cpu: Register a generic CPU device on architectures that currently do not

frv, h8300, m68k, microblaze, openrisc, score, um and xtensa currently
do not register a CPU device.  Add the config option GENERIC_CPU_DEVICES
which causes a generic CPU device to be registered for each present CPU,
and make all these architectures select it.

Richard Weinberger <richard@nod.at> covered UML and suggested using
per_cpu.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

10 files changed, 31 insertions, 0 deletions

diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig
index bbbf7927f238..a685910d2d5c 100644
--- a/arch/frv/Kconfig
+++ b/arch/frv/Kconfig
@@ -8,6 +8,7 @@ config FRV
 	select HAVE_GENERIC_HARDIRQS
 	select GENERIC_IRQ_SHOW
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
+	select GENERIC_CPU_DEVICES
 
 config ZONE_DMA
 	bool
diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig
index d1f377f5d3b6..56e890df5053 100644
--- a/arch/h8300/Kconfig
+++ b/arch/h8300/Kconfig
@@ -4,6 +4,7 @@ config H8300
 	select HAVE_IDE
 	select HAVE_GENERIC_HARDIRQS
 	select GENERIC_IRQ_SHOW
+	select GENERIC_CPU_DEVICES
 
 config SYMBOL_PREFIX
 	string
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 99c363617f27..ae413d4a8bb7 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -6,6 +6,7 @@ config M68K
 	select HAVE_GENERIC_HARDIRQS
 	select GENERIC_IRQ_SHOW
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG if RMW_INSNS
+	select GENERIC_CPU_DEVICES
 
 config RWSEM_GENERIC_SPINLOCK
 	bool
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index f0eead74fff6..74f23a460ba2 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -18,6 +18,7 @@ config MICROBLAZE
 	select GENERIC_IRQ_PROBE
 	select GENERIC_IRQ_SHOW
 	select GENERIC_PCI_IOMAP
+	select GENERIC_CPU_DEVICES
 
 config SWAP
 	def_bool n
diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
index 081a54f1a93d..bc428b5f126c 100644
--- a/arch/openrisc/Kconfig
+++ b/arch/openrisc/Kconfig
@@ -15,6 +15,7 @@ config OPENRISC
 	select GENERIC_IRQ_PROBE
 	select GENERIC_IRQ_SHOW
 	select GENERIC_IOMAP
+	select GENERIC_CPU_DEVICES
 
 config MMU
 	def_bool y
diff --git a/arch/score/Kconfig b/arch/score/Kconfig
index 3df65d39abc1..4b285779ac05 100644
--- a/arch/score/Kconfig
+++ b/arch/score/Kconfig
@@ -8,6 +8,7 @@ config SCORE
        select HAVE_MEMBLOCK
        select HAVE_MEMBLOCK_NODE_MAP
        select ARCH_DISCARD_MEMBLOCK
+       select GENERIC_CPU_DEVICES
 
 choice
 	prompt "System type"
diff --git a/arch/um/Kconfig.common b/arch/um/Kconfig.common
index a9234838e8a2..b37ae706af3e 100644
--- a/arch/um/Kconfig.common
+++ b/arch/um/Kconfig.common
@@ -8,6 +8,7 @@ config UML
 	default y
 	select HAVE_GENERIC_HARDIRQS
 	select GENERIC_IRQ_SHOW
+	select GENERIC_CPU_DEVICES
 
 config MMU
 	bool
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index c346ccdce0df..8a3f8351f438 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -9,6 +9,7 @@ config XTENSA
 	select HAVE_IDE
 	select HAVE_GENERIC_HARDIRQS
 	select GENERIC_IRQ_SHOW
+	select GENERIC_CPU_DEVICES
 	help
 	  Xtensa processors are 32-bit RISC machines designed by Tensilica
 	  primarily for embedded systems.  These processors are both
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index e95c67edb2cb..fcbec8ac134d 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -172,6 +172,10 @@ config SYS_HYPERVISOR
 	bool
 	default n
 
+config GENERIC_CPU_DEVICES
+	bool
+	default n
+
 source "drivers/base/regmap/Kconfig"
 
 config DMA_SHARED_BUFFER
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index bba70d08be6a..db87e78d7459 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -11,6 +11,7 @@
 #include <linux/device.h>
 #include <linux/node.h>
 #include <linux/gfp.h>
+#include <linux/percpu.h>
 
 #include "base.h"
 
@@ -275,11 +276,29 @@ bool cpu_is_hotpluggable(unsigned cpu)
 }
 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
 
+#ifdef CONFIG_GENERIC_CPU_DEVICES
+static DEFINE_PER_CPU(struct cpu, cpu_devices);
+#endif
+
+static void __init cpu_dev_register_generic(void)
+{
+#ifdef CONFIG_GENERIC_CPU_DEVICES
+	int i;
+
+	for_each_possible_cpu(i) {
+		if (register_cpu(&per_cpu(cpu_devices, i), i))
+			panic("Failed to register CPU device");
+	}
+#endif
+}
+
 void __init cpu_dev_init(void)
 {
 	if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
 		panic("Failed to register CPU subsystem");
 
+	cpu_dev_register_generic();
+
 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
 	sched_create_sysfs_power_savings_entries(cpu_subsys.dev_root);
 #endif