From 4c033eb07442959ed76d769fd2b4649612327155 Mon Sep 17 00:00:00 2001
From: Harunobu Kurokawa <harunobu.kurokawa.dn@renesas.com>
Date: Fri, 5 May 2023 14:49:51 +0900
Subject: [PATCH] rpi-cmdline, rpi-u-boot-src: Support USB boot

The Raspberry Pi 4 board can boot the image from USB memory.
But current meta-raspberrypi supports only SD boot.

This commit allows switching SD boot to other device.
For example, if you want to use USB boot, please define
the following parameters in your conf/local.conf file.
CMDLINE_ROOT_PARTITION = "/dev/sda2"
BOOT_MEDIA = "usb"

v4: Update extra-build-config.md to explain more detail for new variable.

v3: Changed variable name to "BOOT_MEDIA" (was "BOOT_DEVTIPE").

v2: Set existing microSD parameter as default. User can overwrite
some parameters.

Signed-off-by: Harunobu Kurokawa <harunobu.kurokawa.dn@renesas.com>
---
 docs/extra-build-config.md                   | 16 ++++++++++++++++
 recipes-bsp/bootfiles/rpi-cmdline.bb         |  4 +++-
 recipes-bsp/rpi-u-boot-scr/files/boot.cmd.in |  4 ++--
 recipes-bsp/rpi-u-boot-scr/rpi-u-boot-scr.bb |  3 +++
 4 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/docs/extra-build-config.md b/docs/extra-build-config.md
index dc5d33a..3d66ffd 100644
--- a/docs/extra-build-config.md
+++ b/docs/extra-build-config.md
@@ -74,6 +74,22 @@ To remove (or adjust) this delay set these variables in local.conf:
     BOOT_DELAY = "0"
     BOOT_DELAY_MS = "0"
 
+## Boot media
+
+The Raspberry Pi 4 board can load the boot image files from SD card and USB memory.
+By default SD card media is used as boot media.
+
+To switch the boot media from SD card to USB memory, the following variables are supported
+in local.conf: `CMDLINE_ROOT_PARTITION` and `BOOT_MEDIA`.
+The default value of `CMDLINE_ROOT_PARTITION` is "/dev/mmcblk0p2" to mount SD card. If you want to mount USB memory partition, set CMDLINE_ROOT_PARTITION to "/dev/sda2".
+`BOOT_MEDIA` allows  `mmc` and `usb`. The "mmc" is required to load an image from the SD card, following the u-boot specification. Similarly, if you want to load a boot image file from USB memory, set BOOT_MEDIA to "usb".
+
+For example, if you want to use USB boot, please define
+the following parameters in your local.conf file.
+
+    CMDLINE_ROOT_PARTITION = "/dev/sda2"
+    BOOT_MEDIA = "usb"
+
 ## Set overclocking options
 
 The Raspberry Pi can be overclocked. As of now overclocking up to the "Turbo
diff --git a/recipes-bsp/bootfiles/rpi-cmdline.bb b/recipes-bsp/bootfiles/rpi-cmdline.bb
index 3ff8251..a22f50d 100644
--- a/recipes-bsp/bootfiles/rpi-cmdline.bb
+++ b/recipes-bsp/bootfiles/rpi-cmdline.bb
@@ -9,7 +9,9 @@ inherit deploy nopackages
 CMDLINE_DWC_OTG ?= "dwc_otg.lpm_enable=0"
 
 CMDLINE_ROOT_FSTYPE ?= "rootfstype=ext4"
-CMDLINE_ROOTFS ?= "root=/dev/mmcblk0p2 ${CMDLINE_ROOT_FSTYPE} rootwait"
+CMDLINE_ROOT_PARTITION ?= "/dev/mmcblk0p2"
+
+CMDLINE_ROOTFS ?= "root=${CMDLINE_ROOT_PARTITION} ${CMDLINE_ROOT_FSTYPE} rootwait"
 
 CMDLINE_SERIAL ?= "${@oe.utils.conditional("ENABLE_UART", "1", "console=serial0,115200", "", d)}"
 
diff --git a/recipes-bsp/rpi-u-boot-scr/files/boot.cmd.in b/recipes-bsp/rpi-u-boot-scr/files/boot.cmd.in
index 627d181..58fd86a 100644
--- a/recipes-bsp/rpi-u-boot-scr/files/boot.cmd.in
+++ b/recipes-bsp/rpi-u-boot-scr/files/boot.cmd.in
@@ -1,4 +1,4 @@
 fdt addr ${fdt_addr} && fdt get value bootargs /chosen bootargs
-fatload mmc 0:1 ${kernel_addr_r} @@KERNEL_IMAGETYPE@@
-if test ! -e mmc 0:1 uboot.env; then saveenv; fi;
+fatload @@BOOT_MEDIA@@ 0:1 ${kernel_addr_r} @@KERNEL_IMAGETYPE@@
+if test ! -e @@BOOT_MEDIA@@ 0:1 uboot.env; then saveenv; fi;
 @@KERNEL_BOOTCMD@@ ${kernel_addr_r} - ${fdt_addr}
diff --git a/recipes-bsp/rpi-u-boot-scr/rpi-u-boot-scr.bb b/recipes-bsp/rpi-u-boot-scr/rpi-u-boot-scr.bb
index 9108f71..1dff808 100644
--- a/recipes-bsp/rpi-u-boot-scr/rpi-u-boot-scr.bb
+++ b/recipes-bsp/rpi-u-boot-scr/rpi-u-boot-scr.bb
@@ -9,9 +9,12 @@ INHIBIT_DEFAULT_DEPS = "1"
 
 SRC_URI = "file://boot.cmd.in"
 
+BOOT_MEDIA ?= "mmc"
+
 do_compile() {
     sed -e 's/@@KERNEL_IMAGETYPE@@/${KERNEL_IMAGETYPE}/' \
         -e 's/@@KERNEL_BOOTCMD@@/${KERNEL_BOOTCMD}/' \
+        -e 's/@@BOOT_MEDIA@@/${BOOT_MEDIA}/' \
         "${WORKDIR}/boot.cmd.in" > "${WORKDIR}/boot.cmd"
     mkimage -A ${UBOOT_ARCH} -T script -C none -n "Boot script" -d "${WORKDIR}/boot.cmd" boot.scr
 }