nvmem: u-boot-env: add Broadcom format support

Broadcom uses U-Boot for a lot of their bcmbca familiy chipsets. They
decided to store U-Boot environment data inside U-Boot partition and to
use a custom header (with "uEnv" magic and env data length).

Add support for Broadcom's specific binding and their custom format.

Ref: 6b0584c1 ("dt-bindings: nvmem: u-boot,env: add Broadcom's variant binding")
Signed-off-by: NRafał Miłecki <rafal@milecki.pl>
Signed-off-by: NSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20221118063932.6418-9-srinivas.kandagatla@linaro.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/nvmem/u-boot-env.c

@@ -16,6 +16,7 @@
 enum u_boot_env_format {
 	U_BOOT_FORMAT_SINGLE,
 	U_BOOT_FORMAT_REDUNDANT,
+	U_BOOT_FORMAT_BROADCOM,
 };
 
 struct u_boot_env {
@@ -40,6 +41,13 @@ struct u_boot_env_image_redundant {
 	uint8_t data[];
 } __packed;
 
+struct u_boot_env_image_broadcom {
+	__le32 magic;
+	__le32 len;
+	__le32 crc32;
+	uint8_t data[0];
+} __packed;
+
 static int u_boot_env_read(void *context, unsigned int offset, void *val,
 			   size_t bytes)
 {
@@ -138,6 +146,11 @@ static int u_boot_env_parse(struct u_boot_env *priv)
 		crc32_data_offset = offsetof(struct u_boot_env_image_redundant, data);
 		data_offset = offsetof(struct u_boot_env_image_redundant, data);
 		break;
+	case U_BOOT_FORMAT_BROADCOM:
+		crc32_offset = offsetof(struct u_boot_env_image_broadcom, crc32);
+		crc32_data_offset = offsetof(struct u_boot_env_image_broadcom, data);
+		data_offset = offsetof(struct u_boot_env_image_broadcom, data);
+		break;
 	}
 	crc32 = le32_to_cpu(*(__le32 *)(buf + crc32_offset));
 	crc32_data_len = priv->mtd->size - crc32_data_offset;
@@ -202,6 +215,7 @@ static const struct of_device_id u_boot_env_of_match_table[] = {
 	{ .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_SINGLE, },
 	{ .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
 	{ .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
+	{ .compatible = "brcm,env", .data = (void *)U_BOOT_FORMAT_BROADCOM, },
 	{},
 };