On Wed, Feb 3, 2016 at 10:40 AM, Trent Piepho <tpie...@kymetacorp.com> wrote: > On Tue, 2016-02-02 at 17:14 -0800, Andrey Smirnov wrote: >> On Mon, Feb 1, 2016 at 11:18 AM, Trent Piepho <tpie...@kymetacorp.com> wrote: >> > The way imx28 works in the kernel is to just store the extension in the >> > OCOTP. The OUI is determined from the board's compatible property and a >> > hard coded table in the kernel. See arch/arm/mach-mxs/mach-mxs.c >> > >> > While, IMHO, the hard coded table is ugly, and should have died long >> > ago, there are board that don't have the entire mac burned into OCOTP. >> > It seems like neither of these bindings could support a board like this. >> > >> >> What if you created a 'nvmem' provider whose only job is to take a >> blob from DT, a phandle to another 'nvmem' provider and to return the >> combined data from both sources. Wouldn't it work for the use-case you >> are describing? > > Not sure what it would look like, example?
I am thinking of something similar to what you describe in "nvmem" thread. You'd have a software scatter-gather "engine" that would just take a description of multiple small chunks of memory and represent it as a continuous property accessible via "nvmem" API. Something like: mac-address-node { compatible = "nvmem-sg" composite_mac: mac@0 { reg = <&nvmem1_cell 0x0 0x4 &nvmem2_cell 0x0 0x2 >; }; }; So you'd get a 'composite_mac' nvmem-cell that in term is comprised of 4 bytes @ offset 0x0 of "nvmem1_cell" and 2 bytes @ offset 0x0 of "nvmem2_cell". > > One thing about the imx28 OCOTP is that the entire MAC isn't in the > OCOTP. The OUI part comes from "elsewhere". > > In the current kernel, that elsewhere is a hardcoded /board/compatible > to OUI mapping. What I did was use the mac-address property to store > the OUI. I think that makes a lot more sense. Actually, storing the > whole MAC in the ocotp would have made a lot more sense! But it's one > time programmable and that's the way all the boards were made. > >From looking at the mach-mxs.c and assuming I didn't miss any important details (which is a big if), it seems to me that it would still be possible to cover this use-case by introducing(or extending 'nvmem' driver) an additional "nvmem" compatible entity whose only job would be is to present data hard coded in its corresponding DT-node via "nvmem" API. So, say for example for apf28(OUI_ARMADEUS) you'd have something like: board-oui-node { board_oui_cell: oui_cell@0 { immediate-data = [0x00 0x1e 0xac]; }; }; and then you should be able to use <&board_oui_cell> in the scatter-gatherer node from above. Andrey _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox