----- On 16 Jan, 2020, at 10:22, Sascha Hauer s.ha...@pengutronix.de wrote:
> On Thu, Jan 16, 2020 at 09:53:41AM +0100, Clément Leger wrote: >> Hi Sasha >> >> ----- On 16 Jan, 2020, at 09:25, Sascha Hauer s.ha...@pengutronix.de wrote: >> >> > Hi Clement, >> > >> > On Wed, Jan 15, 2020 at 11:26:45AM +0100, Clement Leger wrote: >> >> Kalray k1c core is embedded in Kalray Coolidge SoC. This core has the >> >> following features: >> >> - 32/64 bits >> >> - 6-issue VLIW architecture >> >> - 64 x 64bits general purpose registers >> >> - SIMD instructions >> >> - little-endian >> >> >> >> This port is a 64 bits one and allows to boot up to a barebox prompt on a >> >> k200 >> >> board. k1c support for clocksource and watchdog is also part of this port. >> >> >> >> In order to build a usable toolchain, build scripts are provided at the >> >> following address: https://github.com/kalray/build-scripts. >> >> >> >> Kalray uses FOSS which is available at https://github.com/kalray >> >> >> >> Clement Leger (5): >> >> k1c: Initial Kalray Coolidge (k1c) architecture support >> >> k1c: Add processor definitions >> >> k1c: Add support for device tree >> >> clocksource: k1c: Add k1c clocksource support >> >> watchdog: k1c: Add k1c watchdog support >> > >> > From a first look this is all pretty straight forward, looks good ;) >> > >> > barebox is entered at 0x0. According to the linker script and the device >> > tree you have 4MiB of SRAM there, right? >> >> Indeed, you are right, currently, with this setup the processor boots >> at address 0x0. >> Currently, this is used since the JTAG loader can only start an elf >> at address 0 (temporary limitation). The FSBL (First Stage boot loader) >> can however load the elf file at any address. >> >> I have a patch to locate all the barebox code in SDRAM which is used >> by the FSBL (see below) to load barebox in SDRAM. >> >> I can probably contribute this version if you prefer. Moreover, this will >> be the final usage so better get it ok right now. >> >> For your information about SoC memory map, the SDRAM is located at >> 0x100000000 and span on 64G, Additionally, 4G are mirrored at >> 0x80000000 for 32 bits compatibility. >> >> > >> > I don't see any SDRAM setup code in this series, nevertheless it is >> > used. How is SDRAM setup done? Is it done in ROM or is it some board >> > specific binary that runs before barebox? >> >> This is done using ROM code which runs before barebox. Boot flow is the >> following: >> - Processor boots in NOR SPI (XIP) >> - Execute ROM FSBL (First Stage Bootloader) which initialize needed >> peripherals (DDR, PCIe, etc) >> - Load SSBL (second stage bootloader) which is barebox ELF file in our case. >> - .dtb ELF section is patched by this bootloader using the device tree >> flashed into the board SPI NOR. >> - Then jumps to barebox. >> >> So the version I sent you is a bit different since it allow to have a >> builtin DTB. I wanted to be more standard with existing architecture. >> >> In our version, we have an empty .dtb section (which is of fixed size 24K). >> And the tools to load elf files (either the FSBL or JTAG tools) are >> flashing the right dtb (either from flash for FSBL or by board detection >> with JTAG) into the .dtb section. >> >> Tell me if you want me to stay the "standard" way with builtin DTB or if >> I can go with our way (fixed size .dtb section patched dynamically). > > Well, patching the barebox binary with a device tree is not very > standard at all ;) > > How about just passing the dtb as a pointer to barebox? You are probably > passing the device tree to linux as well, right? Maybe you can reuse > your Kernel calling convention for barebox? That way it wouldn't matter > if a started image is barebox or linux, it's both the same. Agreed, moreover, this is already done in our Linux port :) So to sumarize, I should keep the buitlin DTB mecanism + dtb passing via registers. Is it ok ? > >> >> > >> > Generally it seems that the board code is not very well separated from >> > the SoC code. Ideally barebox startup is like: >> > >> > - The entry point is board specific >> > - in this board specific code everything is done that is needed for a >> > properly running SoC with SDRAM enabled. This may require some helper >> > functions to be shared between boards >> > - the entry code jumps to the generic code, passing a pointer to >> > the device tree and if necessary SDRAM base/size >> > >> > With this setup we can build barebox images for multiple boards (or >> > multiple configurations of boards) in one go. As a developer you can >> > test on multiple boards without having to recompile. For a compile >> > tester it reduces the number of configurations to build (faster >> > results). For an integrator it reduces the number of barebox receipts to >> > keep track of. Overall it's worth implementing such a scheme. >> >> Actually, due to the fact we use device tree from the scratch, we don't >> have any board specific code. Almost everything is probed from the device >> tree. So we always have only one barebox binary which runs on multiple >> boards and the .dtb section is patched dynamically. > > Ok, that's good news. With that your barebox startup is just fine and > you don't need any multi image builds, at least as long as you do not > integrate the first stage loader into barebox ;) Yes ! > > Regards, > Sascha > > -- > Pengutronix e.K. | | > Steuerwalder Str. 21 | http://www.pengutronix.de/ | > 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox
