From 99b6b83230277ccf6541de107ce33cfb706e1d5b Mon Sep 17 00:00:00 2001 From: Denis 'GNUtoo' Carikli Date: Sun, 21 Dec 2025 20:04:47 +0100 Subject: [PATCH] gnu: bootloader: Add u-boot-am335x-evm-bootloader. * gnu/bootloader/u-boot.scm (u-boot-am335x-evm-bootloader): New exported variable. Change-Id: I258f7b7b31e7b7597710b8ff30d7a5ed882e147c Signed-off-by: Denis 'GNUtoo' Carikli Signed-off-by: Vagrant Cascadian --- gnu/bootloader/u-boot.scm | 70 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) diff --git a/gnu/bootloader/u-boot.scm b/gnu/bootloader/u-boot.scm index 349bb72418..5d341e97fe 100644 --- a/gnu/bootloader/u-boot.scm +++ b/gnu/bootloader/u-boot.scm @@ -36,6 +36,7 @@ u-boot-a20-olinuxino-lime2-bootloader u-boot-a20-olinuxino-micro-bootloader u-boot-bananapi-m2-ultra-bootloader + u-boot-am335x-evm-bootloader u-boot-beaglebone-black-bootloader u-boot-cubietruck-bootloader u-boot-firefly-rk3399-bootloader @@ -97,6 +98,48 @@ is BLOCK-SIZE * COUNT, or FILE size if COUNT is not given." (if bootloader (error "Failed to install U-Boot")))) +(define install-am335x-evm-u-boot + (write-u-boot-image + ;; According to the "26.1.8.5.5 MMC/SD Read Sector Procedure in Raw Mode" + ;; section in the "AM335x and AMIC110 Sitara™ Processors Technical + ;; Reference Manual", we have offset, the bootrom tries to load code at the + ;; offsets 0x0, 0x20000 (128KB), 0x40000 (256KB) and 0x60000 (384KB). + ;; + ;; The MBR is 512 Bytes + ;; (https://en.wikipedia.org/wiki/Master_boot_record#Sector_layout). + ;; + ;; At the time of writing, u-boot.img is 1.4 MiB, and it is at offset + ;; 0x60000 (384KB) as per CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR. + ;; + ;; We also need to align the first partition to make sure read/writes are + ;; properly aligned. + ;; + ;; Given these constraints, we chose the following partitioning: + ;; + ;; 0 512 Bytes 128 KiB + ;; | | (0x20000) 256 KiB + ;; | | / (0x40000) 384 KiB 4 MiB + ;; | | / | (0x60000) | + ;; | | / | | | + ;; v v / v v v + ;; +-------+ +--------------+---------------+----------------+ + ;; | MBR | ... | First MLO | Second MLO | u-boot.img | + ;; +-------+ +--------------+---------------+----------------+ + ;; <-512 B-> ... <-- 128 KiB --> <-- 128 KiB --> <-- 3712 KiB --> + ;; + ;; The rationale for that is as follows: + ;; + ;; - We add a second copy of the MLO at 256 KiB for improving reliability + ;; as the doc/board/ti/am335x_evm.rst documentation in u-boot advise us + ;; to do that, and also because the space there isn't used. + ;; + ;; - All can fit into 2MiB (u-boot.img can grow up to 1664 KiB), but we + ;; want a bit more space in case u-boot.img grows over time, so we allow + ;; u-boot to grow until the 4 MiB offset. + '(("MLO" 256 256) ;; First MLO + ("MLO" 256 512) ;; Second MLO + ("u-boot.img" 7424 768)) 512)) + (define install-beaglebone-black-u-boot ;; http://wiki.beyondlogic.org/index.php?title=BeagleBoneBlack_Upgrading_uBoot ;; This first stage bootloader called MLO (U-Boot SPL) is expected at @@ -158,6 +201,33 @@ is BLOCK-SIZE * COUNT, or FILE size if COUNT is not given." (installer #f) (disk-image-installer install-u-boot))) +(define u-boot-am335x-evm-bootloader + (bootloader + (inherit u-boot-bootloader) + ;; This bootloader supports the following computers: + ;; - SanCloud BeagleBone Enhanced + ;; - SanCloud BeagleBone Enhanced Extended WiFi + ;; - SanCloud BeagleBone Enhanced Lite + ;; - Seeed Studio BeagleBone Green Eco + ;; - TI AM3359 ICE-V2 + ;; - TI AM335x BeagleBone + ;; - TI AM335x BeagleBone Black + ;; - TI AM335x BeagleBone Green + ;; - TI AM335x EVM + ;; - TI AM335x EVM-SK + ;; - TI AM335x PocketBeagle + ;; + ;; This list was made by retrieving the list of Devicetrees used in + ;; configs/am335x_evm_defconfig in u-boot source code. Once we have that we + ;; can look at each Devicetree in arch/arm/boot/dts/ti/omap/ inside Linux, + ;; and in each file, look at the model property to find the name of the + ;; computers that this image supports. + (package u-boot-am335x-evm) + ;; At the time of writing, our u-boot.img is 1.4 MiB. This is why we can't + ;; reuse install-beaglebone-black-u-boot. And having the same image being + ;; able to boot on multiple computers is useful. + (disk-image-installer install-am335x-evm-u-boot))) + (define u-boot-beaglebone-black-bootloader (bootloader (inherit u-boot-bootloader)