[U-Boot] [PATCH 2/3] spi: Add support for the Aspeed ast2500 SPI controllers

[Cédric Le Goater]

Hello Boris,

On 10/10/18 9:32 AM, Boris Brezillon wrote:
> Hi Cédric,
> 
> On Wed, 10 Oct 2018 11:46:56 +0530
> Jagan Teki <jagan at amarulasolutions.com> wrote:
> 
>> On Mon, Oct 8, 2018 at 11:32 AM Cédric Le Goater <clg at kaod.org> wrote:
>>>
>>> On 10/4/18 5:57 PM, Jagan Teki wrote:  
>>>> On Fri, Sep 28, 2018 at 5:20 PM Cédric Le Goater <clg at kaod.org> wrote:  
>>>>>
>>>>> Hello Simon,
>>>>>
>>>>>
>>>>> The Aspeed AST2500 FMC controller can handle SPI flash and NOR flash memory,
>>>>> and the Aspeed AST2500 SPI Flash Controllers only SPI. If there is some
>>>>> misunderstanding on this driver, it might come from the fact it is closer
>>>>> to a SPI-NOR driver like we have in Linux, than a generic SPI driver.
>>>>> The stm32 SPI driver is somewhat similar.
>>>>>
>>>>> Should we move it under drivers/mtd/spi/ maybe ?  
>>>>
>>>> Seems with new spi-mem in Linux flash memory driver rely on spi-mem
>>>> instead of mtd/spi-nor. So I think you can handle this via new
>>>> spi-mem. have you send any patches to Linux?  
>>>
>>> No, not yet. The patchset is sent  :
>>>
>>>         https://patchwork.ozlabs.org/cover/933293/
>>>
>>> is not using spimem. I was not aware of that change in the spi-nor layer
>>> at the time. I will take a look.  
> 
> Indeed, if you have some time to convert the Linux aspeed driver to
> the spi-mem interface that would be appreciated.

Yes. That's the plan. I have a series on the way but I will see if I can
rework a v2 to use spi-mem. 

Same for the u-boot aspeed spi driver which needs a spi-mem refresh if 
I understand correctly. 

Thanks,

C.

 
>>
>> Yes, but for newly added drivers. added spi-mem guys, may be they can comment.
> 
> Jagan, what's the plan for the spi-nor layer in u-boot? I mean, spi-mem
> is just the controller side of things, but it requires spi-mem drivers
> to support specific SPI memories. We added the spi-nand driver, but
> AFAICT, the spi-nor driver does not exist yet. There's the spi-flash
> layer already, but IIUC you were trying to replace it by a spi-nor
> framework.
> 
> I see 2 options here:
> 
> 1/ copy the spi-nor framework from linux and adjust it to make it work
>    in uboot
> 2/ create a spi-nor driver which interfaces directly with the spi-mem
>    layer
> 
> I know I usually recommend going for #1, but it might be a bit
> different this time around since I'm trying to get rid of the
> spi_nor interface in Linux (the one that allows people to implement
> spi-nor controller drivers) in favor of a native spi-mem driver. So
> I think it's worth considering option #2.
>