[libgpiod][PATCH V9 3/8] bindings: rust: Add gpiosim crate

[Viresh Kumar <viresh.kumar@linaro.org>]

This adds gpiosim rust crate, which provides helpers to emulate GPIO
chips.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 bindings/rust/Cargo.toml         |   1 +
 bindings/rust/gpiosim/Cargo.toml |  22 ++
 bindings/rust/gpiosim/build.rs   |  43 ++++
 bindings/rust/gpiosim/src/lib.rs |  79 ++++++++
 bindings/rust/gpiosim/src/sim.rs | 331 +++++++++++++++++++++++++++++++
 5 files changed, 476 insertions(+)
 create mode 100644 bindings/rust/gpiosim/Cargo.toml
 create mode 100644 bindings/rust/gpiosim/build.rs
 create mode 100644 bindings/rust/gpiosim/src/lib.rs
 create mode 100644 bindings/rust/gpiosim/src/sim.rs

diff --git a/bindings/rust/Cargo.toml b/bindings/rust/Cargo.toml
index c7bbcc798920..b9eea6b3a5ea 100644
--- a/bindings/rust/Cargo.toml
+++ b/bindings/rust/Cargo.toml
@@ -1,5 +1,6 @@
 [workspace]
 
 members = [
+    "gpiosim",
     "libgpiod-sys"
 ]
diff --git a/bindings/rust/gpiosim/Cargo.toml b/bindings/rust/gpiosim/Cargo.toml
new file mode 100644
index 000000000000..f8f7e7f79b77
--- /dev/null
+++ b/bindings/rust/gpiosim/Cargo.toml
@@ -0,0 +1,22 @@
+[package]
+name = "gpiosim"
+version = "0.1.0"
+authors = ["Viresh Kumar <viresh.kumar@linaro.org>"]
+description = "gpiosim header bindings"
+repository = "https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git"
+categories = ["external-ffi-bindings", "os::linux-apis"]
+rust-version = "1.56"
+keywords = ["libgpiod", "gpio", "gpiosim"]
+license = "Apache-2.0 OR BSD-3-Clause"
+edition = "2021"
+
+[dependencies]
+errno = "0.2.8"
+libgpiod = { path = "../libgpiod" }
+
+[features]
+generate = [ "bindgen" ]
+
+[build-dependencies]
+bindgen = { version = "0.59.1", optional = true }
+cc = "1.0.46"
diff --git a/bindings/rust/gpiosim/build.rs b/bindings/rust/gpiosim/build.rs
new file mode 100644
index 000000000000..460fb8c092c3
--- /dev/null
+++ b/bindings/rust/gpiosim/build.rs
@@ -0,0 +1,43 @@
+#[cfg(feature = "generate")]
+extern crate bindgen;
+#[cfg(feature = "generate")]
+use std::env;
+#[cfg(feature = "generate")]
+use std::path::PathBuf;
+
+#[cfg(feature = "generate")]
+fn generate_bindings() {
+    // Tell cargo to invalidate the built crate whenever following files change
+    println!("cargo:rerun-if-changed=../../../tests/gpiosim/gpiosim.h");
+
+    // The bindgen::Builder is the main entry point
+    // to bindgen, and lets you build up options for
+    // the resulting bindings.
+    let bindings = bindgen::Builder::default()
+        // The input header we would like to generate
+        // bindings for.
+        .header("../../../tests/gpiosim/gpiosim.h")
+        // Tell cargo to invalidate the built crate whenever any of the
+        // included header files changed.
+        .parse_callbacks(Box::new(bindgen::CargoCallbacks))
+        // Finish the builder and generate the bindings.
+        .generate()
+        // Unwrap the Result and panic on failure.
+        .expect("Unable to generate bindings");
+
+    // Write the bindings to the $OUT_DIR/bindings.rs file.
+    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
+    bindings
+        .write_to_file(out_path.join("bindings.rs"))
+        .expect("Couldn't write bindings!");
+}
+
+fn main() {
+    #[cfg(feature = "generate")]
+    generate_bindings();
+
+    println!("cargo:rustc-link-lib=kmod");
+    println!("cargo:rustc-link-lib=mount");
+    println!("cargo:rustc-link-search=./../../tests/gpiosim/.libs/");
+    println!("cargo:rustc-link-lib=static=gpiosim");
+}
diff --git a/bindings/rust/gpiosim/src/lib.rs b/bindings/rust/gpiosim/src/lib.rs
new file mode 100644
index 000000000000..e76870e4a094
--- /dev/null
+++ b/bindings/rust/gpiosim/src/lib.rs
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
+//
+// Copyright 2022 Linaro Ltd. All Rights Reserved.
+//     Viresh Kumar <viresh.kumar@linaro.org>
+
+use libgpiod::{Error, Result};
+
+#[allow(non_camel_case_types, non_upper_case_globals)]
+#[cfg_attr(test, allow(deref_nullptr, non_snake_case))]
+#[allow(dead_code)]
+mod bindings_raw {
+    #[cfg(feature = "generate")]
+    include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
+
+    #[cfg(not(feature = "generate"))]
+    include!("bindings.rs");
+}
+use bindings_raw::*;
+
+mod sim;
+pub use sim::*;
+
+/// Value settings.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum Value {
+    /// Active
+    Active,
+    /// Inactive
+    InActive,
+}
+
+impl Value {
+    pub(crate) fn new(val: u32) -> Result<Self> {
+        match val {
+            GPIOSIM_VALUE_INACTIVE => Ok(Value::InActive),
+            GPIOSIM_VALUE_ACTIVE => Ok(Value::Active),
+            _ => Err(Error::InvalidEnumValue("Value", val as u32)),
+        }
+    }
+}
+
+/// Direction settings.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum Direction {
+    /// Direction is input - for reading the value of an externally driven GPIO line.
+    Input,
+    /// Direction is output - for driving the GPIO line, value is high.
+    OutputHigh,
+    /// Direction is output - for driving the GPIO line, value is low.
+    OutputLow,
+}
+
+impl Direction {
+    fn val(self) -> i32 {
+        (match self {
+            Direction::Input => GPIOSIM_HOG_DIR_INPUT,
+            Direction::OutputHigh => GPIOSIM_HOG_DIR_OUTPUT_HIGH,
+            Direction::OutputLow => GPIOSIM_HOG_DIR_OUTPUT_LOW,
+        }) as i32
+    }
+}
+
+/// Internal pull settings.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum Pull {
+    /// The internal pull-up is enabled.
+    Up,
+    /// The internal pull-down is enabled.
+    Down,
+}
+
+impl Pull {
+    fn val(self) -> i32 {
+        (match self {
+            Pull::Up => GPIOSIM_PULL_UP,
+            Pull::Down => GPIOSIM_PULL_DOWN,
+        }) as i32
+    }
+}
diff --git a/bindings/rust/gpiosim/src/sim.rs b/bindings/rust/gpiosim/src/sim.rs
new file mode 100644
index 000000000000..6cafda0d90e2
--- /dev/null
+++ b/bindings/rust/gpiosim/src/sim.rs
@@ -0,0 +1,331 @@
+// SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
+//
+// Copyright 2022 Linaro Ltd. All Rights Reserved.
+//     Viresh Kumar <viresh.kumar@linaro.org>
+
+use std::ffi::{CStr, CString};
+use std::os::raw::c_char;
+use std::path::PathBuf;
+use std::str;
+
+use libgpiod::{line::Offset, Error, OperationType, Result};
+
+use crate::*;
+
+/// Sim Ctx
+#[derive(Debug)]
+struct SimCtx {
+    ctx: *mut gpiosim_ctx,
+}
+
+// Safe as the pointer is guaranteed to be valid and the associated resource
+// won't be freed until the object is dropped.
+unsafe impl Send for SimCtx {}
+
+impl SimCtx {
+    fn new() -> Result<Self> {
+        // SAFETY: `gpiosim_ctx` returned by gpiosim is guaranteed to live
+        // as long as the `struct SimCtx`.
+        let ctx = unsafe { gpiosim_ctx_new() };
+        if ctx.is_null() {
+            return Err(Error::OperationFailed(
+                OperationType::SimCtxNew,
+                errno::errno(),
+            ));
+        }
+
+        Ok(Self { ctx })
+    }
+}
+
+impl Drop for SimCtx {
+    fn drop(&mut self) {
+        // SAFETY: `gpiosim_ctx` is guaranteed to be valid here.
+        unsafe { gpiosim_ctx_unref(self.ctx) }
+    }
+}
+
+/// Sim Dev
+#[derive(Debug)]
+struct SimDev {
+    dev: *mut gpiosim_dev,
+}
+
+// Safe as the pointer is guaranteed to be valid and the associated resource
+// won't be freed until the object is dropped.
+unsafe impl Send for SimDev {}
+
+impl SimDev {
+    fn new(ctx: &SimCtx) -> Result<Self> {
+        // SAFETY: `gpiosim_dev` returned by gpiosim is guaranteed to live
+        // as long as the `struct SimDev`.
+        let dev = unsafe { gpiosim_dev_new(ctx.ctx) };
+        if dev.is_null() {
+            return Err(Error::OperationFailed(
+                OperationType::SimDevNew,
+                errno::errno(),
+            ));
+        }
+
+        Ok(Self { dev })
+    }
+
+    fn enable(&self) -> Result<()> {
+        // SAFETY: `gpiosim_dev` is guaranteed to be valid here.
+        let ret = unsafe { gpiosim_dev_enable(self.dev) };
+
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimDevEnable,
+                errno::errno(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+
+    fn disable(&self) -> Result<()> {
+        // SAFETY: `gpiosim_dev` is guaranteed to be valid here.
+        let ret = unsafe { gpiosim_dev_disable(self.dev) };
+
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimDevDisable,
+                errno::errno(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+}
+
+impl Drop for SimDev {
+    fn drop(&mut self) {
+        // SAFETY: `gpiosim_dev` is guaranteed to be valid here.
+        unsafe { gpiosim_dev_unref(self.dev) }
+    }
+}
+
+/// Sim Bank
+#[derive(Debug)]
+struct SimBank {
+    bank: *mut gpiosim_bank,
+}
+
+// Safe as the pointer is guaranteed to be valid and the associated resource
+// won't be freed until the object is dropped.
+unsafe impl Send for SimBank {}
+
+impl SimBank {
+    fn new(dev: &SimDev) -> Result<Self> {
+        // SAFETY: `gpiosim_bank` returned by gpiosim is guaranteed to live
+        // as long as the `struct SimBank`.
+        let bank = unsafe { gpiosim_bank_new(dev.dev) };
+        if bank.is_null() {
+            return Err(Error::OperationFailed(
+                OperationType::SimBankNew,
+                errno::errno(),
+            ));
+        }
+
+        Ok(Self { bank })
+    }
+
+    fn chip_name(&self) -> Result<&str> {
+        // SAFETY: The string returned by gpiosim is guaranteed to live as long
+        // as the `struct SimBank`.
+        let name = unsafe { gpiosim_bank_get_chip_name(self.bank) };
+
+        // SAFETY: The string is guaranteed to be valid here.
+        unsafe { CStr::from_ptr(name) }
+            .to_str()
+            .map_err(Error::StringNotUtf8)
+    }
+
+    fn dev_path(&self) -> Result<PathBuf> {
+        // SAFETY: The string returned by gpiosim is guaranteed to live as long
+        // as the `struct SimBank`.
+        let path = unsafe { gpiosim_bank_get_dev_path(self.bank) };
+
+        // SAFETY: The string is guaranteed to be valid here.
+        let path = unsafe { CStr::from_ptr(path) }
+            .to_str()
+            .map_err(Error::StringNotUtf8)?;
+
+        Ok(PathBuf::from(path))
+    }
+
+    fn val(&self, offset: Offset) -> Result<Value> {
+        // SAFETY: `gpiosim_bank` is guaranteed to be valid here.
+        let ret = unsafe { gpiosim_bank_get_value(self.bank, offset) };
+
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimBankGetVal,
+                errno::errno(),
+            ))
+        } else {
+            Value::new(ret as u32)
+        }
+    }
+
+    fn set_label(&self, label: &str) -> Result<()> {
+        let label = CString::new(label).map_err(|_| Error::InvalidString)?;
+
+        // SAFETY: `gpiosim_bank` is guaranteed to be valid here.
+        let ret = unsafe { gpiosim_bank_set_label(self.bank, label.as_ptr() as *const c_char) };
+
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimBankSetLabel,
+                errno::errno(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+
+    fn set_num_lines(&self, num: usize) -> Result<()> {
+        // SAFETY: `gpiosim_bank` is guaranteed to be valid here.
+        let ret = unsafe { gpiosim_bank_set_num_lines(self.bank, num.try_into().unwrap()) };
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimBankSetNumLines,
+                errno::errno(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+
+    fn set_line_name(&self, offset: Offset, name: &str) -> Result<()> {
+        let name = CString::new(name).map_err(|_| Error::InvalidString)?;
+
+        // SAFETY: `gpiosim_bank` is guaranteed to be valid here.
+        let ret = unsafe {
+            gpiosim_bank_set_line_name(self.bank, offset, name.as_ptr() as *const c_char)
+        };
+
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimBankSetLineName,
+                errno::errno(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+
+    fn set_pull(&self, offset: Offset, pull: Pull) -> Result<()> {
+        // SAFETY: `gpiosim_bank` is guaranteed to be valid here.
+        let ret = unsafe { gpiosim_bank_set_pull(self.bank, offset, pull.val()) };
+
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimBankSetPull,
+                errno::errno(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+
+    fn hog_line(&self, offset: Offset, name: &str, dir: Direction) -> Result<()> {
+        let name = CString::new(name).map_err(|_| Error::InvalidString)?;
+
+        // SAFETY: `gpiosim_bank` is guaranteed to be valid here.
+        let ret = unsafe {
+            gpiosim_bank_hog_line(self.bank, offset, name.as_ptr() as *const c_char, dir.val())
+        };
+
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimBankHogLine,
+                errno::errno(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+}
+
+impl Drop for SimBank {
+    fn drop(&mut self) {
+        // SAFETY: `gpiosim_bank` is guaranteed to be valid here.
+        unsafe { gpiosim_bank_unref(self.bank) }
+    }
+}
+
+/// GPIO SIM
+#[derive(Debug)]
+pub struct Sim {
+    _ctx: SimCtx,
+    dev: SimDev,
+    bank: SimBank,
+}
+
+impl Sim {
+    pub fn new(ngpio: Option<usize>, label: Option<&str>, enable: bool) -> Result<Self> {
+        let ctx = SimCtx::new()?;
+        let dev = SimDev::new(&ctx)?;
+        let bank = SimBank::new(&dev)?;
+
+        if let Some(ngpio) = ngpio {
+            bank.set_num_lines(ngpio)?;
+        }
+
+        if let Some(label) = label {
+            bank.set_label(label)?;
+        }
+
+        if enable {
+            dev.enable()?;
+        }
+
+        Ok(Self {
+            _ctx: ctx,
+            dev,
+            bank,
+        })
+    }
+
+    pub fn chip_name(&self) -> &str {
+        self.bank.chip_name().unwrap()
+    }
+
+    pub fn dev_path(&self) -> PathBuf {
+        self.bank.dev_path().unwrap()
+    }
+
+    pub fn val(&self, offset: Offset) -> Result<Value> {
+        self.bank.val(offset)
+    }
+
+    pub fn set_label(&self, label: &str) -> Result<()> {
+        self.bank.set_label(label)
+    }
+
+    pub fn set_num_lines(&self, num: usize) -> Result<()> {
+        self.bank.set_num_lines(num)
+    }
+
+    pub fn set_line_name(&self, offset: Offset, name: &str) -> Result<()> {
+        self.bank.set_line_name(offset, name)
+    }
+
+    pub fn set_pull(&self, offset: Offset, pull: Pull) -> Result<()> {
+        self.bank.set_pull(offset, pull)
+    }
+
+    pub fn hog_line(&self, offset: Offset, name: &str, dir: Direction) -> Result<()> {
+        self.bank.hog_line(offset, name, dir)
+    }
+
+    pub fn enable(&self) -> Result<()> {
+        self.dev.enable()
+    }
+
+    pub fn disable(&self) -> Result<()> {
+        self.dev.disable()
+    }
+}
-- 
2.31.1.272.g89b43f80a514