arm_big_little_dt.c
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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/cpufreq.h>
#include <linux/device.h>
#include <linux/export.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/pm_opp.h>
#include <linux/platform_device.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 = of_cpu_device_node_get(cpu);
if (!of_get_property(np, "operating-points", NULL)) {
of_node_put(np);
np = NULL;
}
return np;
}
static int dt_init_opp_table(struct device *cpu_dev)
{
struct device_node *np;
int ret;
np = of_node_get(cpu_dev->of_node);
if (!np) {
pr_err("failed to find cpu%d node\n", cpu_dev->id);
return -ENOENT;
}
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 = of_node_get(cpu_dev->of_node);
if (!np) {
pr_info("Failed to find cpu node. Use CPUFREQ_ETERNAL transition latency\n");
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,
.free_opp_table = of_free_opp_table,
};
static int generic_bL_probe(struct platform_device *pdev)
{
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);
}
static int generic_bL_remove(struct platform_device *pdev)
{
bL_cpufreq_unregister(&dt_bL_ops);
return 0;
}
static struct platform_driver generic_bL_platdrv = {
.driver = {
.name = "arm-bL-cpufreq-dt",
},
.probe = generic_bL_probe,
.remove = generic_bL_remove,
};
module_platform_driver(generic_bL_platdrv);
MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver via DT");
MODULE_LICENSE("GPL v2");