[RFC 3/5] board: starfive: support Milk-V Mars board

[Heinrich Schuchardt]

On 3/8/24 03:06, E Shattow wrote:
> P.S. Found the longer description at 
> https://github.com/milkv-mars/mars-buildroot-sdk/commit/d381610c92827de01b25843786012351b3f35519 <https://github.com/milkv-mars/mars-buildroot-sdk/commit/d381610c92827de01b25843786012351b3f35519> as follows: "if configured as 24c04, its address will occupy 0x51, conflicting with the RTC chip pcf85063 on the IO-Board. Refer to: Documentation/misc-devices/eeprom.rst". What does that even mean, it is for Raspberry Pi Compute IO carrier only?

According to
https://ww1.microchip.com/downloads/en/devicedoc/doc0180.pdf
the chips differ in how their address lines are used. Either they select 
a chip or a memory address.

The chip is at reg 0x50. So it could be that if you read the upper 
memory of atmel,24c04 it would use reg 0x51.

https://datasheets.raspberrypi.com/cm4io/cm4io-datasheet.pdf says the 
CM4IO board has an RTC at address 0x51.

Together with the commit message this really sounds like the smaller 
chip size is faked due to incompatibility.

As you mentioned to have access to a CM module I would like to know what 
its serial number looks like to understand what if it can be used to 
detect if we are running U-Boot on full board or a CM module.

For my Milk-V board I have:

MARS-V11-2340-D008E000-xxxxxxxx

Best regards

Heinrich