xref: /openbmc/linux/drivers/soc/atmel/sfr.c (revision 11795e02)
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