1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * sfr.c - driver for special function registers
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (C) 2019 Bootlin.
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun */
8*4882a593Smuzhiyun #include <linux/mfd/syscon.h>
9*4882a593Smuzhiyun #include <linux/module.h>
10*4882a593Smuzhiyun #include <linux/nvmem-provider.h>
11*4882a593Smuzhiyun #include <linux/random.h>
12*4882a593Smuzhiyun #include <linux/of.h>
13*4882a593Smuzhiyun #include <linux/of_device.h>
14*4882a593Smuzhiyun #include <linux/platform_device.h>
15*4882a593Smuzhiyun #include <linux/regmap.h>
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun #define SFR_SN0 0x4c
18*4882a593Smuzhiyun #define SFR_SN_SIZE 8
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun struct atmel_sfr_priv {
21*4882a593Smuzhiyun struct regmap *regmap;
22*4882a593Smuzhiyun };
23*4882a593Smuzhiyun
atmel_sfr_read(void * context,unsigned int offset,void * buf,size_t bytes)24*4882a593Smuzhiyun static int atmel_sfr_read(void *context, unsigned int offset,
25*4882a593Smuzhiyun void *buf, size_t bytes)
26*4882a593Smuzhiyun {
27*4882a593Smuzhiyun struct atmel_sfr_priv *priv = context;
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun return regmap_bulk_read(priv->regmap, SFR_SN0 + offset,
30*4882a593Smuzhiyun buf, bytes / 4);
31*4882a593Smuzhiyun }
32*4882a593Smuzhiyun
33*4882a593Smuzhiyun static struct nvmem_config atmel_sfr_nvmem_config = {
34*4882a593Smuzhiyun .name = "atmel-sfr",
35*4882a593Smuzhiyun .read_only = true,
36*4882a593Smuzhiyun .word_size = 4,
37*4882a593Smuzhiyun .stride = 4,
38*4882a593Smuzhiyun .size = SFR_SN_SIZE,
39*4882a593Smuzhiyun .reg_read = atmel_sfr_read,
40*4882a593Smuzhiyun };
41*4882a593Smuzhiyun
atmel_sfr_probe(struct platform_device * pdev)42*4882a593Smuzhiyun static int atmel_sfr_probe(struct platform_device *pdev)
43*4882a593Smuzhiyun {
44*4882a593Smuzhiyun struct device *dev = &pdev->dev;
45*4882a593Smuzhiyun struct device_node *np = dev->of_node;
46*4882a593Smuzhiyun struct nvmem_device *nvmem;
47*4882a593Smuzhiyun struct atmel_sfr_priv *priv;
48*4882a593Smuzhiyun u8 sn[SFR_SN_SIZE];
49*4882a593Smuzhiyun int ret;
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun priv = devm_kmalloc(dev, sizeof(*priv), GFP_KERNEL);
52*4882a593Smuzhiyun if (!priv)
53*4882a593Smuzhiyun return -ENOMEM;
54*4882a593Smuzhiyun
55*4882a593Smuzhiyun priv->regmap = syscon_node_to_regmap(np);
56*4882a593Smuzhiyun if (IS_ERR(priv->regmap)) {
57*4882a593Smuzhiyun dev_err(dev, "cannot get parent's regmap\n");
58*4882a593Smuzhiyun return PTR_ERR(priv->regmap);
59*4882a593Smuzhiyun }
60*4882a593Smuzhiyun
61*4882a593Smuzhiyun atmel_sfr_nvmem_config.dev = dev;
62*4882a593Smuzhiyun atmel_sfr_nvmem_config.priv = priv;
63*4882a593Smuzhiyun
64*4882a593Smuzhiyun nvmem = devm_nvmem_register(dev, &atmel_sfr_nvmem_config);
65*4882a593Smuzhiyun if (IS_ERR(nvmem)) {
66*4882a593Smuzhiyun dev_err(dev, "error registering nvmem config\n");
67*4882a593Smuzhiyun return PTR_ERR(nvmem);
68*4882a593Smuzhiyun }
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun ret = atmel_sfr_read(priv, 0, sn, SFR_SN_SIZE);
71*4882a593Smuzhiyun if (ret == 0)
72*4882a593Smuzhiyun add_device_randomness(sn, SFR_SN_SIZE);
73*4882a593Smuzhiyun
74*4882a593Smuzhiyun return ret;
75*4882a593Smuzhiyun }
76*4882a593Smuzhiyun
77*4882a593Smuzhiyun static const struct of_device_id atmel_sfr_dt_ids[] = {
78*4882a593Smuzhiyun {
79*4882a593Smuzhiyun .compatible = "atmel,sama5d2-sfr",
80*4882a593Smuzhiyun }, {
81*4882a593Smuzhiyun .compatible = "atmel,sama5d4-sfr",
82*4882a593Smuzhiyun }, {
83*4882a593Smuzhiyun /* sentinel */
84*4882a593Smuzhiyun },
85*4882a593Smuzhiyun };
86*4882a593Smuzhiyun MODULE_DEVICE_TABLE(of, atmel_sfr_dt_ids);
87*4882a593Smuzhiyun
88*4882a593Smuzhiyun static struct platform_driver atmel_sfr_driver = {
89*4882a593Smuzhiyun .probe = atmel_sfr_probe,
90*4882a593Smuzhiyun .driver = {
91*4882a593Smuzhiyun .name = "atmel-sfr",
92*4882a593Smuzhiyun .of_match_table = atmel_sfr_dt_ids,
93*4882a593Smuzhiyun },
94*4882a593Smuzhiyun };
95*4882a593Smuzhiyun module_platform_driver(atmel_sfr_driver);
96*4882a593Smuzhiyun
97*4882a593Smuzhiyun MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
98*4882a593Smuzhiyun MODULE_DESCRIPTION("Atmel SFR SN driver for SAMA5D2/4 SoC family");
99*4882a593Smuzhiyun MODULE_LICENSE("GPL v2");
100