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