iio: proximity: isl29501: Fix return type of isl29501_register_writegrafted

isl29501_register_write() was returning a u32 instead of an int.
Since the function returns negative error codes (such as -ERANGE or
return values from i2c_smbus_write_byte_data()), returning an unsigned
integer type prevents callers from correctly checking for negative error
conditions.

Fix this by changing the function return type from u32 to int.

This was found through manual code review.

Fixes: 1c28799257bc ("iio: light: isl29501: Add support for the ISL29501 ToF sensor.")
Signed-off-by: Salah Triki <salah.triki@gmail.com>
Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

1 files changed, 179 insertions, 0 deletions

diff --git a/samples/rust/rust_debugfs.rs b/samples/rust/rust_debugfs.rs
new file mode 100644
index 000000000..77c19a437
--- /dev/null
+++ b/samples/rust/rust_debugfs.rs
@@ -0,0 +1,179 @@
+// 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 kernel::{
+    acpi,
+    debugfs::{
+        Dir,
+        File, //
+    },
+    device::Core,
+    new_mutex,
+    of,
+    platform,
+    prelude::*,
+    sizes::*,
+    str::CString,
+    sync::{
+        aref::ARef,
+        atomic::{
+            Atomic,
+            Relaxed, //
+        },
+        Mutex,
+    }, //
+};
+
+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<Atomic<usize>>,
+    #[pin]
+    inner: File<Mutex<Inner>>,
+    #[pin]
+    array_blob: File<Mutex<[u8; 4]>>,
+    #[pin]
+    vector_blob: File<Mutex<KVec<u8>>>,
+}
+
+#[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,
+    <RustDebugFs as platform::Driver>::IdInfo,
+    [(acpi::DeviceId::new(c"LNUXBEEF"), ())]
+);
+
+impl platform::Driver for RustDebugFs {
+    type IdInfo = ();
+    type Data<'bound> = Self;
+    const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
+    const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
+
+    fn probe<'bound>(
+        pdev: &'bound platform::Device<Core<'_>>,
+        _info: Option<&'bound Self::IdInfo>,
+    ) -> impl PinInit<Self, Error> + 'bound {
+        RustDebugFs::new(pdev).pin_chain(|this| {
+            this.counter.store(91, Relaxed);
+            {
+                let mut guard = this.inner.lock();
+                guard.x = guard.y;
+                guard.y = 42;
+            }
+
+            Ok(())
+        })
+    }
+}
+
+impl RustDebugFs {
+    fn build_counter(dir: &Dir) -> impl PinInit<File<Atomic<usize>>> + '_ {
+        dir.read_write_file(c"counter", Atomic::<usize>::new(0))
+    }
+
+    fn build_inner(dir: &Dir) -> impl PinInit<File<Mutex<Inner>>> + '_ {
+        dir.read_write_file(c"pair", new_mutex!(Inner { x: 3, y: 10 }))
+    }
+
+    fn new<'a, 'b>(
+        pdev: &'a platform::Device<Core<'b>>,
+    ) -> impl PinInit<Self, Error> + use<'a, 'b> {
+        let debugfs = Dir::new(c"sample_debugfs");
+        let dev = pdev.as_ref();
+
+        try_pin_init! {
+            Self {
+                _compatible <- debugfs.read_only_file(
+                    c"compatible",
+                    dev.fwnode()
+                        .ok_or(ENOENT)?
+                        .property_read::<CString>(c"compatible")
+                        .required_by(dev)?,
+                ),
+                counter <- Self::build_counter(&debugfs),
+                inner <- Self::build_inner(&debugfs),
+                array_blob <- debugfs.read_write_binary_file(
+                    c"array_blob",
+                    new_mutex!([0x62, 0x6c, 0x6f, 0x62]),
+                ),
+                vector_blob <- debugfs.read_write_binary_file(
+                    c"vector_blob",
+                    new_mutex!(kernel::kvec!(0x42; SZ_4K)?),
+                ),
+                _debugfs: debugfs,
+                pdev: pdev.into(),
+            }
+        }
+    }
+}