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@xxxxxxxxxx>
---
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@xxxxxxxxxxxxxx>
+ * Author: Vincent Guittot <vincent.guittot@xxxxxxxxxxxxxx>
+ *
+ */
+#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
--
1.7.0.4
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