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1// SPDX-License-Identifier: GPL-2.02/*3 * Raspberry Pi cpufreq driver4 *5 * Copyright (C) 2019, Nicolas Saenz Julienne <nsaenzjulienne@suse.de>6 */7 8#include <linux/clk.h>9#include <linux/cpu.h>10#include <linux/cpufreq.h>11#include <linux/module.h>12#include <linux/platform_device.h>13#include <linux/pm_opp.h>14 15#define RASPBERRYPI_FREQ_INTERVAL 10000000016 17static struct platform_device *cpufreq_dt;18 19static int raspberrypi_cpufreq_probe(struct platform_device *pdev)20{21 struct device *cpu_dev;22 unsigned long min, max;23 unsigned long rate;24 struct clk *clk;25 int ret;26 27 cpu_dev = get_cpu_device(0);28 if (!cpu_dev) {29 pr_err("Cannot get CPU for cpufreq driver\n");30 return -ENODEV;31 }32 33 clk = clk_get(cpu_dev, NULL);34 if (IS_ERR(clk)) {35 dev_err(cpu_dev, "Cannot get clock for CPU0\n");36 return PTR_ERR(clk);37 }38 39 /*40 * The max and min frequencies are configurable in the Raspberry Pi41 * firmware, so we query them at runtime.42 */43 min = roundup(clk_round_rate(clk, 0), RASPBERRYPI_FREQ_INTERVAL);44 max = roundup(clk_round_rate(clk, ULONG_MAX), RASPBERRYPI_FREQ_INTERVAL);45 clk_put(clk);46 47 for (rate = min; rate <= max; rate += RASPBERRYPI_FREQ_INTERVAL) {48 ret = dev_pm_opp_add(cpu_dev, rate, 0);49 if (ret)50 goto remove_opp;51 }52 53 cpufreq_dt = platform_device_register_simple("cpufreq-dt", -1, NULL, 0);54 ret = PTR_ERR_OR_ZERO(cpufreq_dt);55 if (ret) {56 dev_err(cpu_dev, "Failed to create platform device, %d\n", ret);57 goto remove_opp;58 }59 60 return 0;61 62remove_opp:63 dev_pm_opp_remove_all_dynamic(cpu_dev);64 65 return ret;66}67 68static void raspberrypi_cpufreq_remove(struct platform_device *pdev)69{70 struct device *cpu_dev;71 72 cpu_dev = get_cpu_device(0);73 if (cpu_dev)74 dev_pm_opp_remove_all_dynamic(cpu_dev);75 76 platform_device_unregister(cpufreq_dt);77}78 79/*80 * Since the driver depends on clk-raspberrypi, which may return EPROBE_DEFER,81 * all the activity is performed in the probe, which may be defered as well.82 */83static struct platform_driver raspberrypi_cpufreq_driver = {84 .driver = {85 .name = "raspberrypi-cpufreq",86 },87 .probe = raspberrypi_cpufreq_probe,88 .remove_new = raspberrypi_cpufreq_remove,89};90module_platform_driver(raspberrypi_cpufreq_driver);91 92MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de");93MODULE_DESCRIPTION("Raspberry Pi cpufreq driver");94MODULE_LICENSE("GPL");95MODULE_ALIAS("platform:raspberrypi-cpufreq");96