + bool + depends on HOTPLUG_CPU diff --git a/arch/arm/common/Makefile b/arch/arm/common/Makefile index e6e8664..d8a66d7 100644 --- a/arch/arm/common/Makefile +++ b/arch/arm/common/Makefile @@ -17,3 +17,4 @@ obj-$(CONFIG_ARCH_IXP2000) += uengine.o obj-$(CONFIG_ARCH_IXP23XX) += uengine.o obj-$(CONFIG_PCI_HOST_ITE8152) += it8152.o obj-$(CONFIG_COMMON_CLKDEV) += clkdev.o +obj-$(CONFIG_USE_COMMON_ARM_HOTPLUG) += hotplug.o diff --git a/arch/arm/common/hotplug.c b/arch/arm/common/hotplug.c new file mode 100644 index 0000000..05f39f9 --- /dev/null +++ b/arch/arm/common/hotplug.c @@ -0,0 +1,85 @@ +/* + * Copyright (C) STMicroelectronics 2009 + * Copyright (C) ST-Ericsson SA 2010 + * + * License Terms: GNU General Public License v2 + * Based on ARM realview platform + * + * Author: Sundar Iyer sundar.iyer@stericsson.com + * Author: Vincent Guittot vincent.guittot@stericsson.com + * + */ +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/smp.h> +#include <linux/completion.h> + +#include <asm/cacheflush.h> +#include <asm/hotplug.h> + +static DECLARE_COMPLETION(cpu_killed); + +int platform_cpu_kill(unsigned int cpu) +{ + int err; + err = wait_for_completion_timeout(&cpu_killed, 5000); +#ifdef DEBUG + printk(KERN_INFO "platform_cpu_kill %d err %d\n", cpu, err); +#endif + return err; +} + +/* + * architecture-specific code to shutdown a CPU + * + * Called with IRQs disabled + */ +void platform_cpu_die(unsigned int cpu) +{ + unsigned long spurious = 0; +#ifdef DEBUG + unsigned int this_cpu = hard_smp_processor_id(); + + if (cpu != this_cpu) { + printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n", + this_cpu, cpu); + BUG(); + } + + printk(KERN_NOTICE "CPU%u: shutdown\n", cpu); +#endif + complete(&cpu_killed); + + flush_cache_all(); + wmb(); + + platform_enter_lowpower(cpu); + + for (;;) { + + if (platform_do_lowpower(cpu) == cpu) { + /* + * OK, proper wakeup, we're done + */ + break; + } + spurious++; + } + + platform_leave_lowpower(cpu); + +#ifdef DEBUG + printk(KERN_NOTICE "CPU%u: wake up (%lu spurious wake up)\n", + cpu, spurious); +#endif + +} + +int platform_cpu_disable(unsigned int cpu) +{ + /* + * we don't allow CPU 0 to be shutdown (it is still too special + * e.g. clock tick interrupts) + */ + return cpu == 0 ? -EPERM : 0; +} diff --git a/arch/arm/include/asm/hotplug.h b/arch/arm/include/asm/hotplug.h new file mode 100644 index 0000000..b38e737 --- /dev/null +++ b/arch/arm/include/asm/hotplug.h @@ -0,0 +1,8 @@ +#ifndef __ASM_MACH_HOTPLUG_H +#define __ASM_MACH_HOTPLUG_H + +extern void platform_enter_lowpower(unsigned int cpu); +extern int platform_do_lowpower(unsigned int cpu); +extern void platform_leave_lowpower(unsigned int cpu); + +#endif