[PATCH v3 6/23] rust: drm: expose HDCP 2.2 message identifiers

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

Add a DRM display module with typed identifiers for the standard
HDCP 2.2 protocol messages. Transport drivers can use the canonical
drm_hdcp.h values without reaching into generated bindings.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Mike Lothian <mike@fireburn.co.uk>
---
 rust/bindings/bindings_helper.h |  1 +
 rust/kernel/drm/display.rs      |  5 +++
 rust/kernel/drm/display/hdcp.rs | 77 +++++++++++++++++++++++++++++++++
 rust/kernel/drm/mod.rs          |  1 +
 4 files changed, 84 insertions(+)
 create mode 100644 rust/kernel/drm/display.rs
 create mode 100644 rust/kernel/drm/display/hdcp.rs

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 8db7fe00fa1b..ae3017539767 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -34,6 +34,7 @@
 
 #include <linux/acpi.h>
 #include <linux/gpu_buddy.h>
+#include <drm/display/drm_hdcp.h>
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/clients/drm_client_setup.h>
diff --git a/rust/kernel/drm/display.rs b/rust/kernel/drm/display.rs
new file mode 100644
index 000000000000..007ed284c551
--- /dev/null
+++ b/rust/kernel/drm/display.rs
@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+
+//! DRM display-helper abstractions.
+
+pub mod hdcp;
diff --git a/rust/kernel/drm/display/hdcp.rs b/rust/kernel/drm/display/hdcp.rs
new file mode 100644
index 000000000000..966fb67c6f31
--- /dev/null
+++ b/rust/kernel/drm/display/hdcp.rs
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+
+//! High-bandwidth Digital Content Protection definitions.
+//!
+//! C header: [`include/drm/display/drm_hdcp.h`](srctree/include/drm/display/drm_hdcp.h)
+
+use crate::bindings;
+
+/// Transmitter nonce length.
+pub const RTX_LEN: usize = bindings::HDCP_2_2_RTX_LEN as usize;
+/// Receiver nonce length.
+pub const RRX_LEN: usize = bindings::HDCP_2_2_RRX_LEN as usize;
+/// Receiver RSA modulus length.
+pub const RSA_MODULUS_LEN: usize = bindings::HDCP_2_2_K_PUB_RX_MOD_N_LEN as usize;
+/// Receiver RSA public exponent length.
+pub const RSA_EXPONENT_LEN: usize = bindings::HDCP_2_2_K_PUB_RX_EXP_E_LEN as usize;
+/// Encrypted master-key length.
+pub const ENCRYPTED_MASTER_KEY_LEN: usize = bindings::HDCP_2_2_E_KPUB_KM_LEN as usize;
+/// H-prime verifier length.
+pub const H_PRIME_LEN: usize = bindings::HDCP_2_2_H_PRIME_LEN as usize;
+/// Locality-check nonce length.
+pub const RN_LEN: usize = bindings::HDCP_2_2_RN_LEN as usize;
+/// L-prime verifier length.
+pub const L_PRIME_LEN: usize = bindings::HDCP_2_2_L_PRIME_LEN as usize;
+/// Encrypted session-key length.
+pub const ENCRYPTED_SESSION_KEY_LEN: usize = bindings::HDCP_2_2_E_DKEY_KS_LEN as usize;
+/// Session-key nonce length.
+pub const RIV_LEN: usize = bindings::HDCP_2_2_RIV_LEN as usize;
+/// One half of the repeater V-prime verifier.
+pub const V_PRIME_HALF_LEN: usize = bindings::HDCP_2_2_V_PRIME_HALF_LEN as usize;
+
+/// An HDCP 2.2 protocol message identifier.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub struct MessageId(u8);
+
+impl MessageId {
+    /// No message.
+    pub const NULL: Self = Self(bindings::HDCP_2_2_NULL_MSG as u8);
+    /// Authentication and Key Exchange initialization.
+    pub const AKE_INIT: Self = Self(bindings::HDCP_2_2_AKE_INIT as u8);
+    /// Receiver certificate.
+    pub const AKE_SEND_CERT: Self = Self(bindings::HDCP_2_2_AKE_SEND_CERT as u8);
+    /// Encrypted master key for a receiver without stored pairing information.
+    pub const AKE_NO_STORED_KM: Self = Self(bindings::HDCP_2_2_AKE_NO_STORED_KM as u8);
+    /// Encrypted master key and pairing nonce for a paired receiver.
+    pub const AKE_STORED_KM: Self = Self(bindings::HDCP_2_2_AKE_STORED_KM as u8);
+    /// Receiver's H-prime authentication value.
+    pub const AKE_SEND_H_PRIME: Self = Self(bindings::HDCP_2_2_AKE_SEND_HPRIME as u8);
+    /// Receiver pairing information.
+    pub const AKE_SEND_PAIRING_INFO: Self = Self(bindings::HDCP_2_2_AKE_SEND_PAIRING_INFO as u8);
+    /// Locality-check initialization.
+    pub const LC_INIT: Self = Self(bindings::HDCP_2_2_LC_INIT as u8);
+    /// Receiver's L-prime locality-check value.
+    pub const LC_SEND_L_PRIME: Self = Self(bindings::HDCP_2_2_LC_SEND_LPRIME as u8);
+    /// Session-key exchange.
+    pub const SKE_SEND_EKS: Self = Self(bindings::HDCP_2_2_SKE_SEND_EKS as u8);
+    /// Repeater receiver-ID list.
+    pub const REPEATERAUTH_SEND_RECEIVERID_LIST: Self =
+        Self(bindings::HDCP_2_2_REP_SEND_RECVID_LIST as u8);
+    /// Repeater receiver-ID-list acknowledgment.
+    pub const REPEATERAUTH_SEND_ACK: Self = Self(bindings::HDCP_2_2_REP_SEND_ACK as u8);
+    /// Repeater stream-management request.
+    pub const REPEATERAUTH_STREAM_MANAGE: Self = Self(bindings::HDCP_2_2_REP_STREAM_MANAGE as u8);
+    /// Repeater stream-ready response.
+    pub const REPEATERAUTH_STREAM_READY: Self = Self(bindings::HDCP_2_2_REP_STREAM_READY as u8);
+
+    /// Return the wire value.
+    pub const fn as_u8(self) -> u8 {
+        self.0
+    }
+}
+
+impl From<MessageId> for u8 {
+    fn from(value: MessageId) -> Self {
+        value.as_u8()
+    }
+}
diff --git a/rust/kernel/drm/mod.rs b/rust/kernel/drm/mod.rs
index 786cd9c1ec07..4576d66a6bb6 100644
--- a/rust/kernel/drm/mod.rs
+++ b/rust/kernel/drm/mod.rs
@@ -3,6 +3,7 @@
 //! DRM subsystem abstractions.
 
 pub mod device;
+pub mod display;
 pub mod driver;
 pub mod file;
 pub mod fourcc;