ESP32: SPI Driver Support

[zephyrbot]

Reported by Christopher Turner:

Implement driver for Serial Peripheral Interface (SPI) Master and Serial Peripheral Interface (SPI) Slave.

(Imported from Jira ZEP-2292)

[nashif]

is this still for 1.10?

[lpereira]

Yes. I'm working on this; it's taking more time than I anticipated due to some hardware oddities.

[lpereira]

@iha Are you still working with ESP32 devices in your spare time?

[iha]

@lpereira , Sorry, I wasn't working on ESP32 in the past few months. But I was planning to get back to work on it next weekends to finish at least the PRs I need to fix :)

[locomuco]

@lpereira @iha is it possible to push a WIP branch to upstream, we would like to contribute without reinventing the wheel...

[lpereira]

@locomuco @iha Here's my current WIP (warning: really messy code) branch, but it's far from being finished. In fact, the SPI depends on DMA to work properly, and the DMA controller wasn't documented in the Technical Reference Manual when I started writing the driver: https://github.com/lpereira/zephyr/tree/esp32-spi

[iha]

@lpereira, sorry I couldn't get enough time to do this driver :/

[ExtremeGTX]

anyone made some progress here ? or shall i continue what @lpereira started ?

[locomuco]

@ExtremeGTX the base, to get esp32 running, is to get flash cache up and running, see https://github.com/locomuco/zephyr-esp32 as a reference, otherwise I did not follow up on SPI