xref: /openbmc/linux/drivers/nvmem/apple-efuses.c (revision 26e2fe4c)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Apple SoC eFuse driver
4  *
5  * Copyright (C) The Asahi Linux Contributors
6  */
7 
8 #include <linux/io.h>
9 #include <linux/mod_devicetable.h>
10 #include <linux/module.h>
11 #include <linux/nvmem-provider.h>
12 #include <linux/platform_device.h>
13 
14 struct apple_efuses_priv {
15 	void __iomem *fuses;
16 };
17 
apple_efuses_read(void * context,unsigned int offset,void * val,size_t bytes)18 static int apple_efuses_read(void *context, unsigned int offset, void *val,
19 			     size_t bytes)
20 {
21 	struct apple_efuses_priv *priv = context;
22 	u32 *dst = val;
23 
24 	while (bytes >= sizeof(u32)) {
25 		*dst++ = readl_relaxed(priv->fuses + offset);
26 		bytes -= sizeof(u32);
27 		offset += sizeof(u32);
28 	}
29 
30 	return 0;
31 }
32 
apple_efuses_probe(struct platform_device * pdev)33 static int apple_efuses_probe(struct platform_device *pdev)
34 {
35 	struct apple_efuses_priv *priv;
36 	struct resource *res;
37 	struct nvmem_config config = {
38 		.dev = &pdev->dev,
39 		.add_legacy_fixed_of_cells = true,
40 		.read_only = true,
41 		.reg_read = apple_efuses_read,
42 		.stride = sizeof(u32),
43 		.word_size = sizeof(u32),
44 		.name = "apple_efuses_nvmem",
45 		.id = NVMEM_DEVID_AUTO,
46 		.root_only = true,
47 	};
48 
49 	priv = devm_kzalloc(config.dev, sizeof(*priv), GFP_KERNEL);
50 	if (!priv)
51 		return -ENOMEM;
52 
53 	priv->fuses = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
54 	if (IS_ERR(priv->fuses))
55 		return PTR_ERR(priv->fuses);
56 
57 	config.priv = priv;
58 	config.size = resource_size(res);
59 
60 	return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config));
61 }
62 
63 static const struct of_device_id apple_efuses_of_match[] = {
64 	{ .compatible = "apple,efuses", },
65 	{}
66 };
67 
68 MODULE_DEVICE_TABLE(of, apple_efuses_of_match);
69 
70 static struct platform_driver apple_efuses_driver = {
71 	.driver = {
72 		.name = "apple_efuses",
73 		.of_match_table = apple_efuses_of_match,
74 	},
75 	.probe = apple_efuses_probe,
76 };
77 
78 module_platform_driver(apple_efuses_driver);
79 
80 MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
81 MODULE_LICENSE("GPL");
82