drivers/nvmem/apple-efuses.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Apple SoC eFuse driver
   4  *
   5  * Copyright (C) The Asahi Linux Contributors
   6  */
   7
   8 #include <linux/io.h>
   9 #include <linux/mod_devicetable.h>
  10 #include <linux/module.h>
  11 #include <linux/nvmem-provider.h>
  12 #include <linux/platform_device.h>
  13
  14 struct apple_efuses_priv {
  15         void __iomem *fuses;
  16 };
  17
  18 static int apple_efuses_read(void *context, unsigned int offset, void *val,
  19                              size_t bytes)
  20 {
  21         struct apple_efuses_priv *priv = context;
  22         u32 *dst = val;
  23
  24         while (bytes >= sizeof(u32)) {
  25                 *dst++ = readl_relaxed(priv->fuses + offset);
  26                 bytes -= sizeof(u32);
  27                 offset += sizeof(u32);
  28         }
  29
  30         return 0;
  31 }
  32
  33 static int apple_efuses_probe(struct platform_device *pdev)
  34 {
  35         struct apple_efuses_priv *priv;
  36         struct resource *res;
  37         struct nvmem_config config = {
  38                 .dev = &pdev->dev,
  39                 .add_legacy_fixed_of_cells = true,
  40                 .read_only = true,
  41                 .reg_read = apple_efuses_read,
  42                 .stride = sizeof(u32),
  43                 .word_size = sizeof(u32),
  44                 .name = "apple_efuses_nvmem",
  45                 .id = NVMEM_DEVID_AUTO,
  46                 .root_only = true,
  47         };
  48
  49         priv = devm_kzalloc(config.dev, sizeof(*priv), GFP_KERNEL);
  50         if (!priv)
  51                 return -ENOMEM;
  52
  53         priv->fuses = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
  54         if (IS_ERR(priv->fuses))
  55                 return PTR_ERR(priv->fuses);
  56
  57         config.priv = priv;
  58         config.size = resource_size(res);
  59
  60         return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config));
  61 }
  62
  63 static const struct of_device_id apple_efuses_of_match[] = {
  64         { .compatible = "apple,efuses", },
  65         {}
  66 };
  67
  68 MODULE_DEVICE_TABLE(of, apple_efuses_of_match);
  69
  70 static struct platform_driver apple_efuses_driver = {
  71         .driver = {
  72                 .name = "apple_efuses",
  73                 .of_match_table = apple_efuses_of_match,
  74         },
  75         .probe = apple_efuses_probe,
  76 };
  77
  78 module_platform_driver(apple_efuses_driver);
  79
  80 MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
  81 MODULE_DESCRIPTION("Apple SoC eFuse driver");
  82 MODULE_LICENSE("GPL");