Re: [PATCH RFC 2/2] mfd: add Renesas RPC-IF driver

[Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>]

Hello!

On 06/18/2019 02:34 PM, Lee Jones wrote:

>>>>> So is an RPC-IF a real hardware device.  Can you share the datasheet?
>>>>
>>>> Unfortunately the datasheet for the R-Car Gen3 and RZ/G2 SoCs is
>>>> not yet public.
>>>
>>> When will it be public?
>>
>> Dunno. RZ/G1 documentation became public a few months after the SoC
>> release.
>>
>>> Do you have access to it?
>>
>> Yes I do.
> 
> Great.  Maybe you can help Sergei with his 'undocumented bits' issue.

   You're an optimist. :-)
   I think I have the same gen3 manual v1.50 as Geert. It won't help as the
bits that constitute the magic numbers in the driver are not described (not
even the default values are listed for the most of them).

>>>> However, a very similar hardware block is present in the RZ/A2M SoC.
>>>> Please see Chapter 20 ("SPI Multi I/O Bus Controller") of the "RZ/A2M Group
>>>> User’s Manual: Hardware", which you can download from
>>>> https://www.renesas.com/eu/en/products/microcontrollers-microprocessors/rz/rza/rza2m.html#documents
>>>
>>>   "The SPI multi I/O bus controller enables the direct connection of
>>>    serial flash, OctaFlashTM, XccelaTM flash, or HyperFlashTM memory
>>>    devices to this LSI chip.
>>>
>>>    This module allows the connected serial flash, OctaFlashTM, XccelaTM
>>>    flash, or HyperFlashTM memory devices to be accessed by reading the
>>>    external address space, or using Manual mode to transmit and receive
>>>    data."
>>>
>>> Looks like a flash device to me.
>>
>> The external address space is a small window.

   Yeah, it only provides 64 MiB window into the flash chip.

>>> Can the SPI portion be used to connect generic SPI devices?
>>
>> I'll defer that to the people who worked on the driver...

   Yes. Or at least it should, looking at the driver code...

MBR, Sergei