98 строки
2.3 KiB
C
98 строки
2.3 KiB
C
// 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");
|