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