Hello,
Currently southbridge/amd/cs5536/cs5536.c:chipset_flash_setup() sets up NAND flash if enable_ide_nand_flash is set to "1" in the device tree based on a static const structure in the same file - FlashInitTable.
The code itself supports having different NAND interfaces, specify extra NOR for the setup and so on, based on the struct values. However in practice this can't be used, because the struct is defined in the southbridge code, and can't be overriden by board specific dts files through any means - effectively telling things like "This board has NAND on CS1" is not possible.
Due to that the ArtecGroup ThinCan DBE61 and DBE62 do not set up NAND flash properly in coreboot-v3. They could have (and DBE62 does) enable_ide_nand_flash enabled in dts, but that enables it on CS0, and not on CS1.
I don't know how it's best to solve this. I think the most generic way would be to make the whole 4 member array struct definable or overridable in dts, but I don't think our dtc code supports anything like that - at best we could have a variable length array (cells) that is used for unwanted_vpci as well, telling that it has to come in three member chunks, where first tells the type, second the interface and third the (page size?) mask. But that is very suboptimal too - a zero would terminate the array immediately, the type is really an enum, not a 4 byte cell, etc.
Another option is to just assume there is only one NAND to enable, and give the chip select location in dts - this doesn't regress what is in practice currently supported, while being the minimum necessary to setup up NAND for ThinCan boards properly. An initial patch for that is attached.
Or maybe the call to chipset_flash_setup() should be pushed down to be the responsibility of board specific C code, so it could pass in its own FlashInitTable, after chipset_flash_setup is modified to take such a struct instead of using the file global const struct defined in the southbridge file?
Thoughts?
Mart Raudsepp Artec Design LLC