apis/i2c_master: Initial support

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

Cargo.toml

@@ -25,6 +25,7 @@ libtock_buzzer = { path = "apis/buzzer" }
 libtock_console = { path = "apis/console" }
 libtock_debug_panic = { path = "panic_handlers/debug_panic" }
 libtock_gpio = { path = "apis/gpio" }
+libtock_i2c_master = { path = "apis/i2c_master" }
 libtock_i2c_master_slave = { path = "apis/i2c_master_slave" }
 libtock_leds = { path = "apis/leds" }
 libtock_low_level_debug = { path = "apis/low_level_debug" }
@@ -60,6 +61,7 @@ members = [
     "apis/buzzer",
     "apis/console",
     "apis/gpio",
+    "apis/i2c_master",
     "apis/i2c_master_slave",
     "apis/leds",
     "apis/low_level_debug",

apis/i2c_master/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "libtock_i2c_master"
+version = "0.1.0"
+authors = [
+    "Tock Project Developers <tock-dev@googlegroups.com>",
+    "Alistair Francis <alistair.francis@wdc.com>",
+]
+license = "Apache-2.0 OR MIT"
+edition = "2021"
+repository = "https://www.github.com/tock/libtock-rs"
+rust-version.workspace = true
+description = "libtock I2C master driver"
+
+[dependencies]
+libtock_platform = { path = "../../platform" }
+

apis/i2c_master/src/lib.rs

@@ -0,0 +1,216 @@
+#![no_std]
+
+use core::cell::Cell;
+use libtock_platform as platform;
+use libtock_platform::allow_rw::AllowRw;
+use libtock_platform::share;
+use libtock_platform::subscribe::Subscribe;
+use libtock_platform::{DefaultConfig, ErrorCode, Syscalls};
+
+pub struct I2CMaster<S: Syscalls, C: Config = DefaultConfig>(S, C);
+
+impl<S: Syscalls, C: Config> I2CMaster<S, C> {
+    pub fn exists() -> Result<(), ErrorCode> {
+        S::command(DRIVER_NUM, i2c_master_cmd::EXISTS, 0, 0).to_result()
+    }
+
+    /// # Summary
+    ///
+    /// Perform an I2C write followed by a read.
+    ///
+    /// TODO: Add async support
+    ///
+    /// # Parameter
+    ///
+    /// * `addr`: Slave device address
+    /// * `buf`: Buffer
+    /// * `w_len`: Number of bytes to write from @w_buf
+    /// * `r_len`: Number of bytes to read into @r_buf
+    ///
+    /// # Returns
+    /// On success: Returns Ok(())
+    /// On failure: Err(ErrorCode)
+    pub fn i2c_master_write_read_sync(
+        addr: u16,
+        buf: &mut [u8],
+        w_len: u16,
+        r_len: u16,
+    ) -> Result<(), ErrorCode> {
+        if w_len as usize > buf.len() || r_len as usize > buf.len() {
+            return Err(ErrorCode::NoMem);
+        }
+        let called: Cell<Option<(u32, u32, u32)>> = Cell::new(None);
+        let cmd_arg0: u32 = (w_len as u32) << 8 | addr as u32;
+        share::scope::<
+            (
+                AllowRw<_, DRIVER_NUM, { rw_allow::MASTER }>,
+                Subscribe<_, DRIVER_NUM, { subscribe::MASTER_WRITE }>,
+            ),
+            _,
+            _,
+        >(|handle| {
+            let (allow_rw, subscribe) = handle.split();
+            S::allow_rw::<C, DRIVER_NUM, { rw_allow::MASTER }>(allow_rw, buf)?;
+            S::subscribe::<_, _, C, DRIVER_NUM, { subscribe::MASTER_READ_WRITE }>(
+                subscribe, &called,
+            )?;
+
+            S::command(
+                DRIVER_NUM,
+                i2c_master_cmd::MASTER_WRITE,
+                cmd_arg0.into(),
+                r_len.into(),
+            )
+            .to_result()?;
+
+            loop {
+                S::yield_wait();
+                if let Some((r0, status, _)) = called.get() {
+                    assert_eq!(r0, 0);
+                    return match status {
+                        0 => Ok(()),
+                        e_status => Err(e_status.try_into().unwrap_or(ErrorCode::Fail)),
+                    };
+                }
+            }
+        })
+    }
+
+    /// # Summary
+    ///
+    /// Write to an I2C device the data from the buffer pointed by @buf. This function is
+    /// synchronous and returns only when the operation has completed.
+    ///
+    /// TODO: Add async support
+    ///
+    /// # Parameter
+    ///
+    /// * `addr`: Slave device address
+    /// * `buf`: Storage buffer, this should be bigger than @len
+    /// * `len`: Number of bytes to read into @buf
+    ///
+    /// # Returns
+    /// On success: Returns Ok(())
+    /// On failure: Err(ErrorCode)
+    pub fn i2c_master_write_sync(addr: u16, buf: &mut [u8], len: u16) -> Result<(), ErrorCode> {
+        let called: Cell<Option<(u32, u32, u32)>> = Cell::new(None);
+        share::scope::<
+            (
+                AllowRw<_, DRIVER_NUM, { rw_allow::MASTER }>,
+                Subscribe<_, DRIVER_NUM, { subscribe::MASTER_WRITE }>,
+            ),
+            _,
+            _,
+        >(|handle| {
+            let (allow_rw, subscribe) = handle.split();
+            S::allow_rw::<C, DRIVER_NUM, { rw_allow::MASTER }>(allow_rw, buf)?;
+            S::subscribe::<_, _, C, DRIVER_NUM, { subscribe::MASTER_WRITE }>(subscribe, &called)?;
+
+            S::command(
+                DRIVER_NUM,
+                i2c_master_cmd::MASTER_WRITE,
+                addr.into(),
+                len.into(),
+            )
+            .to_result()?;
+
+            loop {
+                S::yield_wait();
+                if let Some((r0, status, _)) = called.get() {
+                    assert_eq!(r0, 0);
+                    return match status {
+                        0 => Ok(()),
+                        e_status => Err(e_status.try_into().unwrap_or(ErrorCode::Fail)),
+                    };
+                }
+            }
+        })
+    }
+
+    /// # Summary
+    ///
+    /// Read from an I2C device the data to the buffer pointed by @buf. This function is
+    /// synchronous and returns only when the operation has completed.
+    ///
+    /// TODO: Add async support
+    ///
+    /// # Parameter
+    ///
+    /// * `addr`: Slave device address
+    /// * `buf`: Storage buffer, this should be bigger than @len
+    /// * `len`: Number of bytes to read into @buf
+    ///
+    /// # Returns
+    /// On success: Returns Ok(())
+    /// On failure: Err(ErrorCode)
+    pub fn i2c_master_read_sync(addr: u16, buf: &mut [u8], len: u16) -> Result<(), ErrorCode> {
+        let called: Cell<Option<(u32, u32, u32)>> = Cell::new(None);
+        share::scope::<
+            (
+                AllowRw<_, DRIVER_NUM, { rw_allow::MASTER }>,
+                Subscribe<_, DRIVER_NUM, { subscribe::MASTER_READ }>,
+            ),
+            _,
+            _,
+        >(|handle| {
+            let (allow_rw, subscribe) = handle.split();
+            S::allow_rw::<C, DRIVER_NUM, { rw_allow::MASTER }>(allow_rw, buf)?;
+            S::subscribe::<_, _, C, DRIVER_NUM, { subscribe::MASTER_READ }>(subscribe, &called)?;
+
+            S::command(
+                DRIVER_NUM,
+                i2c_master_cmd::MASTER_READ,
+                addr.into(),
+                len.into(),
+            )
+            .to_result()?;
+
+            loop {
+                S::yield_wait();
+                if let Some((r0, status, _)) = called.get() {
+                    assert_eq!(r0, 0);
+                    return match status {
+                        0 => Ok(()),
+                        e_status => Err(e_status.try_into().unwrap_or(ErrorCode::Fail)),
+                    };
+                }
+            }
+        })
+    }
+}
+
+/// System call configuration trait for `I2CMaster`.
+pub trait Config:
+    platform::allow_ro::Config + platform::allow_rw::Config + platform::subscribe::Config
+{
+}
+impl<T: platform::allow_ro::Config + platform::allow_rw::Config + platform::subscribe::Config>
+    Config for T
+{
+}
+
+// -----------------------------------------------------------------------------
+// Driver number and command IDs
+// -----------------------------------------------------------------------------
+const DRIVER_NUM: u32 = 0x20003;
+
+#[allow(unused)]
+mod subscribe {
+    pub const MASTER_READ: u32 = 0;
+    pub const MASTER_WRITE: u32 = 0;
+    pub const MASTER_READ_WRITE: u32 = 0;
+}
+
+/// Ids for read-write allow buffers
+#[allow(unused)]
+mod rw_allow {
+    pub const MASTER: u32 = 1;
+}
+
+#[allow(unused)]
+mod i2c_master_cmd {
+    pub const EXISTS: u32 = 0;
+    pub const MASTER_WRITE: u32 = 1;
+    pub const MASTER_READ: u32 = 2;
+    pub const MASTER_WRITE_READ: u32 = 3;
+}

src/lib.rs

@@ -51,6 +51,10 @@ pub mod gpio {
         PullDown, PullNone, PullUp,
     };
 }
+pub mod i2c_master {
+    use libtock_i2c_master as i2c_master;
+    pub type I2CMaster = i2c_master::I2CMaster<super::runtime::TockSyscalls>;
+}
 pub mod i2c_master_slave {
     use libtock_i2c_master_slave as i2c_master_slave;
     pub type I2CMasterSlave = i2c_master_slave::I2CMasterSlave<super::runtime::TockSyscalls>;