[PATCH v2 5/6] msm: hotplug: support cpu hotplug on msm

Jeff Ohlstein
2010-12-08T04:28:43Z

Signed-off-by: Jeff Ohlstein <johlstei@codeaurora.org>
---
arch/arm/mach-msm/Makefile | 2 +
arch/arm/mach-msm/hotplug.c | 103 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 105 insertions(+), 0 deletions(-)
create mode 100644 arch/arm/mach-msm/hotplug.c

diff --git a/arch/arm/mach-msm/Makefile b/arch/arm/mach-msm/Makefile
index 34cd0a8..7a11b4a 100644
--- a/arch/arm/mach-msm/Makefile
+++ b/arch/arm/mach-msm/Makefile
@@ -20,6 +20,8 @@ obj-$(CONFIG_MSM_SMD) += smd.o smd_debug.o
obj-$(CONFIG_MSM_SMD) += last_radio_log.o
obj-$(CONFIG_MSM_SCM) += scm.o scm-boot.o

+obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
+
obj-$(CONFIG_MACH_TROUT) += board-trout.o board-trout-gpio.o board-trout-mmc.o devices-msm7x00.o
obj-$(CONFIG_MACH_HALIBUT) += board-halibut.o devices-msm7x00.o
obj-$(CONFIG_ARCH_MSM7X30) += board-msm7x30.o devices-msm7x30.o
diff --git a/arch/arm/mach-msm/hotplug.c b/arch/arm/mach-msm/hotplug.c
new file mode 100644
index 0000000..59c1dfa
--- /dev/null
+++ b/arch/arm/mach-msm/hotplug.c
@@ -0,0 +1,103 @@
+/*
+ * 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 <linux/completion.h>
+#include <linux/irq.h>
+
+#include <asm/cacheflush.h>
+
+#include <mach/smp.h>
+
+static DECLARE_COMPLETION(cpu_killed);
+
+static inline void cpu_enter_lowpower(void)
+{
+ flush_cache_all();
+}
+
+static inline void cpu_leave_lowpower(void)
+{
+ pen_release = -1;
+ smp_wmb();
+}
+
+static inline void platform_do_lowpower(unsigned int cpu)
+{
+ /* Just enter wfe for now. */
+ for (;;) {
+ asm("wfe");
+ if (pen_release == cpu) {
+ /*
+ * OK, proper wakeup, we're done
+ */
+ break;
+ }
+ smp_rmb();
+
+ /*
+ * 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
+ */
+ pr_debug("CPU%u: spurious wakeup call\n", cpu);
+ }
+}
+
+int platform_cpu_kill(unsigned int cpu)
+{
+ return wait_for_completion_timeout(&cpu_killed, 50000);
+}
+
+/*
+ * 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 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;
+}