SPI driver for Microchip MEC5 HAL based QSPI controller. QSPI
hardware supports full duplex, dual, and quad operation. MEC5
QSPI controller also includes three local DMA channels per
direction to off load firmware. The driver API supports full
or half-duplex. Due to QSPI hardware not supporting one wire
half-duplex, this driver supports full-duplex only. QSPI hardware
design requires it to control chip select and current hardware
supports up to two chip selects. Zephyr's SPI DT macros store the
child SPI device's reg properity as the "slave" member of the SPI
configuration structure. The driver uses the "slave" value as the
chip select. Additional timing settings specific to SPI flash devices
are in a new SPI device YAM file: "microchip,mec5-qspi-device.yaml"
which includes the standard "spi-device.yaml". If the new YAML is not
used, the QSPI controller will use default timing values for chip
select and I/O line taps.
Signed-off-by: Scott Worley <scott.worley@microchip.com>
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