Re: Shark LED and I2C drivers

[Jason Thorpe <thorpej%me.com@localhost>]

> On Apr 21, 2021, at 10:31 PM, Julian Coleman <jdc%coris.org.uk@localhost> wrote:
> 
> Hi all,
> 
> I was looking at the DNARD User Guide and noticed that it mentioned an I2C
> bus connected to the Sequoia chip to communicate with the DIMM's, and also
> mentioned which pins were used.  After a bit of experimentation, I have a
> working bit-bang I2C bus.  While looking at our sequoia code, it seemed
> easy to manipulate the front and debug LED's too.
> 
> I've attached a patch that:
> 
>  adds the additional devices (shark_machdep.c)
>  configures the additional devices (ofisa.c)
>  handles register configuration for the I2C bus and the LED's (sequoia.c)
>  adds glue for the devices (shark_iic.c and shark_led.c)

I'm going to merge this into my thorpej-i2c-spi-conf branch.  I am trying to reduce the proliferation of "add more child devices in dictionaries", so I'd prefer they don't land in the trunk in current form.

> 
> Output on my 64MB shark is:
> 
> [   1.0000000] sharkled0 at ofisa0: front, debug
> [   1.0000000] sharkiic0 at ofisa0
> [   1.0000000] iic0 at sharkiic0: I2C bus
> [   1.0000000] spdmem0 at iic0 addr 0x50
> [   1.0000000] spdmem0: SDRAM, no parity or ECC, 32MB, 100MHz (PC-100)
> [   1.0000000] spdmem1 at iic0 addr 0x51
> [   1.0000000] spdmem1: SDRAM, no parity or ECC, 32MB, 100MHz (PC-100)
> 
> and my 32MB shark:
> 
> [   1.0000000] sharkled0 at ofisa0: front, debug
> [   1.0000000] sharkiic0 at ofisa0
> [   1.0000000] iic0 at sharkiic0: I2C bus
> [   1.0000000] seeprom0 at iic0 addr 0x50: AT24Cxx or compatible EEPROM: size 256
> [   1.0000000] seeprom1 at iic0 addr 0x51: AT24Cxx or compatible EEPROM: size 256
> 
> Seeprom attaches because the DIMM's are not SPD-compatible.  I was however,
> able to inspect their contents using:
> 
>  for i in 0 1; do dd if=/dev/seeprom$i bs=256k count=1 | hexdump -C; done
> 
> and see that it has 2 Samsung KMM366S203BTN-G2 (16MB PC-66) DIMM's installed.

Where is the documentation for the eeprom data format?\

> 
> Comments appreciated.
> 
> Regards,
> 
> Julian
> <shark-iic-led.diff>

-- thorpej