From mboxrd@z Thu Jan  1 00:00:00 1970
From: b32955@freescale.com (Huang Shijie)
Date: Fri, 6 Dec 2013 11:07:14 +0800
Subject: [PATCH 0/4] mtd: spi-nor: add a new framework for SPI NOR
In-Reply-To: <20131205092048.GE4636@norris.computersforpeace.net>
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To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Thu, Dec 05, 2013 at 01:20:48AM -0800, Brian Norris wrote:
> SPI is not used only for SPI NOR; it is useful for other things, like
> communicating with off-chip peripherals or microcontrollers, supporting
> touchscreens, LEDs, media controllers, etc. So with a SPI NOR framework
> living only in the MTD subsystem, I have to write two drivers: one
> (under drivers/spi/) to use only-(a) for controlling non-flash SPI
> devices, and one (under drivers/mtd/) to manage (a)+(b) on SPI NOR
> flash.

If the NOR is connected to a SPI bus controller which can attaches other SPI
devices too, I think you use a pure SPI driver to access it;

If the NOR is connected to a SPI-NOR controller such as your spi-nor controller
, you can use a SPI-NOR driver to access it.


Does your NOR flash connect to both the SPI bus controller and SPI-NOR
controller at the same time? :) If it does connect to both of the controllers,
I do not know how to handle it too.	   


> 
> If, however, we can define a spi_nor_transfer like Angus suggested, and
> if we take that a step further and make it a first-class (but optional)
> citizen of the SPI framework, then we could have drivers that support
> SPI-only, SPI-NOR-only, or both.
> 
I guess Mark will not agree with this. :)


thanks
Huang Shijie


> Now, I'm not sure how exactly that sort of proposal would work yet, but
> I wanted to test the waters to see
>   - if this is a complete distortion of what Angus or David may have
>     suggested;
>   - if Mark thinks this is reasonable, or if he thinks I'm spouting
>     nonsense; and
>   - if there is some obvious alternate way to support what I describe
>     without moving the SPI-NOR layer into the SPI subsystem.
> 
> Brian
>