cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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sfr.c (2253B)

      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");