fastboot: add command to select the eMMC boot configuration

Add command oem bootbus which executes the command
``mmc bootbus <id> <arg>`` on the current fastboot mmc device
(<i> = CONFIG_FASTBOOT_FLASH_MMC_DEV) to set the eMMC boot
configuration on first update, with
<arg> =  boot_bus_width reset_boot_bus_width boot_mode

$> fastboot oem bootbus:<boot_bus_width> <reset_boot_bus_width> <boot_mode>

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
diff --git a/doc/android/fastboot.rst b/doc/android/fastboot.rst
index d8cb642..16b1139 100644
--- a/doc/android/fastboot.rst
+++ b/doc/android/fastboot.rst
@@ -25,6 +25,7 @@
 - ``oem format`` - this executes ``gpt write mmc %x $partitions``
 - ``oem partconf`` - this executes ``mmc partconf %x <arg> 0`` to configure eMMC
   with <arg> = boot_ack boot_partition
+- ``oem bootbus``  - this executes ``mmc bootbus %x %s`` to configure eMMC
 
 Support for both eMMC and NAND devices is included.
 
diff --git a/drivers/fastboot/Kconfig b/drivers/fastboot/Kconfig
index 1bcc8d4..a17e488 100644
--- a/drivers/fastboot/Kconfig
+++ b/drivers/fastboot/Kconfig
@@ -196,6 +196,13 @@
 	  Add support for the "oem partconf" command from a client. This set
 	  the mmc boot-partition for the selecting eMMC device.
 
+config FASTBOOT_CMD_OEM_BOOTBUS
+	bool "Enable the 'oem bootbus' command"
+	depends on FASTBOOT_FLASH_MMC && SUPPORT_EMMC_BOOT
+	help
+	  Add support for the "oem bootbus" command from a client. This set
+	  the mmc boot configuration for the selecting eMMC device.
+
 endif # FASTBOOT
 
 endmenu
diff --git a/drivers/fastboot/fb_command.c b/drivers/fastboot/fb_command.c
index ae4a7dc..41fc8d7 100644
--- a/drivers/fastboot/fb_command.c
+++ b/drivers/fastboot/fb_command.c
@@ -45,6 +45,9 @@
 #if CONFIG_IS_ENABLED(FASTBOOT_CMD_OEM_PARTCONF)
 static void oem_partconf(char *, char *);
 #endif
+#if CONFIG_IS_ENABLED(FASTBOOT_CMD_OEM_BOOTBUS)
+static void oem_bootbus(char *, char *);
+#endif
 
 static const struct {
 	const char *command;
@@ -108,6 +111,12 @@
 		.dispatch = oem_partconf,
 	},
 #endif
+#if CONFIG_IS_ENABLED(FASTBOOT_CMD_OEM_BOOTBUS)
+	[FASTBOOT_COMMAND_OEM_BOOTBUS] = {
+		.command = "oem bootbus",
+		.dispatch = oem_bootbus,
+	},
+#endif
 };
 
 /**
@@ -410,3 +419,30 @@
 		fastboot_okay(NULL, response);
 }
 #endif
+
+#if CONFIG_IS_ENABLED(FASTBOOT_CMD_OEM_BOOTBUS)
+/**
+ * oem_bootbus() - Execute the OEM bootbus command
+ *
+ * @cmd_parameter: Pointer to command parameter
+ * @response: Pointer to fastboot response buffer
+ */
+static void oem_bootbus(char *cmd_parameter, char *response)
+{
+	char cmdbuf[32];
+
+	if (!cmd_parameter) {
+		fastboot_fail("Expected command parameter", response);
+		return;
+	}
+
+	/* execute 'mmc bootbus' command with cmd_parameter arguments*/
+	snprintf(cmdbuf, sizeof(cmdbuf), "mmc bootbus %x %s",
+		 CONFIG_FASTBOOT_FLASH_MMC_DEV, cmd_parameter);
+	printf("Execute: %s\n", cmdbuf);
+	if (run_command(cmdbuf, 0))
+		fastboot_fail("Cannot set oem bootbus", response);
+	else
+		fastboot_okay(NULL, response);
+}
+#endif
diff --git a/include/fastboot.h b/include/fastboot.h
index 80dd825..797d7df 100644
--- a/include/fastboot.h
+++ b/include/fastboot.h
@@ -41,6 +41,9 @@
 #if CONFIG_IS_ENABLED(FASTBOOT_CMD_OEM_PARTCONF)
 	FASTBOOT_COMMAND_OEM_PARTCONF,
 #endif
+#if CONFIG_IS_ENABLED(FASTBOOT_CMD_OEM_BOOTBUS)
+	FASTBOOT_COMMAND_OEM_BOOTBUS,
+#endif
 
 	FASTBOOT_COMMAND_COUNT
 };