cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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raspberrypi-cpufreq.c (2373B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Raspberry Pi cpufreq driver
      4 *
      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	100000000
     16
     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 Pi
     41	 * 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 int 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	return 0;
     79}
     80
     81/*
     82 * Since the driver depends on clk-raspberrypi, which may return EPROBE_DEFER,
     83 * all the activity is performed in the probe, which may be defered as well.
     84 */
     85static struct platform_driver raspberrypi_cpufreq_driver = {
     86	.driver = {
     87		.name = "raspberrypi-cpufreq",
     88	},
     89	.probe          = raspberrypi_cpufreq_probe,
     90	.remove		= raspberrypi_cpufreq_remove,
     91};
     92module_platform_driver(raspberrypi_cpufreq_driver);
     93
     94MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de");
     95MODULE_DESCRIPTION("Raspberry Pi cpufreq driver");
     96MODULE_LICENSE("GPL");
     97MODULE_ALIAS("platform:raspberrypi-cpufreq");