From 93c3d329707e0d8dc98e5f86938bbedbe15b5349 Mon Sep 17 00:00:00 2001 From: Sean Anderson Date: Tue, 22 Mar 2022 17:16:05 -0400 Subject: ls1046ardb: Add support for JTAG boot This adds support for booting entirely from JTAG while using a hard-coded RCW. With these steps, it is not necessary to program a "good" RCW using CodeWarrior. The method here can be performed with any JTAG adapter supported by OpenOCD, including the on-board CMSIS-DAP (albeit very slowly). These steps require LS1046A support in OpenOCD, which was added in [1]. [1] https://sourceforge.net/p/openocd/code/ci/5b70c1f679755677c925b4e6dd2c3d8be4715717/ Signed-off-by: Sean Anderson [trini: Add reference to doc/board/nxp/ls1046ardb.rst] --- doc/board/nxp/ls1046ardb.rst | 73 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) (limited to 'doc/board') diff --git a/doc/board/nxp/ls1046ardb.rst b/doc/board/nxp/ls1046ardb.rst index e4499a13fb7..35465d00612 100644 --- a/doc/board/nxp/ls1046ardb.rst +++ b/doc/board/nxp/ls1046ardb.rst @@ -110,6 +110,79 @@ SD boot and eMMC boot ``{ SW5[0:8], SW4[0] }`` should be ``0010_0000_0``. eMMC is selected only if there is no SD card in the slot. +.. _ls1046ardb_jtag: + +JTAG boot +^^^^^^^^^ + +To recover a bricked board, or to perform initial programming, the ls1046 +supports using two hard-coded Reset Configuration Words (RCWs). Unfortunately, +this configuration disables most functionality, including the uarts and ethernet. +However, the SD/MMC and flash controllers are still functional. To get around +the lack of a serial console, we will use ARM semihosting instead. When +enabled, OpenOCD will interpret certain instructions as calls to the host +operating system. This allows U-Boot to use the console, read/write files, or +run arbitrary commands (!). + +When configuring U-Boot, ensure that ``CONFIG_SEMIHOSTING``, +``CONFIG_SPL_SEMIHOSTING``, and ``CONFIG_SEMIHOSTING_SERIAL`` are enabled. +``{ SW5[0:8], SW4[0] }`` should be ``0100_1111_0``. Additionally, ``SW4[7]`` +should be set to ``0``. Connect to the "console" USB connector on the front of +the enclosure. + +Create a new file called ``u-boot.tcl`` (or whatever you choose) with the +following contents:: + + # Load the configuration for the LS1046ARDB + source [find board/nxp_rdb-ls1046a.cfg] + # Initialize the scan chain + init + # Stop the processor + halt + # Enable semihosting + arm semihosting enable + # Load U-Boot SPL + load_image spl/u-boot-spl 0 elf + # Start executing SPL at the beginning of OCRAM + resume 0x10000000 + +Then, launch openocd like:: + + openocd -f u-boot.tcl + +You should see the U-boot SPL banner followed by the banner for U-Boot proper +in the output of openocd. The CMSIS-DAP adapter is slow, so this can take a +long time. If you don't see it, something has gone wrong. After a while, you +should see the prompt. You can load an image using semihosting by running:: + + => load hostfs - $loadaddr + +Note that openocd's terminal is "cooked," so commands will only be sent to +U-Boot when you press enter, and all commands will be echoed twice. +Additionally, openocd will block when waiting for input, ignoring gdb, JTAG +events, and Ctrl-Cs. To make openocd process these events, just hit enter. + +Using an external JTAG adapter +"""""""""""""""""""""""""""""" + +The CMSIS-DAP adapter can be rather slow. To speed up booting, use an external +JTAG adapter. The following examples assume you are using a J-Link, though any +adapter supported by OpenOCD will do. Ensure that ``SW4[7]`` is ``1``. Attach +your jtag adapter to J22. Modify ``u-boot.tcl`` and replace the first two lines +with the following:: + + # Load the J-Link configuration (or whatever your adapter is) + source [find interface/jlink.cfg] + # Use JTAG, since the J-Link also supports SWD + transport select jtag + # The reset pin resets the whole CPU + reset_config srst_only + # Load the LS1046A config + source [find target/ls1046a.cfg] + +You can proceed as normal through the rest of the steps above. I got a speedup +of around 100x by using a J-Link. + Debug UART ---------- -- cgit v1.2.3