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Commit 7e5930aa authored by Juri Lelli's avatar Juri Lelli Committed by Russell King
Browse files

ARM: 8622/3: add sysfs cpu_capacity attribute 



Add a sysfs cpu_capacity attribute with which it is possible to read and
write (thus over-writing default values) CPUs capacity. This might be
useful in situations where values needs changing after boot.

The new attribute shows up as:

 /sys/devices/system/cpu/cpu*/cpu_capacity

Signed-off-by: default avatarJuri Lelli <juri.lelli@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 06073ee2

arch/arm/kernel/topology.c

+64 −0
Original line number Diff line number Diff line
@@ -22,7 +22,9 @@ 
#include <linux/of.h>

#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/string.h>



#include <asm/cpu.h>

#include <asm/cputype.h>

#include <asm/topology.h>
@@ -42,6 +44,7 @@ 
 * updated during this sequence.

 */

static DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;

static DEFINE_MUTEX(cpu_scale_mutex);



unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu)

{
@@ -53,6 +56,65 @@ static void set_capacity_scale(unsigned int cpu, unsigned long capacity) 
	per_cpu(cpu_scale, cpu) = capacity;

}



#ifdef CONFIG_PROC_SYSCTL

static ssize_t cpu_capacity_show(struct device *dev,

				 struct device_attribute *attr,

				 char *buf)

{

	struct cpu *cpu = container_of(dev, struct cpu, dev);



	return sprintf(buf, "%lu\n",

			arch_scale_cpu_capacity(NULL, cpu->dev.id));

}



static ssize_t cpu_capacity_store(struct device *dev,

				  struct device_attribute *attr,

				  const char *buf,

				  size_t count)

{

	struct cpu *cpu = container_of(dev, struct cpu, dev);

	int this_cpu = cpu->dev.id, i;

	unsigned long new_capacity;

	ssize_t ret;



	if (count) {

		ret = kstrtoul(buf, 0, &new_capacity);

		if (ret)

			return ret;

		if (new_capacity > SCHED_CAPACITY_SCALE)

			return -EINVAL;



		mutex_lock(&cpu_scale_mutex);

		for_each_cpu(i, &cpu_topology[this_cpu].core_sibling)

			set_capacity_scale(i, new_capacity);

		mutex_unlock(&cpu_scale_mutex);

	}



	return count;

}



static DEVICE_ATTR_RW(cpu_capacity);



static int register_cpu_capacity_sysctl(void)

{

	int i;

	struct device *cpu;



	for_each_possible_cpu(i) {

		cpu = get_cpu_device(i);

		if (!cpu) {

			pr_err("%s: too early to get CPU%d device!\n",

			       __func__, i);

			continue;

		}

		device_create_file(cpu, &dev_attr_cpu_capacity);

	}



	return 0;

}

subsys_initcall(register_cpu_capacity_sysctl);

#endif



#ifdef CONFIG_OF

struct cpu_efficiency {

	const char *compatible;
@@ -132,6 +194,7 @@ static void normalize_cpu_capacity(void) 
		return;



	pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale);

	mutex_lock(&cpu_scale_mutex);

	for_each_possible_cpu(cpu) {

		capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT)

			/ capacity_scale;
@@ -139,6 +202,7 @@ static void normalize_cpu_capacity(void) 
		pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",

			cpu, arch_scale_cpu_capacity(NULL, cpu));

	}

	mutex_unlock(&cpu_scale_mutex);

}



#ifdef CONFIG_CPU_FREQ