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102 lines
2.9 KiB
Rust
102 lines
2.9 KiB
Rust
//! GPIO module.
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use super::memory_map::gpio::*;
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/// The number of pin for the raspberry 3.
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const NUMBER_PIN: usize = 54;
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/// Value to select the INPUT function of a PIN.
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const FSEL_INPUT: u32 = 0b000;
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/// Value to select the OUTPUT function of a PIN.
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const FSEL_OUTPUT: u32 = 0b001;
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/// Value to select the Alternate function 0 of a PIN.
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const FSEL_ALTF0: u32 = 0b100;
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/// Value to select the Alternate function 1 of a PIN.
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const FSEL_ALTF1: u32 = 0b101;
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/// Value to select the Alternate function 2 of a PIN.
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const FSEL_ALTF2: u32 = 0b110;
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/// Value to select the Alternate function 3 of a PIN.
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const FSEL_ALTF3: u32 = 0b111;
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/// Value to select the Alternate function 4 of a PIN.
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const FSEL_ALTF4: u32 = 0b011;
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/// Value to select the Alternate function 5 of a PIN.
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const FSEL_ALTF5: u32 = 0b010;
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/// The possible PIN functions.
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pub enum PinFunction {
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Input,
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Output,
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AltFunc0,
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AltFunc1,
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AltFunc2,
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AltFunc3,
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AltFunc4,
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AltFunc5,
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}
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/// The possible PIN state when in Output mode.
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pub enum PinOutputState {
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High,
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Low,
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}
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impl From<PinFunction> for u32 {
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fn from(function: PinFunction) -> u32 {
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match function {
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PinFunction::Input => FSEL_INPUT,
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PinFunction::Output => FSEL_OUTPUT,
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PinFunction::AltFunc0 => FSEL_ALTF0,
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PinFunction::AltFunc1 => FSEL_ALTF1,
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PinFunction::AltFunc2 => FSEL_ALTF2,
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PinFunction::AltFunc3 => FSEL_ALTF3,
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PinFunction::AltFunc4 => FSEL_ALTF4,
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PinFunction::AltFunc5 => FSEL_ALTF5,
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}
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}
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}
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// TODO: remove Result and use an enum instead of usize
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/// Set the function of a Pin.
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///
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/// # Result
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///
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/// Return an error if the PIN does not exist.
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pub fn set_pin_fonction(n: usize, function: PinFunction) -> Result<(), &'static str> {
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if n >= NUMBER_PIN {
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return Err("The pin does not exist.");
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}
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let field = get_fsel(n);
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// TODO: SYNC
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let address = field.get_address();
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let mut val = unsafe { core::ptr::read_volatile(address as *mut u32) };
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val &= !field.get_mask();
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val |= Into::<u32>::into(function) << field.get_offset();
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unsafe {
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core::ptr::write_volatile(address as *mut u32, val);
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}
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Ok(())
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}
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// TODO: remove Result and use an enum instead of usize
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/// Set the state of an output Pin.
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///
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/// # Result
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///
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/// Return an error if the PIN does not exist.
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pub fn set_pin_output_state(n: usize, state: PinOutputState) -> Result<(), &'static str> {
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if n >= NUMBER_PIN {
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return Err("The pin does not exist.");
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}
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let field = match state {
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PinOutputState::High => get_set(n),
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PinOutputState::Low => get_clr(n),
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};
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let val = field.get_mask();
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let address = field.get_address();
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// 0 has no effect on this field: no nead to read-modify-write
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unsafe {
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core::ptr::write_volatile(address as *mut u32, val);
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}
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Ok(())
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}
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