mmc/core/pwrseq_emmc.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (C) 2015, Samsung Electronics Co., Ltd.
0004  *
0005  * Author: Marek Szyprowski <m.szyprowski@samsung.com>
0006  *
0007  * Simple eMMC hardware reset provider
0008  */
0009 #include <linux/delay.h>
0010 #include <linux/kernel.h>
0011 #include <linux/init.h>
0012 #include <linux/platform_device.h>
0013 #include <linux/module.h>
0014 #include <linux/slab.h>
0015 #include <linux/device.h>
0016 #include <linux/err.h>
0017 #include <linux/gpio/consumer.h>
0018 #include <linux/reboot.h>
0019
0020 #include <linux/mmc/host.h>
0021
0022 #include "pwrseq.h"
0023
0024 struct mmc_pwrseq_emmc {
0025     struct mmc_pwrseq pwrseq;
0026     struct notifier_block reset_nb;
0027     struct gpio_desc *reset_gpio;
0028 };
0029
0030 #define to_pwrseq_emmc(p) container_of(p, struct mmc_pwrseq_emmc, pwrseq)
0031
0032 static void mmc_pwrseq_emmc_reset(struct mmc_host *host)
0033 {
0034     struct mmc_pwrseq_emmc *pwrseq =  to_pwrseq_emmc(host->pwrseq);
0035
0036     gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
0037     udelay(1);
0038     gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
0039     udelay(200);
0040 }
0041
0042 static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,
0043                     unsigned long mode, void *cmd)
0044 {
0045     struct mmc_pwrseq_emmc *pwrseq = container_of(this,
0046                     struct mmc_pwrseq_emmc, reset_nb);
0047     gpiod_set_value(pwrseq->reset_gpio, 1);
0048     udelay(1);
0049     gpiod_set_value(pwrseq->reset_gpio, 0);
0050     udelay(200);
0051
0052     return NOTIFY_DONE;
0053 }
0054
0055 static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
0056     .reset = mmc_pwrseq_emmc_reset,
0057 };
0058
0059 static int mmc_pwrseq_emmc_probe(struct platform_device *pdev)
0060 {
0061     struct mmc_pwrseq_emmc *pwrseq;
0062     struct device *dev = &pdev->dev;
0063
0064     pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
0065     if (!pwrseq)
0066         return -ENOMEM;
0067
0068     pwrseq->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
0069     if (IS_ERR(pwrseq->reset_gpio))
0070         return PTR_ERR(pwrseq->reset_gpio);
0071
0072     if (!gpiod_cansleep(pwrseq->reset_gpio)) {
0073         /*
0074          * register reset handler to ensure emmc reset also from
0075          * emergency_reboot(), priority 255 is the highest priority
0076          * so it will be executed before any system reboot handler.
0077          */
0078         pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;
0079         pwrseq->reset_nb.priority = 255;
0080         register_restart_handler(&pwrseq->reset_nb);
0081     } else {
0082         dev_notice(dev, "EMMC reset pin tied to a sleepy GPIO driver; reset on emergency-reboot disabled\n");
0083     }
0084
0085     pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
0086     pwrseq->pwrseq.dev = dev;
0087     pwrseq->pwrseq.owner = THIS_MODULE;
0088     platform_set_drvdata(pdev, pwrseq);
0089
0090     return mmc_pwrseq_register(&pwrseq->pwrseq);
0091 }
0092
0093 static int mmc_pwrseq_emmc_remove(struct platform_device *pdev)
0094 {
0095     struct mmc_pwrseq_emmc *pwrseq = platform_get_drvdata(pdev);
0096
0097     unregister_restart_handler(&pwrseq->reset_nb);
0098     mmc_pwrseq_unregister(&pwrseq->pwrseq);
0099
0100     return 0;
0101 }
0102
0103 static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
0104     { .compatible = "mmc-pwrseq-emmc",},
0105     {/* sentinel */},
0106 };
0107
0108 MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
0109
0110 static struct platform_driver mmc_pwrseq_emmc_driver = {
0111     .probe = mmc_pwrseq_emmc_probe,
0112     .remove = mmc_pwrseq_emmc_remove,
0113     .driver = {
0114         .name = "pwrseq_emmc",
0115         .of_match_table = mmc_pwrseq_emmc_of_match,
0116     },
0117 };
0118
0119 module_platform_driver(mmc_pwrseq_emmc_driver);
0120 MODULE_LICENSE("GPL v2");