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