Trait imxrt_hal::usbd::Peripherals
source · pub unsafe trait Peripherals {
// Required methods
fn usb(&self) -> *const ();
fn usbphy(&self) -> *const ();
}Expand description
A type that owns all USB register blocks
An implementation of Peripherals is expected to own the USB1
or USB2 registers. This includes
- USB core registers
- USB PHY registers
When an instance of Peripherals exists, you must make sure that
nothing else, other than the owner of the Peripherals object,
accesses those registers.
Safety
Peripherals should only be implemented on a type that
owns the various register blocks required for all USB
operation. Incorrect usage, or failure to ensure exclusive
ownership, could lead to data races and incorrect USB functionality.
All pointers are expected to point at the starting register block for the specified peripheral. Calls to the functions must return the the same value every time they’re called.
Example
A safe implementation of Peripherals that works with the
imxrt-ral register access layer.
use imxrt_ral as ral;
use ral::usb;
struct Peripherals {
usb: ral::usb::Instance,
phy: ral::usbphy::Instance,
_nc: ral::usbnc::Instance,
_analog: ral::usb_analog::Instance,
}
impl Peripherals {
/// Panics if the instances are already taken
fn usb1() -> Peripherals {
Self {
usb: ral::usb::USB1::take().unwrap(),
phy: ral::usbphy::USBPHY1::take().unwrap(),
_nc: ral::usbnc::USBNC1::take().unwrap(),
_analog: ral::usb_analog::USB_ANALOG::take().unwrap(),
}
}
}
// This implementation is safe, because a `Peripherals` object
// owns the four imxrt-ral instances, which are
// guaranteed to be singletons. Given this approach, no one else
// can safely access the USB registers.
unsafe impl imxrt_usbd::Peripherals for Peripherals {
fn usb(&self) -> *const () {
let rb: &ral::usb::RegisterBlock = &self.usb;
(rb as *const ral::usb::RegisterBlock).cast()
}
fn usbphy(&self) -> *const () {
let rb: &ral::usbphy::RegisterBlock = &self.phy;
(rb as *const ral::usbphy::RegisterBlock).cast()
}
}
let peripherals = Peripherals::usb1();
let bus = imxrt_usbd::BusAdapter::new(
peripherals,
// Rest of setup...
);