From e05f0677637b2816c5aef852b3e52b135b51ae7e Mon Sep 17 00:00:00 2001
From: Fabien Parent <fabien.parent@linaro.org>
Date: Wed, 3 May 2023 01:01:08 +0200
Subject: [PATCH] samples: rust: add debugfs samples
Add some basic debugfs sample module to show how to use the debugfs API.
The sample module is showing:
* How to create a directory
* How to define and register a debugfs file by implementing
file::Operations
* How to use the attribute macro to expose simple numerical debugfs
values. This is the equivalent of the C macro
DEFINE_DEBUGFS_ATTRIBUTE{,_SIGNED}
Signed-off-by: Fabien Parent <fabien.parent@linaro.org>
---
samples/rust/Kconfig | 10 +++
samples/rust/Makefile | 1 +
samples/rust/rust_debugfs.rs | 114 +++++++++++++++++++++++++++++++++++
3 files changed, 125 insertions(+)
create mode 100644 samples/rust/rust_debugfs.rs
diff --git a/samples/rust/Kconfig b/samples/rust/Kconfig
index b0f74a81c8f9ad..fc26dafc6fa386 100644
--- a/samples/rust/Kconfig
+++ b/samples/rust/Kconfig
@@ -10,6 +10,16 @@ menuconfig SAMPLES_RUST
if SAMPLES_RUST
+config SAMPLE_RUST_DEBUGFS
+ tristate "Debugfs"
+ help
+ This option builds the Rust debugfs module sample.
+
+ To compile this as a module, choose M here:
+ the module will be called rust_debugfs.
+
+ If unsure, say N.
+
config SAMPLE_RUST_MINIMAL
tristate "Minimal"
help
diff --git a/samples/rust/Makefile b/samples/rust/Makefile
index 03086dabbea44f..f80ff73028b40c 100644
--- a/samples/rust/Makefile
+++ b/samples/rust/Makefile
@@ -1,5 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_SAMPLE_RUST_DEBUGFS) += rust_debugfs.o
obj-$(CONFIG_SAMPLE_RUST_MINIMAL) += rust_minimal.o
obj-$(CONFIG_SAMPLE_RUST_PRINT) += rust_print.o
diff --git a/samples/rust/rust_debugfs.rs b/samples/rust/rust_debugfs.rs
new file mode 100644
index 00000000000000..063cfd21ea324c
--- /dev/null
+++ b/samples/rust/rust_debugfs.rs
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust debugfs device sample
+
+#![allow(missing_docs)]
+
+use kernel::{
+ c_str, debugfs, file,
+ file::File,
+ io_buffer::IoBufferWriter,
+ prelude::*,
+ sync::{Arc, SpinLock},
+ types::Mode,
+};
+
+struct SampleFile;
+
+#[vtable]
+impl file::Operations for SampleFile {
+ fn open(_data: &(), _file: &File) -> Result {
+ Ok(())
+ }
+
+ fn read(
+ _data: (),
+ _file: &File,
+ writer: &mut impl IoBufferWriter,
+ offset: u64,
+ ) -> Result<usize> {
+ let data = b"Sample debugfs file implementing file::Operations\n";
+ let offset = offset as usize;
+
+ if offset > data.len() {
+ return Ok(0);
+ }
+
+ let len = core::cmp::min(writer.len(), data.len() - offset);
+ writer.write_slice(&data[offset..(offset + len)])?;
+ Ok(len)
+ }
+}
+
+#[pin_data]
+struct IncAttribute {
+ #[pin]
+ data: SpinLock<i64>,
+}
+
+impl debugfs::attr::Attribute<i64> for IncAttribute {
+ fn get(&self) -> Result<i64> {
+ let mut guard = self.data.lock();
+ let ret = *guard;
+ *guard = ret + 1;
+ Ok(ret)
+ }
+
+ fn set(&self, val: i64) -> Result {
+ let mut guard = self.data.lock();
+ *guard = val;
+ Ok(())
+ }
+}
+
+debugfs::attribute_signed!(IncAttribute, "%#d\n");
+
+struct RustDebugfs {
+ _sample_file: debugfs::PinnedRegistration,
+ _inc_attribute: debugfs::PinnedRegistration<Arc<IncAttribute>>,
+ _symlink: debugfs::Registration<()>,
+}
+impl kernel::Module for RustDebugfs {
+ fn init(_module: &'static ThisModule) -> Result<Self> {
+ let dir = Arc::try_new(debugfs::Registration::register_dir(
+ c_str!("rust_samples"),
+ None,
+ )?)?;
+
+ let sample_file = debugfs::Registration::register_file::<SampleFile>(
+ c_str!("sample"),
+ Mode::from_int(0444),
+ (),
+ Some(dir.clone()),
+ )?;
+
+ let symlink = debugfs::Registration::register_symlink(
+ c_str!("sample_symlink"),
+ Some(dir.clone()),
+ c_str!("sample"),
+ )?;
+
+ let attribute = Arc::pin_init(pin_init!(IncAttribute {
+ data <- kernel::new_spinlock!(0x42),
+ }))?;
+ let inc_attribute = attribute.register(
+ c_str!("inc_attribute"),
+ Mode::from_int(0666),
+ Some(dir.clone()),
+ )?;
+
+ Ok(Self {
+ _sample_file: sample_file,
+ _inc_attribute: inc_attribute,
+ _symlink: symlink,
+ })
+ }
+}
+
+module! {
+ type: RustDebugfs,
+ name: "rust_debugfs",
+ author: "Fabien Parent <fabien.parent@linaro.org>",
+ description: "Rust debugfs sample",
+ license: "GPL",
+}