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// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2025 Google LLC.
//! Sample DebugFS exporting platform driver
//!
//! To successfully probe this driver with ACPI, use an ssdt that looks like
//!
//! ```dsl
//! DefinitionBlock ("", "SSDT", 2, "TEST", "VIRTACPI", 0x00000001)
//! {
//! Scope (\_SB)
//! {
//! Device (T432)
//! {
//! Name (_HID, "LNUXBEEF") // ACPI hardware ID to match
//! Name (_UID, 1)
//! Name (_STA, 0x0F) // Device present, enabled
//! Name (_DSD, Package () { // Sample attribute
//! ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
//! Package() {
//! Package(2) {"compatible", "sample-debugfs"}
//! }
//! })
//! Name (_CRS, ResourceTemplate ()
//! {
//! Memory32Fixed (ReadWrite, 0xFED00000, 0x1000)
//! })
//! }
//! }
//! }
//! ```
use core::str::FromStr;
use core::sync::atomic::AtomicUsize;
use core::sync::atomic::Ordering;
use kernel::c_str;
use kernel::debugfs::{Dir, File};
use kernel::new_mutex;
use kernel::prelude::*;
use kernel::sync::Mutex;
use kernel::{acpi, device::Core, of, platform, str::CString, types::ARef};
kernel::module_platform_driver! {
type: RustDebugFs,
name: "rust_debugfs",
authors: ["Matthew Maurer"],
description: "Rust DebugFS usage sample",
license: "GPL",
}
#[pin_data]
struct RustDebugFs {
pdev: ARef<platform::Device>,
// As we only hold these for drop effect (to remove the directory/files) we have a leading
// underscore to indicate to the compiler that we don't expect to use this field directly.
_debugfs: Dir,
#[pin]
_compatible: File<CString>,
#[pin]
counter: File<AtomicUsize>,
#[pin]
inner: File<Mutex<Inner>>,
}
#[derive(Debug)]
struct Inner {
x: u32,
y: u32,
}
impl FromStr for Inner {
type Err = Error;
fn from_str(s: &str) -> Result<Self> {
let mut parts = s.split_whitespace();
let x = parts
.next()
.ok_or(EINVAL)?
.parse::<u32>()
.map_err(|_| EINVAL)?;
let y = parts
.next()
.ok_or(EINVAL)?
.parse::<u32>()
.map_err(|_| EINVAL)?;
if parts.next().is_some() {
return Err(EINVAL);
}
Ok(Inner { x, y })
}
}
kernel::acpi_device_table!(
ACPI_TABLE,
MODULE_ACPI_TABLE,
<RustDebugFs as platform::Driver>::IdInfo,
[(acpi::DeviceId::new(c_str!("LNUXBEEF")), ())]
);
impl platform::Driver for RustDebugFs {
type IdInfo = ();
const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
fn probe(
pdev: &platform::Device<Core>,
_info: Option<&Self::IdInfo>,
) -> Result<Pin<KBox<Self>>> {
let result = KBox::try_pin_init(RustDebugFs::new(pdev), GFP_KERNEL)?;
// We can still mutate fields through the files which are atomic or mutexed:
result.counter.store(91, Ordering::Relaxed);
{
let mut guard = result.inner.lock();
guard.x = guard.y;
guard.y = 42;
}
Ok(result)
}
}
impl RustDebugFs {
fn build_counter(dir: &Dir) -> impl PinInit<File<AtomicUsize>> + '_ {
dir.read_write_file(c_str!("counter"), AtomicUsize::new(0))
}
fn build_inner(dir: &Dir) -> impl PinInit<File<Mutex<Inner>>> + '_ {
dir.read_write_file(c_str!("pair"), new_mutex!(Inner { x: 3, y: 10 }))
}
fn new(pdev: &platform::Device<Core>) -> impl PinInit<Self, Error> + '_ {
let debugfs = Dir::new(c_str!("sample_debugfs"));
let dev = pdev.as_ref();
try_pin_init! {
Self {
_compatible <- debugfs.read_only_file(
c_str!("compatible"),
dev.fwnode()
.ok_or(ENOENT)?
.property_read::<CString>(c_str!("compatible"))
.required_by(dev)?,
),
counter <- Self::build_counter(&debugfs),
inner <- Self::build_inner(&debugfs),
_debugfs: debugfs,
pdev: pdev.into(),
}
}
}
}
|
