CPU: Introduce ARCH_HAS_CPU_AUTOPROBE and X86 parts

This patch is based on Andi Kleen's work:
Implement autoprobing/loading of modules serving CPU
specific features (x86cpu autoloading).

And Kay Siever's work to get rid of sysdev cpu structures
and making use of struct device instead.

Before, the cpuid driver had to be loaded to get the x86cpu
autoloading feature. With this patch autoloading works through
the /sys/devices/system/cpu object

Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/base/cpu.c

@@ -11,6 +11,7 @@
 #include <linux/device.h>
 #include <linux/node.h>
 #include <linux/gfp.h>
+#include <linux/slab.h>
 #include <linux/percpu.h>
 
 #include "base.h"
@@ -223,6 +224,9 @@ int __cpuinit register_cpu(struct cpu *cpu, int num)
 	cpu->node_id = cpu_to_node(num);
 	cpu->dev.id = num;
 	cpu->dev.bus = &cpu_subsys;
+#ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
+	cpu->dev.bus->uevent = arch_cpu_uevent;
+#endif
 	error = device_register(&cpu->dev);
 	if (!error && cpu->hotpluggable)
 		register_cpu_control(cpu);
@@ -247,6 +251,10 @@ struct device *get_cpu_device(unsigned cpu)
 }
 EXPORT_SYMBOL_GPL(get_cpu_device);
 
+#ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
+static DEVICE_ATTR(modalias, 0444, arch_print_cpu_modalias, NULL);
+#endif
+
 static struct attribute *cpu_root_attrs[] = {
 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
 	&dev_attr_probe.attr,
@@ -257,6 +265,9 @@ static struct attribute *cpu_root_attrs[] = {
 	&cpu_attrs[2].attr.attr,
 	&dev_attr_kernel_max.attr,
 	&dev_attr_offline.attr,
+#ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
+	&dev_attr_modalias.attr,
+#endif
 	NULL
 };