On 03/29/2012 04:21 PM, Prafulla Wadaskar wrote: >> On 03/28/2012 09:48 AM, Prafulla Wadaskar wrote: >>>> On 03/26/2012 11:58 AM, Valentin Longchamp wrote: >>>>> Some kirkwood based boards may need to implement such function due >> >> Correct, this is exactly our use case: we have the NAND Flash >> Controller and the >> SPI controller that share the same pins. >> >>> >>> But this is not board specific whereas, it should be feature >> enhancement for Kirkwood spi driver. >> >> This is correct for the mpp part of spi_claim_bus. If you look at the >> actual >> implementation that we do in our board specific function, there is an >> additional >> step that is needed by our board design. >> >>> >>> You should add this support very similar to multiple CS pin >> selection support added to the Kirkwood driver, no external (board >> specific triggers needed) >>> >>> Here are my suggestions: >>> 1. Configure these mpps in your board specific files as NF pins. >>> 2. Populate below logic for claim/release bus feature in Kirkwood >> spi driver. >>> 2.a. When spi_claim_bus will be called, backup current mpps status >> and reconfigure these mpps for SPI in Kirkwood_spi driver. >>> 2.b. When spi_release_bus will be called, reconfigure with backed up >> mfg as SPI pins >>> 2.c. Add check for to avoid multiple claim for same bus >>> >> >> OK, I agree with this, but I would add: >> 2.d. call weak attribute functions boad_spi_claim/release_bus at the >> end of >> spi_claim/release_bus functions > > With above logic, SPI driver will manage the show cleanly. > Then, why do you need these weak attribute functions? >
Because this is in our case not sufficient: we have an external device that takes care of "disabling" the the SPI bus from the "bus" when we do some NF accesses (and vice-versa), so that the SPI devices do not try interpret the NF signal toggling as SPI accesses. This external "mux" is driver by a GPIO and that's what I want to put in these board weak attribute functions. They belong to spi_claim/release_bus but really are specific to our device/boards and that's why I would need such functions. -- Valentin Longchamp Embedded Software Engineer Hardware and Chip Integration ______________________________________ KEYMILE AG Schwarzenburgstr. 73 CH-3097 Liebefeld Phone +41 31 377 1318 Fax +41 31 377 1212 valentin.longch...@keymile.com www.keymile.com ______________________________________ KEYMILE: A Specialist as a Partner _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
