stm32_eth/ptp/
pps_pin.rs

1/// Pins that can be used as PPS output
2///
3/// SAFETY: only pins that are capable of being a PPS output according
4/// to the datasheets of respective parts may implement this trait.
5pub unsafe trait PPSPin {
6    /// The output type of this pin, in which it acts as a PPS output.
7    type Output;
8
9    /// Enable the PPS output.
10    fn enable(self) -> Self::Output;
11}
12
13#[allow(unused_macros)]
14macro_rules! impl_pps_pin {
15    ($([$name:ty, $output:ty]),*) => {
16        $(
17            unsafe impl super::PPSPin for $name {
18                type Output = $output;
19
20                fn enable(self) -> Self::Output {
21                    self.into_alternate()
22                }
23            }
24        )*
25    };
26}
27
28#[cfg(feature = "stm32f4xx-hal")]
29mod impl_pps_pin {
30    use crate::hal::gpio::{Alternate, Output, PushPull, PB5, PG8};
31
32    impl_pps_pin!([PG8<Output<PushPull>>, PG8<Alternate<11>>], [PB5<Output<PushPull>>, PB5<Alternate<11>>]);
33}
34
35#[cfg(feature = "stm32f7xx-hal")]
36mod impl_pps_pin {
37    use crate::hal::gpio::{Alternate, Output, PushPull, PB5, PG8};
38
39    impl_pps_pin!([PG8<Output<PushPull>>, PG8<Alternate<11>>], [PB5<Output<PushPull>>, PB5<Alternate<11>>]);
40}
41
42#[cfg(feature = "stm32f1xx-hal")]
43mod impl_pps_pin {
44    use crate::hal::gpio::{Alternate, Output, PushPull, PB5};
45
46    unsafe impl super::PPSPin for PB5<Output<PushPull>> {
47        type Output = PB5<Alternate<PushPull>>;
48
49        fn enable(self) -> Self::Output {
50            // Within this critical section, modifying the `CRL` register can
51            // only be unsound if this critical section preempts other code
52            // that is modifying the same register
53            cortex_m::interrupt::free(|_| {
54                // SAFETY: this is sound as long as the API of the HAL and structure of the CRL
55                // struct does not change. In case the size of the `CRL` struct is changed, compilation
56                // will fail as `mem::transmute` can only convert between types of the same size.
57                //
58                // This guards us from unsound behaviour introduced by point releases of the f1 hal
59                let cr: &mut _ = &mut unsafe { core::mem::transmute(()) };
60                // The speed can only be changed on output pins
61                self.into_alternate_push_pull(cr)
62            })
63        }
64    }
65}
stm32_eth/ptp/pps_pin.rs

stm32_eth/ptp/
pps_pin.rs
