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//! System configuration: the registers that wire peripherals to each other
//! rather than to the outside world.
//!
//! Only `EXTISS` is covered so far, and it is not public: the port an EXTI line
//! listens to is picked by [`crate::exti::ExtiLine::source`], which owns the pin
//! it names.
use crate::pac;
use crate::rcu::Rcu;
/// Owns the SYSCFG registers, so nothing else can reach them.
pub struct Syscfg {
syscfg: pac::Syscfg,
}
impl Syscfg {
/// Points EXTI line `line` at the port encoded by `code`.
///
/// `pub(crate)`: writing this behind a line's back would leave the line's
/// type naming one pin while the hardware listens to another.
///
/// # Panics
///
/// If `line` is above 15 — the lines above that have no source to select.
pub(crate) fn set_extiss(&mut self, line: u8, code: u8) {
match line {
l @ 0..=3 => self.syscfg.extiss0().modify(|_, w| match l {
0 => unsafe { w.exti0_ss().bits(code) },
1 => unsafe { w.exti1_ss().bits(code) },
2 => unsafe { w.exti2_ss().bits(code) },
_ => unsafe { w.exti3_ss().bits(code) },
}),
l @ 4..=7 => self.syscfg.extiss1().modify(|_, w| match l {
4 => unsafe { w.exti4_ss().bits(code) },
5 => unsafe { w.exti5_ss().bits(code) },
6 => unsafe { w.exti6_ss().bits(code) },
_ => unsafe { w.exti7_ss().bits(code) },
}),
l @ 8..=11 => self.syscfg.extiss2().modify(|_, w| match l {
8 => unsafe { w.exti8_ss().bits(code) },
9 => unsafe { w.exti9_ss().bits(code) },
10 => unsafe { w.exti10_ss().bits(code) },
_ => unsafe { w.exti11_ss().bits(code) },
}),
l @ 12..=15 => self.syscfg.extiss3().modify(|_, w| match l {
12 => unsafe { w.exti12_ss().bits(code) },
13 => unsafe { w.exti13_ss().bits(code) },
14 => unsafe { w.exti14_ss().bits(code) },
_ => unsafe { w.exti15_ss().bits(code) },
}),
_ => unreachable!(),
}
}
}
/// Takes the raw peripheral into [`Syscfg`].
pub trait SyscfgExt {
/// Switches the SYSCFG clock on and hands back the owning type.
///
/// The clock bit is shared with the comparator, so this also brings CMP out
/// of reset-off; see [`crate::rcu::Rcu::enable_cfgcmp`].
fn constrain(self, rcu: &mut Rcu) -> Syscfg;
}
impl SyscfgExt for pac::Syscfg {
fn constrain(self, rcu: &mut Rcu) -> Syscfg {
rcu.enable_cfgcmp();
Syscfg { syscfg: self }
}
}