6 files changed, 77 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index a703b9e9aeb9..d868a11c94a5 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -62,6 +62,21 @@ Description:	CPU topology files that describe kernel limits related to
                 See Documentation/cputopology.txt for more information.
 
 
+What:           /sys/devices/system/cpu/probe
+                /sys/devices/system/cpu/release
+Date:           November 2009
+Contact:        Linux kernel mailing list <linux-kernel@vger.kernel.org>
+Description:    Dynamic addition and removal of CPU's.  This is not hotplug
+                removal, this is meant complete removal/addition of the CPU
+                from the system.
+
+                probe: writes to this file will dynamically add a CPU to the
+                system.  Information written to the file to add CPU's is
+                architecture specific.
+
+                release: writes to this file dynamically remove a CPU from
+                the system.  Information writtento the file to remove CPU's
+                is architecture specific.
 
 What:           /sys/devices/system/cpu/cpu#/node
 Date:           October 2009
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 5dbd375a3f2a..0df57466e783 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -320,6 +320,10 @@ config HOTPLUG_CPU
 
           Say N if you are unsure.
 
+config ARCH_CPU_PROBE_RELEASE
+        def_bool y
+        depends on HOTPLUG_CPU
+
 config ARCH_ENABLE_MEMORY_HOTPLUG
         def_bool y
 
diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index 9efa2be78331..9f0fc9e6ce0d 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -266,6 +266,11 @@ struct machdep_calls {
         void (*suspend_disable_irqs)(void);
         void (*suspend_enable_irqs)(void);
 #endif
+
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
+        ssize_t (*cpu_probe)(const char *, size_t);
+        ssize_t (*cpu_release)(const char *, size_t);
+#endif
 };
 
 extern void e500_idle(void);
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index 956ab33fd73f..e235e52dc4fe 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -461,6 +461,25 @@ static void unregister_cpu_online(unsigned int cpu)
 
         cacheinfo_cpu_offline(cpu);
 }
+
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
+ssize_t arch_cpu_probe(const char *buf, size_t count)
+{
+        if (ppc_md.cpu_probe)
+                return ppc_md.cpu_probe(buf, count);
+
+        return -EINVAL;
+}
+
+ssize_t arch_cpu_release(const char *buf, size_t count)
+{
+        if (ppc_md.cpu_release)
+                return ppc_md.cpu_release(buf, count);
+
+        return -EINVAL;
+}
+#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
+
 #endif /* CONFIG_HOTPLUG_CPU */
 
 static int __cpuinit sysfs_cpu_notify(struct notifier_block *self,
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index e62a4ccea54d..7c03af7b84a9 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -72,6 +72,38 @@ void unregister_cpu(struct cpu *cpu)
         per_cpu(cpu_sys_devices, logical_cpu) = NULL;
         return;
 }
+
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
+static ssize_t cpu_probe_store(struct class *class, const char *buf,
+                               size_t count)
+{
+        return arch_cpu_probe(buf, count);
+}
+
+static ssize_t cpu_release_store(struct class *class, const char *buf,
+                                 size_t count)
+{
+        return arch_cpu_release(buf, count);
+}
+
+static CLASS_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
+static CLASS_ATTR(release, S_IWUSR, NULL, cpu_release_store);
+
+int __init cpu_probe_release_init(void)
+{
+        int rc;
+
+        rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
+                               &class_attr_probe.attr);
+        if (!rc)
+                rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
+                                       &class_attr_release.attr);
+
+        return rc;
+}
+device_initcall(cpu_probe_release_init);
+#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
+
 #else /* ... !CONFIG_HOTPLUG_CPU */
 static inline void register_cpu_control(struct cpu *cpu)
 {
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 47536197ffdd..c972f7ccb7d3 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -43,6 +43,8 @@ extern int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls);
 
 #ifdef CONFIG_HOTPLUG_CPU
 extern void unregister_cpu(struct cpu *cpu);
+extern ssize_t arch_cpu_probe(const char *, size_t);
+extern ssize_t arch_cpu_release(const char *, size_t);
 #endif
 struct notifier_block;