pub trait IntoChipSelect<T, POLARITY> {
// Required method
fn into_cs(self) -> T;
}Expand description
A type that can be converted to the appropriate type for
SpiMaster::ChipSelect for a particular
POLARITY.
Instantiating a driver for any SPI peripheral should require a type that
implements IntoChipSelect. That enforces that whatever object is
used as the chip select can support the correct polarity for the
particular SPI peripheral. This is mostly commonly handled by the
component for the peripheral, which requires an object with type
IntoChipSelect and then converts the object to the
SpiMaster::ChipSelect type.
§Examples:
Some SPI host controllers only support active low or active high chip
select pins. Such a controller might provide a unit implementation of
this trait only for the ActiveLow marker.
use kernel::hil::spi::cs::*;
#[derive(Copy, Clone)]
enum PeripheralSelect {
Peripheral0,
Peripheral1,
}
impl IntoChipSelect<PeripheralSelect, ActiveLow> for PeripheralSelect {
fn into_cs(self) -> Self { self }
}Many other controllers can handle both active low and active high chip
select pins, in which case, they should implement both the ActiveLow
and ActiveHigh variants, for example, using the ChipSelectPolar
wrapper struct (which implements both).