Store singleton directly in I2C type to take ownership

Make the I2C type generic over a new I2cTrait so that all I2C busses are suppored.

Author: phil-opp

src/bin/async-await.rs

@@ -21,7 +21,6 @@ extern crate futures;
 extern crate smoltcp;
 extern crate spin;
 
-use alloc::boxed::Box;
 use alloc::sync::Arc;
 use alloc::vec::Vec;
 use alloc_cortex_m::CortexMHeap;
@@ -43,6 +42,7 @@ use smoltcp::{
 };
 use stm32f7::stm32f7x6::{
     CorePeripherals, Interrupt, Peripherals, ETHERNET_DMA, ETHERNET_MAC, RCC, SAI2, SYSCFG,
+    self as device,
 };
 use stm32f7_discovery::{
     ethernet,
@@ -135,7 +135,7 @@ fn run() -> ! {
     // example allocation
     let _xs = vec![1, 2, 3];
 
-    let mut i2c_3 = init::init_i2c_3(Box::leak(Box::new(peripherals.I2C3)), &mut rcc);
+    let mut i2c_3 = init::init_i2c_3(peripherals.I2C3, &mut rcc);
     i2c_3.test_1();
     i2c_3.test_2();
 
@@ -340,7 +340,7 @@ where
     F: Framebuffer,
 {
     touch_int_stream: S,
-    i2c_3_mutex: Arc<FutureMutex<I2C<'static>>>,
+    i2c_3_mutex: Arc<FutureMutex<I2C<device::I2C3>>>,
     layer_mutex: Arc<FutureMutex<Layer<F>>>,
 }
 

src/bin/polling.rs

@@ -32,7 +32,7 @@ use smoltcp::{
     wire::{EthernetAddress, IpEndpoint, Ipv4Address, IpCidr},
     dhcp::Dhcpv4Client,
 };
-use stm32f7::stm32f7x6::{CorePeripherals, Interrupt, Peripherals};
+use stm32f7::stm32f7x6::{self as device, CorePeripherals, Interrupt, Peripherals};
 use stm32f7_discovery::{
     ethernet,
     gpio::{GpioPort, InputPin, OutputPin},
@@ -111,7 +111,7 @@ fn main() -> ! {
 
     let _xs = vec![1, 2, 3];
 
-    let mut i2c_3 = init::init_i2c_3(&peripherals.I2C3, &mut rcc);
+    let mut i2c_3 = init::init_i2c_3(peripherals.I2C3, &mut rcc);
     i2c_3.test_1();
     i2c_3.test_2();
 

src/i2c.rs

@@ -2,16 +2,24 @@
 
 use core::iter::TrustedLen;
 use core::marker::PhantomData;
+use core::ops::Deref;
 use embedded_hal;
 use stm32f7::stm32f7x6::{
-    i2c1::{self, RegisterBlock},
+    i2c1,
     RCC,
+    self as device,
 };
 
-// TODO use &mut when svd2rust API has changed (modification should require &mut)
-//pub struct I2C<'a>(&'a mut RegisterBlock);
+pub trait I2cTrait: Deref<Target = i2c1::RegisterBlock> {
+
+}
+
+impl I2cTrait for device::I2C1 {}
+impl I2cTrait for device::I2C2 {}
+impl I2cTrait for device::I2C3 {}
+
 /// Represents an I2C (Inter-Integrated Circuit) bus.
-pub struct I2C<'a>(&'a RegisterBlock);
+pub struct I2C<I: I2cTrait>(I);
 
 /// Errors that can happen while accessing the I2C bus.
 #[derive(Debug)]
@@ -49,8 +57,8 @@ fn icr_clear_all(w: &mut i2c1::icr::W) -> &mut i2c1::icr::W {
 /// An active connection to a device on the I2C bus.
 ///
 /// Allows reading and writing the registers of the device.
-pub struct I2cConnection<'a, 'i: 'a, T: RegisterType> {
-    i2c: &'a mut I2C<'i>,
+pub struct I2cConnection<'a, I: I2cTrait, T: RegisterType> {
+    i2c: &'a mut I2C<I>,
     device_address: Address,
     register_type: PhantomData<T>,
 }
@@ -107,7 +115,7 @@ impl RegisterType for u16 {
     }
 }
 
-impl<'a, 'i: 'a, T: RegisterType> I2cConnection<'a, 'i, T> {
+impl<'a, I: I2cTrait, T: RegisterType> I2cConnection<'a, I, T> {
     fn start(&mut self, read: bool, bytes: u8) {
         self.i2c.0.cr2.write(|w| {
             w.sadd().bits(self.device_address.0); // slave_address
@@ -213,15 +221,15 @@ impl<'a, 'i: 'a, T: RegisterType> I2cConnection<'a, 'i, T> {
     }
 }
 
-impl<'a> I2C<'a> {
+impl<I: I2cTrait> I2C<I> {
     /// Connects to the specified device and run the closure `f` with the connection as argument.
     ///
     /// This function takes an exclusive reference to the `I2C` type because it blocks the I2C
     /// bus. The connection is active until the closure `f` returns.
     pub fn connect<T, F>(&mut self, device_address: Address, f: F) -> Result<(), Error>
     where
         T: RegisterType,
-        F: FnOnce(I2cConnection<T>) -> Result<(), Error>,
+        F: FnOnce(I2cConnection<I, T>) -> Result<(), Error>,
     {
         {
             let conn = I2cConnection {
@@ -384,29 +392,29 @@ impl<'a> I2C<'a> {
     }
 }
 
-impl<'a> embedded_hal::blocking::i2c::Read for I2C<'a> {
+impl<I: I2cTrait> embedded_hal::blocking::i2c::Read for I2C<I> {
     type Error = Error;
 
     fn read(&mut self, address: u8, buffer: &mut [u8]) -> Result<(), Self::Error> {
         self.connect(
             Address::bits_7(address),
-            |mut connection: I2cConnection<u8>| connection.read_bytes_raw(buffer.iter_mut()),
+            |mut connection: I2cConnection<I, u8>| connection.read_bytes_raw(buffer.iter_mut()),
         )
     }
 }
 
-impl<'a> embedded_hal::blocking::i2c::Write for I2C<'a> {
+impl<I: I2cTrait> embedded_hal::blocking::i2c::Write for I2C<I> {
     type Error = Error;
 
     fn write(&mut self, address: u8, bytes: &[u8]) -> Result<(), Self::Error> {
         self.connect(
             Address::bits_7(address),
-            |mut connection: I2cConnection<u8>| connection.write_bytes(bytes.iter().map(|b| *b)),
+            |mut connection: I2cConnection<I, u8>| connection.write_bytes(bytes.iter().map(|b| *b)),
         )
     }
 }
 
-impl<'a> embedded_hal::blocking::i2c::WriteRead for I2C<'a> {
+impl<I: I2cTrait> embedded_hal::blocking::i2c::WriteRead for I2C<I> {
     type Error = Error;
 
     fn write_read(
@@ -417,7 +425,7 @@ impl<'a> embedded_hal::blocking::i2c::WriteRead for I2C<'a> {
     ) -> Result<(), Self::Error> {
         self.connect(
             Address::bits_7(address),
-            |mut connection: I2cConnection<u8>| {
+            |mut connection: I2cConnection<I, u8>| {
                 connection.write_bytes(bytes.iter().map(|b| *b))?;
                 connection.read_bytes_raw(buffer.iter_mut())
             },
@@ -426,12 +434,7 @@ impl<'a> embedded_hal::blocking::i2c::WriteRead for I2C<'a> {
 }
 
 /// Initialize the I2C bus and return an `I2C` type.
-///
-/// The IC2 type assumes that it has ownership of the I2C buffer. Therefore it is unsafe to access
-/// the passed RegisterBlock as long as the I2C lives. (This function should take a
-/// `&mut RegisterBlock`, but this is not possible due to the API that svd2rust generates. See
-/// [stm32f7-discovery#72](https://github.com/embed-rs/stm32f7-discovery/issues/72) for more info.
-pub fn init<'a>(i2c: &'a RegisterBlock, rcc: &mut RCC) -> I2C<'a> {
+pub fn init<I: I2cTrait>(i2c: I, rcc: &mut RCC) -> I2C<I> {
     // enable clocks
     rcc.apb1enr.modify(|_, w| w.i2c3en().enabled());
 

src/init/mod.rs

@@ -1,9 +1,9 @@
 //! Provides various hardware initialization functions.
 
-use crate::i2c::{self, I2C};
+use crate::i2c::{self, I2C, I2cTrait};
 use crate::lcd::{self, Lcd};
 use crate::system_clock;
-use stm32f7::stm32f7x6::{i2c1, FLASH, FMC, LTDC, PWR, RCC, SAI2, SYST};
+use stm32f7::stm32f7x6::{self as device, i2c1, FLASH, FMC, LTDC, PWR, RCC, SAI2, SYST};
 
 pub use self::pins::init as pins;
 
@@ -298,7 +298,7 @@ pub fn init_lcd<'a>(ltdc: &'a mut LTDC, rcc: &mut RCC) -> Lcd<'a> {
 /// Initializes the I2C3 bus.
 ///
 /// This function is equivalent to [`i2c::init`](crate::i2c::init).
-pub fn init_i2c_3<'a>(i2c: &'a i2c1::RegisterBlock, rcc: &mut RCC) -> I2C<'a> {
+pub fn init_i2c_3(i2c: device::I2C3, rcc: &mut RCC) -> I2C<device::I2C3> {
     i2c::init(i2c, rcc)
 }
 
@@ -525,7 +525,7 @@ const WM8994_ADDRESS: i2c::Address = i2c::Address::bits_7(0b0011010);
 /// Initializes the WM8994 audio controller.
 ///
 /// Required for audio input.
-pub fn init_wm8994(i2c_3: &mut i2c::I2C) -> Result<(), i2c::Error> {
+pub fn init_wm8994(i2c_3: &mut i2c::I2C<device::I2C3>) -> Result<(), i2c::Error> {
     i2c_3.connect::<u16, _>(WM8994_ADDRESS, |mut conn| {
         // read and check device family ID
         assert_eq!(conn.read(0).ok(), Some(0x8994));

src/touch.rs

@@ -2,6 +2,7 @@
 
 use crate::i2c::{self, I2C};
 use arrayvec::ArrayVec;
+use stm32f7::stm32f7x6 as device;
 
 const FT5336_ADDRESS: i2c::Address = i2c::Address::bits_7(0b0111000);
 const FT5336_FAMILY_ID_REGISTER: u8 = 0xA8;
@@ -11,7 +12,7 @@ const FT5336_STATUS_REGISTER: u8 = 0x02;
 const FT5336_DATA_REGISTERS: [u8; 5] = [0x03, 0x09, 0x0F, 0x15, 0x1B];
 
 /// Checks the whether the device familiy ID register contains the expected value.
-pub fn check_family_id(i2c_3: &mut I2C) -> Result<(), i2c::Error> {
+pub fn check_family_id(i2c_3: &mut I2C<device::I2C3>) -> Result<(), i2c::Error> {
     i2c_3.connect::<u8, _>(FT5336_ADDRESS, |mut conn| {
         // read and check device family ID
         assert_eq!(conn.read(FT5336_FAMILY_ID_REGISTER).ok(), Some(0x51));
@@ -27,7 +28,7 @@ pub struct Touch {
 }
 
 /// Returns a list of active touch points.
-pub fn touches(i2c_3: &mut I2C) -> Result<ArrayVec<[Touch; 5]>, i2c::Error> {
+pub fn touches(i2c_3: &mut I2C<device::I2C3>) -> Result<ArrayVec<[Touch; 5]>, i2c::Error> {
     let mut touches = ArrayVec::new();
     i2c_3.connect::<u8, _>(FT5336_ADDRESS, |mut conn| {
         let status = conn.read(FT5336_STATUS_REGISTER)?;