1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2022 Rafał Miłecki <rafal@milecki.pl>
4  */
5 
6 #include <linux/mod_devicetable.h>
7 #include <linux/module.h>
8 #include <linux/mtd/mtd.h>
9 #include <linux/nvmem-provider.h>
10 #include <linux/of.h>
11 #include <linux/platform_device.h>
12 #include <linux/slab.h>
13 
14 #include "layouts/u-boot-env.h"
15 
16 struct u_boot_env {
17 	struct device *dev;
18 	struct nvmem_device *nvmem;
19 	enum u_boot_env_format format;
20 
21 	struct mtd_info *mtd;
22 };
23 
u_boot_env_read(void * context,unsigned int offset,void * val,size_t bytes)24 static int u_boot_env_read(void *context, unsigned int offset, void *val,
25 			   size_t bytes)
26 {
27 	struct u_boot_env *priv = context;
28 	struct device *dev = priv->dev;
29 	size_t bytes_read;
30 	int err;
31 
32 	err = mtd_read(priv->mtd, offset, bytes, &bytes_read, val);
33 	if (err && !mtd_is_bitflip(err)) {
34 		dev_err(dev, "Failed to read from mtd: %d\n", err);
35 		return err;
36 	}
37 
38 	if (bytes_read != bytes) {
39 		dev_err(dev, "Failed to read %zu bytes\n", bytes);
40 		return -EIO;
41 	}
42 
43 	return 0;
44 }
45 
u_boot_env_probe(struct platform_device * pdev)46 static int u_boot_env_probe(struct platform_device *pdev)
47 {
48 	struct nvmem_config config = {
49 		.name = "u-boot-env",
50 		.reg_read = u_boot_env_read,
51 	};
52 	struct device *dev = &pdev->dev;
53 	struct device_node *np = dev->of_node;
54 	struct u_boot_env *priv;
55 
56 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
57 	if (!priv)
58 		return -ENOMEM;
59 	priv->dev = dev;
60 
61 	priv->format = (uintptr_t)of_device_get_match_data(dev);
62 
63 	priv->mtd = of_get_mtd_device_by_node(np);
64 	if (IS_ERR(priv->mtd)) {
65 		dev_err_probe(dev, PTR_ERR(priv->mtd), "Failed to get %pOF MTD\n", np);
66 		return PTR_ERR(priv->mtd);
67 	}
68 
69 	config.dev = dev;
70 	config.priv = priv;
71 	config.size = priv->mtd->size;
72 
73 	priv->nvmem = devm_nvmem_register(dev, &config);
74 	if (IS_ERR(priv->nvmem))
75 		return PTR_ERR(priv->nvmem);
76 
77 	return u_boot_env_parse(dev, priv->nvmem, priv->format);
78 }
79 
80 static const struct of_device_id u_boot_env_of_match_table[] = {
81 	{ .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_SINGLE, },
82 	{ .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
83 	{ .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
84 	{ .compatible = "brcm,env", .data = (void *)U_BOOT_FORMAT_BROADCOM, },
85 	{},
86 };
87 
88 static struct platform_driver u_boot_env_driver = {
89 	.probe = u_boot_env_probe,
90 	.driver = {
91 		.name = "u_boot_env",
92 		.of_match_table = u_boot_env_of_match_table,
93 	},
94 };
95 module_platform_driver(u_boot_env_driver);
96 
97 MODULE_AUTHOR("Rafał Miłecki");
98 MODULE_DESCRIPTION("U-Boot environment variables support module");
99 MODULE_LICENSE("GPL");
100 MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);
101