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// SPDX-License-Identifier: GPL-2.0
/*
* Raspberry Pi cpufreq driver
*
* Copyright (C) 2019, Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
*/
#include <linux/clk.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>
#define RASPBERRYPI_FREQ_INTERVAL 100000000
static struct platform_device *cpufreq_dt;
static int raspberrypi_cpufreq_probe(struct platform_device *pdev)
{
struct device *cpu_dev;
unsigned long min, max;
unsigned long rate;
struct clk *clk;
int ret;
cpu_dev = get_cpu_device(0);
if (!cpu_dev) {
pr_err("Cannot get CPU for cpufreq driver\n");
return -ENODEV;
}
clk = clk_get(cpu_dev, NULL);
if (IS_ERR(clk)) {
dev_err(cpu_dev, "Cannot get clock for CPU0\n");
return PTR_ERR(clk);
}
/*
* The max and min frequencies are configurable in the Raspberry Pi
* firmware, so we query them at runtime.
*/
min = roundup(clk_round_rate(clk, 0), RASPBERRYPI_FREQ_INTERVAL);
max = roundup(clk_round_rate(clk, ULONG_MAX), RASPBERRYPI_FREQ_INTERVAL);
clk_put(clk);
for (rate = min; rate <= max; rate += RASPBERRYPI_FREQ_INTERVAL) {
ret = dev_pm_opp_add(cpu_dev, rate, 0);
if (ret)
goto remove_opp;
}
cpufreq_dt = platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
ret = PTR_ERR_OR_ZERO(cpufreq_dt);
if (ret) {
dev_err(cpu_dev, "Failed to create platform device, %d\n", ret);
goto remove_opp;
}
return 0;
remove_opp:
dev_pm_opp_remove_all_dynamic(cpu_dev);
return ret;
}
static int raspberrypi_cpufreq_remove(struct platform_device *pdev)
{
struct device *cpu_dev;
cpu_dev = get_cpu_device(0);
if (cpu_dev)
dev_pm_opp_remove_all_dynamic(cpu_dev);
platform_device_unregister(cpufreq_dt);
return 0;
}
/*
* Since the driver depends on clk-raspberrypi, which may return EPROBE_DEFER,
* all the activity is performed in the probe, which may be defered as well.
*/
static struct platform_driver raspberrypi_cpufreq_driver = {
.driver = {
.name = "raspberrypi-cpufreq",
},
.probe = raspberrypi_cpufreq_probe,
.remove = raspberrypi_cpufreq_remove,
};
module_platform_driver(raspberrypi_cpufreq_driver);
MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de");
MODULE_DESCRIPTION("Raspberry Pi cpufreq driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:raspberrypi-cpufreq");
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