[PATCH V3 41/63] ST SPEAr13xx: Adding CPU hotplug support added for SMP platforms

[Viresh Kumar]

From: Deepak Sikri <deepak.sikri at st.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 |  135 +++++++++++++++++++++++++++++++++++++
 2 files changed, 136 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 799eefa..869afb4 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 fsmc-nor.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..a3259bf
--- /dev/null
+++ b/arch/arm/mach-spear13xx/hotplug.c
@@ -0,0 +1,135 @@
+/*
+ * 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 <linux/completion.h>
+#include <asm/cacheflush.h>
+#include <asm/system.h>
+
+extern volatile int pen_release;
+
+static DECLARE_COMPLETION(cpu_killed);
+
+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, #0x04\n"
+	"	mcr	p15, 0, %0, c1, c0, 0\n"
+	  : "=&r" (v)
+	  : "r" (0)
+	  : "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, #0x04\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)
+	  :
+	  : "cc");
+}
+
+static inline void platform_do_lowpower(unsigned int cpu)
+{
+	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
+		 *
+		 * 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
+		 */
+#ifdef DEBUG
+		pr_crit("CPU%u: spurious wakeup call\n", cpu);
+#endif
+	}
+}
+
+int platform_cpu_kill(unsigned int cpu)
+{
+	return wait_for_completion_timeout(&cpu_killed, 5000);
+}
+
+/*
+ * platform-specific code to shutdown a CPU
+ *
+ * Called with IRQs disabled
+ */
+void __cpuinit platform_cpu_die(unsigned int cpu)
+{
+#ifdef DEBUG
+	unsigned int this_cpu = hard_smp_processor_id();
+
+	if (cpu != this_cpu) {
+		pr_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;
+}
-- 
1.7.2.2