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