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