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