equation314
6 years ago
parent
cc936ded35
commit
addf49ffdb
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[package]
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name = "bcm2837"
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version = "0.1.0"
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authors = ["equation314 <equation618@gmail.com>"]
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[dependencies]
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volatile = "0.2.4"
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//! utility assembly instructions
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/// delay for some clocks
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#[inline]
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pub unsafe fn delay(clock: u32) {
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#[cfg(target_arch = "aarch64")]
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asm!("1: subs x0, x0, #1; bne 1b;"
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:: "{x0}"(clock)
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:: "volatile");
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}
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use super::IO_BASE;
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use super::asm::delay;
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use core::marker::PhantomData;
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use volatile::{ReadOnly, Volatile, WriteOnly};
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/// The base address of the `GPIO` registers.
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const GPIO_BASE: usize = IO_BASE + 0x200000;
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/// An alternative GPIO function.
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#[repr(u8)]
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pub enum Function {
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Input = 0b000,
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Output = 0b001,
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Alt0 = 0b100,
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Alt1 = 0b101,
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Alt2 = 0b110,
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Alt3 = 0b111,
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Alt4 = 0b011,
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Alt5 = 0b010,
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}
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#[repr(C)]
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#[allow(non_snake_case)]
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struct Registers {
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FSEL: [Volatile<u32>; 6],
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__reserved0: u32,
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SET: [WriteOnly<u32>; 2],
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__reserved1: u32,
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CLR: [WriteOnly<u32>; 2],
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__reserved2: u32,
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LEV: [ReadOnly<u32>; 2],
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__reserved3: u32,
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EDS: [Volatile<u32>; 2],
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__reserved4: u32,
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REN: [Volatile<u32>; 2],
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__reserved5: u32,
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FEN: [Volatile<u32>; 2],
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__reserved6: u32,
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HEN: [Volatile<u32>; 2],
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__reserved7: u32,
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LEN: [Volatile<u32>; 2],
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__reserved8: u32,
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AREN: [Volatile<u32>; 2],
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__reserved9: u32,
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AFEN: [Volatile<u32>; 2],
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__reserved10: u32,
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PUD: Volatile<u32>,
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PUDCLK: [Volatile<u32>; 2],
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}
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/// Possible states for a GPIO pin.
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pub enum Uninitialized {}
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pub enum Input {}
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pub enum Output {}
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pub enum Alt {}
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/// A GPIO pin in state `State`.
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///
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/// The `State` generic always corresponds to an uninstantiatable type that is
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/// use solely to mark and track the state of a given GPIO pin. A `Gpio`
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/// structure starts in the `Uninitialized` state and must be transitions into
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/// one of `Input`, `Output`, or `Alt` via the `into_input`, `into_output`, and
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/// `into_alt` methods before it can be used.
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pub struct Gpio<State> {
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pin: u8,
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registers: &'static mut Registers,
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_state: PhantomData<State>,
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}
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impl<T> Gpio<T> {
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/// Transitions `self` to state `S`, consuming `self` and returning a new
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/// `Gpio` instance in state `S`. This method should _never_ be exposed to
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/// the public!
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#[inline(always)]
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fn transition<S>(self) -> Gpio<S> {
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Gpio {
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pin: self.pin,
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registers: self.registers,
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_state: PhantomData,
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}
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}
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/// Set the Gpio pull-up/pull-down state for values in `pin_value`
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pub fn set_gpio_pd(&mut self, pud_value: u8) {
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unsafe {
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let index = if self.pin >= 32 { 1 } else { 0 };
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self.registers.PUD.write(pud_value as u32);
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delay(150);
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self.registers.PUDCLK[index as usize].write((1 << self.pin) as u32);
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delay(150);
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self.registers.PUD.write(0);
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self.registers.PUDCLK[index as usize].write(0);
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}
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}
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}
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impl Gpio<Uninitialized> {
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/// Returns a new `GPIO` structure for pin number `pin`.
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///
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/// # Panics
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///
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/// Panics if `pin` > `53`.
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pub fn new(pin: u8) -> Gpio<Uninitialized> {
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if pin > 53 {
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panic!("Gpio::new(): pin {} exceeds maximum of 53", pin);
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}
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Gpio {
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registers: unsafe { &mut *(GPIO_BASE as *mut Registers) },
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pin: pin,
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_state: PhantomData,
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}
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}
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/// Enables the alternative function `function` for `self`. Consumes self
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/// and returns a `Gpio` structure in the `Alt` state.
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pub fn into_alt(self, function: Function) -> Gpio<Alt> {
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self.registers.FSEL[(self.pin / 10) as usize]
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.write((function as u32) << (3 * (self.pin % 10)));
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self.transition()
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}
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/// Sets this pin to be an _output_ pin. Consumes self and returns a `Gpio`
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/// structure in the `Output` state.
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pub fn into_output(self) -> Gpio<Output> {
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self.into_alt(Function::Output).transition()
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}
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/// Sets this pin to be an _input_ pin. Consumes self and returns a `Gpio`
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/// structure in the `Input` state.
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pub fn into_input(self) -> Gpio<Input> {
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self.into_alt(Function::Input).transition()
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}
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}
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impl Gpio<Output> {
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/// Sets (turns on) the pin.
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pub fn set(&mut self) {
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let index = if self.pin >= 32 { 1 } else { 0 };
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self.registers.SET[index as usize].write(1 << (self.pin - index * 32));
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}
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/// Clears (turns off) the pin.
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pub fn clear(&mut self) {
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let index = if self.pin >= 32 { 1 } else { 0 };
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self.registers.CLR[index as usize].write(1 << (self.pin - index * 32));
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}
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}
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impl Gpio<Input> {
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/// Reads the pin's value. Returns `true` if the level is high and `false`
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/// if the level is low.
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pub fn level(&mut self) -> bool {
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let index = if self.pin >= 32 { 1 } else { 0 };
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let high = 1 << (self.pin - index * 32);
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(self.registers.LEV[index as usize].read() & high) == high
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}
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}
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@ -0,0 +1,11 @@
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#![no_std]
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#![feature(asm)]
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extern crate volatile;
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mod asm;
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pub mod gpio;
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pub mod mini_uart;
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pub const IO_BASE: usize = 0x3F000000;
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@ -0,0 +1 @@
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use super::IO_BASE;
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@ -1,5 +1,9 @@
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//! Raspberry PI 3 Model B/B+
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extern crate bcm2837;
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pub fn init() {
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// TODO
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bcm2837::gpio::Gpio::new(14).set_gpio_pd(0);
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bcm2837::gpio::Gpio::new(15).set_gpio_pd(0);
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}
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