Forgot to add Mark in Cc: On 27/06/2016 at 14:44:32 +0200, Alexandre Belloni wrote : > On 27/06/2016 at 14:50:49 +0300, Sergei Ianovich wrote : > > On Mon, 2016-06-27 at 20:19 +0900, Akinobu Mita wrote: > > > The rtc-ds1302 driver now implemented using SPI 3wire mode. > > > But I would like to access it with using three wires connected to > > > GPIO > > > lines. > > > > > > This adds abstraction layer for DS1302 register access in order to > > > prepare to support for using GPIO lines. This enables to share > > > common > > > code between SPI driver and GPIO driver. > > > > I don't think this is the right way. DS-1302 is an SPI device, not a > > GPIO one. It can be connected to a hardware SPI controller or a > > software one (on top of GPIO or memory). > > > > Your patch re-adds Microwire SPI control logic to RTC subsystem, which > > was cleared by my rewrite of drivers/rtc/rtc-ds1302.c. The logic is > > already present in bitbang_txrx_be_cpha0_lsb() in drivers/spi/spi- > > lp8841-rtc.c. > > > > I still think you need to implement spi-gpio-3wire with LSB-first > > support in SPI subsystem instead. It wasn't done when I was adding > > LP8841 support, because LP8841 was the only use case of Microwire SPI > > control logic. If you add it, drivers/spi/spi-lp8841-rtc.c can be > > removed and replaced by a GPIO driver to host a new spi-gpio-3wire > > device. > > Well, back in April, we concluded it was not easily doable after > discussing with Mark and there was still issues after implementing it in > spi-gpio. > > My understanding is that while microwire seems compatible with SPI mode > 0, it actually isn't and this should be treated as a different mode. > If we want to do something generic, I think we should have a > microwire-gpio driver. Maybe in the SPI subsystem? > > How do yo currently select microwire mode for PX270? > > -- > Alexandre Belloni, Free Electrons > Embedded Linux, Kernel and Android engineering > http://free-electrons.com
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