Hi Michal, On 7/3/22 2:20 PM, Michal Suchanek wrote: > > Hello, > > many ARM SoCs have a mask rom feature that provides interface for > downloading firmware over USB. > > Downstream rockchip u-boot has 'brom' or 'rbrom' command for this > purpose, and downstream sunxi u-boot provides 'efex' command. p-boot has > code for entering FEL on A64 SoC. > > With this patch I am able to activate the USB downloader on a rk3399 but > the rkflashtool fails to communicate with the device. On a H2+ I can get > into the FEL mode and get flash parameters. YMMV > > I don't have any great idea how to structure this so that the command > does not need platform-specific code. Is there an example of a command > that has platform-specific implementations?
Generally you would do this by having the driver interact with some DM uclass. Platforms may or may not provide a driver implementing that uclass; the details are hidden behind the uclass's interface. All the command has to do is search for a DM device by uclass, and if one is found, call some operation on it. In this case, UCLASS_REBOOT_MODE already exists. It sounds like what we need is the inverse of dm_reboot_mode_update() -- a function that takes a string and programs the device with the corresponding mode value. To be generic, you could call this function from do_reset() if some positional argument is provided, allowing usage like "reset bootloader" or "reset fel". Rockchip platforms already have syscon-reboot-mode hooked up in their devicetrees. The driver for this should be trivial. Allwinner platforms would need to add a nvmem-reboot-mode node, and a bit more driver infrastructure. U-Boot does not have NVMEM uclass, so you would need to add one or reuse UCLASS_MISC. Regards, Samuel
