sfr.c 2.2 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * sfr.c - driver for special function registers
  4. *
  5. * Copyright (C) 2019 Bootlin.
  6. *
  7. */
  8. #include <linux/mfd/syscon.h>
  9. #include <linux/module.h>
  10. #include <linux/nvmem-provider.h>
  11. #include <linux/random.h>
  12. #include <linux/of.h>
  13. #include <linux/of_device.h>
  14. #include <linux/platform_device.h>
  15. #include <linux/regmap.h>
  16. #define SFR_SN0 0x4c
  17. #define SFR_SN_SIZE 8
  18. struct atmel_sfr_priv {
  19. struct regmap *regmap;
  20. };
  21. static int atmel_sfr_read(void *context, unsigned int offset,
  22. void *buf, size_t bytes)
  23. {
  24. struct atmel_sfr_priv *priv = context;
  25. return regmap_bulk_read(priv->regmap, SFR_SN0 + offset,
  26. buf, bytes / 4);
  27. }
  28. static struct nvmem_config atmel_sfr_nvmem_config = {
  29. .name = "atmel-sfr",
  30. .read_only = true,
  31. .word_size = 4,
  32. .stride = 4,
  33. .size = SFR_SN_SIZE,
  34. .reg_read = atmel_sfr_read,
  35. };
  36. static int atmel_sfr_probe(struct platform_device *pdev)
  37. {
  38. struct device *dev = &pdev->dev;
  39. struct device_node *np = dev->of_node;
  40. struct nvmem_device *nvmem;
  41. struct atmel_sfr_priv *priv;
  42. u8 sn[SFR_SN_SIZE];
  43. int ret;
  44. priv = devm_kmalloc(dev, sizeof(*priv), GFP_KERNEL);
  45. if (!priv)
  46. return -ENOMEM;
  47. priv->regmap = syscon_node_to_regmap(np);
  48. if (IS_ERR(priv->regmap)) {
  49. dev_err(dev, "cannot get parent's regmap\n");
  50. return PTR_ERR(priv->regmap);
  51. }
  52. atmel_sfr_nvmem_config.dev = dev;
  53. atmel_sfr_nvmem_config.priv = priv;
  54. nvmem = devm_nvmem_register(dev, &atmel_sfr_nvmem_config);
  55. if (IS_ERR(nvmem)) {
  56. dev_err(dev, "error registering nvmem config\n");
  57. return PTR_ERR(nvmem);
  58. }
  59. ret = atmel_sfr_read(priv, 0, sn, SFR_SN_SIZE);
  60. if (ret == 0)
  61. add_device_randomness(sn, SFR_SN_SIZE);
  62. return ret;
  63. }
  64. static const struct of_device_id atmel_sfr_dt_ids[] = {
  65. {
  66. .compatible = "atmel,sama5d2-sfr",
  67. }, {
  68. .compatible = "atmel,sama5d4-sfr",
  69. }, {
  70. /* sentinel */
  71. },
  72. };
  73. MODULE_DEVICE_TABLE(of, atmel_sfr_dt_ids);
  74. static struct platform_driver atmel_sfr_driver = {
  75. .probe = atmel_sfr_probe,
  76. .driver = {
  77. .name = "atmel-sfr",
  78. .of_match_table = atmel_sfr_dt_ids,
  79. },
  80. };
  81. module_platform_driver(atmel_sfr_driver);
  82. MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
  83. MODULE_DESCRIPTION("Atmel SFR SN driver for SAMA5D2/4 SoC family");
  84. MODULE_LICENSE("GPL v2");