Merge tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core and debugfs updates from Greg KH:
 "Here is the big set of driver core and debugfs updates for 6.14-rc1.

  Included in here is a bunch of driver core, PCI, OF, and platform rust
  bindings (all acked by the different subsystem maintainers), hence the
  merge conflict with the rust tree, and some driver core api updates to
  mark things as const, which will also require some fixups due to new
  stuff coming in through other trees in this merge window.

  There are also a bunch of debugfs updates from Al, and there is at
  least one user that does have a regression with these, but Al is
  working on tracking down the fix for it. In my use (and everyone
  else's linux-next use), it does not seem like a big issue at the
  moment.

  Here's a short list of the things in here:

   - driver core rust bindings for PCI, platform, OF, and some i/o
     functions.

     We are almost at the "write a real driver in rust" stage now,
     depending on what you want to do.

   - misc device rust bindings and a sample driver to show how to use
     them

   - debugfs cleanups in the fs as well as the users of the fs api for
     places where drivers got it wrong or were unnecessarily doing
     things in complex ways.

   - driver core const work, making more of the api take const * for
     different parameters to make the rust bindings easier overall.

   - other small fixes and updates

  All of these have been in linux-next with all of the aforementioned
  merge conflicts, and the one debugfs issue, which looks to be resolved
  "soon""

* tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (95 commits)
  rust: device: Use as_char_ptr() to avoid explicit cast
  rust: device: Replace CString with CStr in property_present()
  devcoredump: Constify 'struct bin_attribute'
  devcoredump: Define 'struct bin_attribute' through macro
  rust: device: Add property_present()
  saner replacement for debugfs_rename()
  orangefs-debugfs: don't mess with ->d_name
  octeontx2: don't mess with ->d_parent or ->d_parent->d_name
  arm_scmi: don't mess with ->d_parent->d_name
  slub: don't mess with ->d_name
  sof-client-ipc-flood-test: don't mess with ->d_name
  qat: don't mess with ->d_name
  xhci: don't mess with ->d_iname
  mtu3: don't mess wiht ->d_iname
  greybus/camera - stop messing with ->d_iname
  mediatek: stop messing with ->d_iname
  netdevsim: don't embed file_operations into your structs
  b43legacy: make use of debugfs_get_aux()
  b43: stop embedding struct file_operations into their objects
  carl9170: stop embedding file_operations into their objects
  ...

1 files changed, 201 insertions, 0 deletions

diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
new file mode 100644
index 0000000000000..942376f6f3af4
--- /dev/null
+++ b/rust/kernel/devres.rs
@@ -0,0 +1,201 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Devres abstraction
+//!
+//! [`Devres`] represents an abstraction for the kernel devres (device resource management)
+//! implementation.
+
+use crate::{
+    alloc::Flags,
+    bindings,
+    device::Device,
+    error::{Error, Result},
+    ffi::c_void,
+    prelude::*,
+    revocable::Revocable,
+    sync::Arc,
+    types::ARef,
+};
+
+use core::ops::Deref;
+
+#[pin_data]
+struct DevresInner<T> {
+    dev: ARef<Device>,
+    callback: unsafe extern "C" fn(*mut c_void),
+    #[pin]
+    data: Revocable<T>,
+}
+
+/// This abstraction is meant to be used by subsystems to containerize [`Device`] bound resources to
+/// manage their lifetime.
+///
+/// [`Device`] bound resources should be freed when either the resource goes out of scope or the
+/// [`Device`] is unbound respectively, depending on what happens first.
+///
+/// To achieve that [`Devres`] registers a devres callback on creation, which is called once the
+/// [`Device`] is unbound, revoking access to the encapsulated resource (see also [`Revocable`]).
+///
+/// After the [`Devres`] has been unbound it is not possible to access the encapsulated resource
+/// anymore.
+///
+/// [`Devres`] users should make sure to simply free the corresponding backing resource in `T`'s
+/// [`Drop`] implementation.
+///
+/// # Example
+///
+/// ```no_run
+/// # use kernel::{bindings, c_str, device::Device, devres::Devres, io::{Io, IoRaw}};
+/// # use core::ops::Deref;
+///
+/// // See also [`pci::Bar`] for a real example.
+/// struct IoMem<const SIZE: usize>(IoRaw<SIZE>);
+///
+/// impl<const SIZE: usize> IoMem<SIZE> {
+///     /// # Safety
+///     ///
+///     /// [`paddr`, `paddr` + `SIZE`) must be a valid MMIO region that is mappable into the CPUs
+///     /// virtual address space.
+///     unsafe fn new(paddr: usize) -> Result<Self>{
+///         // SAFETY: By the safety requirements of this function [`paddr`, `paddr` + `SIZE`) is
+///         // valid for `ioremap`.
+///         let addr = unsafe { bindings::ioremap(paddr as _, SIZE as _) };
+///         if addr.is_null() {
+///             return Err(ENOMEM);
+///         }
+///
+///         Ok(IoMem(IoRaw::new(addr as _, SIZE)?))
+///     }
+/// }
+///
+/// impl<const SIZE: usize> Drop for IoMem<SIZE> {
+///     fn drop(&mut self) {
+///         // SAFETY: `self.0.addr()` is guaranteed to be properly mapped by `Self::new`.
+///         unsafe { bindings::iounmap(self.0.addr() as _); };
+///     }
+/// }
+///
+/// impl<const SIZE: usize> Deref for IoMem<SIZE> {
+///    type Target = Io<SIZE>;
+///
+///    fn deref(&self) -> &Self::Target {
+///         // SAFETY: The memory range stored in `self` has been properly mapped in `Self::new`.
+///         unsafe { Io::from_raw(&self.0) }
+///    }
+/// }
+/// # fn no_run() -> Result<(), Error> {
+/// # // SAFETY: Invalid usage; just for the example to get an `ARef<Device>` instance.
+/// # let dev = unsafe { Device::get_device(core::ptr::null_mut()) };
+///
+/// // SAFETY: Invalid usage for example purposes.
+/// let iomem = unsafe { IoMem::<{ core::mem::size_of::<u32>() }>::new(0xBAAAAAAD)? };
+/// let devres = Devres::new(&dev, iomem, GFP_KERNEL)?;
+///
+/// let res = devres.try_access().ok_or(ENXIO)?;
+/// res.writel(0x42, 0x0);
+/// # Ok(())
+/// # }
+/// ```
+pub struct Devres<T>(Arc<DevresInner<T>>);
+
+impl<T> DevresInner<T> {
+    fn new(dev: &Device, data: T, flags: Flags) -> Result<Arc<DevresInner<T>>> {
+        let inner = Arc::pin_init(
+            pin_init!( DevresInner {
+                dev: dev.into(),
+                callback: Self::devres_callback,
+                data <- Revocable::new(data),
+            }),
+            flags,
+        )?;
+
+        // Convert `Arc<DevresInner>` into a raw pointer and make devres own this reference until
+        // `Self::devres_callback` is called.
+        let data = inner.clone().into_raw();
+
+        // SAFETY: `devm_add_action` guarantees to call `Self::devres_callback` once `dev` is
+        // detached.
+        let ret =
+            unsafe { bindings::devm_add_action(dev.as_raw(), Some(inner.callback), data as _) };
+
+        if ret != 0 {
+            // SAFETY: We just created another reference to `inner` in order to pass it to
+            // `bindings::devm_add_action`. If `bindings::devm_add_action` fails, we have to drop
+            // this reference accordingly.
+            let _ = unsafe { Arc::from_raw(data) };
+            return Err(Error::from_errno(ret));
+        }
+
+        Ok(inner)
+    }
+
+    fn as_ptr(&self) -> *const Self {
+        self as _
+    }
+
+    fn remove_action(this: &Arc<Self>) {
+        // SAFETY:
+        // - `self.inner.dev` is a valid `Device`,
+        // - the `action` and `data` pointers are the exact same ones as given to devm_add_action()
+        //   previously,
+        // - `self` is always valid, even if the action has been released already.
+        let ret = unsafe {
+            bindings::devm_remove_action_nowarn(
+                this.dev.as_raw(),
+                Some(this.callback),
+                this.as_ptr() as _,
+            )
+        };
+
+        if ret == 0 {
+            // SAFETY: We leaked an `Arc` reference to devm_add_action() in `DevresInner::new`; if
+            // devm_remove_action_nowarn() was successful we can (and have to) claim back ownership
+            // of this reference.
+            let _ = unsafe { Arc::from_raw(this.as_ptr()) };
+        }
+    }
+
+    #[allow(clippy::missing_safety_doc)]
+    unsafe extern "C" fn devres_callback(ptr: *mut kernel::ffi::c_void) {
+        let ptr = ptr as *mut DevresInner<T>;
+        // Devres owned this memory; now that we received the callback, drop the `Arc` and hence the
+        // reference.
+        // SAFETY: Safe, since we leaked an `Arc` reference to devm_add_action() in
+        //         `DevresInner::new`.
+        let inner = unsafe { Arc::from_raw(ptr) };
+
+        inner.data.revoke();
+    }
+}
+
+impl<T> Devres<T> {
+    /// Creates a new [`Devres`] instance of the given `data`. The `data` encapsulated within the
+    /// returned `Devres` instance' `data` will be revoked once the device is detached.
+    pub fn new(dev: &Device, data: T, flags: Flags) -> Result<Self> {
+        let inner = DevresInner::new(dev, data, flags)?;
+
+        Ok(Devres(inner))
+    }
+
+    /// Same as [`Devres::new`], but does not return a `Devres` instance. Instead the given `data`
+    /// is owned by devres and will be revoked / dropped, once the device is detached.
+    pub fn new_foreign_owned(dev: &Device, data: T, flags: Flags) -> Result {
+        let _ = DevresInner::new(dev, data, flags)?;
+
+        Ok(())
+    }
+}
+
+impl<T> Deref for Devres<T> {
+    type Target = Revocable<T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0.data
+    }
+}
+
+impl<T> Drop for Devres<T> {
+    fn drop(&mut self) {
+        DevresInner::remove_action(&self.0);
+    }
+}