On Monday 08 December 2014 16:23:01 Rafał Miłecki wrote: > On 8 December 2014 at 16:03, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > > Hi Rafał, > > > > On Mon, Dec 8, 2014 at 3:47 PM, Rafał Miłecki <zajec5@xxxxxxxxx> wrote: > >> On 8 December 2014 at 15:41, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > >>> On Mon, Dec 8, 2014 at 3:27 PM, Rafał Miłecki <zajec5@xxxxxxxxx> wrote: > >>>> SN54HC595 and SN74HC595 are devices based on shift registers controlled > >>>> with 5 input signals (serial-in) and providing 8 outputs (parallel-out). > >>>> > >>>> They are present on some Broadcom home router boards where manufacturer > >>>> needed few extra GPIOs. > >>>> > >>>> This driver simply uses specified GPIOs to control shift registers and > >>>> registers another GPIO chip. So you can call it a GPIO extender. > >>>> > >>>> Due to the hardware design only output direction is supported. Reading > >>>> values is handled using tiny internal cache. > >>>> > >>>> Signed-off-by: Rafał Miłecki <zajec5@xxxxxxxxx> > >>>> --- > >>>> .../devicetree/bindings/gpio/gpio-sn54hc595.txt | 35 ++++ > >>>> drivers/gpio/Kconfig | 11 ++ > >>>> drivers/gpio/Makefile | 1 + > >>>> drivers/gpio/gpio-sn54hc595.c | 219 +++++++++++++++++++++ > >>> > >>> The '595 is already handled by drivers/gpio/gpio-74x164.c. > >> > >> gpio-74x164.c seems to be tight closely to the SPI. In my case it's > >> GPIO-controller '595. > > > > Right. gpio-74x164.c uses the SPI framework, so it will work with any SPI > > master controller, while your driver contains a very simple variant (without any > > timing constraints) of spi-gpio.c, and is limited to connecting to GPIO pins. > > > >> Do you have any other idea how we could handle this? > > > > Your driver does provide OE support, which gpio-74x164 doesn't support. > > Perhaps that can be added to gpio-74x164 instead? > > It's not the missing OE support in gpio-74x164 that worries me, but > the whole rest. > > I would need to modify gpio-74x164 to: > 1) Use another OF table with different entry > 2) Use different probe function that doesn't take spi_device parameter > and doesn't do spi setup > 3) Extend struct gen_74x164_chip to include GPIOs > 4) Use totally different __gen_74x164_write_config I think the suggestion was to use the spi-gpio driver in combination with gpio-74x164. Arnd -- 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
