-----Original Message----- From: Valentin Longchamp [mailto:valentin.longchamp@keymile.com] Sent: 30 March 2012 17:45 To: Prafulla Wadaskar Cc: u-boot@lists.denx.de; Gerlando Falauto; Holger Brunck Subject: Re: [PATCH v2] spi/kirkwood: add weak functions board_spi_bus_claim/release
Hi Prafulla,
For the simplicity of the discussion, I have removed everything in the discussion that is not relevant for the current open point.
On 03/30/2012 01:34 PM, Prafulla Wadaskar wrote:
In Kirkwood specific claim_bus API, you will backup default
configuration (which is NF in your case) for these particular pins (SPI_SI, SPI_SCK, SPI_CSn, MOSI, MISO).
But which MPP are these particular pins ?
Let's have a look at a single signal, SPI_SCK for instance. From the 88F6281 Hardware Spec [1], page 53, SPI_SCK can be MPP[2], MPP[10]. How can the generic driver know which one actually is wired to the SPI device SCK pin on the currently running hardware (when none is configured as then, since by default for us MPP[2] is NF_IO[4] and MPP[10] is UA0_TXD ) ? This is a board specific !
If you tell me how I easily can find this out in the kirkwood driver,
Dear Valentin
Please make a use of CONFIG_SF_DEFAULT_CS for this. By default this is defined to 0, lets map it to our default use case i.e. using MPP0-3 for default SPI signals
One may pre-define this in his board config as per specific need, and we can use this effectively in Kirkwood_spi driver. i.e. bit0 to be used to configure SPI_CSn bit1 to be used to configure SPI_MOSI... and so on
so if my needs are to use 1. MPP7 as SPI_CSn I will define CONFIG_SF_DEFAULT_CS to 0x01 2. MPP6 as SPI_MOSI I will define CONFIG_SF_DEFAULT_CS to 0x02 2. MPP6 as SPI_MOSI and MPP7 as SPI_CSn, I will define CONFIG_SF_DEFAULT_CS to 0x03 .. and so on.
Regards.. Prafulla . . .
I will be happy to implement your proposed solution. Otherwise, I think we should stick with the board specific function.
[1] http://www.marvell.com/embedded- processors/kirkwood/assets/HW_88F6281_OpenSource.pdf
Regards
-- 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.longchamp@keymile.com www.keymile.com ______________________________________ KEYMILE: A Specialist as a Partner