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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pwrseq_emmc.c (3155B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (C) 2015, Samsung Electronics Co., Ltd.
      4 *
      5 * Author: Marek Szyprowski <m.szyprowski@samsung.com>
      6 *
      7 * Simple eMMC hardware reset provider
      8 */
      9#include <linux/delay.h>
     10#include <linux/kernel.h>
     11#include <linux/init.h>
     12#include <linux/platform_device.h>
     13#include <linux/module.h>
     14#include <linux/slab.h>
     15#include <linux/device.h>
     16#include <linux/err.h>
     17#include <linux/gpio/consumer.h>
     18#include <linux/reboot.h>
     19
     20#include <linux/mmc/host.h>
     21
     22#include "pwrseq.h"
     23
     24struct mmc_pwrseq_emmc {
     25	struct mmc_pwrseq pwrseq;
     26	struct notifier_block reset_nb;
     27	struct gpio_desc *reset_gpio;
     28};
     29
     30#define to_pwrseq_emmc(p) container_of(p, struct mmc_pwrseq_emmc, pwrseq)
     31
     32static void mmc_pwrseq_emmc_reset(struct mmc_host *host)
     33{
     34	struct mmc_pwrseq_emmc *pwrseq =  to_pwrseq_emmc(host->pwrseq);
     35
     36	gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
     37	udelay(1);
     38	gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
     39	udelay(200);
     40}
     41
     42static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,
     43				    unsigned long mode, void *cmd)
     44{
     45	struct mmc_pwrseq_emmc *pwrseq = container_of(this,
     46					struct mmc_pwrseq_emmc, reset_nb);
     47	gpiod_set_value(pwrseq->reset_gpio, 1);
     48	udelay(1);
     49	gpiod_set_value(pwrseq->reset_gpio, 0);
     50	udelay(200);
     51
     52	return NOTIFY_DONE;
     53}
     54
     55static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
     56	.reset = mmc_pwrseq_emmc_reset,
     57};
     58
     59static int mmc_pwrseq_emmc_probe(struct platform_device *pdev)
     60{
     61	struct mmc_pwrseq_emmc *pwrseq;
     62	struct device *dev = &pdev->dev;
     63
     64	pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
     65	if (!pwrseq)
     66		return -ENOMEM;
     67
     68	pwrseq->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
     69	if (IS_ERR(pwrseq->reset_gpio))
     70		return PTR_ERR(pwrseq->reset_gpio);
     71
     72	if (!gpiod_cansleep(pwrseq->reset_gpio)) {
     73		/*
     74		 * register reset handler to ensure emmc reset also from
     75		 * emergency_reboot(), priority 255 is the highest priority
     76		 * so it will be executed before any system reboot handler.
     77		 */
     78		pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;
     79		pwrseq->reset_nb.priority = 255;
     80		register_restart_handler(&pwrseq->reset_nb);
     81	} else {
     82		dev_notice(dev, "EMMC reset pin tied to a sleepy GPIO driver; reset on emergency-reboot disabled\n");
     83	}
     84
     85	pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
     86	pwrseq->pwrseq.dev = dev;
     87	pwrseq->pwrseq.owner = THIS_MODULE;
     88	platform_set_drvdata(pdev, pwrseq);
     89
     90	return mmc_pwrseq_register(&pwrseq->pwrseq);
     91}
     92
     93static int mmc_pwrseq_emmc_remove(struct platform_device *pdev)
     94{
     95	struct mmc_pwrseq_emmc *pwrseq = platform_get_drvdata(pdev);
     96
     97	unregister_restart_handler(&pwrseq->reset_nb);
     98	mmc_pwrseq_unregister(&pwrseq->pwrseq);
     99
    100	return 0;
    101}
    102
    103static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
    104	{ .compatible = "mmc-pwrseq-emmc",},
    105	{/* sentinel */},
    106};
    107
    108MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
    109
    110static struct platform_driver mmc_pwrseq_emmc_driver = {
    111	.probe = mmc_pwrseq_emmc_probe,
    112	.remove = mmc_pwrseq_emmc_remove,
    113	.driver = {
    114		.name = "pwrseq_emmc",
    115		.of_match_table = mmc_pwrseq_emmc_of_match,
    116	},
    117};
    118
    119module_platform_driver(mmc_pwrseq_emmc_driver);
    120MODULE_LICENSE("GPL v2");