On 5 October 2015 at 10:22, Daniel Thompson <daniel.thompson@xxxxxxxxxx> wrote: > On 4 October 2015 at 11:32, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: >> On Sat, Oct 3, 2015 at 10:35 PM, Daniel Thompson >> 3. I took out the datasheet for Nomadik STn8820 and it seems that >> the hardware is very similar to what this driver is trying to drive. >> CR, SR and DR are in the same place, can you check if you also even >> have the PrimeCell magic in the words at offset 0xfe0 thru 0xffc? > > The register window for the STM32 RNG is only 0x400 (and I'll fix the > DT for v2 ;-) ) so the STM32 version isn't primecell-like. > > >> In any case it seems likely that this driver should supercede and replace >> drivers/char/hw_random/nomadik-rng.c >> still using the PrimeCell bus, and if it doesn't have the PrimeCell >> IDs in hardware, this can be specified in the device tree using >> arm,primecell-periphid = <0x000805e1>; in the node if need be. >> The in-tree driver is dangerously simple and assume too much IMO. > > Not sure about this, but I'll take a closer look. There is a certain > family resemblance in the register set but there are significant > differences in data transfer between the Nomadik and STM32 hardware. Having looked at this I don't really think we would gain very much from combining these drivers. The cells have different (albeit slightly similar) register layouts, different ways to transfer data (16- versus 32-bit) and different ways to report test/report incorrect clocking. In the case of the RNG the differences therefore span the entire of its feature set. I think combining them just results in two drivers that happen to share a file and I dislike having to add "fake" information to the devicetree to make it hang together. Is that convincing for you? Daniel. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
