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