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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syscon-poweroff.c (2303B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Generic Syscon Poweroff Driver
      4 *
      5 * Copyright (c) 2015, National Instruments Corp.
      6 * Author: Moritz Fischer <moritz.fischer@ettus.com>
      7 */
      8
      9#include <linux/delay.h>
     10#include <linux/io.h>
     11#include <linux/notifier.h>
     12#include <linux/mfd/syscon.h>
     13#include <linux/of_address.h>
     14#include <linux/of_device.h>
     15#include <linux/platform_device.h>
     16#include <linux/pm.h>
     17#include <linux/regmap.h>
     18
     19static struct regmap *map;
     20static u32 offset;
     21static u32 value;
     22static u32 mask;
     23
     24static void syscon_poweroff(void)
     25{
     26	/* Issue the poweroff */
     27	regmap_update_bits(map, offset, mask, value);
     28
     29	mdelay(1000);
     30
     31	pr_emerg("Unable to poweroff system\n");
     32}
     33
     34static int syscon_poweroff_probe(struct platform_device *pdev)
     35{
     36	int mask_err, value_err;
     37
     38	map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
     39	if (IS_ERR(map)) {
     40		dev_err(&pdev->dev, "unable to get syscon");
     41		return PTR_ERR(map);
     42	}
     43
     44	if (of_property_read_u32(pdev->dev.of_node, "offset", &offset)) {
     45		dev_err(&pdev->dev, "unable to read 'offset'");
     46		return -EINVAL;
     47	}
     48
     49	value_err = of_property_read_u32(pdev->dev.of_node, "value", &value);
     50	mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &mask);
     51	if (value_err && mask_err) {
     52		dev_err(&pdev->dev, "unable to read 'value' and 'mask'");
     53		return -EINVAL;
     54	}
     55
     56	if (value_err) {
     57		/* support old binding */
     58		value = mask;
     59		mask = 0xFFFFFFFF;
     60	} else if (mask_err) {
     61		/* support value without mask*/
     62		mask = 0xFFFFFFFF;
     63	}
     64
     65	if (pm_power_off) {
     66		dev_err(&pdev->dev, "pm_power_off already claimed for %ps",
     67			pm_power_off);
     68		return -EBUSY;
     69	}
     70
     71	pm_power_off = syscon_poweroff;
     72
     73	return 0;
     74}
     75
     76static int syscon_poweroff_remove(struct platform_device *pdev)
     77{
     78	if (pm_power_off == syscon_poweroff)
     79		pm_power_off = NULL;
     80
     81	return 0;
     82}
     83
     84static const struct of_device_id syscon_poweroff_of_match[] = {
     85	{ .compatible = "syscon-poweroff" },
     86	{}
     87};
     88
     89static struct platform_driver syscon_poweroff_driver = {
     90	.probe = syscon_poweroff_probe,
     91	.remove = syscon_poweroff_remove,
     92	.driver = {
     93		.name = "syscon-poweroff",
     94		.of_match_table = syscon_poweroff_of_match,
     95	},
     96};
     97
     98static int __init syscon_poweroff_register(void)
     99{
    100	return platform_driver_register(&syscon_poweroff_driver);
    101}
    102device_initcall(syscon_poweroff_register);