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Subject[PATCH] PPC64 pmac hotplug cpu
I found the following very handy for use as a reference platform when 
working on i386 hotplug cpu recently.

It's been tested on a G5 system with a cpu going on/offline every second
and make -j. I've also tried a number of config options to avoid compile
breakage.

Signed-off-by: Zwane Mwaikambo <zwane@arm.linux.org.uk>

Index: linux-2.6.10-mm3/arch/ppc64/Kconfig
===================================================================
RCS file: /home/cvsroot/linux-2.6.10-mm3/arch/ppc64/Kconfig,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 Kconfig
--- linux-2.6.10-mm3/arch/ppc64/Kconfig 13 Jan 2005 16:27:26 -0000 1.1.1.1
+++ linux-2.6.10-mm3/arch/ppc64/Kconfig 13 Jan 2005 16:35:39 -0000
@@ -305,7 +305,7 @@ source "drivers/pci/Kconfig"

config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs"
- depends on SMP && EXPERIMENTAL && PPC_PSERIES
+ depends on SMP && EXPERIMENTAL && (PPC_PSERIES || PPC_PMAC)
select HOTPLUG
---help---
Say Y here to be able to turn CPUs off and on.
Index: linux-2.6.10-mm3/arch/ppc64/kernel/idle.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.10-mm3/arch/ppc64/kernel/idle.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 idle.c
--- linux-2.6.10-mm3/arch/ppc64/kernel/idle.c 13 Jan 2005 16:27:26 -0000 1.1.1.1
+++ linux-2.6.10-mm3/arch/ppc64/kernel/idle.c 13 Jan 2005 16:34:24 -0000
@@ -364,7 +364,7 @@ int idle_setup(void)
}
}
#endif /* CONFIG_PPC_PSERIES */
-#ifndef CONFIG_PPC_ISERIES
+#if !defined(CONFIG_PPC_ISERIES) && !defined(CONFIG_HOTPLUG_CPU)
if (systemcfg->platform == PLATFORM_POWERMAC ||
systemcfg->platform == PLATFORM_MAPLE) {
printk(KERN_INFO "Using native/NAP idle loop\n");
Index: linux-2.6.10-mm3/arch/ppc64/kernel/irq.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.10-mm3/arch/ppc64/kernel/irq.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 irq.c
--- linux-2.6.10-mm3/arch/ppc64/kernel/irq.c 13 Jan 2005 16:27:26 -0000 1.1.1.1
+++ linux-2.6.10-mm3/arch/ppc64/kernel/irq.c 13 Jan 2005 23:51:29 -0000
@@ -479,3 +479,31 @@ EXPORT_SYMBOL(do_softirq);

#endif /* CONFIG_IRQSTACKS */

+#ifdef CONFIG_HOTPLUG_CPU
+void fixup_irqs(cpumask_t map)
+{
+ unsigned int irq;
+ static int warned;
+
+ for_each_irq(irq) {
+ cpumask_t mask;
+
+ if (irq_desc[irq].status & IRQ_PER_CPU)
+ continue;
+
+ cpus_and(mask, irq_affinity[irq], map);
+ if (any_online_cpu(mask) == NR_CPUS) {
+ printk("Breaking affinity for irq %i\n", irq);
+ mask = map;
+ }
+ if (irq_desc[irq].handler->set_affinity)
+ irq_desc[irq].handler->set_affinity(irq, mask);
+ else if (irq_desc[irq].action && !(warned++))
+ printk("Cannot set affinity for irq %i\n", irq);
+ }
+
+ local_irq_enable();
+ mdelay(1);
+ local_irq_disable();
+}
+#endif
Index: linux-2.6.10-mm3/arch/ppc64/kernel/pSeries_setup.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.10-mm3/arch/ppc64/kernel/pSeries_setup.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 pSeries_setup.c
--- linux-2.6.10-mm3/arch/ppc64/kernel/pSeries_setup.c 13 Jan 2005 16:27:27 -0000 1.1.1.1
+++ linux-2.6.10-mm3/arch/ppc64/kernel/pSeries_setup.c 13 Jan 2005 20:44:05 -0000
@@ -327,8 +327,9 @@ static void __init pSeries_discover_pic
}
}

-static void pSeries_cpu_die(void)
+static void pSeries_mach_cpu_die(void)
{
+ idle_task_exit();
local_irq_disable();
/* Some hardware requires clearing the CPPR, while other hardware does not
* it is safe either way
@@ -606,7 +607,7 @@ struct machdep_calls __initdata pSeries_
.power_off = rtas_power_off,
.halt = rtas_halt,
.panic = rtas_os_term,
- .cpu_die = pSeries_cpu_die,
+ .cpu_die = pSeries_mach_cpu_die,
.get_boot_time = pSeries_get_boot_time,
.get_rtc_time = pSeries_get_rtc_time,
.set_rtc_time = pSeries_set_rtc_time,
Index: linux-2.6.10-mm3/arch/ppc64/kernel/pmac.h
===================================================================
RCS file: /home/cvsroot/linux-2.6.10-mm3/arch/ppc64/kernel/pmac.h,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 pmac.h
--- linux-2.6.10-mm3/arch/ppc64/kernel/pmac.h 13 Jan 2005 16:27:27 -0000 1.1.1.1
+++ linux-2.6.10-mm3/arch/ppc64/kernel/pmac.h 13 Jan 2005 16:34:24 -0000
@@ -8,6 +8,9 @@
* Declaration for the various functions exported by the
* pmac_* files. Mostly for use by pmac_setup
*/
+#ifdef CONFIG_HOTPLUG_CPU
+DECLARE_PER_CPU(int, cpu_state);
+#endif

extern void pmac_get_boot_time(struct rtc_time *tm);
extern void pmac_get_rtc_time(struct rtc_time *tm);
Index: linux-2.6.10-mm3/arch/ppc64/kernel/pmac_setup.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.10-mm3/arch/ppc64/kernel/pmac_setup.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 pmac_setup.c
--- linux-2.6.10-mm3/arch/ppc64/kernel/pmac_setup.c 13 Jan 2005 16:27:27 -0000 1.1.1.1
+++ linux-2.6.10-mm3/arch/ppc64/kernel/pmac_setup.c 13 Jan 2005 16:34:24 -0000
@@ -229,6 +229,25 @@ void __pmac pmac_halt(void)
pmac_power_off();
}

+#ifdef CONFIG_HOTPLUG_CPU
+static void pmac_mach_cpu_die(void)
+{
+ unsigned int cpu;
+
+ local_irq_disable();
+ cpu = smp_processor_id();
+ printk(KERN_DEBUG "CPU%d offline\n", cpu);
+ __get_cpu_var(cpu_state) = CPU_DEAD;
+ wmb();
+ while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
+ cpu_relax();
+
+ flush_tlb_pending();
+ cpu_set(cpu, cpu_online_map);
+ local_irq_enable();
+}
+#endif
+
#ifdef CONFIG_BOOTX_TEXT
static int dummy_getc_poll(void)
{
@@ -455,5 +474,8 @@ struct machdep_calls __initdata pmac_md
.calibrate_decr = pmac_calibrate_decr,
.feature_call = pmac_do_feature_call,
.progress = pmac_progress,
- .check_legacy_ioport = pmac_check_legacy_ioport
+ .check_legacy_ioport = pmac_check_legacy_ioport,
+#ifdef CONFIG_HOTPLUG_CPU
+ .cpu_die = pmac_mach_cpu_die,
+#endif
};
Index: linux-2.6.10-mm3/arch/ppc64/kernel/pmac_smp.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.10-mm3/arch/ppc64/kernel/pmac_smp.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 pmac_smp.c
--- linux-2.6.10-mm3/arch/ppc64/kernel/pmac_smp.c 13 Jan 2005 16:27:27 -0000 1.1.1.1
+++ linux-2.6.10-mm3/arch/ppc64/kernel/pmac_smp.c 14 Jan 2005 00:32:10 -0000
@@ -35,6 +35,7 @@
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/irq.h>
+#include <linux/delay.h>

#include <asm/ptrace.h>
#include <asm/atomic.h>
@@ -296,6 +297,38 @@ static void __init smp_core99_setup_cpu(
}
}

+#ifdef CONFIG_HOTPLUG_CPU
+/* State of each CPU during hotplug phases */
+DEFINE_PER_CPU(int, cpu_state) = { 0 };
+
+static int pmac_cpu_disable(void)
+{
+ unsigned int cpu = smp_processor_id();
+
+ if (cpu == boot_cpuid)
+ return -EBUSY;
+
+ systemcfg->processorCount--;
+ cpu_clear(cpu, cpu_online_map);
+ fixup_irqs(cpu_online_map);
+ return 0;
+}
+
+static void pmac_cpu_die(unsigned int cpu)
+{
+ int i;
+
+ for (i = 0; i < 100; i++) {
+ rmb();
+ if (per_cpu(cpu_state, cpu) == CPU_DEAD)
+ return;
+ msleep(100);
+ }
+ printk(KERN_ERR "CPU%d didn't die...\n", cpu);
+}
+
+#endif
+
struct smp_ops_t core99_smp_ops __pmacdata = {
.message_pass = smp_mpic_message_pass,
.probe = smp_core99_probe,
@@ -308,4 +341,8 @@ struct smp_ops_t core99_smp_ops __pmacda
void __init pmac_setup_smp(void)
{
smp_ops = &core99_smp_ops;
+#ifdef CONFIG_HOTPLUG_CPU
+ smp_ops->cpu_disable = pmac_cpu_disable;
+ smp_ops->cpu_die = pmac_cpu_die;
+#endif
}
Index: linux-2.6.10-mm3/arch/ppc64/kernel/setup.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.10-mm3/arch/ppc64/kernel/setup.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 setup.c
--- linux-2.6.10-mm3/arch/ppc64/kernel/setup.c 13 Jan 2005 16:27:26 -0000 1.1.1.1
+++ linux-2.6.10-mm3/arch/ppc64/kernel/setup.c 13 Jan 2005 21:26:48 -0000
@@ -1345,9 +1345,6 @@ early_param("xmon", early_xmon);

void cpu_die(void)
{
- idle_task_exit();
if (ppc_md.cpu_die)
ppc_md.cpu_die();
- local_irq_disable();
- for (;;);
}
Index: linux-2.6.10-mm3/arch/ppc64/kernel/smp.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.10-mm3/arch/ppc64/kernel/smp.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 smp.c
--- linux-2.6.10-mm3/arch/ppc64/kernel/smp.c 13 Jan 2005 16:27:27 -0000 1.1.1.1
+++ linux-2.6.10-mm3/arch/ppc64/kernel/smp.c 14 Jan 2005 00:26:26 -0000
@@ -406,10 +406,39 @@ void __devinit smp_prepare_boot_cpu(void
current_set[boot_cpuid] = current->thread_info;
}

+#if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PPC_PMAC)
+#include "pmac.h"
+static int cpu_enable(unsigned int cpu)
+{
+ if (systemcfg->platform == PLATFORM_PSERIES_LPAR)
+ return -ENOSYS;
+
+ /* get the target out of it's holding state */
+ per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
+ wmb();
+
+ while (!cpu_online(cpu))
+ cpu_relax();
+
+ fixup_irqs(cpu_online_map);
+ /* counter the irq disable in fixup_irqs */
+ local_irq_enable();
+ return 0;
+}
+#else
+static int cpu_enable(unsigned int cpu)
+{
+ return -ENOSYS;
+}
+#endif
+
int __devinit __cpu_up(unsigned int cpu)
{
int c;

+ if (system_state == SYSTEM_RUNNING && !cpu_enable(cpu))
+ return 0;
+
/* At boot, don't bother with non-present cpus -JSCHOPP */
if (system_state < SYSTEM_RUNNING && !cpu_present(cpu))
return -ENOENT;
Index: linux-2.6.10-mm3/arch/ppc64/kernel/sysfs.c
===================================================================
RCS file: /home/cvsroot/linux-2.6.10-mm3/arch/ppc64/kernel/sysfs.c,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 sysfs.c
--- linux-2.6.10-mm3/arch/ppc64/kernel/sysfs.c 13 Jan 2005 16:27:27 -0000 1.1.1.1
+++ linux-2.6.10-mm3/arch/ppc64/kernel/sysfs.c 13 Jan 2005 16:36:23 -0000
@@ -18,7 +18,7 @@
#include <asm/systemcfg.h>
#include <asm/paca.h>
#include <asm/lppaca.h>
-
+#include <asm/machdep.h>

static DEFINE_PER_CPU(struct cpu, cpu_devices);

@@ -413,9 +413,7 @@ static int __init topology_init(void)
* CPU. For instance, the boot cpu might never be valid
* for hotplugging.
*/
-#ifdef CONFIG_HOTPLUG_CPU
- if (systemcfg->platform != PLATFORM_PSERIES_LPAR)
-#endif
+ if (!ppc_md.cpu_die)
c->no_control = 1;

if (cpu_online(cpu) || (c->no_control == 0)) {
Index: linux-2.6.10-mm3/include/asm-ppc64/smp.h
===================================================================
RCS file: /home/cvsroot/linux-2.6.10-mm3/include/asm-ppc64/smp.h,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 smp.h
--- linux-2.6.10-mm3/include/asm-ppc64/smp.h 13 Jan 2005 16:27:35 -0000 1.1.1.1
+++ linux-2.6.10-mm3/include/asm-ppc64/smp.h 13 Jan 2005 16:34:24 -0000
@@ -29,7 +29,7 @@
extern int boot_cpuid;
extern int boot_cpuid_phys;

-extern void cpu_die(void) __attribute__((noreturn));
+extern void cpu_die(void);

#ifdef CONFIG_SMP

@@ -37,6 +37,9 @@ extern void smp_send_debugger_break(int
struct pt_regs;
extern void smp_message_recv(int, struct pt_regs *);

+#ifdef CONFIG_HOTPLUG_CPU
+extern void fixup_irqs(cpumask_t map);
+#endif

#define smp_processor_id() (get_paca()->paca_index)
#define hard_smp_processor_id() (get_paca()->hw_cpu_id)
-
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