1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2022 Rafał Miłecki <rafal@milecki.pl>
  4 */
  5
  6#include <linux/crc32.h>
  7#include <linux/etherdevice.h>
  8#include <linux/if_ether.h>
  9#include <linux/mod_devicetable.h>
 10#include <linux/module.h>
 11#include <linux/mtd/mtd.h>
 12#include <linux/nvmem-consumer.h>
 13#include <linux/nvmem-provider.h>
 14#include <linux/of.h>
 15#include <linux/platform_device.h>
 16#include <linux/slab.h>
 17
 18enum u_boot_env_format {
 19	U_BOOT_FORMAT_SINGLE,
 20	U_BOOT_FORMAT_REDUNDANT,
 21	U_BOOT_FORMAT_BROADCOM,
 22};
 23
 24struct u_boot_env {
 25	struct device *dev;
 26	struct nvmem_device *nvmem;
 27	enum u_boot_env_format format;
 28
 29	struct mtd_info *mtd;
 30};
 31
 32struct u_boot_env_image_single {
 33	__le32 crc32;
 34	uint8_t data[];
 35} __packed;
 36
 37struct u_boot_env_image_redundant {
 38	__le32 crc32;
 39	u8 mark;
 40	uint8_t data[];
 41} __packed;
 42
 43struct u_boot_env_image_broadcom {
 44	__le32 magic;
 45	__le32 len;
 46	__le32 crc32;
 47	DECLARE_FLEX_ARRAY(uint8_t, data);
 48} __packed;
 49
 50static int u_boot_env_read(void *context, unsigned int offset, void *val,
 51			   size_t bytes)
 52{
 53	struct u_boot_env *priv = context;
 54	struct device *dev = priv->dev;
 55	size_t bytes_read;
 56	int err;
 57
 58	err = mtd_read(priv->mtd, offset, bytes, &bytes_read, val);
 59	if (err && !mtd_is_bitflip(err)) {
 60		dev_err(dev, "Failed to read from mtd: %d\n", err);
 61		return err;
 62	}
 63
 64	if (bytes_read != bytes) {
 65		dev_err(dev, "Failed to read %zu bytes\n", bytes);
 66		return -EIO;
 67	}
 68
 69	return 0;
 70}
 71
 72static int u_boot_env_read_post_process_ethaddr(void *context, const char *id, int index,
 73						unsigned int offset, void *buf, size_t bytes)
 74{
 75	u8 mac[ETH_ALEN];
 76
 77	if (bytes != 3 * ETH_ALEN - 1)
 78		return -EINVAL;
 79
 80	if (!mac_pton(buf, mac))
 81		return -EINVAL;
 82
 83	if (index)
 84		eth_addr_add(mac, index);
 85
 86	ether_addr_copy(buf, mac);
 87
 88	return 0;
 89}
 90
 91static int u_boot_env_add_cells(struct u_boot_env *priv, uint8_t *buf,
 92				size_t data_offset, size_t data_len)
 93{
 94	struct nvmem_device *nvmem = priv->nvmem;
 95	struct device *dev = priv->dev;
 96	char *data = buf + data_offset;
 97	char *var, *value, *eq;
 98
 99	for (var = data;
100	     var < data + data_len && *var;
101	     var = value + strlen(value) + 1) {
102		struct nvmem_cell_info info = {};
103
104		eq = strchr(var, '=');
105		if (!eq)
106			break;
107		*eq = '\0';
108		value = eq + 1;
109
110		info.name = devm_kstrdup(dev, var, GFP_KERNEL);
111		if (!info.name)
112			return -ENOMEM;
113		info.offset = data_offset + value - data;
114		info.bytes = strlen(value);
115		info.np = of_get_child_by_name(dev->of_node, info.name);
116		if (!strcmp(var, "ethaddr")) {
117			info.raw_len = strlen(value);
118			info.bytes = ETH_ALEN;
119			info.read_post_process = u_boot_env_read_post_process_ethaddr;
120		}
121
122		nvmem_add_one_cell(nvmem, &info);
123	}
124
125	return 0;
126}
127
128static int u_boot_env_parse(struct u_boot_env *priv)
129{
130	struct nvmem_device *nvmem = priv->nvmem;
131	struct device *dev = priv->dev;
132	size_t crc32_data_offset;
133	size_t crc32_data_len;
134	size_t crc32_offset;
135	__le32 *crc32_addr;
136	size_t data_offset;
137	size_t data_len;
138	size_t dev_size;
139	uint32_t crc32;
140	uint32_t calc;
141	uint8_t *buf;
142	int bytes;
143	int err;
144
145	dev_size = nvmem_dev_size(nvmem);
146
147	buf = kzalloc(dev_size, GFP_KERNEL);
148	if (!buf) {
149		err = -ENOMEM;
150		goto err_out;
151	}
152
153	bytes = nvmem_device_read(nvmem, 0, dev_size, buf);
154	if (bytes < 0) {
155		err = bytes;
156		goto err_kfree;
157	} else if (bytes != dev_size) {
158		err = -EIO;
159		goto err_kfree;
160	}
161
162	switch (priv->format) {
163	case U_BOOT_FORMAT_SINGLE:
164		crc32_offset = offsetof(struct u_boot_env_image_single, crc32);
165		crc32_data_offset = offsetof(struct u_boot_env_image_single, data);
166		data_offset = offsetof(struct u_boot_env_image_single, data);
167		break;
168	case U_BOOT_FORMAT_REDUNDANT:
169		crc32_offset = offsetof(struct u_boot_env_image_redundant, crc32);
170		crc32_data_offset = offsetof(struct u_boot_env_image_redundant, data);
171		data_offset = offsetof(struct u_boot_env_image_redundant, data);
172		break;
173	case U_BOOT_FORMAT_BROADCOM:
174		crc32_offset = offsetof(struct u_boot_env_image_broadcom, crc32);
175		crc32_data_offset = offsetof(struct u_boot_env_image_broadcom, data);
176		data_offset = offsetof(struct u_boot_env_image_broadcom, data);
177		break;
178	}
179	crc32_addr = (__le32 *)(buf + crc32_offset);
180	crc32 = le32_to_cpu(*crc32_addr);
181	crc32_data_len = dev_size - crc32_data_offset;
182	data_len = dev_size - data_offset;
183
184	calc = crc32(~0, buf + crc32_data_offset, crc32_data_len) ^ ~0L;
185	if (calc != crc32) {
186		dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 0x%08x)\n", calc, crc32);
187		err = -EINVAL;
188		goto err_kfree;
189	}
190
191	buf[dev_size - 1] = '\0';
192	err = u_boot_env_add_cells(priv, buf, data_offset, data_len);
193
194err_kfree:
195	kfree(buf);
196err_out:
197	return err;
198}
199
200static int u_boot_env_probe(struct platform_device *pdev)
201{
202	struct nvmem_config config = {
203		.name = "u-boot-env",
204		.reg_read = u_boot_env_read,
205	};
206	struct device *dev = &pdev->dev;
207	struct device_node *np = dev->of_node;
208	struct u_boot_env *priv;
209
210	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
211	if (!priv)
212		return -ENOMEM;
213	priv->dev = dev;
214
215	priv->format = (uintptr_t)of_device_get_match_data(dev);
216
217	priv->mtd = of_get_mtd_device_by_node(np);
218	if (IS_ERR(priv->mtd)) {
219		dev_err_probe(dev, PTR_ERR(priv->mtd), "Failed to get %pOF MTD\n", np);
220		return PTR_ERR(priv->mtd);
221	}
222
223	config.dev = dev;
224	config.priv = priv;
225	config.size = priv->mtd->size;
226
227	priv->nvmem = devm_nvmem_register(dev, &config);
228	if (IS_ERR(priv->nvmem))
229		return PTR_ERR(priv->nvmem);
230
231	return u_boot_env_parse(priv);
232}
233
234static const struct of_device_id u_boot_env_of_match_table[] = {
235	{ .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_SINGLE, },
236	{ .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
237	{ .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
238	{ .compatible = "brcm,env", .data = (void *)U_BOOT_FORMAT_BROADCOM, },
239	{},
240};
241
242static struct platform_driver u_boot_env_driver = {
243	.probe = u_boot_env_probe,
244	.driver = {
245		.name = "u_boot_env",
246		.of_match_table = u_boot_env_of_match_table,
247	},
248};
249module_platform_driver(u_boot_env_driver);
250
251MODULE_AUTHOR("Rafał Miłecki");
252MODULE_LICENSE("GPL");
253MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);