LXR linux/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
  20struct atmel_sfr_priv {
  21        struct regmap                   *regmap;
  22};
  23
  24static 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
  33static 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
  42static 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
  77static 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};
  86MODULE_DEVICE_TABLE(of, atmel_sfr_dt_ids);
  87
  88static 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};
  95module_platform_driver(atmel_sfr_driver);
  96
  97MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
  98MODULE_DESCRIPTION("Atmel SFR SN driver for SAMA5D2/4 SoC family");
  99MODULE_LICENSE("GPL v2");
 100