[PATCH V7 5/8] libgpiod: Add gpiosim rust crate

[Viresh Kumar <viresh.kumar@xxxxxxxxxx>]

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

Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
 bindings/rust/Cargo.toml         |   3 +-
 bindings/rust/gpiosim/Cargo.toml |  18 ++
 bindings/rust/gpiosim/build.rs   |  43 ++++
 bindings/rust/gpiosim/src/lib.rs |  25 +++
 bindings/rust/gpiosim/src/sim.rs | 323 +++++++++++++++++++++++++++++++
 5 files changed, 411 insertions(+), 1 deletion(-)
 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 1e57ef2c0002..8721bc610b86 100644
--- a/bindings/rust/Cargo.toml
+++ b/bindings/rust/Cargo.toml
@@ -2,5 +2,6 @@
 
 members = [
     "libgpiod-sys",
-    "libgpiod"
+    "libgpiod",
+    "gpiosim"
 ]
diff --git a/bindings/rust/gpiosim/Cargo.toml b/bindings/rust/gpiosim/Cargo.toml
new file mode 100644
index 000000000000..d6b4cc34339b
--- /dev/null
+++ b/bindings/rust/gpiosim/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "gpiosim"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+libc = ">=0.2.39"
+libgpiod = { path = "../libgpiod" }
+vmm-sys-util = "=0.10.0"
+
+[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..94d0ddb38e0f
--- /dev/null
+++ b/bindings/rust/gpiosim/src/lib.rs
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#[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::*;
+
+pub use bindings_raw::{
+    GPIOSIM_HOG_DIR_INPUT, GPIOSIM_HOG_DIR_OUTPUT_HIGH, GPIOSIM_HOG_DIR_OUTPUT_LOW,
+    GPIOSIM_PULL_DOWN, GPIOSIM_PULL_UP, GPIOSIM_VALUE_ACTIVE, GPIOSIM_VALUE_INACTIVE,
+};
+
+#[allow(dead_code)]
+mod sim;
+
+#[allow(unused_imports)]
+pub use sim::*;
diff --git a/bindings/rust/gpiosim/src/sim.rs b/bindings/rust/gpiosim/src/sim.rs
new file mode 100644
index 000000000000..50977ea54ebb
--- /dev/null
+++ b/bindings/rust/gpiosim/src/sim.rs
@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
+//
+// Copyright 2022 Linaro Ltd. All Rights Reserved.
+//     Viresh Kumar <viresh.kumar@xxxxxxxxxx>
+
+use libc::strlen;
+use std::os::raw::c_char;
+use std::path::PathBuf;
+use std::{slice, str};
+
+use vmm_sys_util::errno::Error as Errno;
+
+use libgpiod::{Error, Offset, OperationType, Result};
+
+use crate::*;
+
+/// Sim Ctx
+#[derive(Debug)]
+struct SimCtx {
+    ctx: *mut gpiosim_ctx,
+}
+
+unsafe impl Send for SimCtx {}
+unsafe impl Sync for SimCtx {}
+
+impl SimCtx {
+    fn new() -> Result<Self> {
+        let ctx = unsafe { gpiosim_ctx_new() };
+        if ctx.is_null() {
+            return Err(Error::OperationFailed(
+                OperationType::SimCtxNew,
+                Errno::last(),
+            ));
+        }
+
+        Ok(Self { ctx })
+    }
+
+    fn ctx(&self) -> *mut gpiosim_ctx {
+        self.ctx
+    }
+}
+
+impl Drop for SimCtx {
+    fn drop(&mut self) {
+        unsafe { gpiosim_ctx_unref(self.ctx) }
+    }
+}
+
+/// Sim Dev
+#[derive(Debug)]
+struct SimDev {
+    dev: *mut gpiosim_dev,
+}
+
+unsafe impl Send for SimDev {}
+unsafe impl Sync for SimDev {}
+
+impl SimDev {
+    fn new(ctx: &SimCtx) -> Result<Self> {
+        let dev = unsafe { gpiosim_dev_new(ctx.ctx()) };
+        if dev.is_null() {
+            return Err(Error::OperationFailed(
+                OperationType::SimDevNew,
+                Errno::last(),
+            ));
+        }
+
+        Ok(Self { dev })
+    }
+
+    fn dev(&self) -> *mut gpiosim_dev {
+        self.dev
+    }
+
+    fn enable(&self) -> Result<()> {
+        let ret = unsafe { gpiosim_dev_enable(self.dev) };
+
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimDevEnable,
+                Errno::last(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+
+    fn disable(&self) -> Result<()> {
+        let ret = unsafe { gpiosim_dev_disable(self.dev) };
+
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimDevDisable,
+                Errno::last(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+}
+
+impl Drop for SimDev {
+    fn drop(&mut self) {
+        unsafe { gpiosim_dev_unref(self.dev) }
+    }
+}
+
+/// Sim Bank
+#[derive(Debug)]
+struct SimBank {
+    bank: *mut gpiosim_bank,
+}
+
+unsafe impl Send for SimBank {}
+unsafe impl Sync for SimBank {}
+
+impl SimBank {
+    fn new(dev: &SimDev) -> Result<Self> {
+        let bank = unsafe { gpiosim_bank_new(dev.dev()) };
+        if bank.is_null() {
+            return Err(Error::OperationFailed(
+                OperationType::SimBankNew,
+                Errno::last(),
+            ));
+        }
+
+        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.
+        str::from_utf8(unsafe { slice::from_raw_parts(name as *const u8, strlen(name) as usize) })
+            .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 = str::from_utf8(unsafe {
+            slice::from_raw_parts(path as *const u8, strlen(path) as usize)
+        })
+        .map_err(Error::StringNotUtf8)?;
+
+        Ok(PathBuf::from(path))
+    }
+
+    fn val(&self, offset: Offset) -> Result<u32> {
+        let ret = unsafe { gpiosim_bank_get_value(self.bank, offset) };
+
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimBankGetVal,
+                Errno::last(),
+            ))
+        } else {
+            Ok(ret as u32)
+        }
+    }
+
+    fn set_label(&self, label: &str) -> Result<()> {
+        // Null-terminate the string
+        let label = label.to_owned() + "\0";
+
+        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::last(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+
+    fn set_num_lines(&self, num: u64) -> Result<()> {
+        let ret = unsafe { gpiosim_bank_set_num_lines(self.bank, num) };
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimBankSetNumLines,
+                Errno::last(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+
+    fn set_line_name(&self, offset: Offset, name: &str) -> Result<()> {
+        // Null-terminate the string
+        let name = name.to_owned() + "\0";
+
+        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::last(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+
+    fn set_pull(&self, offset: Offset, pull: i32) -> Result<()> {
+        let ret = unsafe { gpiosim_bank_set_pull(self.bank, offset, pull) };
+
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimBankSetPull,
+                Errno::last(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+
+    fn hog_line(&self, offset: Offset, name: &str, dir: i32) -> Result<()> {
+        // Null-terminate the string
+        let name = name.to_owned() + "\0";
+
+        let ret = unsafe {
+            gpiosim_bank_hog_line(self.bank, offset, name.as_ptr() as *const c_char, dir)
+        };
+
+        if ret == -1 {
+            Err(Error::OperationFailed(
+                OperationType::SimBankHogLine,
+                Errno::last(),
+            ))
+        } else {
+            Ok(())
+        }
+    }
+}
+
+impl Drop for SimBank {
+    fn drop(&mut self) {
+        unsafe { gpiosim_bank_unref(self.bank) }
+    }
+}
+
+/// GPIO SIM
+#[derive(Debug)]
+pub struct Sim {
+    ctx: SimCtx,
+    dev: SimDev,
+    bank: SimBank,
+}
+
+unsafe impl Send for Sim {}
+unsafe impl Sync for Sim {}
+
+impl Sim {
+    pub fn new(ngpio: Option<u64>, 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, 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<u32> {
+        self.bank.val(offset)
+    }
+
+    pub fn set_label(&self, label: &str) -> Result<()> {
+        self.bank.set_label(label)
+    }
+
+    pub fn set_num_lines(&self, num: u64) -> 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: i32) -> Result<()> {
+        self.bank.set_pull(offset, pull)
+    }
+
+    pub fn hog_line(&self, offset: Offset, name: &str, dir: i32) -> 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