[PATCH v3 5/23] rust: drm: kms: add common state and connector helpers

[Mike Lothian <mike@fireburn.co.uk>]

Add safe KMS helpers for hotplug events, mode timings, CRTC modes,
plane destination sizes, and EDID mode enumeration.

Propagate drm_edid_connector_update() failures and release the
temporary EDID on every path.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Mike Lothian <mike@fireburn.co.uk>
---
 rust/kernel/drm/kms.rs           | 18 +++++---
 rust/kernel/drm/kms/connector.rs | 35 ++++++++++++++-
 rust/kernel/drm/kms/crtc.rs      | 12 ++++-
 rust/kernel/drm/kms/encoder.rs   |  9 +---
 rust/kernel/drm/kms/modes.rs     | 77 +++++++++++++++++++++++++++++++-
 rust/kernel/drm/kms/plane.rs     | 14 +++++-
 rust/kernel/drm/kms/vblank.rs    |  2 +-
 7 files changed, 148 insertions(+), 19 deletions(-)

diff --git a/rust/kernel/drm/kms.rs b/rust/kernel/drm/kms.rs
index 8baf9c2906f5..c10b2488af9b 100644
--- a/rust/kernel/drm/kms.rs
+++ b/rust/kernel/drm/kms.rs
@@ -77,7 +77,7 @@ unsafe fn setup_kms(_drm: &Device<Self::Driver>) -> Result<ModeConfigInfo> {
 /// generate said functions for any kind of type which the original mode object driver trait can be
 /// derived from. All conversions check the mode object's vtable. For example:
 ///
-/// ```compile_fail
+/// ```ignore
 /// impl<'a, T: DriverConnectorState> ConnectorState<T> {
 ///     impl_from_opaque_mode_obj! {
 ///         // | An optional lifetime and param-variables to declare for each function
@@ -245,10 +245,7 @@ pub trait KmsDriver: Driver {
     type Encoder: encoder::DriverEncoder<Driver = Self>;
 
     /// Return a [`ModeConfigInfo`] structure for this [`device::Device`].
-    fn mode_config_info(
-        dev: &device::Device,
-        drm_data: &Self::Data,
-    ) -> Result<ModeConfigInfo>;
+    fn mode_config_info(dev: &device::Device, drm_data: &Self::Data) -> Result<ModeConfigInfo>;
 
     /// Create mode objects like [`crtc::Crtc`], [`plane::Plane`], etc. for this device
     fn create_objects(drm: &UnregisteredKmsDevice<'_, Self>) -> Result
@@ -360,6 +357,17 @@ impl<T: Driver> private::KmsImpl for PhantomData<T> {
 
 impl<T: Driver> KmsImpl for PhantomData<T> {}
 
+impl<T: KmsDriver, C: crate::drm::device::DeviceContext> Device<T, C> {
+    /// Send a hotplug uevent to userspace, prompting it to re-probe connector state.
+    ///
+    /// This is useful for drivers which detect connector changes out of band, for example when a
+    /// dock supplies an EDID after bring-up.
+    pub fn hotplug_event(&self) {
+        // SAFETY: `self.as_raw()` is a live KMS-capable DRM device.
+        unsafe { bindings::drm_kms_helper_hotplug_event(self.as_raw()) };
+    }
+}
+
 /// Various device-wide information for a [`Device`] that is provided during initialization.
 #[derive(Copy, Clone)]
 pub struct ModeConfigInfo {
diff --git a/rust/kernel/drm/kms/connector.rs b/rust/kernel/drm/kms/connector.rs
index b36d138ae950..793a7bb5bfef 100644
--- a/rust/kernel/drm/kms/connector.rs
+++ b/rust/kernel/drm/kms/connector.rs
@@ -5,7 +5,7 @@
 //! C header: [`include/drm/drm_connector.h`](srctree/include/drm/drm_connector.h)
 
 use super::{
-    atomic::*, encoder::*, KmsDriver, ModeConfigGuard, ModeObject, ModeObjectVtable, Sealed
+    atomic::*, encoder::*, KmsDriver, ModeConfigGuard, ModeObject, ModeObjectVtable, Sealed,
 };
 use crate::{
     alloc::KBox,
@@ -587,6 +587,39 @@ pub fn set_preferred_mode(&self, (h_pref, w_pref): (u32, u32)) {
         // SAFETY: We hold the locks required to call this via our type invariants.
         unsafe { bindings::drm_set_preferred_mode(self.as_raw(), h_pref, w_pref) }
     }
+
+    /// Parse an EDID, update the connector information, and add its advertised modes.
+    ///
+    /// Returns the number of modes added.
+    pub fn add_edid_modes(&self, edid: &[u8]) -> Result<i32> {
+        const EDID_BASE_BLOCK_LEN: usize = 128;
+
+        if edid.len() < EDID_BASE_BLOCK_LEN {
+            return Err(EINVAL);
+        }
+
+        // SAFETY: `edid` points to `edid.len()` initialized bytes, which the helper copies.
+        let drm_edid = unsafe { bindings::drm_edid_alloc(edid.as_ptr().cast(), edid.len()) };
+        if drm_edid.is_null() {
+            return Err(ENOMEM);
+        }
+
+        // SAFETY: The connector is live and the guard holds the mode-config lock. `drm_edid`
+        // points to an allocation returned by `drm_edid_alloc` above.
+        let ret = unsafe { bindings::drm_edid_connector_update(self.as_raw(), drm_edid) };
+        if let Err(err) = to_result(ret) {
+            // SAFETY: `drm_edid` was allocated above and has not been freed.
+            unsafe { bindings::drm_edid_free(drm_edid) };
+            return Err(err);
+        }
+
+        // SAFETY: The connector information was successfully updated from this EDID above.
+        let count = unsafe { bindings::drm_edid_connector_add_modes(self.as_raw()) };
+        // SAFETY: `drm_edid` was allocated above and is no longer needed.
+        unsafe { bindings::drm_edid_free(drm_edid) };
+
+        Ok(count)
+    }
 }
 
 /// A trait implemented by any type which can produce a reference to a
diff --git a/rust/kernel/drm/kms/crtc.rs b/rust/kernel/drm/kms/crtc.rs
index 683d9ee4ec25..a3217f8c55e8 100644
--- a/rust/kernel/drm/kms/crtc.rs
+++ b/rust/kernel/drm/kms/crtc.rs
@@ -5,8 +5,8 @@
 //! C header: [`include/drm/drm_crtc.h`](srctree/include/drm/drm_crtc.h)
 
 use super::{
-    atomic::*, plane::*, vblank::*, KmsDriver, ModeObject, ModeObjectVtable, StaticModeObject,
-    UnregisteredKmsDevice, Sealed,
+    atomic::*, modes::DisplayMode, plane::*, vblank::*, KmsDriver, ModeObject, ModeObjectVtable,
+    Sealed, StaticModeObject, UnregisteredKmsDevice,
 };
 use crate::{
     alloc::KBox,
@@ -644,6 +644,7 @@ pub trait AsRawCrtcState: private::AsRawCrtcState {
 pub(crate) mod private {
     use super::*;
 
+    /// The raw-pointer half of [`AsRawCrtcState`](super::AsRawCrtcState).
     #[allow(unreachable_pub)]
     pub trait AsRawCrtcState {
         /// Return a raw pointer to the DRM CRTC state
@@ -678,6 +679,13 @@ fn active(&self) -> bool {
         // this access is serialized
         unsafe { (*self.as_raw()).active }
     }
+
+    /// Return the display mode programmed into this CRTC state.
+    fn mode(&self) -> &DisplayMode {
+        // SAFETY: `mode` is embedded in the CRTC state and therefore has the same lifetime. The
+        // atomic-state API serializes access while the mode can be changed.
+        unsafe { DisplayMode::as_ref(core::ptr::addr_of!((*self.as_raw()).mode)) }
+    }
 }
 impl<T: AsRawCrtcState> RawCrtcState for T {}
 
diff --git a/rust/kernel/drm/kms/encoder.rs b/rust/kernel/drm/kms/encoder.rs
index f90d139cdb04..8758a9459bcc 100644
--- a/rust/kernel/drm/kms/encoder.rs
+++ b/rust/kernel/drm/kms/encoder.rs
@@ -5,7 +5,7 @@
 //! C header: [`include/drm/drm_encoder.h`](srctree/include/drm/drm_encoder.h)
 
 use super::{
-    KmsDriver, ModeObject, ModeObjectVtable, StaticModeObject, UnregisteredKmsDevice, Sealed
+    KmsDriver, ModeObject, ModeObjectVtable, Sealed, StaticModeObject, UnregisteredKmsDevice,
 };
 use crate::{
     alloc::KBox,
@@ -15,12 +15,7 @@
     types::{NotThreadSafe, Opaque},
 };
 use bindings;
-use core::{
-    marker::*,
-    mem,
-    ops::Deref,
-    ptr::null,
-};
+use core::{marker::*, mem, ops::Deref, ptr::null};
 use macros::paste;
 
 /// A macro for generating our type ID enumerator.
diff --git a/rust/kernel/drm/kms/modes.rs b/rust/kernel/drm/kms/modes.rs
index 0f29a9c00062..cc3c486eecf1 100644
--- a/rust/kernel/drm/kms/modes.rs
+++ b/rust/kernel/drm/kms/modes.rs
@@ -1,7 +1,12 @@
 // SPDX-License-Identifier: GPL-2.0
+//!
+//! DRM display modes.
+//!
+//! C header: [`include/drm/drm_modes.h`](srctree/include/drm/drm_modes.h)
+
 use bindings;
 
-use crate::{prelude::*, types::Opaque};
+use crate::types::Opaque;
 
 /// DRM kernel-internal display mode structure.
 ///
@@ -73,4 +78,74 @@ pub fn crtc_vtotal(&self) -> u16 {
         // SAFETY: Reading these fields is safe via our type invariants
         unsafe { (*self.as_raw()).crtc_vtotal }
     }
+
+    /// Return the horizontal active pixels.
+    #[inline]
+    pub fn hdisplay(&self) -> u16 {
+        // SAFETY: Reading this field is safe via the type invariants.
+        unsafe { (*self.as_raw()).hdisplay }
+    }
+
+    /// Return the start of the horizontal sync pulse.
+    #[inline]
+    pub fn hsync_start(&self) -> u16 {
+        // SAFETY: Reading this field is safe via the type invariants.
+        unsafe { (*self.as_raw()).hsync_start }
+    }
+
+    /// Return the end of the horizontal sync pulse.
+    #[inline]
+    pub fn hsync_end(&self) -> u16 {
+        // SAFETY: Reading this field is safe via the type invariants.
+        unsafe { (*self.as_raw()).hsync_end }
+    }
+
+    /// Return the total horizontal pixels including blanking.
+    #[inline]
+    pub fn htotal(&self) -> u16 {
+        // SAFETY: Reading this field is safe via the type invariants.
+        unsafe { (*self.as_raw()).htotal }
+    }
+
+    /// Return the vertical active scanlines.
+    #[inline]
+    pub fn vdisplay(&self) -> u16 {
+        // SAFETY: Reading this field is safe via the type invariants.
+        unsafe { (*self.as_raw()).vdisplay }
+    }
+
+    /// Return the start of the vertical sync pulse.
+    #[inline]
+    pub fn vsync_start(&self) -> u16 {
+        // SAFETY: Reading this field is safe via the type invariants.
+        unsafe { (*self.as_raw()).vsync_start }
+    }
+
+    /// Return the end of the vertical sync pulse.
+    #[inline]
+    pub fn vsync_end(&self) -> u16 {
+        // SAFETY: Reading this field is safe via the type invariants.
+        unsafe { (*self.as_raw()).vsync_end }
+    }
+
+    /// Return the total vertical scanlines including blanking.
+    #[inline]
+    pub fn vtotal(&self) -> u16 {
+        // SAFETY: Reading this field is safe via the type invariants.
+        unsafe { (*self.as_raw()).vtotal }
+    }
+
+    /// Return the pixel clock in kHz.
+    #[inline]
+    pub fn clock(&self) -> i32 {
+        // SAFETY: Reading this field is safe via the type invariants.
+        unsafe { (*self.as_raw()).clock }
+    }
+
+    /// Return the refresh rate in Hz as computed by DRM.
+    #[inline]
+    pub fn vrefresh(&self) -> i32 {
+        // SAFETY: `drm_mode_vrefresh` only reads this valid display mode.
+        unsafe { bindings::drm_mode_vrefresh(self.as_raw()) }
+    }
 }
diff --git a/rust/kernel/drm/kms/plane.rs b/rust/kernel/drm/kms/plane.rs
index f52f9c872de3..3a95c45b6728 100644
--- a/rust/kernel/drm/kms/plane.rs
+++ b/rust/kernel/drm/kms/plane.rs
@@ -5,8 +5,8 @@
 //! C header: [`include/drm/drm_plane.h`](srctree/include/drm/drm_plane.h)
 
 use super::{
-    atomic::*, crtc::*, framebuffer::*, KmsDriver, ModeObject, ModeObjectVtable, StaticModeObject,
-    UnregisteredKmsDevice, Sealed
+    atomic::*, crtc::*, framebuffer::*, KmsDriver, ModeObject, ModeObjectVtable, Sealed,
+    StaticModeObject, UnregisteredKmsDevice,
 };
 use crate::{
     alloc::KBox,
@@ -617,6 +617,16 @@ fn plane(&self) -> &Self::Plane {
         unsafe { Self::Plane::from_raw(self.as_raw().plane) }
     }
 
+    /// Return the width of this plane's destination rectangle in CRTC pixels.
+    fn crtc_w(&self) -> u32 {
+        self.as_raw().crtc_w
+    }
+
+    /// Return the height of this plane's destination rectangle in CRTC pixels.
+    fn crtc_h(&self) -> u32 {
+        self.as_raw().crtc_h
+    }
+
     /// Return the current [`OpaqueCrtc`] assigned to this plane, if there is one.
     ///
     /// The returned CRTC reference cannot outlive the plane-state borrow:
diff --git a/rust/kernel/drm/kms/vblank.rs b/rust/kernel/drm/kms/vblank.rs
index dc34e02e8ccb..a725a46110d8 100644
--- a/rust/kernel/drm/kms/vblank.rs
+++ b/rust/kernel/drm/kms/vblank.rs
@@ -4,7 +4,7 @@
 //!
 //! C header: [`include/drm/drm_vblank.h`](srcfree/include/drm/drm_vblank.h)
 
-use super::{crtc::*, ModeObject, modes::*, Sealed};
+use super::{crtc::*, modes::*, ModeObject};
 use bindings;
 use core::{
     marker::*,