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