riscv/bl602: Implement SPI Cmd/Data

[lupyuen]

Summary

To control the Data/Command Pin on ST7789 SPI Display, the SPI Driver flips the MISO Pin as though it was a GPIO.

To implement this on BL602, we reconfigure MISO from SPI Pin to GPIO Pin on the fly inside bl602_spi_cmddata().

When the SPI Port is deselected (after the SPI operation), we revert MISO back from GPIO Pin to SPI Pin. We implement this inside bl602_spi_select().

More Details Here

Impact

This change impacts 3 LCD drivers that call SPI_CMDDATA(): ST7735, ST7789, GC9A01.

Previously the BL602 SPI Driver would fail with "SPI cmddata not supported" when the above drivers are used.

After the change, the above drivers will set the LCD Data/Command Pin correctly.

Testing

We tested this implementation of SPI Cmd/Data with NuttX ST7789 Driver and a Logic Analyser on PineCone BL602:

• Testing with Logic Analyser

We also tested LVGL with ST7789 on PineCone BL602:

• Testing with LVGL

As for regular SPI Devices that don't require SPI Cmd/Data, we tested CONFIG_SPI_CMDDATA=y with Semtech SX1262 SPI Transceiver on PineCone BL602:

• Testing Cmd/Data