On Thu, Mar 26, 2009 at 11:02:06AM -0600, Grant Likely wrote: [] > >> Here is another thought. The binding is describing that address lines > >> are used to activate CS lines. Offset for chip access purposes is > >> derived from the address line, but it doesn't directly describe the > >> hardware. The following may be a better description of the hardware. > >> > >> fsl,upm-addr-line-cs = <9 10>; > > > > The TQM8548 hardware has some logic connected to the two address lines > > allowing to select up to 4 chips with two address lines: > > > > fsl,upm-addr-line-cs-offsets = <0x0 0x200 0x400 0x600> > > Ah. I see. This is board specific then. I think it is premature to > try and define a generic solution here because it depends on custom > board hardware and different boards could use very different logic. > The next board could end up doing something completely different. I'd > rather start to see trends in multiple boards implementing the same > scheme before trying to craft a generic scheme. > > In other words, this device is not register-level compatible with the > fsl,upm-nand device. Give the node a new compatible value > (tqc,tqm8548-upm-nand) and add another entry to the of_fun_match table > for the new device. Use the .data element in the match table to > supply an alternate fun_cmd_ctrl() function for this board (instead of > using a property value do decide which fun_cmd_ctrl() behaviour to > use). New boards that *do* use the same addressing scheme can claim > compatibility with tqc,tqm8548-upm-nand.
I don't like this. :-/ UPM is an universal thing, so there are thousands of ways we can connect NAND to the UPM. Of which only ~10 would be sane (others are insane, and nobody would do this. If they do, _then_ we'll fall back to <board>-upm-nand scheme for a particular board). I don't see any problem with fsl,upm-addr-line-cs-offsets. It can describe any scheme in "addr lines are cs" connection, it's a common setup for multi-chip memory, we shouldn't treat it is as something extraordinary. -- Anton Vorontsov email: cbouatmai...@gmail.com irc://irc.freenode.net/bd2 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
