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authorRussell King <rmk@dyn-67.arm.linux.org.uk>2005-11-09 13:50:57 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2005-11-09 13:50:57 +0000
commit97a63ecff4bd06da5d8feb8c0394a4d020f2d34d (patch)
tree9211d6ea20eb0145bfe844c8b1ff474190bcba41 /arch/arm
parent2a98beb6390aef8fad85103ea25b3b1ace8015b5 (diff)
[ARM SMP] Add CPU hotplug support for Realview MPcore
Add platform specific parts for hotplug CPU support for the Realview board. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/mach-realview/Makefile1
-rw-r--r--arch/arm/mach-realview/hotplug.c138
2 files changed, 139 insertions, 0 deletions
diff --git a/arch/arm/mach-realview/Makefile b/arch/arm/mach-realview/Makefile
index a6a40dac26a..36e76ba937f 100644
--- a/arch/arm/mach-realview/Makefile
+++ b/arch/arm/mach-realview/Makefile
@@ -5,4 +5,5 @@
obj-y := core.o clock.o
obj-$(CONFIG_MACH_REALVIEW_EB) += realview_eb.o
obj-$(CONFIG_SMP) += platsmp.o headsmp.o
+obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
obj-$(CONFIG_LOCAL_TIMERS) += localtimer.o
diff --git a/arch/arm/mach-realview/hotplug.c b/arch/arm/mach-realview/hotplug.c
new file mode 100644
index 00000000000..09748cbcd10
--- /dev/null
+++ b/arch/arm/mach-realview/hotplug.c
@@ -0,0 +1,138 @@
+/*
+ * 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>
+
+extern volatile int pen_release;
+
+static DECLARE_COMPLETION(cpu_killed);
+
+static inline void cpu_enter_lowpower(void)
+{
+ unsigned int v;
+
+ asm volatile( "mcr p15, 0, %1, c7, c14, 0\n"
+ " 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, #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");
+}
+
+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)
+{
+ /*
+ * there is no power-control hardware on this platform, so all
+ * we can do is put the core into WFI; this is safe as the calling
+ * code will have already disabled interrupts
+ */
+ for (;;) {
+ /*
+ * here's the WFI
+ */
+ asm(".word 0xe320f003\n"
+ :
+ :
+ : "memory", "cc");
+
+ 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
+ printk("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 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 mach_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;
+}