[PATCH V5 40/63] ST SPEAr13xx: Adding CPU hotplug support added for SMP platforms
From: Viresh Kumar <hidden>
Date: 2011-01-20 07:26:18
Subsystem:
arm port, the rest · Maintainers:
Russell King, Linus Torvalds
From: Deepak Sikri <redacted> Signed-off-by: Deepak Sikri <redacted> Signed-off-by: shiraz hashim <redacted> Signed-off-by: Viresh Kumar <redacted> --- arch/arm/mach-spear13xx/Makefile | 1 + arch/arm/mach-spear13xx/hotplug.c | 121 +++++++++++++++++++++++++++++++++++++ 2 files changed, 122 insertions(+), 0 deletions(-) create mode 100644 arch/arm/mach-spear13xx/hotplug.c
diff --git a/arch/arm/mach-spear13xx/Makefile b/arch/arm/mach-spear13xx/Makefile
index 0611278..42d378e 100644
--- a/arch/arm/mach-spear13xx/Makefile
+++ b/arch/arm/mach-spear13xx/Makefile@@ -5,6 +5,7 @@ # common files obj-y += spear13xx.o clock.o obj-$(CONFIG_SMP) += platsmp.o headsmp.o +obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o obj-$(CONFIG_LOCAL_TIMERS) += localtimer.o obj-$(CONFIG_PCIEPORTBUS) += pcie.o obj-$(CONFIG_PM) += pm.o sleep.o
diff --git a/arch/arm/mach-spear13xx/hotplug.c b/arch/arm/mach-spear13xx/hotplug.c
new file mode 100644
index 0000000..ee6b06d
--- /dev/null
+++ b/arch/arm/mach-spear13xx/hotplug.c@@ -0,0 +1,121 @@ +/* + * linux/arch/arm/mach-spear13xx/hotplug.c + * + * Copyright (C) 2010 ST Microelectronics Ltd. + * Deepak Sikri <deepak.sikri@st.com> + * + * based upon 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 <linux/kernel.h> +#include <linux/errno.h> +#include <linux/smp.h> +#include <asm/cacheflush.h> +#include <asm/system.h> + +extern volatile int pen_release; + +static inline void cpu_enter_lowpower(void) +{ + unsigned int v; + + flush_cache_all(); + asm volatile( + " mcr p15, 0, %1, c7, c5, 0\n" + " dsb\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, %2\n" + " mcr p15, 0, %0, c1, c0, 0\n" + : "=&r" (v) + : "r" (0), "Ir" (CR_C) + : "cc", "memory"); +} + +static 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, #0x20\n" + " mcr p15, 0, %0, c1, c0, 1\n" + : "=&r" (v) + : "Ir" (CR_C) + : "cc"); +} + +static inline void platform_do_lowpower(unsigned int cpu, int *spurious) +{ + for (;;) { + wfi(); + + 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 + * + * Just note it happening - when we're woken, we can report + * its occurrence. + */ + (*spurious)++; + } +} + +int platform_cpu_kill(unsigned int cpu) +{ + return 1; +} + +/* + * platform-specific code to shutdown a CPU + * + * Called with IRQs disabled + */ +void __cpuinit platform_cpu_die(unsigned int cpu) +{ + int spurious = 0; + + /* + * we're ready for shutdown now, so do it + */ + cpu_enter_lowpower(); + platform_do_lowpower(cpu, &spurious); + + /* + * bring this CPU back into the world of cache + * coherency, and then restore interrupts + */ + cpu_leave_lowpower(); + + if (spurious) + pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); +} + +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; +}
--
1.7.3.4