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 is currently in the process of being upstreamed [1]. [1] https://review.openocd.org/c/openocd/+/6855 Signed-off-by: Sean Anderson <sean.ander...@seco.com> --- arch/arm/cpu/armv8/fsl-layerscape/spl.c | 2 + doc/board/nxp/ls1046ardb.rst | 71 +++++++++++++++++++++++++ include/configs/ls1046ardb.h | 2 + 3 files changed, 75 insertions(+) diff --git a/arch/arm/cpu/armv8/fsl-layerscape/spl.c b/arch/arm/cpu/armv8/fsl-layerscape/spl.c index 564cc27c8b..1a7dde30a5 100644 --- a/arch/arm/cpu/armv8/fsl-layerscape/spl.c +++ b/arch/arm/cpu/armv8/fsl-layerscape/spl.c @@ -27,6 +27,8 @@ DECLARE_GLOBAL_DATA_PTR; u32 spl_boot_device(void) { + if (IS_ENABLED(CONFIG_SPL_SEMIHOSTING)) + return BOOT_DEVICE_SMH; #ifdef CONFIG_SPL_MMC return BOOT_DEVICE_MMC1; #endif diff --git a/doc/board/nxp/ls1046ardb.rst b/doc/board/nxp/ls1046ardb.rst index c73516c070..ffb9d4550b 100644 --- a/doc/board/nxp/ls1046ardb.rst +++ b/doc/board/nxp/ls1046ardb.rst @@ -109,3 +109,74 @@ 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. + +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, and +``CONFIG_SYS_NS16550`` is disabled. ``{ 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 <name of file> + +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. diff --git a/include/configs/ls1046ardb.h b/include/configs/ls1046ardb.h index 8ed1dceb23..ed549c33b6 100644 --- a/include/configs/ls1046ardb.h +++ b/include/configs/ls1046ardb.h @@ -143,6 +143,8 @@ #endif #endif +#define CONFIG_SPL_FS_LOAD_PAYLOAD_NAME "u-boot.img" + #include <asm/fsl_secure_boot.h> #endif /* __LS1046ARDB_H__ */ -- 2.25.1
