arasan,sdhci.txt "compatibility" DT binding

[Rameshwar Sahu]

Hi Mason,

Nowhere in the documentation do they specify an "IP version".
Some documents do provide a revision number, but that's just
a *documentation* revision number, e.g.

changes in version 3.6 : fix typos
changes in version 9.1a : update company logo

That's why Xilinx used "arasan,sdhci-8.9a" and APM used
"arasan,sdhci-4.9a". These are documentation revisions.
In my opinion, that information is mostly worthless.

Arasan SD/SDIO/eMMC IP has a register which tells about the SD
specification version and  Vendor version number
Reg Name: Host controller version register (offset 0FEh)
bit [15:8] is for vendor version number,
But, I have seen that Arasaan vendor version number is same as
document revision number.

On Mon, Nov 28, 2016 at 10:22 PM, Mason <slash.tmp at free.fr> wrote:
> On 28/11/2016 17:15, Arnd Bergmann wrote:
>
>> On Monday, November 28, 2016 4:44:39 PM CET Mason wrote:
>>
>>> Hello,
>>>
>>> @Shawn Lin, could you take a look below and tell me exactly
>>> which IP core(s) Rockchip is using in its SoCs?
>>>
>>> Based on the feedback I received, here is an updated list of
>>> compatible strings and controller versions dealt with by the
>>> drivers/mmc/host/sdhci-of-arasan.c code.
>>>
>>>
>>> Xilinx Zynq:
>>> "SD2.0 / SDIO2.0 / MMC3.31 AHB Host Controller"
>>> "arasan,sdhci-8.9a"
>>> NB: 8.9a is the documentation revision (dated 2011-10-19)
>>> subsequent tweaks labeled 9.0a, 9.1a, 9.2a
>>>
>>> Xilinx ZynqMP:
>>> "SD3.0 / SDIO3.0 / eMMC4.51 AHB Host Controller"
>>> "arasan,sdhci-8.9a"
>>> NB: using the same compatible string as Zynq
>>>
>>> Sigma SMP87xx
>>> "SD3.0 / SDIO3.0 / eMMC4.4 AHB Host Controller"
>>> no compatible string yet, platform-specific init required
>>>
>>> APM:
>>> "SD3.0 / SDIO3.0 / eMMC4.41 AHB Host Controller"
>>> "arasan,sdhci-4.9a"
>>> NB: 4.9a appears to be the documentation revision
>>> no functional diff with "arasan,sdhci-8.9a"
>>>
>>> Rockchip
>>> Exact IP unknown, waiting for Shawn's answer
>>> "arasan,sdhci-5.1"
>>> NB: 5.1 appears to refer to the eMMC standard supported
>>>
>>>
>>> On a final note, there are many variations of the Arasan IP.
>>> I've tracked down at least the following:
>>>
>>> SD_2.0_SDIO_2.0__MMC_3.31_AHB_Host_Controller.pdf
>>> SD_3.0_SDIO_3.0_eMMC_4.41_OCP_Host_Controller.pdf
>>> SD_3.0_SDIO_3.0_eMMC_4.4__AHB_Host_Controller.pdf
>>> SD_3.0_SDIO_3.0_eMMC_4.51_Host_Controller.pdf
>>> SD_3.0_SDIO_3.0_eMMC_4.5__Host_Controller.pdf
>>> SD_4.1_SDIO_4.1_eMMC_4.51_Host_Controller.pdf
>>> SD_4.1_SDIO_4.1_eMMC_5.1__Host_Controller.pdf
>>>
>>> It seems to me the compatible string should specify
>>> the SD/SDIO version AND the eMMC version, since it
>>> seems many combinations are allowed, e.g. eMMC 4.51
>>> has two possible SD versions.
>>>
>>> What do you think?
>>
>> It seems wrong to have the eMMC or SD version in the compatible
>> string.  Is that the only difference between the documents you
>> found? Normally there should be a version of IP block itself,
>> besides the supported protocol.
>
> But that is exactly the problem :-)
>
> Nowhere in the documentation do they specify an "IP version".
> Some documents do provide a revision number, but that's just
> a *documentation* revision number, e.g.
>
> changes in version 3.6 : fix typos
> changes in version 9.1a : update company logo
>
> That's why Xilinx used "arasan,sdhci-8.9a" and APM used
> "arasan,sdhci-4.9a". These are documentation revisions.
> In my opinion, that information is mostly worthless.
>
>
> Looking more closely at SD_3.0_SDIO_3.0_eMMC_4.4__AHB_Host_Controller.pdf
> (User Guide, which has more info than Datasheet) I see this:
>
> Changed Host Controller Version Register value from 16'h0002 to 16'h7501
> Changed Host Controller Version Register value from 16'h8301 to 16'h8401
> Changed Host Controller Version Register value from 16'h8401 to 16'h8501
> Changed Host Controller Version Register to 16'h9502
> Changed Host Controller Version Register to 16'h9602
> Changed Host Controller Version Register to 16'h9902
>
> Host controller version register (offset 0FEh)
>
> Vendor Version Number 15:8
> HwInit=0x99
> This status is reserved for the vendor version number.
> The HD should not use this status.
>
> Specification Version Number 7:0
> HwInit=0x02
> This status indicates the Host Controller Spec. Version.
> The upper and lower 4-bits indicate the version.
> Description
> 00 - SD Host Specification version 1.0
> 01 - SD Host Specification version 2.00
> including only the feature of the Test Register
> 02 - SD Host Specification Version 3.00
> others - Reserved
>
> I'm not sure what this "Vendor Version Number" specifies, nor if is
> guaranteed to be unique across controllers.
>
> In SD_3.0_SDIO_3.0_eMMC_4.5__Host_Controller_UserGuide.pdf,
> they write "The Vendor Version Number is set to 0x10 (1.0)"
>
> I don't have a UserGuide for "arasan,sdhci-5.1".
>
> Regards.
>