[PATCH] ppc32: support hotplug cpu on powermacs
This allows cpus to be off-lined on 32-bit SMP powermacs. When a cpu
is off-lined, it is put into sleep mode with interrupts disabled. It
can be on-lined again by asserting its soft-reset pin, which is
connected to a GPIO pin.
With this I can off-line the second cpu in my dual G4 powermac, which
means that I can then suspend the machine (the suspend/resume code
refuses to suspend if more than one cpu is online, and making it cope
with multiple cpus is surprisingly messy).
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/ppc/kernel/idle.c b/arch/ppc/kernel/idle.c
index 53547b6..fba29c8 100644
--- a/arch/ppc/kernel/idle.c
+++ b/arch/ppc/kernel/idle.c
@@ -22,6 +22,7 @@
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
+#include <linux/cpu.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
@@ -35,6 +36,7 @@
void default_idle(void)
{
void (*powersave)(void);
+ int cpu = smp_processor_id();
powersave = ppc_md.power_save;
@@ -44,7 +46,7 @@
#ifdef CONFIG_SMP
else {
set_thread_flag(TIF_POLLING_NRFLAG);
- while (!need_resched())
+ while (!need_resched() && !cpu_is_offline(cpu))
barrier();
clear_thread_flag(TIF_POLLING_NRFLAG);
}
@@ -52,6 +54,8 @@
}
if (need_resched())
schedule();
+ if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
+ cpu_die();
}
/*