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 		.read_only = true,
40 		.reg_read = apple_efuses_read,
41 		.stride = sizeof(u32),
42 		.word_size = sizeof(u32),
43 		.name = "apple_efuses_nvmem",
44 		.id = NVMEM_DEVID_AUTO,
45 		.root_only = true,
46 	};
47 
48 	priv = devm_kzalloc(config.dev, sizeof(*priv), GFP_KERNEL);
49 	if (!priv)
50 		return -ENOMEM;
51 
52 	priv->fuses = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
53 	if (IS_ERR(priv->fuses))
54 		return PTR_ERR(priv->fuses);
55 
56 	config.priv = priv;
57 	config.size = resource_size(res);
58 
59 	return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config));
60 }
61 
62 static const struct of_device_id apple_efuses_of_match[] = {
63 	{ .compatible = "apple,efuses", },
64 	{}
65 };
66 
67 MODULE_DEVICE_TABLE(of, apple_efuses_of_match);
68 
69 static struct platform_driver apple_efuses_driver = {
70 	.driver = {
71 		.name = "apple_efuses",
72 		.of_match_table = apple_efuses_of_match,
73 	},
74 	.probe = apple_efuses_probe,
75 };
76 
77 module_platform_driver(apple_efuses_driver);
78 
79 MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
80 MODULE_LICENSE("GPL");
81