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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regulator-poweroff.c (2069B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Force-disables a regulator to power down a device
      4 *
      5 * Michael Klein <michael@fossekall.de>
      6 *
      7 * Copyright (C) 2020 Michael Klein
      8 *
      9 * Based on the gpio-poweroff driver.
     10 */
     11#include <linux/delay.h>
     12#include <linux/module.h>
     13#include <linux/of.h>
     14#include <linux/platform_device.h>
     15#include <linux/pm.h>
     16#include <linux/regulator/consumer.h>
     17
     18#define TIMEOUT_MS 3000
     19
     20/*
     21 * Hold configuration here, cannot be more than one instance of the driver
     22 * since pm_power_off itself is global.
     23 */
     24static struct regulator *cpu_regulator;
     25
     26static void regulator_poweroff_do_poweroff(void)
     27{
     28	if (cpu_regulator && regulator_is_enabled(cpu_regulator))
     29		regulator_force_disable(cpu_regulator);
     30
     31	/* give it some time */
     32	mdelay(TIMEOUT_MS);
     33
     34	WARN_ON(1);
     35}
     36
     37static int regulator_poweroff_probe(struct platform_device *pdev)
     38{
     39	/* If a pm_power_off function has already been added, leave it alone */
     40	if (pm_power_off != NULL) {
     41		dev_err(&pdev->dev,
     42			"%s: pm_power_off function already registered\n",
     43			__func__);
     44		return -EBUSY;
     45	}
     46
     47	cpu_regulator = devm_regulator_get(&pdev->dev, "cpu");
     48	if (IS_ERR(cpu_regulator))
     49		return PTR_ERR(cpu_regulator);
     50
     51	pm_power_off = &regulator_poweroff_do_poweroff;
     52	return 0;
     53}
     54
     55static int regulator_poweroff_remove(__maybe_unused struct platform_device *pdev)
     56{
     57	if (pm_power_off == &regulator_poweroff_do_poweroff)
     58		pm_power_off = NULL;
     59
     60	return 0;
     61}
     62
     63static const struct of_device_id of_regulator_poweroff_match[] = {
     64	{ .compatible = "regulator-poweroff", },
     65	{},
     66};
     67MODULE_DEVICE_TABLE(of, of_regulator_poweroff_match);
     68
     69static struct platform_driver regulator_poweroff_driver = {
     70	.probe = regulator_poweroff_probe,
     71	.remove = regulator_poweroff_remove,
     72	.driver = {
     73		.name = "poweroff-regulator",
     74		.of_match_table = of_regulator_poweroff_match,
     75	},
     76};
     77
     78module_platform_driver(regulator_poweroff_driver);
     79
     80MODULE_AUTHOR("Michael Klein <michael@fossekall.de>");
     81MODULE_DESCRIPTION("Regulator poweroff driver");
     82MODULE_LICENSE("GPL v2");
     83MODULE_ALIAS("platform:poweroff-regulator");