iio: proximity: vl53l0x-i2c: claim direct mode for raw readsgrafted

vl53l0x_read_raw() starts a single-shot ranging measurement and reads
back the result. Once the triggered buffer is enabled the sensor runs in
continuous mode and its data-ready interrupt is routed to the trigger,
so a concurrent in_distance_raw read disturbs the streaming setup and
never gets its completion, returning -ETIMEDOUT.

The original submission claimed direct mode here, but it was dropped
during review because the driver had no buffer support at the time [1].
Continuous (buffered) mode was later added without restoring the
claim [2], reintroducing the conflict.

Reject direct reads while buffered capture is active by claiming direct
mode around the measurement, as the vl53l1x sibling already does.

Fixes: 762186c6e7b1 ("iio: proximity: vl53l0x-i2c: Added continuous mode support")
Link: https://lore.kernel.org/linux-iio/20180911160300.GA9212@himanshu-Vostro-3559/ [1]
Link: https://lore.kernel.org/linux-iio/20240909101508.263085-3-abhashkumarjha123@gmail.com/ [2]
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@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(),
+            }
+        }
+    }
+}