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:
- Configure these mpps in your board specific files as NF pins.
- 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.