configs/warpboard: Generate an sdcard image

Generate an sdcard.img image to make it easier the deployment of a
Buildroot image.

[Peter: drop unneeded exit statement in post-image script]
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

board/freescale/warpboard/README

@@ -9,7 +9,9 @@ Build all components:
 
 You will find in ./output/images/ the following files:
   - imx6sl-warp.dtb
+  - rootfs.ext4
   - rootfs.tar
+  - sdcard.img
   - u-boot.imx
   - zImage
 
@@ -42,14 +44,16 @@ Update uboot
 Update linux & rootfs
 =====================
 
-Run the 'ums' command from the U-Boot prompt to mount the eMMC as mass
-storage and update zImage, device tree (imx6sl-warp.dtb) and rootfs
-file (rootfs.tar) :
+Run the 'ums' command from the U-Boot prompt to mount the eMMC as USB mass
+storage:
 
 => ums 0 mmc 0
 
-Put the zImage and DTB files in the warp-vfat partition and extract as
-root the rootfs.tar tarball in the warp-rootfs partition.
+And then flash the sdcard.img into the eMMC:
+
+  dd if=output/images/sdcard.img of=/dev/<your-sd-device>
+
+*** WARNING! This will destroy all the eMMC content. Use it with care! ***
 
 Using bluetooth
 ================

board/freescale/warpboard/genimage.cfg

@@ -0,0 +1,41 @@
+# Minimal SD card image for the Warp board
+#
+# We mimic the .sdcard Freescale's image format for i.MX6SL:
+# * the microSD card must have 1 kB free space at the beginning,
+# * U-Boot is dumped as is,
+# * a FAT partition at offset 8 MB is containing zImage and dtbs,
+# * a single root filesystem partition is required (Ext4 in this case).
+#
+
+image boot.vfat {
+  vfat {
+    files = {
+      "imx6sl-warp.dtb",
+      "zImage"
+    }
+  }
+  size = 16M
+}
+
+image sdcard.img {
+  hdimage {
+  }
+
+  partition u-boot {
+    in-partition-table = "no"
+    image = "u-boot.imx"
+    offset = 1024
+  }
+
+  partition boot {
+    partition-type = 0xC
+    bootable = "true"
+    image = "boot.vfat"
+    offset = 8M
+  }
+
+  partition rootfs {
+    partition-type = 0x83
+    image = "rootfs.ext4"
+  }
+}

board/freescale/warpboard/post-image.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+
+BOARD_DIR="$(dirname $0)"
+GENIMAGE_CFG="${BOARD_DIR}/genimage.cfg"
+GENIMAGE_TMP="${BUILD_DIR}/genimage.tmp"
+
+rm -rf "${GENIMAGE_TMP}"
+
+genimage \
+  --rootpath "${TARGET_DIR}" \
+  --tmppath "${GENIMAGE_TMP}" \
+  --inputpath "${BINARIES_DIR}" \
+  --outputpath "${BINARIES_DIR}" \
+  --config "${GENIMAGE_CFG}"

configs/warpboard_defconfig

@@ -37,3 +37,13 @@ BR2_TARGET_UBOOT_FORMAT_IMX=y
 # host utility
 BR2_PACKAGE_HOST_DFU_UTIL=y
 BR2_PACKAGE_HOST_IMX_USB_LOADER=y
+
+# Filesystem
+BR2_ROOTFS_POST_IMAGE_SCRIPT="board/freescale/warpboard/post-image.sh"
+BR2_TARGET_ROOTFS_EXT2=y
+BR2_TARGET_ROOTFS_EXT2_4=y
+
+# required tools to create the eMMC image
+BR2_PACKAGE_HOST_DOSFSTOOLS=y
+BR2_PACKAGE_HOST_GENIMAGE=y
+BR2_PACKAGE_HOST_MTOOLS=y