stm32/spi: Add implementation of low-level SPI protocol.
Can be used, for example, to configure external SPI flash using a hardware
SPI interface (code to be put in a board's bdev.c file):
STATIC const spi_proto_cfg_t hard_spi_bus = {
.spi = &spi_obj[5],
.baudrate = 10000000,
.polarity = 0,
.phase = 0,
.bits = 8,
.firstbit = SPI_FIRSTBIT_MSB,
};
STATIC mp_spiflash_cache_t spi_bdev_cache;
const mp_spiflash_config_t spiflash_config = {
.bus_kind = MP_SPIFLASH_BUS_SPI,
.bus.u_spi.cs = pin_A0,
.bus.u_spi.data = (void*)&hard_spi_bus,
.bus.u_spi.proto = &spi_proto,
.cache = &spi_bdev_cache,
};
spi_bdev_t spi_bdev;
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