pwrseq_emmc.c 3.1 KB

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  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. #include <linux/mmc/host.h>
  20. #include "pwrseq.h"
  21. struct mmc_pwrseq_emmc {
  22. struct mmc_pwrseq pwrseq;
  23. struct notifier_block reset_nb;
  24. struct gpio_desc *reset_gpio;
  25. };
  26. #define to_pwrseq_emmc(p) container_of(p, struct mmc_pwrseq_emmc, pwrseq)
  27. static void mmc_pwrseq_emmc_reset(struct mmc_host *host)
  28. {
  29. struct mmc_pwrseq_emmc *pwrseq = to_pwrseq_emmc(host->pwrseq);
  30. gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
  31. udelay(1);
  32. gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
  33. udelay(200);
  34. }
  35. static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this,
  36. unsigned long mode, void *cmd)
  37. {
  38. struct mmc_pwrseq_emmc *pwrseq = container_of(this,
  39. struct mmc_pwrseq_emmc, reset_nb);
  40. gpiod_set_value(pwrseq->reset_gpio, 1);
  41. udelay(1);
  42. gpiod_set_value(pwrseq->reset_gpio, 0);
  43. udelay(200);
  44. return NOTIFY_DONE;
  45. }
  46. static const struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = {
  47. .reset = mmc_pwrseq_emmc_reset,
  48. };
  49. static int mmc_pwrseq_emmc_probe(struct platform_device *pdev)
  50. {
  51. struct mmc_pwrseq_emmc *pwrseq;
  52. struct device *dev = &pdev->dev;
  53. pwrseq = devm_kzalloc(dev, sizeof(*pwrseq), GFP_KERNEL);
  54. if (!pwrseq)
  55. return -ENOMEM;
  56. pwrseq->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
  57. if (IS_ERR(pwrseq->reset_gpio))
  58. return PTR_ERR(pwrseq->reset_gpio);
  59. if (!gpiod_cansleep(pwrseq->reset_gpio)) {
  60. /*
  61. * register reset handler to ensure emmc reset also from
  62. * emergency_reboot(), priority 255 is the highest priority
  63. * so it will be executed before any system reboot handler.
  64. */
  65. pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb;
  66. pwrseq->reset_nb.priority = 255;
  67. register_restart_handler(&pwrseq->reset_nb);
  68. } else {
  69. dev_notice(dev, "EMMC reset pin tied to a sleepy GPIO driver; reset on emergency-reboot disabled\n");
  70. }
  71. pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops;
  72. pwrseq->pwrseq.dev = dev;
  73. pwrseq->pwrseq.owner = THIS_MODULE;
  74. platform_set_drvdata(pdev, pwrseq);
  75. return mmc_pwrseq_register(&pwrseq->pwrseq);
  76. }
  77. static int mmc_pwrseq_emmc_remove(struct platform_device *pdev)
  78. {
  79. struct mmc_pwrseq_emmc *pwrseq = platform_get_drvdata(pdev);
  80. unregister_restart_handler(&pwrseq->reset_nb);
  81. mmc_pwrseq_unregister(&pwrseq->pwrseq);
  82. return 0;
  83. }
  84. static const struct of_device_id mmc_pwrseq_emmc_of_match[] = {
  85. { .compatible = "mmc-pwrseq-emmc",},
  86. {/* sentinel */},
  87. };
  88. MODULE_DEVICE_TABLE(of, mmc_pwrseq_emmc_of_match);
  89. static struct platform_driver mmc_pwrseq_emmc_driver = {
  90. .probe = mmc_pwrseq_emmc_probe,
  91. .remove = mmc_pwrseq_emmc_remove,
  92. .driver = {
  93. .name = "pwrseq_emmc",
  94. .of_match_table = mmc_pwrseq_emmc_of_match,
  95. },
  96. };
  97. module_platform_driver(mmc_pwrseq_emmc_driver);
  98. MODULE_LICENSE("GPL v2");