[PATCH v4 6/8] gpu: nova-core: gsp: add types for RM control RPCs

[Eliot Courtney <ecourtney@nvidia.com>]

Add `RmControlMsgFunction` which mirrors `MsgFunction` in fw.rs. This
denotes the type of RM control RPC. For now it contains a single
discriminant only (which will be used later), which is needed to prevent
compile errors when using an otherwise empty enum.

Add `GspRmControl` which wraps the RM control RPC structure from the
bindings.

Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
---
 drivers/gpu/nova-core/gsp/commands.rs             |  1 -
 drivers/gpu/nova-core/gsp/fw.rs                   |  1 +
 drivers/gpu/nova-core/gsp/fw/r570_144/bindings.rs |  1 +
 drivers/gpu/nova-core/gsp/fw/rm.rs                | 91 +++++++++++++++++++++++
 4 files changed, 93 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/nova-core/gsp/commands.rs b/drivers/gpu/nova-core/gsp/commands.rs
index 8a19ef689731..bf0e8533a71c 100644
--- a/drivers/gpu/nova-core/gsp/commands.rs
+++ b/drivers/gpu/nova-core/gsp/commands.rs
@@ -78,7 +78,6 @@ pub(crate) fn new(raw: u32) -> Self {
     }
 
     /// Returns the raw handle value.
-    #[expect(dead_code)]
     pub(crate) fn as_raw(self) -> u32 {
         self.0
     }
diff --git a/drivers/gpu/nova-core/gsp/fw.rs b/drivers/gpu/nova-core/gsp/fw.rs
index 5fabb815a919..1f5c61bea645 100644
--- a/drivers/gpu/nova-core/gsp/fw.rs
+++ b/drivers/gpu/nova-core/gsp/fw.rs
@@ -2,6 +2,7 @@
 
 pub(crate) mod commands;
 mod r570_144;
+pub(crate) mod rm;
 
 // Alias to avoid repeating the version number with every use.
 use r570_144 as bindings;
diff --git a/drivers/gpu/nova-core/gsp/fw/r570_144/bindings.rs b/drivers/gpu/nova-core/gsp/fw/r570_144/bindings.rs
index 05e205e6dc58..ece31cc32f5b 100644
--- a/drivers/gpu/nova-core/gsp/fw/r570_144/bindings.rs
+++ b/drivers/gpu/nova-core/gsp/fw/r570_144/bindings.rs
@@ -44,6 +44,7 @@ fn fmt(&self, fmt: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
 pub const GSP_FW_WPR_META_MAGIC: i64 = -2577556379034558285;
 pub const REGISTRY_TABLE_ENTRY_TYPE_DWORD: u32 = 1;
 pub const GSP_MSG_QUEUE_ELEMENT_SIZE_MAX: u32 = 65536;
+pub const NV2080_CTRL_CMD_CE_GET_FAULT_METHOD_BUFFER_SIZE: u32 = 545270280;
 pub type __u8 = ffi::c_uchar;
 pub type __u16 = ffi::c_ushort;
 pub type __u32 = ffi::c_uint;
diff --git a/drivers/gpu/nova-core/gsp/fw/rm.rs b/drivers/gpu/nova-core/gsp/fw/rm.rs
new file mode 100644
index 000000000000..e51fdcec1f27
--- /dev/null
+++ b/drivers/gpu/nova-core/gsp/fw/rm.rs
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use kernel::{
+    prelude::*,
+    transmute::{
+        AsBytes,
+        FromBytes, //
+    }, //
+};
+
+use crate::gsp::commands::{
+    Client,
+    Handle, //
+};
+
+use super::{
+    bindings,
+    GspMsgRmStatus, //
+};
+
+/// Command code for RM control RPCs sent using [`MsgFunction::GspRmControl`].
+#[derive(Copy, Clone, Debug, PartialEq)]
+#[repr(u32)]
+pub(crate) enum RmControlMsgFunction {
+    /// Get the CE fault method buffer size.
+    CeGetFaultMethodBufferSize = bindings::NV2080_CTRL_CMD_CE_GET_FAULT_METHOD_BUFFER_SIZE,
+}
+
+// TODO[FPRI]: This is a temporary solution to be replaced with the corresponding derive macros
+// once they land.
+impl TryFrom<u32> for RmControlMsgFunction {
+    type Error = kernel::error::Error;
+
+    fn try_from(value: u32) -> Result<Self> {
+        match value {
+            bindings::NV2080_CTRL_CMD_CE_GET_FAULT_METHOD_BUFFER_SIZE => {
+                Ok(Self::CeGetFaultMethodBufferSize)
+            }
+            _ => Err(EINVAL),
+        }
+    }
+}
+
+impl From<RmControlMsgFunction> for u32 {
+    fn from(value: RmControlMsgFunction) -> Self {
+        // CAST: `RmControlMsgFunction` is `repr(u32)` and can thus be cast losslessly.
+        value as u32
+    }
+}
+
+/// RM control message element structure.
+#[repr(transparent)]
+pub(crate) struct GspRmControl {
+    inner: bindings::rpc_gsp_rm_control_v03_00,
+}
+
+#[expect(dead_code)]
+impl GspRmControl {
+    /// Creates a new RM control command.
+    pub(crate) fn new<T>(
+        client: Handle<Client>,
+        object: Handle<T>,
+        cmd: RmControlMsgFunction,
+        params_size: u32,
+    ) -> Self {
+        Self {
+            inner: bindings::rpc_gsp_rm_control_v03_00 {
+                hClient: client.as_raw(),
+                hObject: object.as_raw(),
+                cmd: u32::from(cmd),
+                status: 0,
+                paramsSize: params_size,
+                flags: 0,
+                params: Default::default(),
+            },
+        }
+    }
+
+    /// Returns the status from the RM control response.
+    ///
+    /// This is distinct from the RPC transport status in the RPC message header.
+    pub(crate) fn status(&self) -> Result<GspMsgRmStatus> {
+        self.inner.status.try_into()
+    }
+}
+
+// SAFETY: This struct only contains integer types for which all bit patterns are valid.
+unsafe impl FromBytes for GspRmControl {}
+
+// SAFETY: This struct contains no padding.
+unsafe impl AsBytes for GspRmControl {}

-- 
2.53.0