[PATCH V6 07/10] ST SPEAr13xx: Adding CPU hotplug support added for SMP platforms
Viresh Kumar
viresh.kumar at st.com
Tue Mar 1 06:27:07 EST 2011
From: Deepak Sikri <deepak.sikri at st.com>
Reviewed-by: Stanley Miao <stanley.miao at windriver.com>
Signed-off-by: Deepak Sikri <deepak.sikri at st.com>
Signed-off-by: shiraz hashim <shiraz.hashim at st.com>
Signed-off-by: Viresh Kumar <viresh.kumar at st.com>
---
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 cb5ae9e..09b71e4 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
# spear1300 specific files
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 at 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;
+}
--
1.7.2.2
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