SPI Slave additional features

[MabezDev]

Extracted from

esp-hal/esp-hal/src/spi/slave.rs

Lines 49 to 58 in 381ce95

	//! TODO:
	//! - Notify the Spi user when the master wants to send or receive data, if
	//! possible
	//! - Blocking transfers
	//! - Half duplex
	//! - Segmented transfers
	//! - Interrupt support
	//! - Custom interrupts from segmented transfer commands
	//! - Dual and quad SPI
	//! - CPU mode

• Notify the Spi user when the master wants to send or receive data, if
  [ ] possible
• Blocking transfers
• Half duplex
• Segmented transfers
• Interrupt support
• Custom interrupts from segmented transfer commands
• Dual and quad SPI
• CPU mode