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/*
* Generic big.LITTLE CPUFreq Interface driver
*
* It provides necessary ops to arm_big_little cpufreq driver and gets
* Frequency information from Device Tree. Freq table in DT must be in KHz.
*
* Copyright (C) 2013 Linaro.
* Viresh Kumar <viresh.kumar@linaro.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed "as is" WITHOUT ANY WARRANTY of any
* kind, whether express or implied; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/device.h>
#include <linux/export.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/opp.h>
#include <linux/slab.h>
#include <linux/types.h>
#include "arm_big_little.h"
/* get cpu node with valid operating-points */
static struct device_node *get_cpu_node_with_valid_op(int cpu)
{
struct device_node *np = NULL, *parent;
int count = 0;
parent = of_find_node_by_path("/cpus");
if (!parent) {
pr_err("failed to find OF /cpus\n");
return NULL;
}
for_each_child_of_node(parent, np) {
if (count++ != cpu)
continue;
if (!of_get_property(np, "operating-points", NULL)) {
of_node_put(np);
np = NULL;
}
break;
}
of_node_put(parent);
return np;
}
static int dt_init_opp_table(struct device *cpu_dev)
{
struct device_node *np;
int ret;
np = get_cpu_node_with_valid_op(cpu_dev->id);
if (!np)
return -ENODATA;
cpu_dev->of_node = np;
ret = of_init_opp_table(cpu_dev);
of_node_put(np);
return ret;
}
static int dt_get_transition_latency(struct device *cpu_dev)
{
struct device_node *np;
u32 transition_latency = CPUFREQ_ETERNAL;
np = get_cpu_node_with_valid_op(cpu_dev->id);
if (!np)
return CPUFREQ_ETERNAL;
of_property_read_u32(np, "clock-latency", &transition_latency);
of_node_put(np);
pr_debug("%s: clock-latency: %d\n", __func__, transition_latency);
return transition_latency;
}
static struct cpufreq_arm_bL_ops dt_bL_ops = {
.name = "dt-bl",
.get_transition_latency = dt_get_transition_latency,
.init_opp_table = dt_init_opp_table,
};
static int generic_bL_init(void)
{
struct device_node *np;
np = get_cpu_node_with_valid_op(0);
if (!np)
return -ENODEV;
of_node_put(np);
return bL_cpufreq_register(&dt_bL_ops);
}
module_init(generic_bL_init);
static void generic_bL_exit(void)
{
return bL_cpufreq_unregister(&dt_bL_ops);
}
module_exit(generic_bL_exit);
MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver via DT");
MODULE_LICENSE("GPL");
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