Re: [PATCH v2 1/2] rtc: ds1302: add register access abstraction layer
From: Alexandre Belloni <hidden>
Date: 2016-06-27 12:44:32
Also in:
linux-rtc
Possibly related (same subject, not in this thread)
- 2016-07-27 · Re: [PATCH v2 1/2] rtc: ds1302: add register access abstraction layer · Mark Brown <hidden>
- 2016-07-19 · Re: [PATCH v2 1/2] rtc: ds1302: add register access abstraction layer · Alexandre Belloni <hidden>
- 2016-06-27 · Re: [PATCH v2 1/2] rtc: ds1302: add register access abstraction layer · Sergei Ianovich <hidden>
- 2016-06-27 · Re: [PATCH v2 1/2] rtc: ds1302: add register access abstraction layer · Alexandre Belloni <hidden>
- 2016-06-27 · Re: [PATCH v2 1/2] rtc: ds1302: add register access abstraction layer · Sergei Ianovich <hidden>
On 27/06/2016 at 14:50:49 +0300, Sergei Ianovich wrote :
On Mon, 2016-06-27 at 20:19 +0900, Akinobu Mita wrote:quoted
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 -- You received this message because you are subscribed to "rtc-linux". Membership options at http://groups.google.com/group/rtc-linux . Please read http://groups.google.com/group/rtc-linux/web/checklist before submitting a driver. --- You received this message because you are subscribed to the Google Groups "rtc-linux" group. To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit https://groups.google.com/d/optout.