configs/am574x_idk_defconfig: new defconfig

This patch adds a basic support for AM574x Industrial Development Kit
[1].

Use multi_v7_defconfig as kernel configuration file instead of
the deprecated omap2plus_defconfig [2].

The main differences between upstream kernels and the TI vendor tree
(5.10.x based) are:

  - pru based 100M ethernet ports will not work with upstream kernels
  since the prueth driver for AM57 is not upstream yet (as of 6.8-rc2)
  [3].

  - The ARM/DSP examples provided by TI [4] will not work either since
  they requires an experimental patch [5] adding "remote-processor
  messaging sockets".

  - There is no support for the POWERVR GPU SGX544 that requires
  additional userpace vendor (closed source) libraries.

[1] https://www.ti.com/tool/TMDSIDK574
[2] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=cca9f6838bac3441a42fa906314bf5e3bff50ac5
[3] https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/commit/?id=792b57aac224416f66175c15d60379a4cf581d0f
[4] https://git.ti.com/cgit/processor-sdk/big-data-ipc-examples
[5] https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/commit/?id=f4b978a978c38149f712ddd137f12ed5fb914161

Signed-off-by: Romain Naour <romain.naour@smile.fr>
Reviewed-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Tested-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Romain Naour <romain.naour@smile.fr>

board/ti/am574x-idk/extlinux.conf

@@ -0,0 +1,4 @@
+label am5749-idk-buildroot
+  kernel /zImage
+  fdtdir /
+  append console=ttyS0,115200n8 root=/dev/mmcblk0p2 rw rootfstype=ext4 rootwait

board/ti/am574x-idk/genimage.cfg

@@ -0,0 +1,30 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"MLO",
+			"u-boot.img",
+			"zImage",
+			"am574x-idk.dtb",
+			"extlinux"
+		}
+	}
+
+	size = 16M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition u-boot {
+		partition-type = 0xC
+		bootable = "true"
+                image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+		size = 1G
+	}
+}

board/ti/am574x-idk/post-build.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+BOARD_DIR="$(dirname "$0")"
+
+install -m 0644 -D "${BOARD_DIR}"/extlinux.conf "${BINARIES_DIR}"/extlinux/extlinux.conf

board/ti/am574x-idk/readme.txt

@@ -0,0 +1,28 @@
+Texas Instuments AM574x IDK Test and Development Board
+
+Description
+===========
+
+This configuration will build a basic image for the TI AM574x IDK
+board: https://www.ti.com/tool/TMDSIDK574
+
+How to build it
+===============
+
+Configure Buildroot:
+
+    $ make am574x_idk_defconfig
+
+Compile everything and build the USB flash drive image:
+
+    $ make
+
+How to write the SD card
+========================
+
+Once the build process is finished you will have an image called "sdcard.img"
+in the output/images/ directory.
+
+Copy the bootable "sdcard.img" onto an SD card with "dd":
+
+  $ sudo dd if=output/images/sdcard.img of=/dev/sdX