fastboot: add support for writing MBR

Add special target "mbr" (otherwise configurable via CONFIG_FASTBOOT_MBR_NAME)
to write MBR partition table.
Partitions are now searched using the generic function which finds any
partiiton by name. For MBR the partition names hda1, sda1, etc. are used.

Signed-off-by: Petr Kulhavy <brain@jikos.cz>
Reviewed-by: Tom Rini <trini@konsulko.com>
Acked-by: Steve Rae <steve.rae@raedomain.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

README

@@ -1683,6 +1683,13 @@ The following options need to be configured:
 		"fastboot flash" command line matches this value.
 		Default is GPT_ENTRY_NAME (currently "gpt") if undefined.
 
+		CONFIG_FASTBOOT_MBR_NAME
+		The fastboot "flash" command supports writing the downloaded
+		image to DOS MBR.
+		This occurs when the "partition name" specified on the
+		"fastboot flash" command line matches this value.
+		If not defined the default value "mbr" is used.
+
 - Journaling Flash filesystem support:
 		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
 		CONFIG_JFFS2_NAND_DEV

common/fb_mmc.c

@@ -14,15 +14,20 @@
 #include <mmc.h>
 #include <div64.h>
 
-#ifndef CONFIG_FASTBOOT_GPT_NAME
+#if defined(CONFIG_EFI_PARTITION) && !defined(CONFIG_FASTBOOT_GPT_NAME)
 #define CONFIG_FASTBOOT_GPT_NAME GPT_ENTRY_NAME
 #endif
 
+
+#if defined(CONFIG_DOS_PARTITION) && !defined(CONFIG_FASTBOOT_MBR_NAME)
+#define CONFIG_FASTBOOT_MBR_NAME "mbr"
+#endif
+
 struct fb_mmc_sparse {
 	struct blk_desc	*dev_desc;
 };
 
-static int part_get_info_efi_by_name_or_alias(struct blk_desc *dev_desc,
+static int part_get_info_by_name_or_alias(struct blk_desc *dev_desc,
 		const char *name, disk_partition_t *info)
 {
 	int ret;
@@ -103,6 +108,7 @@ void fb_mmc_flash_write(const char *cmd, void *download_buffer,
 		return;
 	}
 
+#ifdef CONFIG_EFI_PARTITION
 	if (strcmp(cmd, CONFIG_FASTBOOT_GPT_NAME) == 0) {
 		printf("%s: updating MBR, Primary and Backup GPT(s)\n",
 		       __func__);
@@ -114,14 +120,36 @@ void fb_mmc_flash_write(const char *cmd, void *download_buffer,
 		}
 		if (write_mbr_and_gpt_partitions(dev_desc, download_buffer)) {
 			printf("%s: writing GPT partitions failed\n", __func__);
-			fastboot_fail(
+			fastboot_fail("writing GPT partitions failed");
-				      "writing GPT partitions failed");
 			return;
 		}
 		printf("........ success\n");
 		fastboot_okay("");
 		return;
-	} else if (part_get_info_efi_by_name_or_alias(dev_desc, cmd, &info)) {
+	}
+#endif
+
+#ifdef CONFIG_DOS_PARTITION
+	if (strcmp(cmd, CONFIG_FASTBOOT_MBR_NAME) == 0) {
+		printf("%s: updating MBR\n", __func__);
+		if (is_valid_dos_buf(download_buffer)) {
+			printf("%s: invalid MBR - refusing to write to flash\n",
+			       __func__);
+			fastboot_fail("invalid MBR partition");
+			return;
+		}
+		if (write_mbr_partition(dev_desc, download_buffer)) {
+			printf("%s: writing MBR partition failed\n", __func__);
+			fastboot_fail("writing MBR partition failed");
+			return;
+		}
+		printf("........ success\n");
+		fastboot_okay("");
+		return;
+	}
+#endif
+
+	if (part_get_info_by_name_or_alias(dev_desc, cmd, &info)) {
 		error("cannot find partition: '%s'\n", cmd);
 		fastboot_fail("cannot find partition");
 		return;
@@ -172,7 +200,7 @@ void fb_mmc_erase(const char *cmd)
 		return;
 	}
 
-	ret = part_get_info_efi_by_name_or_alias(dev_desc, cmd, &info);
+	ret = part_get_info_by_name_or_alias(dev_desc, cmd, &info);
 	if (ret) {
 		error("cannot find partition: '%s'", cmd);
 		fastboot_fail("cannot find partition");

disk/part_dos.c

@@ -297,6 +297,26 @@ int part_get_info_dos(struct blk_desc *dev_desc, int part,
 	return part_get_info_extended(dev_desc, 0, 0, 1, part, info, 0);
 }
 
+int is_valid_dos_buf(void *buf)
+{
+	return test_block_type(buf) == DOS_MBR ? 0 : -1;
+}
+
+int write_mbr_partition(struct blk_desc *dev_desc, void *buf)
+{
+	if (is_valid_dos_buf(buf))
+		return -1;
+
+	/* write MBR */
+	if (blk_dwrite(dev_desc, 0, 1, buf) != 1) {
+		printf("%s: failed writing '%s' (1 blks at 0x0)\n",
+		       __func__, "MBR");
+		return 1;
+	}
+
+	return 0;
+}
+
 U_BOOT_PART_TYPE(dos) = {
 	.name		= "DOS",
 	.part_type	= PART_TYPE_DOS,

doc/README.android-fastboot

@@ -59,6 +59,43 @@ To define a partition alias add an environment variable similar to:
 fastboot_partition_alias_<alias partition name>=<actual partition name>
 Example: fastboot_partition_alias_boot=LNX
 
+Partition Names
+===============
+The Fastboot implementation in U-boot allows to write images into disk
+partitions (currently on eMMC). Target partitions are referred on the host
+computer by their names.
+
+For GPT/EFI the respective partition name is used.
+
+For MBR the partitions are referred by generic names according to the
+following schema:
+
+  <device type> <device index letter> <partition index>
+
+Example: hda3, sdb1, usbda1
+
+The device type is as follows:
+
+  * IDE, ATAPI and SATA disks: hd
+  * SCSI disks: sd
+  * USB media: usbd
+  * Disk on chip: docd
+  * other: xx
+
+The device index starts from 'a' and refers to the interface (e.g. USB
+controller, SD/MMC controller) or disk index. The partition index starts
+from 1 and describes the partition number on the particular device.
+
+Writing Partition Table
+=======================
+Fastboot also allows to write the partition table to the media. This can be
+done by writing the respective partition table image to a special target
+"gpt" or "mbr". These names can be customized by defining the following
+configuration options:
+
+CONFIG_FASTBOOT_GPT_NAME
+CONFIG_FASTBOOT_MBR_NAME
+
 In Action
 =========
 Enter into fastboot by executing the fastboot command in u-boot and you

include/part.h

@@ -351,4 +351,27 @@ int gpt_verify_partitions(struct blk_desc *dev_desc,
 			  gpt_header *gpt_head, gpt_entry **gpt_pte);
 #endif
 
+#ifdef CONFIG_DOS_PARTITION
+/**
+ * is_valid_dos_buf() - Ensure that a DOS MBR image is valid
+ *
+ * @param buf - buffer which contains the MBR
+ *
+ * @return - '0' on success, otherwise error
+ */
+int is_valid_dos_buf(void *buf);
+
+/**
+ * write_mbr_partition() - write DOS MBR
+ *
+ * @param dev_desc - block device descriptor
+ * @param buf - buffer which contains the MBR
+ *
+ * @return - '0' on success, otherwise error
+ */
+int write_mbr_partition(struct blk_desc *dev_desc, void *buf);
+
+#endif
+
+
 #endif /* _PART_H */