u-boot-env.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2022 - 2023 Rafał Miłecki <rafal@milecki.pl>
  4 */
  5
  6#include <linux/crc32.h>
  7#include <linux/etherdevice.h>
  8#include <linux/export.h>
  9#include <linux/if_ether.h>
 10#include <linux/nvmem-consumer.h>
 11#include <linux/nvmem-provider.h>
 12#include <linux/of.h>
 13#include <linux/slab.h>
 14
 15#include "u-boot-env.h"
 16
 17struct u_boot_env_image_single {
 18	__le32 crc32;
 19	uint8_t data[];
 20} __packed;
 21
 22struct u_boot_env_image_redundant {
 23	__le32 crc32;
 24	u8 mark;
 25	uint8_t data[];
 26} __packed;
 27
 28struct u_boot_env_image_broadcom {
 29	__le32 magic;
 30	__le32 len;
 31	__le32 crc32;
 32	DECLARE_FLEX_ARRAY(uint8_t, data);
 33} __packed;
 34
 35static int u_boot_env_read_post_process_ethaddr(void *context, const char *id, int index,
 36						unsigned int offset, void *buf, size_t bytes)
 37{
 38	u8 mac[ETH_ALEN];
 39
 40	if (bytes != MAC_ADDR_STR_LEN)
 41		return -EINVAL;
 42
 43	if (!mac_pton(buf, mac))
 44		return -EINVAL;
 45
 46	if (index)
 47		eth_addr_add(mac, index);
 48
 49	ether_addr_copy(buf, mac);
 50
 51	return 0;
 52}
 53
 54static int u_boot_env_parse_cells(struct device *dev, struct nvmem_device *nvmem, uint8_t *buf,
 55				  size_t data_offset, size_t data_len)
 56{
 57	char *data = buf + data_offset;
 58	char *var, *value, *eq;
 59
 60	for (var = data;
 61	     var < data + data_len && *var;
 62	     var = value + strlen(value) + 1) {
 63		struct nvmem_cell_info info = {};
 64
 65		eq = strchr(var, '=');
 66		if (!eq)
 67			break;
 68		*eq = '\0';
 69		value = eq + 1;
 70
 71		info.name = devm_kstrdup(dev, var, GFP_KERNEL);
 72		if (!info.name)
 73			return -ENOMEM;
 74		info.offset = data_offset + value - data;
 75		info.bytes = strlen(value);
 76		info.np = of_get_child_by_name(dev->of_node, info.name);
 77		if (!strcmp(var, "ethaddr")) {
 78			info.raw_len = strlen(value);
 79			info.bytes = ETH_ALEN;
 80			info.read_post_process = u_boot_env_read_post_process_ethaddr;
 81		}
 82
 83		nvmem_add_one_cell(nvmem, &info);
 84	}
 85
 86	return 0;
 87}
 88
 89int u_boot_env_parse(struct device *dev, struct nvmem_device *nvmem,
 90		     enum u_boot_env_format format)
 91{
 92	size_t crc32_data_offset;
 93	size_t crc32_data_len;
 94	size_t crc32_offset;
 95	uint32_t *crc32_addr;
 96	size_t data_offset;
 97	size_t data_len;
 98	size_t dev_size;
 99	uint32_t crc32;
100	uint32_t calc;
101	uint8_t *buf;
102	u32 env_size;
103	int bytes;
104	int err;
105
106	dev_size = device_property_read_u32(dev, "env-size", &env_size) ?
107		nvmem_dev_size(nvmem) : (size_t)env_size;
108
109	buf = kzalloc(dev_size, GFP_KERNEL);
110	if (!buf) {
111		err = -ENOMEM;
112		goto err_out;
113	}
114
115	bytes = nvmem_device_read(nvmem, 0, dev_size, buf);
116	if (bytes < 0) {
117		err = bytes;
118		goto err_kfree;
119	} else if (bytes != dev_size) {
120		err = -EIO;
121		goto err_kfree;
122	}
123
124	switch (format) {
125	case U_BOOT_FORMAT_SINGLE:
126		crc32_offset = offsetof(struct u_boot_env_image_single, crc32);
127		crc32_data_offset = offsetof(struct u_boot_env_image_single, data);
128		data_offset = offsetof(struct u_boot_env_image_single, data);
129		break;
130	case U_BOOT_FORMAT_REDUNDANT:
131		crc32_offset = offsetof(struct u_boot_env_image_redundant, crc32);
132		crc32_data_offset = offsetof(struct u_boot_env_image_redundant, data);
133		data_offset = offsetof(struct u_boot_env_image_redundant, data);
134		break;
135	case U_BOOT_FORMAT_BROADCOM:
136		crc32_offset = offsetof(struct u_boot_env_image_broadcom, crc32);
137		crc32_data_offset = offsetof(struct u_boot_env_image_broadcom, data);
138		data_offset = offsetof(struct u_boot_env_image_broadcom, data);
139		break;
140	}
141
142	if (dev_size < data_offset) {
143		dev_err(dev, "Device too small for u-boot-env\n");
144		err = -EIO;
145		goto err_kfree;
146	}
147
148	crc32_addr = (uint32_t *)(buf + crc32_offset);
149	crc32 = *crc32_addr;
150	crc32_data_len = dev_size - crc32_data_offset;
151	data_len = dev_size - data_offset;
152
153	calc = crc32_le(~0, buf + crc32_data_offset, crc32_data_len) ^ ~0L;
154	if (calc != crc32) {
155		dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 0x%08x)\n", calc, crc32);
156		err = -EINVAL;
157		goto err_kfree;
158	}
159
160	buf[dev_size - 1] = '\0';
161	err = u_boot_env_parse_cells(dev, nvmem, buf, data_offset, data_len);
162
163err_kfree:
164	kfree(buf);
165err_out:
166	return err;
167}
168EXPORT_SYMBOL_GPL(u_boot_env_parse);
169
170static int u_boot_env_add_cells(struct nvmem_layout *layout)
171{
172	struct device *dev = &layout->dev;
173	enum u_boot_env_format format;
174
175	format = (uintptr_t)device_get_match_data(dev);
176
177	return u_boot_env_parse(dev, layout->nvmem, format);
178}
179
180static int u_boot_env_probe(struct nvmem_layout *layout)
181{
182	layout->add_cells = u_boot_env_add_cells;
183
184	return nvmem_layout_register(layout);
185}
186
187static void u_boot_env_remove(struct nvmem_layout *layout)
188{
189	nvmem_layout_unregister(layout);
190}
191
192static const struct of_device_id u_boot_env_of_match_table[] = {
193	{ .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_SINGLE, },
194	{ .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
195	{ .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
196	{ .compatible = "brcm,env", .data = (void *)U_BOOT_FORMAT_BROADCOM, },
197	{},
198};
199
200static struct nvmem_layout_driver u_boot_env_layout = {
201	.driver = {
202		.name = "u-boot-env-layout",
203		.of_match_table = u_boot_env_of_match_table,
204	},
205	.probe = u_boot_env_probe,
206	.remove = u_boot_env_remove,
207};
208module_nvmem_layout_driver(u_boot_env_layout);
209
210MODULE_AUTHOR("Rafał Miłecki");
211MODULE_LICENSE("GPL");
212MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);
213MODULE_DESCRIPTION("NVMEM layout driver for U-Boot environment variables");