Add support for i2c-tiny-usb: usb to iic bridge

[0xDRRB]

Add support for i2c-tiny-usb via a new i2ctinyusb driver.

It's a device you can create yourself using an AVR ATtiny45 microcontroller or a Raspberry Pi Pico board, and which allows you to use sensors and other i2c modules (RTC, EEPROM, HSM/TPM, oled screen, etc.).

ugen2.4: <Nicolai Electronics I2C adapter> at usbus2
iichb0: <I2C-Tiny-USB I2C interface> on uhub3
iichb0: <I2C interface> on usbus2
iicbus8: <Philips I2C bus> on iichb0
iic8: <I2C generic I/O> on iicbus8

Once the driver has been loaded and the device connected, the new bus can be accessed via /dev/iic* just like any other:

$ i2c -f /dev/iic8 -s
23 3c 50 60 68 76

$ i2c -f /dev/iic8 -a 0x68 -d r -c 1
26

$ i2c -i "r 8 0x50 16BE 0x10 16"
95f9f6526d207bb45d43d1c73af99577

[bsdimp]

Thanks for the submission. I'll take a look at it in a few days. It looks quite interesting. Are these boards available to buy, or just in gerber/design form? I didn't see a 'buy it here' link in the above links, though I might have missed it.

Also, next time you update, could you 'git rebase -i main' and then force push with --force-with-lease? That makes merging it a little easier.

[0xDRRB]

Thanks for the submission. I'll take a look at it in a few days. It looks quite interesting. Are these boards available to buy, or just in gerber/design form? I didn't see a 'buy it here' link in the above links, though I might have missed it.

The historical hardware implementation uses an Atmel ATtiny45-based DIY circuit, but a more modern version just uses a Raspberry Pi Pico board and nothing else is needed. It's easier and cheaper than a CP2112 module, for which a driver already exists.

Also, next time you update, could you 'git rebase -i main' and then force push with --force-with-lease? That makes merging it a little easier.

Duly noted. Sorry about that.

[bsdimp]

Thanks for this very interesting contribution. I was on the fence about it, but talking with others convinced me it was OK. Sorry this process took so long...

[0xDRRB]

Thank you very much. That made my day :)