1*c3277f8eSKamel Bouhara // SPDX-License-Identifier: GPL-2.0-only
2*c3277f8eSKamel Bouhara /*
3*c3277f8eSKamel Bouhara * sfr.c - driver for special function registers
4*c3277f8eSKamel Bouhara *
5*c3277f8eSKamel Bouhara * Copyright (C) 2019 Bootlin.
6*c3277f8eSKamel Bouhara *
7*c3277f8eSKamel Bouhara */
8*c3277f8eSKamel Bouhara #include <linux/mfd/syscon.h>
9*c3277f8eSKamel Bouhara #include <linux/module.h>
10*c3277f8eSKamel Bouhara #include <linux/nvmem-provider.h>
11*c3277f8eSKamel Bouhara #include <linux/random.h>
12*c3277f8eSKamel Bouhara #include <linux/of.h>
13*c3277f8eSKamel Bouhara #include <linux/platform_device.h>
14*c3277f8eSKamel Bouhara #include <linux/regmap.h>
15*c3277f8eSKamel Bouhara
16*c3277f8eSKamel Bouhara #define SFR_SN0 0x4c
17*c3277f8eSKamel Bouhara #define SFR_SN_SIZE 8
18*c3277f8eSKamel Bouhara
19*c3277f8eSKamel Bouhara struct atmel_sfr_priv {
20*c3277f8eSKamel Bouhara struct regmap *regmap;
21*c3277f8eSKamel Bouhara };
22*c3277f8eSKamel Bouhara
atmel_sfr_read(void * context,unsigned int offset,void * buf,size_t bytes)23*c3277f8eSKamel Bouhara static int atmel_sfr_read(void *context, unsigned int offset,
24*c3277f8eSKamel Bouhara void *buf, size_t bytes)
25*c3277f8eSKamel Bouhara {
26*c3277f8eSKamel Bouhara struct atmel_sfr_priv *priv = context;
27*c3277f8eSKamel Bouhara
28*c3277f8eSKamel Bouhara return regmap_bulk_read(priv->regmap, SFR_SN0 + offset,
29*c3277f8eSKamel Bouhara buf, bytes / 4);
30*c3277f8eSKamel Bouhara }
31*c3277f8eSKamel Bouhara
32*c3277f8eSKamel Bouhara static struct nvmem_config atmel_sfr_nvmem_config = {
33*c3277f8eSKamel Bouhara .name = "atmel-sfr",
34*c3277f8eSKamel Bouhara .read_only = true,
35*c3277f8eSKamel Bouhara .word_size = 4,
36*c3277f8eSKamel Bouhara .stride = 4,
37*c3277f8eSKamel Bouhara .size = SFR_SN_SIZE,
38*c3277f8eSKamel Bouhara .reg_read = atmel_sfr_read,
39*c3277f8eSKamel Bouhara };
40*c3277f8eSKamel Bouhara
atmel_sfr_probe(struct platform_device * pdev)41*c3277f8eSKamel Bouhara static int atmel_sfr_probe(struct platform_device *pdev)
42*c3277f8eSKamel Bouhara {
43*c3277f8eSKamel Bouhara struct device *dev = &pdev->dev;
44*c3277f8eSKamel Bouhara struct device_node *np = dev->of_node;
45*c3277f8eSKamel Bouhara struct nvmem_device *nvmem;
46*c3277f8eSKamel Bouhara struct atmel_sfr_priv *priv;
47*c3277f8eSKamel Bouhara u8 sn[SFR_SN_SIZE];
48*c3277f8eSKamel Bouhara int ret;
49*c3277f8eSKamel Bouhara
50*c3277f8eSKamel Bouhara priv = devm_kmalloc(dev, sizeof(*priv), GFP_KERNEL);
51*c3277f8eSKamel Bouhara if (!priv)
52*c3277f8eSKamel Bouhara return -ENOMEM;
53*c3277f8eSKamel Bouhara
54*c3277f8eSKamel Bouhara priv->regmap = syscon_node_to_regmap(np);
55*c3277f8eSKamel Bouhara if (IS_ERR(priv->regmap)) {
56*c3277f8eSKamel Bouhara dev_err(dev, "cannot get parent's regmap\n");
57*c3277f8eSKamel Bouhara return PTR_ERR(priv->regmap);
58*c3277f8eSKamel Bouhara }
59*c3277f8eSKamel Bouhara
60*c3277f8eSKamel Bouhara atmel_sfr_nvmem_config.dev = dev;
61*c3277f8eSKamel Bouhara atmel_sfr_nvmem_config.priv = priv;
62*c3277f8eSKamel Bouhara
63*c3277f8eSKamel Bouhara nvmem = devm_nvmem_register(dev, &atmel_sfr_nvmem_config);
64*c3277f8eSKamel Bouhara if (IS_ERR(nvmem)) {
65*c3277f8eSKamel Bouhara dev_err(dev, "error registering nvmem config\n");
66*c3277f8eSKamel Bouhara return PTR_ERR(nvmem);
67*c3277f8eSKamel Bouhara }
68*c3277f8eSKamel Bouhara
69*c3277f8eSKamel Bouhara ret = atmel_sfr_read(priv, 0, sn, SFR_SN_SIZE);
70*c3277f8eSKamel Bouhara if (ret == 0)
71*c3277f8eSKamel Bouhara add_device_randomness(sn, SFR_SN_SIZE);
72*c3277f8eSKamel Bouhara
73*c3277f8eSKamel Bouhara return ret;
74*c3277f8eSKamel Bouhara }
75*c3277f8eSKamel Bouhara
76*c3277f8eSKamel Bouhara static const struct of_device_id atmel_sfr_dt_ids[] = {
77*c3277f8eSKamel Bouhara {
78*c3277f8eSKamel Bouhara .compatible = "atmel,sama5d2-sfr",
79*c3277f8eSKamel Bouhara }, {
80*c3277f8eSKamel Bouhara .compatible = "atmel,sama5d4-sfr",
81*c3277f8eSKamel Bouhara }, {
82*c3277f8eSKamel Bouhara /* sentinel */
83*c3277f8eSKamel Bouhara },
84*c3277f8eSKamel Bouhara };
85*c3277f8eSKamel Bouhara MODULE_DEVICE_TABLE(of, atmel_sfr_dt_ids);
86*c3277f8eSKamel Bouhara
87*c3277f8eSKamel Bouhara static struct platform_driver atmel_sfr_driver = {
88*c3277f8eSKamel Bouhara .probe = atmel_sfr_probe,
89*c3277f8eSKamel Bouhara .driver = {
90*c3277f8eSKamel Bouhara .name = "atmel-sfr",
91*c3277f8eSKamel Bouhara .of_match_table = atmel_sfr_dt_ids,
92*c3277f8eSKamel Bouhara },
93*c3277f8eSKamel Bouhara };
94*c3277f8eSKamel Bouhara module_platform_driver(atmel_sfr_driver);
95*c3277f8eSKamel Bouhara
96*c3277f8eSKamel Bouhara MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
97*c3277f8eSKamel Bouhara MODULE_DESCRIPTION("Atmel SFR SN driver for SAMA5D2/4 SoC family");
98*c3277f8eSKamel Bouhara MODULE_LICENSE("GPL v2");
99