There are situations where a pointer to a `struct device` will become
necessary (e.g. for calling into dev_*() functions).  This accessor
allows callers to pull this out from the `struct miscdevice`.

Signed-off-by: Lee Jones <lee@kernel.org>
---
 rust/kernel/miscdevice.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs
index 7e2a79b3ae26..55340f316006 100644
--- a/rust/kernel/miscdevice.rs
+++ b/rust/kernel/miscdevice.rs
@@ -10,11 +10,13 @@
 
 use crate::{
     bindings,
+    device::Device,
     error::{to_result, Error, Result, VTABLE_DEFAULT_ERROR},
     prelude::*,
     str::CStr,
     types::{ForeignOwnable, Opaque},
 };
+
 use core::{
     ffi::{c_int, c_long, c_uint, c_ulong},
     marker::PhantomData,
@@ -84,6 +86,13 @@ pub fn register(opts: MiscDeviceOptions) -> impl PinInit<Self, Error> {
     pub fn as_raw(&self) -> *mut bindings::miscdevice {
         self.inner.get()
     }
+
+    /// Returns a pointer to the current Device
+    pub fn device(&self) -> &Device {
+        // SAFETY: This is only accessible after a successful register() which always
+        // initialises this_device with a valid device.
+        unsafe { Device::as_ref((*self.as_raw()).this_device) }
+    }
 }
 
 #[pinned_drop]
-- 
2.47.0.338.g60cca15819-goog

On Fri, Dec 6, 2024 at 10:05 AM Lee Jones <lee@kernel.org> wrote:
>
> +    /// Returns a pointer to the current Device

Nit: please use intra-doc links wherever possible (if not possible,
please at least format type names as code). We also end sentences with
periods in docs and comments. So e.g.:

    /// Returns a pointer to the current [`Device`].

There was a comment about this line in the previous version, v3, but
there does not seem to be a change. But then again, the title of this
patch is v3 and not v4 -- not sure what happened here.

Thanks!

Cheers,
Miguel

On Fri, 06 Dec 2024, Miguel Ojeda wrote:

> On Fri, Dec 6, 2024 at 10:05 AM Lee Jones <lee@kernel.org> wrote:
> >
> > +    /// Returns a pointer to the current Device
> 
> Nit: please use intra-doc links wherever possible (if not possible,
> please at least format type names as code). We also end sentences with
> periods in docs and comments. So e.g.:
> 
>     /// Returns a pointer to the current [`Device`].
> 
> There was a comment about this line in the previous version, v3, but
> there does not seem to be a change. But then again, the title of this
> patch is v3 and not v4 -- not sure what happened here.

This patch should no longer be part of the set after v3.

Looks like v3 was still in the output folder so was sent again with v4
by mistake.  My tooling usually strips out old versions, so I'm not sure
what went wrong specifically.

Thanks for the comment style tips.  I'll make the changes.

-- 
Lee Jones [李琼斯]