On Mon, May 20, 2013 at 3:33 PM, Sanjay Singh Rawat
<sanjay.rawat@linaro.org> wrote:
Add function which prepare arm processors to enter the low power for hotplug
functionality and handle the return path.
Signed-off-by: Sanjay Singh Rawat <sanjay.rawat@linaro.org>
---
arch/arm/include/asm/hotplug.h | 24 +++++++++++++++
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/cpuhotplug.c | 64 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 89 insertions(+)
create mode 100644 arch/arm/include/asm/hotplug.h
create mode 100644 arch/arm/kernel/cpuhotplug.c
diff --git a/arch/arm/include/asm/hotplug.h b/arch/arm/include/asm/hotplug.h
new file mode 100644
index 0000000..ae80f0e
--- /dev/null
+++ b/arch/arm/include/asm/hotplug.h
@@ -0,0 +1,24 @@
+/*
+ * arch/arm/include/asm/hotplug.h
+ *
+ * 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.
+ */
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+extern inline void cpu_enter_lowpower(void);
+extern inline void cpu_leave_lowpower(void);
+
+#else
+static inline void cpu_enter_lowpower(void)
+{
+ return -ENODEV;
+}
+static inline void cpu_leave_lowpower(void)
+{
+ return -ENODEV;
+}
+
+#endif
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 5f3338e..9bd370b 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -33,6 +33,7 @@ obj-$(CONFIG_ISA_DMA) += dma-isa.o
obj-$(CONFIG_PCI) += bios32.o isa.o
obj-$(CONFIG_ARM_CPU_SUSPEND) += sleep.o suspend.o
obj-$(CONFIG_SMP) += smp.o smp_tlb.o
+obj-$(CONFIG_HOTPLUG_CPU) += cpuhotplug.o
obj-$(CONFIG_HAVE_ARM_SCU) += smp_scu.o
obj-$(CONFIG_HAVE_ARM_TWD) += smp_twd.o
obj-$(CONFIG_ARM_ARCH_TIMER) += arch_timer.o
diff --git a/arch/arm/kernel/cpuhotplug.c b/arch/arm/kernel/cpuhotplug.c
new file mode 100644
index 0000000..8651b96
--- /dev/null
+++ b/arch/arm/kernel/cpuhotplug.c
@@ -0,0 +1,64 @@
+/*
+ * 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 <asm/cp15.h>
+
+/*
+ * For Cortex-A9 processor
+ */
+static inline void ca9_enter_lowpower(void)
+{
+ unsigned int v;
+
+ asm volatile(
+ " 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, %3\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), "Ir" (0x40)
+ : "cc");
+}
+
+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, %2\n"
+ " mcr p15, 0, %0, c1, c0, 1\n"
+ : "=&r" (v)
+ : "Ir" (CR_C), "Ir" (0x40)
+ : "cc");
+}
+
+void cpu_enter_lowpower(void)
+{
+ int id = 0;
+
+ /* check the cpuid */
+ asm("mrc p15, 0, %0, c0, c0, 0" : "=r"(id) : : "cc");
do you want to call it every time? doesn't better to run it once and use the variable? or make function pointer and use it.
+
+ if ((id & 0xffffffff) == 0x411fc090)
+ ca9_enter_lowpower();
+ else
+ pr_warn(KERN_WARNING "Unknown CPU type\n");
+}
Thank you,
Kyungmin Park
--
1.7.9.5
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