On Tuesday 11 March 2008 01:45, David Gibson wrote: > On Mon, Mar 10, 2008 at 12:00:22PM -0500, Rune Torgersen wrote: > > [EMAIL PROTECTED] wrote: > > > Hi everybody, > > > > > > as part of a ARCH=ppc to ARCH=powerpc migration process, I'm > > > looking for an > > > OpenFirmware compatible way to handle a RAM-based MTD device. > > > > > > On the platform_device based ppc architecture, the > > > drivers/mtd/maps/plat-ram.c > > > driver handled "mtd-ram" platform devices. There is no such > > > driver for the > > > OF-based powerpc architecture. > > > > > > As a temporary workaround I hacked the physmap_of driver to > > > handle "direct-mapped" OF devices oh type "ram" by adding a > > > corresponding entry in the of_flash_match[] array. This seems to work > > > fine. > > > > > > What would be the preferred way to handle OF-compatible RAM-based MTD > > > devices ? The 3 ways I can think of are > > > > > > 1. porting the plat-ram driver to OF (the driver isn't used > > > in the kernel tree > > > but I suspect it is used by out-of-tree boards) > > > > > > 2. creating a new plat-ram-of driver, much like the > > > physmap_of driver comes > > > from the physmap driver > > > > > > 3. extending the physmap_of driver to handle RAM devices (in > > > which case > > > references to "flash" in the function names should probably > > > be replaced > > > by "mtd") > > > > > > I live option 3 better so far. > > > > > > Has anyone already worked on this ? Is there any defined > > > device tree mapping > > > for MTD RAM devices ? > > > > We ran ito the same issue. > > We did option 3, as it was efinetly the easiest, > > I think this is the best option in principle.
I'll implement that and post a patch after completing the ppc-to-powerpc migration. > > here is the sram entry in our dts: > > Except that your implementation of it is not good. > > You're relying on the old obsolete flash binding with the "probe-type" > field. The solution should be adapted to the new approach which uses > values in the "compatible" field to indicate various sorts of flash > device. What "compatible" values should I use for ROM and RAM mappings ? Best regards, -- Laurent Pinchart CSE Semaphore Belgium Chaussée de Bruxelles, 732A B-1410 Waterloo Belgium T +32 (2) 387 42 59 F +32 (2) 387 42 75
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