Merge #471

471: Synchornous ADC API r=jrvanwhy a=AnneOnciulescu

### Pull Request Overview

This PR adds a Synchornous ADC API, which includes:

- function for checking the existence of the driver
- functions for initating reading of a sample, registering and unregistering a listener
- function for synchronous sample readings
- unit tests

Alongside the API, this PR adds a fake driver (and unit tests for it) for testing the API.
### Testing Strategy

This pull request was tested using unit tests made specifically for this API and fake driver.

### TODO or Help Wanted

This pull request still needs feedback / code review.
Tests needed for get_resolution_bits() and get_reference_voltage_mv().
Another PR will follow up with the implementation and tests for continuous sampling.

Co-authored-by: Anne Onciulescu <anne.onciulescu@gmail.com>

Cargo.toml

@@ -10,6 +10,7 @@ repository = "https://www.github.com/tock/libtock-rs"
 version = "0.1.0"
 
 [dependencies]
+libtock_adc = { path = "apis/adc"}
 libtock_alarm = { path = "apis/alarm" }
 libtock_ambient_light = { path = "apis/ambient_light" }
 libtock_buttons = { path = "apis/buttons" }
@@ -39,6 +40,7 @@ debug = true
 [workspace]
 exclude = ["tock"]
 members = [
+    "apis/adc",
     "apis/alarm",
     "apis/gpio",
     "apis/buttons",

apis/adc/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "libtock_adc"
+version = "0.1.0"
+authors = ["Tock Project Developers <tock-dev@googlegroups.com>"]
+license = "MIT/Apache-2.0"
+edition = "2021"
+repository = "https://www.github.com/tock/libtock-rs"
+description = "libtock adc driver"
+
+[dependencies]
+libtock_platform = { path = "../../platform" }
+
+[dev-dependencies]
+libtock_unittest = { path = "../../unittest" }

apis/adc/src/lib.rs

@@ -0,0 +1,93 @@
+#![no_std]
+
+use core::cell::Cell;
+use libtock_platform::{
+    share, subscribe::OneId, DefaultConfig, ErrorCode, Subscribe, Syscalls, Upcall,
+};
+
+pub struct Adc<S: Syscalls>(S);
+
+impl<S: Syscalls> Adc<S> {
+    /// Returns Ok() if the driver was present.This does not necessarily mean
+    /// that the driver is working.
+    pub fn exists() -> Result<(), ErrorCode> {
+        S::command(DRIVER_NUM, EXISTS, 0, 0).to_result()
+    }
+
+    // Initiate a sample reading
+    pub fn read_single_sample() -> Result<(), ErrorCode> {
+        S::command(DRIVER_NUM, SINGLE_SAMPLE, 0, 0).to_result()
+    }
+
+    // Register a listener to be called when the ADC conversion is finished
+    pub fn register_listener<'share, F: Fn(u16)>(
+        listener: &'share ADCListener<F>,
+        subscribe: share::Handle<Subscribe<'share, S, DRIVER_NUM, 0>>,
+    ) -> Result<(), ErrorCode> {
+        S::subscribe::<_, _, DefaultConfig, DRIVER_NUM, 0>(subscribe, listener)
+    }
+
+    /// Unregister the events listener
+    pub fn unregister_listener() {
+        S::unsubscribe(DRIVER_NUM, 0)
+    }
+
+    /// Initiates a synchronous ADC conversion
+    /// Returns the converted ADC value or an error
+    pub fn read_single_sample_sync() -> Result<u16, ErrorCode> {
+        let sample: Cell<Option<u16>> = Cell::new(None);
+        let listener = ADCListener(|adc_val| {
+            sample.set(Some(adc_val));
+        });
+        share::scope(|subscribe| {
+            Self::register_listener(&listener, subscribe)?;
+            Self::read_single_sample()?;
+            while sample.get() == None {
+                S::yield_wait();
+            }
+
+            match sample.get() {
+                None => Err(ErrorCode::Busy),
+                Some(adc_val) => Ok(adc_val),
+            }
+        })
+    }
+
+    /// Returns the number of ADC resolution bits
+    pub fn get_resolution_bits() -> Result<u32, ErrorCode> {
+        S::command(DRIVER_NUM, GET_RES_BITS, 0, 0).to_result()
+    }
+
+    /// Returns the reference voltage in millivolts (mV)
+    pub fn get_reference_voltage_mv() -> Result<u32, ErrorCode> {
+        S::command(DRIVER_NUM, GET_VOLTAGE_REF, 0, 0).to_result()
+    }
+}
+
+pub struct ADCListener<F: Fn(u16)>(pub F);
+
+impl<F: Fn(u16)> Upcall<OneId<DRIVER_NUM, 0>> for ADCListener<F> {
+    fn upcall(&self, adc_val: u32, _arg1: u32, _arg2: u32) {
+        self.0(adc_val as u16)
+    }
+}
+
+#[cfg(test)]
+mod tests;
+
+// -----------------------------------------------------------------------------
+// Driver number and command IDs
+// -----------------------------------------------------------------------------
+
+const DRIVER_NUM: u32 = 0x5;
+
+// Command IDs
+
+const EXISTS: u32 = 0;
+const SINGLE_SAMPLE: u32 = 1;
+// const REPEAT_SINGLE_SAMPLE: u32 = 2;
+// const MULTIPLE_SAMPLE: u32 = 3;
+// const CONTINUOUS_BUFF_SAMPLE: u32 = 4;
+// const STOP_SAMPLE: u32 = 5;
+const GET_RES_BITS: u32 = 101;
+const GET_VOLTAGE_REF: u32 = 102;

apis/adc/src/tests.rs

@@ -0,0 +1,71 @@
+use core::cell::Cell;
+use libtock_platform::{share, ErrorCode, Syscalls, YieldNoWaitReturn};
+use libtock_unittest::fake;
+
+type Adc = super::Adc<fake::Syscalls>;
+
+#[test]
+fn no_driver() {
+    let _kernel = fake::Kernel::new();
+    assert_eq!(Adc::exists(), Err(ErrorCode::NoDevice));
+}
+
+#[test]
+fn driver_check() {
+    let kernel = fake::Kernel::new();
+    let driver = fake::Adc::new();
+    kernel.add_driver(&driver);
+
+    assert_eq!(Adc::exists(), Ok(()));
+}
+
+#[test]
+fn read_single_sample() {
+    let kernel = fake::Kernel::new();
+    let driver = fake::Adc::new();
+    kernel.add_driver(&driver);
+
+    assert_eq!(Adc::read_single_sample(), Ok(()));
+    assert!(driver.is_busy());
+
+    assert_eq!(Adc::read_single_sample(), Err(ErrorCode::Busy));
+    assert_eq!(Adc::read_single_sample_sync(), Err(ErrorCode::Busy));
+}
+
+#[test]
+fn register_unregister_listener() {
+    let kernel = fake::Kernel::new();
+    let driver = fake::Adc::new();
+    kernel.add_driver(&driver);
+
+    let sample: Cell<Option<u16>> = Cell::new(None);
+    let listener = crate::ADCListener(|adc_val| {
+        sample.set(Some(adc_val));
+    });
+    share::scope(|subscribe| {
+        assert_eq!(Adc::read_single_sample(), Ok(()));
+        driver.set_value(100);
+        assert_eq!(fake::Syscalls::yield_no_wait(), YieldNoWaitReturn::NoUpcall);
+
+        assert_eq!(Adc::register_listener(&listener, subscribe), Ok(()));
+        assert_eq!(Adc::read_single_sample(), Ok(()));
+        driver.set_value(100);
+        assert_eq!(fake::Syscalls::yield_no_wait(), YieldNoWaitReturn::Upcall);
+        assert_eq!(sample.get(), Some(100));
+
+        Adc::unregister_listener();
+        assert_eq!(Adc::read_single_sample(), Ok(()));
+        driver.set_value(100);
+        assert_eq!(fake::Syscalls::yield_no_wait(), YieldNoWaitReturn::NoUpcall);
+    });
+}
+
+#[test]
+fn read_single_sample_sync() {
+    let kernel = fake::Kernel::new();
+    let driver = fake::Adc::new();
+    kernel.add_driver(&driver);
+
+    driver.set_value_sync(1000);
+    assert_eq!(Adc::read_single_sample_sync(), Ok(1000));
+}

examples/adc.rs

@@ -0,0 +1,31 @@
+//! A simple libtock-rs example. Checks for adc driver
+//! and samples the sensor every 2 seconds.
+
+#![no_main]
+#![no_std]
+
+use core::fmt::Write;
+use libtock::console::Console;
+
+use libtock::adc::Adc;
+use libtock::alarm::{Alarm, Milliseconds};
+use libtock::runtime::{set_main, stack_size};
+
+set_main! {main}
+stack_size! {0x200}
+
+fn main() {
+    if Adc::exists().is_err() {
+        writeln!(Console::writer(), "adc driver unavailable").unwrap();
+        return;
+    }
+
+    loop {
+        match Adc::read_single_sample_sync() {
+            Ok(adc_val) => writeln!(Console::writer(), "Sample: {}\n", adc_val).unwrap(),
+            Err(_) => writeln!(Console::writer(), "error while reading sample",).unwrap(),
+        }
+
+        Alarm::sleep_for(Milliseconds(2000)).unwrap();
+    }
+}

src/lib.rs

@@ -6,6 +6,11 @@ extern crate libtock_debug_panic;
 pub use libtock_platform as platform;
 pub use libtock_runtime as runtime;
 
+pub mod adc {
+    use libtock_adc as adc;
+    pub type Adc = adc::Adc<super::runtime::TockSyscalls>;
+    pub use adc::ADCListener;
+}
 pub mod alarm {
     use libtock_alarm as alarm;
     pub type Alarm = alarm::Alarm<super::runtime::TockSyscalls>;

unittest/src/fake/adc/mod.rs

@@ -0,0 +1,84 @@
+//! Fake implementation of the Adc API, documented here:
+//!
+//! Like the real API, `Adc` controls a fake Adc sensor. It provides
+//! a function `set_value` used to immediately call an upcall with a Adc value read by the sensor
+//! and a function 'set_value_sync' used to call the upcall when the read command is received.
+
+use crate::{DriverInfo, DriverShareRef};
+use libtock_platform::{CommandReturn, ErrorCode};
+use std::cell::Cell;
+
+// The `upcall_on_command` field is set to Some(value) if an upcall(with value as its argument) should be called when read command is received,
+// or None otherwise. It was needed for testing `read_sync` library function which simulates a synchronous Adc read,
+// because it was impossible to schedule an upcall during the `synchronous` read in other ways.
+pub struct Adc {
+    busy: Cell<bool>,
+    upcall_on_command: Cell<Option<i32>>,
+    share_ref: DriverShareRef,
+}
+
+impl Adc {
+    pub fn new() -> std::rc::Rc<Adc> {
+        std::rc::Rc::new(Adc {
+            busy: Cell::new(false),
+            upcall_on_command: Cell::new(None),
+            share_ref: Default::default(),
+        })
+    }
+
+    pub fn is_busy(&self) -> bool {
+        self.busy.get()
+    }
+    pub fn set_value(&self, value: i32) {
+        if self.busy.get() {
+            self.share_ref
+                .schedule_upcall(0, (value as u32, 0, 0))
+                .expect("Unable to schedule upcall");
+            self.busy.set(false);
+        }
+    }
+    pub fn set_value_sync(&self, value: i32) {
+        self.upcall_on_command.set(Some(value));
+    }
+}
+
+impl crate::fake::SyscallDriver for Adc {
+    fn info(&self) -> DriverInfo {
+        DriverInfo::new(DRIVER_NUM).upcall_count(1)
+    }
+
+    fn register(&self, share_ref: DriverShareRef) {
+        self.share_ref.replace(share_ref);
+    }
+
+    fn command(&self, command_id: u32, _argument0: u32, _argument1: u32) -> CommandReturn {
+        match command_id {
+            EXISTS => crate::command_return::success(),
+
+            SINGLE_SAMPLE => {
+                if self.busy.get() {
+                    return crate::command_return::failure(ErrorCode::Busy);
+                }
+                self.busy.set(true);
+                if let Some(val) = self.upcall_on_command.take() {
+                    self.set_value(val);
+                }
+                crate::command_return::success()
+            }
+            _ => crate::command_return::failure(ErrorCode::NoSupport),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests;
+// -----------------------------------------------------------------------------
+// Driver number and command IDs
+// -----------------------------------------------------------------------------
+
+const DRIVER_NUM: u32 = 0x5;
+
+// Command IDs
+
+const EXISTS: u32 = 0;
+const SINGLE_SAMPLE: u32 = 1;

unittest/src/fake/adc/tests.rs

@@ -0,0 +1,67 @@
+use crate::fake::{self, SyscallDriver};
+use fake::adc::*;
+use libtock_platform::{share, DefaultConfig, YieldNoWaitReturn};
+
+//Test the command implementation
+#[test]
+fn command() {
+    let adc = Adc::new();
+
+    assert!(adc.command(EXISTS, 1, 2).is_success());
+
+    assert!(adc.command(SINGLE_SAMPLE, 0, 0).is_success());
+
+    assert_eq!(
+        adc.command(SINGLE_SAMPLE, 0, 0).get_failure(),
+        Some(ErrorCode::Busy)
+    );
+
+    adc.set_value(100);
+    assert!(adc.command(SINGLE_SAMPLE, 0, 1).is_success());
+    adc.set_value(100);
+
+    adc.set_value_sync(100);
+    assert!(adc.command(SINGLE_SAMPLE, 0, 1).is_success());
+    assert!(adc.command(SINGLE_SAMPLE, 0, 1).is_success());
+}
+
+// Integration test that verifies Adc works with fake::Kernel and
+// libtock_platform::Syscalls.
+#[test]
+fn kernel_integration() {
+    use libtock_platform::Syscalls;
+    let kernel = fake::Kernel::new();
+    let adc = Adc::new();
+    kernel.add_driver(&adc);
+    assert!(fake::Syscalls::command(DRIVER_NUM, EXISTS, 1, 2).is_success());
+    assert!(fake::Syscalls::command(DRIVER_NUM, SINGLE_SAMPLE, 0, 0).is_success());
+    assert_eq!(
+        fake::Syscalls::command(DRIVER_NUM, SINGLE_SAMPLE, 0, 0).get_failure(),
+        Some(ErrorCode::Busy)
+    );
+    adc.set_value(100);
+    assert!(fake::Syscalls::command(DRIVER_NUM, SINGLE_SAMPLE, 0, 1).is_success());
+
+    let listener = Cell::<Option<(u32,)>>::new(None);
+    share::scope(|subscribe| {
+        assert_eq!(
+            fake::Syscalls::subscribe::<_, _, DefaultConfig, DRIVER_NUM, 0>(subscribe, &listener),
+            Ok(())
+        );
+
+        adc.set_value(100);
+        assert_eq!(fake::Syscalls::yield_no_wait(), YieldNoWaitReturn::Upcall);
+        assert_eq!(listener.get(), Some((100,)));
+
+        adc.set_value(200);
+        assert_eq!(fake::Syscalls::yield_no_wait(), YieldNoWaitReturn::NoUpcall);
+
+        assert!(fake::Syscalls::command(DRIVER_NUM, SINGLE_SAMPLE, 0, 1).is_success());
+        adc.set_value(200);
+        assert_eq!(fake::Syscalls::yield_no_wait(), YieldNoWaitReturn::Upcall);
+
+        adc.set_value_sync(200);
+        assert!(fake::Syscalls::command(DRIVER_NUM, SINGLE_SAMPLE, 0, 1).is_success());
+        assert_eq!(fake::Syscalls::yield_no_wait(), YieldNoWaitReturn::Upcall);
+    });
+}