I2C device tree descriptions in TOML

[bcantrill]

This work adds a description of I2C in TOML as part of an application
definition, allowing this description to be pulled out of hand-written
code, and into code that is automatically generated as part of the
build process. This allows for Humility to know the I2C device tree
based on the archive -- which in turn allows for much more robust
tooling for I2C and I2C-based protcols like PMBus. In addition to
adding support for I2C in TOML and definitions for every platform that
supports I2C, this work also:

• Adds a preliminary Sidecar image
• Adds QSPI support for the Nucleo board
• Eliminates the notion of Port::Default
• Adds a HIF sleep function and I2C bulk write function
• Adds a HIF QSPI function to verify an image
• Corrects the HIF QSPI error conditions

[cbiffle]

This is looking good.

Be careful include!-ing generated files into a module with user definitions. Currently defining things in the config named, say, main will cause weird compile errors. Wrapping the include! in a module, e.g. mod i2c { ... }, would fix that.

[bcantrill]

This is looking good.

Be careful include!-ing generated files into a module with user definitions. Currently defining things in the config named, say, main will cause weird compile errors. Wrapping the include! in a module, e.g. mod i2c { ... }, would fix that.

Agreed; all of the generated code is wrapped with mod i2c_config to avoid this kind of pollution.