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
19struct atmel_sfr_priv {
20	struct regmap			*regmap;
21};
22
23static 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
32static 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
41static 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
76static 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};
85MODULE_DEVICE_TABLE(of, atmel_sfr_dt_ids);
86
87static 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};
94module_platform_driver(atmel_sfr_driver);
95
96MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
97MODULE_DESCRIPTION("Atmel SFR SN driver for SAMA5D2/4 SoC family");
98MODULE_LICENSE("GPL v2");
99