drivers/soc/atmel/sfr.c

   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/platform_device.h>
  14 #include <linux/regmap.h>
  15
  16 #define SFR_SN0         0x4c
  17 #define SFR_SN_SIZE     8
  18
  19 struct atmel_sfr_priv {
  20         struct regmap                   *regmap;
  21 };
  22
  23 static int atmel_sfr_read(void *context, unsigned int offset,
  24                           void *buf, size_t bytes)
  25 {
  26         struct atmel_sfr_priv *priv = context;
  27
  28         return regmap_bulk_read(priv->regmap, SFR_SN0 + offset,
  29                                 buf, bytes / 4);
  30 }
  31
  32 static struct nvmem_config atmel_sfr_nvmem_config = {
  33         .name = "atmel-sfr",
  34         .read_only = true,
  35         .word_size = 4,
  36         .stride = 4,
  37         .size = SFR_SN_SIZE,
  38         .reg_read = atmel_sfr_read,
  39 };
  40
  41 static int atmel_sfr_probe(struct platform_device *pdev)
  42 {
  43         struct device *dev = &pdev->dev;
  44         struct device_node *np = dev->of_node;
  45         struct nvmem_device *nvmem;
  46         struct atmel_sfr_priv *priv;
  47         u8 sn[SFR_SN_SIZE];
  48         int ret;
  49
  50         priv = devm_kmalloc(dev, sizeof(*priv), GFP_KERNEL);
  51         if (!priv)
  52                 return -ENOMEM;
  53
  54         priv->regmap = syscon_node_to_regmap(np);
  55         if (IS_ERR(priv->regmap)) {
  56                 dev_err(dev, "cannot get parent's regmap\n");
  57                 return PTR_ERR(priv->regmap);
  58         }
  59
  60         atmel_sfr_nvmem_config.dev = dev;
  61         atmel_sfr_nvmem_config.priv = priv;
  62
  63         nvmem = devm_nvmem_register(dev, &atmel_sfr_nvmem_config);
  64         if (IS_ERR(nvmem)) {
  65                 dev_err(dev, "error registering nvmem config\n");
  66                 return PTR_ERR(nvmem);
  67         }
  68
  69         ret = atmel_sfr_read(priv, 0, sn, SFR_SN_SIZE);
  70         if (ret == 0)
  71                 add_device_randomness(sn, SFR_SN_SIZE);
  72
  73         return ret;
  74 }
  75
  76 static const struct of_device_id atmel_sfr_dt_ids[] = {
  77         {
  78                 .compatible = "atmel,sama5d2-sfr",
  79         }, {
  80                 .compatible = "atmel,sama5d4-sfr",
  81         }, {
  82                 /* sentinel */
  83         },
  84 };
  85 MODULE_DEVICE_TABLE(of, atmel_sfr_dt_ids);
  86
  87 static struct platform_driver atmel_sfr_driver = {
  88         .probe = atmel_sfr_probe,
  89         .driver = {
  90                 .name = "atmel-sfr",
  91                 .of_match_table = atmel_sfr_dt_ids,
  92         },
  93 };
  94 module_platform_driver(atmel_sfr_driver);
  95
  96 MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
  97 MODULE_DESCRIPTION("Atmel SFR SN driver for SAMA5D2/4 SoC family");
  98 MODULE_LICENSE("GPL v2");