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Date:	Thu, 22 May 2014 11:07:28 +0530
From:	Viresh Kumar <>
	Viresh Kumar <>,
	Greg Kroah-Hartman <>,
	Amit Daniel Kachhap <>,
	Kukjin Kim <>,
	Shawn Guo <>
Subject: [PATCH V3 4/8] driver/core: cpu: initialize opp table

Drivers expecting CPU's OPPs from device tree initialize OPP table themselves by
calling of_init_opp_table() and there is nothing driver specific in that. They
all do it in the same redundant way.

It would be better if we can get rid of redundancy by initializing CPU OPPs from
CPU core code for all CPUs (that have a "operating-points" property defined in
their node).

This patch adds another routine in cpu.c: of_init_cpu_opp_table() and calls it
right after CPU device is registered in register_cpu(). A dummy implementation
is also provided to make it lightweight for platforms that don't need it.

Cc: Greg Kroah-Hartman <>
Cc: Amit Daniel Kachhap <>
Cc: Kukjin Kim <>
Cc: Shawn Guo <>
Signed-off-by: Viresh Kumar <>
 drivers/base/cpu.c | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 006b1bc..818cfe8 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -16,6 +16,7 @@
 #include <linux/acpi.h>
 #include <linux/of.h>
 #include <linux/cpufeature.h>
+#include <linux/pm_opp.h>
 #include "base.h"
@@ -322,6 +323,25 @@ static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
+#if defined(CONFIG_PM_OPP) && defined(CONFIG_OF)
+static inline void of_init_cpu_opp_table(struct cpu *cpu)
+	int error;
+	/* Initialize CPU's OPP table */
+	error = of_init_opp_table(&cpu->dev);
+	if (!error)
+		dev_dbg(&cpu->dev, "%s: created OPP table for cpu: %d\n",
+			__func__, cpu->;
+	/* Print error only if there is an issue with OPP table */
+	else if (error != -ENOSYS && error != -ENODEV)
+		dev_err(&cpu->dev, "%s: failed to init OPP table for cpu%d, err: %d\n",
+			__func__, cpu->, error);
+static inline void of_init_cpu_opp_table(struct cpu *cpu) {}
  * register_cpu - Setup a sysfs device for a CPU.
  * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
@@ -349,10 +369,12 @@ int register_cpu(struct cpu *cpu, int num)
 	if (cpu->hotpluggable)
 		cpu->dev.groups = hotplugable_cpu_attr_groups;
 	error = device_register(&cpu->dev);
-	if (!error)
-		per_cpu(cpu_sys_devices, num) = &cpu->dev;
-	if (!error)
-		register_cpu_under_node(num, cpu_to_node(num));
+	if (error)
+		return error;
+	per_cpu(cpu_sys_devices, num) = &cpu->dev;
+	register_cpu_under_node(num, cpu_to_node(num));
+	of_init_cpu_opp_table(cpu);
 	return error;

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