brcm_nvram.c 3.8 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * Copyright (C) 2021 Rafał Miłecki <[email protected]>
  4. */
  5. #include <linux/io.h>
  6. #include <linux/mod_devicetable.h>
  7. #include <linux/module.h>
  8. #include <linux/nvmem-consumer.h>
  9. #include <linux/nvmem-provider.h>
  10. #include <linux/of.h>
  11. #include <linux/platform_device.h>
  12. #include <linux/slab.h>
  13. #define NVRAM_MAGIC "FLSH"
  14. struct brcm_nvram {
  15. struct device *dev;
  16. void __iomem *base;
  17. struct nvmem_cell_info *cells;
  18. int ncells;
  19. };
  20. struct brcm_nvram_header {
  21. char magic[4];
  22. __le32 len;
  23. __le32 crc_ver_init; /* 0:7 crc, 8:15 ver, 16:31 sdram_init */
  24. __le32 config_refresh; /* 0:15 sdram_config, 16:31 sdram_refresh */
  25. __le32 config_ncdl; /* ncdl values for memc */
  26. };
  27. static int brcm_nvram_read(void *context, unsigned int offset, void *val,
  28. size_t bytes)
  29. {
  30. struct brcm_nvram *priv = context;
  31. u8 *dst = val;
  32. while (bytes--)
  33. *dst++ = readb(priv->base + offset++);
  34. return 0;
  35. }
  36. static int brcm_nvram_add_cells(struct brcm_nvram *priv, uint8_t *data,
  37. size_t len)
  38. {
  39. struct device *dev = priv->dev;
  40. char *var, *value, *eq;
  41. int idx;
  42. priv->ncells = 0;
  43. for (var = data + sizeof(struct brcm_nvram_header);
  44. var < (char *)data + len && *var;
  45. var += strlen(var) + 1) {
  46. priv->ncells++;
  47. }
  48. priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
  49. if (!priv->cells)
  50. return -ENOMEM;
  51. for (var = data + sizeof(struct brcm_nvram_header), idx = 0;
  52. var < (char *)data + len && *var;
  53. var = value + strlen(value) + 1, idx++) {
  54. eq = strchr(var, '=');
  55. if (!eq)
  56. break;
  57. *eq = '\0';
  58. value = eq + 1;
  59. priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL);
  60. if (!priv->cells[idx].name)
  61. return -ENOMEM;
  62. priv->cells[idx].offset = value - (char *)data;
  63. priv->cells[idx].bytes = strlen(value);
  64. priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
  65. }
  66. return 0;
  67. }
  68. static int brcm_nvram_parse(struct brcm_nvram *priv)
  69. {
  70. struct device *dev = priv->dev;
  71. struct brcm_nvram_header header;
  72. uint8_t *data;
  73. size_t len;
  74. int err;
  75. memcpy_fromio(&header, priv->base, sizeof(header));
  76. if (memcmp(header.magic, NVRAM_MAGIC, 4)) {
  77. dev_err(dev, "Invalid NVRAM magic\n");
  78. return -EINVAL;
  79. }
  80. len = le32_to_cpu(header.len);
  81. data = kzalloc(len, GFP_KERNEL);
  82. if (!data)
  83. return -ENOMEM;
  84. memcpy_fromio(data, priv->base, len);
  85. data[len - 1] = '\0';
  86. err = brcm_nvram_add_cells(priv, data, len);
  87. if (err) {
  88. dev_err(dev, "Failed to add cells: %d\n", err);
  89. return err;
  90. }
  91. kfree(data);
  92. return 0;
  93. }
  94. static int brcm_nvram_probe(struct platform_device *pdev)
  95. {
  96. struct nvmem_config config = {
  97. .name = "brcm-nvram",
  98. .reg_read = brcm_nvram_read,
  99. };
  100. struct device *dev = &pdev->dev;
  101. struct resource *res;
  102. struct brcm_nvram *priv;
  103. int err;
  104. priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
  105. if (!priv)
  106. return -ENOMEM;
  107. priv->dev = dev;
  108. res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  109. priv->base = devm_ioremap_resource(dev, res);
  110. if (IS_ERR(priv->base))
  111. return PTR_ERR(priv->base);
  112. err = brcm_nvram_parse(priv);
  113. if (err)
  114. return err;
  115. config.dev = dev;
  116. config.cells = priv->cells;
  117. config.ncells = priv->ncells;
  118. config.priv = priv;
  119. config.size = resource_size(res);
  120. return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
  121. }
  122. static const struct of_device_id brcm_nvram_of_match_table[] = {
  123. { .compatible = "brcm,nvram", },
  124. {},
  125. };
  126. static struct platform_driver brcm_nvram_driver = {
  127. .probe = brcm_nvram_probe,
  128. .driver = {
  129. .name = "brcm_nvram",
  130. .of_match_table = brcm_nvram_of_match_table,
  131. },
  132. };
  133. static int __init brcm_nvram_init(void)
  134. {
  135. return platform_driver_register(&brcm_nvram_driver);
  136. }
  137. subsys_initcall_sync(brcm_nvram_init);
  138. MODULE_AUTHOR("Rafał Miłecki");
  139. MODULE_LICENSE("GPL");
  140. MODULE_DEVICE_TABLE(of, brcm_nvram_of_match_table);