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 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");