From 97a63ecff4bd06da5d8feb8c0394a4d020f2d34d Mon Sep 17 00:00:00 2001 From: Russell King Date: Wed, 9 Nov 2005 13:50:57 +0000 Subject: [PATCH] [ARM SMP] Add CPU hotplug support for Realview MPcore Add platform specific parts for hotplug CPU support for the Realview board. Signed-off-by: Russell King --- arch/arm/mach-realview/Makefile | 1 + arch/arm/mach-realview/hotplug.c | 138 +++++++++++++++++++++++++++++++ 2 files changed, 139 insertions(+) create mode 100644 arch/arm/mach-realview/hotplug.c diff --git a/arch/arm/mach-realview/Makefile b/arch/arm/mach-realview/Makefile index a6a40dac26a9..36e76ba937fc 100644 --- a/arch/arm/mach-realview/Makefile +++ b/arch/arm/mach-realview/Makefile @@ -5,4 +5,5 @@ obj-y := core.o clock.o obj-$(CONFIG_MACH_REALVIEW_EB) += realview_eb.o obj-$(CONFIG_SMP) += platsmp.o headsmp.o +obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o obj-$(CONFIG_LOCAL_TIMERS) += localtimer.o diff --git a/arch/arm/mach-realview/hotplug.c b/arch/arm/mach-realview/hotplug.c new file mode 100644 index 000000000000..09748cbcd10e --- /dev/null +++ b/arch/arm/mach-realview/hotplug.c @@ -0,0 +1,138 @@ +/* + * linux/arch/arm/mach-realview/hotplug.c + * + * 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 +#include +#include +#include + +extern volatile int pen_release; + +static DECLARE_COMPLETION(cpu_killed); + +static inline void cpu_enter_lowpower(void) +{ + unsigned int v; + + asm volatile( "mcr p15, 0, %1, c7, c14, 0\n" + " 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, #0x20\n" + " mcr p15, 0, %0, c1, c0, 1\n" + " mrc p15, 0, %0, c1, c0, 0\n" + " bic %0, %0, #0x04\n" + " mcr p15, 0, %0, c1, c0, 0\n" + : "=&r" (v) + : "r" (0) + : "cc"); +} + +static inline void cpu_leave_lowpower(void) +{ + unsigned int v; + + asm volatile( "mrc p15, 0, %0, c1, c0, 0\n" + " orr %0, %0, #0x04\n" + " mcr p15, 0, %0, c1, c0, 0\n" + " mrc p15, 0, %0, c1, c0, 1\n" + " orr %0, %0, #0x20\n" + " mcr p15, 0, %0, c1, c0, 1\n" + : "=&r" (v) + : + : "cc"); +} + +static inline void platform_do_lowpower(unsigned int cpu) +{ + /* + * there is no power-control hardware on this platform, so all + * we can do is put the core into WFI; this is safe as the calling + * code will have already disabled interrupts + */ + for (;;) { + /* + * here's the WFI + */ + asm(".word 0xe320f003\n" + : + : + : "memory", "cc"); + + if (pen_release == cpu) { + /* + * OK, proper wakeup, we're done + */ + break; + } + + /* + * getting here, means that we have come out of WFI without + * having been woken up - this shouldn't happen + * + * The trouble is, letting people know about this is not really + * possible, since we are currently running incoherently, and + * therefore cannot safely call printk() or anything else + */ +#ifdef DEBUG + printk("CPU%u: spurious wakeup call\n", cpu); +#endif + } +} + +int platform_cpu_kill(unsigned int cpu) +{ + return wait_for_completion_timeout(&cpu_killed, 5000); +} + +/* + * platform-specific code to shutdown a CPU + * + * Called with IRQs disabled + */ +void platform_cpu_die(unsigned int cpu) +{ +#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(); + } +#endif + + printk(KERN_NOTICE "CPU%u: shutdown\n", cpu); + complete(&cpu_killed); + + /* + * we're ready for shutdown now, so do it + */ + cpu_enter_lowpower(); + platform_do_lowpower(cpu); + + /* + * bring this CPU back into the world of cache + * coherency, and then restore interrupts + */ + cpu_leave_lowpower(); +} + +int mach_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; +}