[PATCH v3 7/9] gpu: nova-core: gsp: add RM control command infrastructure

[Eliot Courtney <ecourtney@nvidia.com>]

Add `RawRmControl` which implements CommandToGsp for sending RM control
RPCs. Add `RmControlReply` which implements MessageFromGsp for getting
the reply back. Add the `RmControlCommand` trait for defining an RM
control message.

Add `RmControl` which sends an RM control RPC via the command queue
using the above structures.

This gives a generic way to send each RM control RPC. Each new RM
control RPC can be added by extending RmControlMsgFunction, adding its
bindings wrappers and writing an implementation of `RmControlCommand`
that can be sent using `RmControl`.

Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
---
 drivers/gpu/nova-core/gsp.rs             |   1 +
 drivers/gpu/nova-core/gsp/fw/rm.rs       |   1 -
 drivers/gpu/nova-core/gsp/rm.rs          |   3 +
 drivers/gpu/nova-core/gsp/rm/commands.rs | 141 +++++++++++++++++++++++++++++++
 4 files changed, 145 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/nova-core/gsp.rs b/drivers/gpu/nova-core/gsp.rs
index 04e3976127cc..09d6e673aa65 100644
--- a/drivers/gpu/nova-core/gsp.rs
+++ b/drivers/gpu/nova-core/gsp.rs
@@ -21,6 +21,7 @@
 pub(crate) mod cmdq;
 pub(crate) mod commands;
 mod fw;
+pub(crate) mod rm;
 mod sequencer;
 
 pub(crate) use fw::{
diff --git a/drivers/gpu/nova-core/gsp/fw/rm.rs b/drivers/gpu/nova-core/gsp/fw/rm.rs
index 4a4f97d88ecf..1c6e8b4c4865 100644
--- a/drivers/gpu/nova-core/gsp/fw/rm.rs
+++ b/drivers/gpu/nova-core/gsp/fw/rm.rs
@@ -53,7 +53,6 @@ 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>(
diff --git a/drivers/gpu/nova-core/gsp/rm.rs b/drivers/gpu/nova-core/gsp/rm.rs
new file mode 100644
index 000000000000..10e879a3e842
--- /dev/null
+++ b/drivers/gpu/nova-core/gsp/rm.rs
@@ -0,0 +1,3 @@
+// SPDX-License-Identifier: GPL-2.0
+
+pub(crate) mod commands;
diff --git a/drivers/gpu/nova-core/gsp/rm/commands.rs b/drivers/gpu/nova-core/gsp/rm/commands.rs
new file mode 100644
index 000000000000..8845ca0a0225
--- /dev/null
+++ b/drivers/gpu/nova-core/gsp/rm/commands.rs
@@ -0,0 +1,141 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use core::array;
+
+use kernel::prelude::*;
+
+use crate::{
+    driver::Bar0,
+    gsp::{
+        cmdq::{
+            Cmdq,
+            CommandToGsp,
+            MessageFromGsp, //
+        },
+        commands::{
+            Client,
+            Handle, //
+        },
+        fw::{
+            rm::*,
+            MsgFunction,
+            NvStatus, //
+        },
+    },
+    sbuffer::SBufferIter, //
+};
+
+/// Wraps a [`RmControl`] command to provide the infrastructure for sending it on the command queue.
+struct RawRmControl<'a, T>(&'a RmControl<T>)
+where
+    T: RmControlCommand;
+
+impl<'a, T: RmControlCommand> CommandToGsp for RawRmControl<'a, T> {
+    const FUNCTION: MsgFunction = MsgFunction::GspRmControl;
+    type Command = GspRmControl;
+    type Reply = RmControlReply;
+    type InitError = Error;
+
+    fn init(&self) -> impl Init<Self::Command, Self::InitError> {
+        let params_size: u32 = T::LEN.try_into()?;
+        Ok(GspRmControl::new(
+            self.0.client,
+            self.0.object,
+            T::FUNCTION,
+            params_size,
+        ))
+    }
+
+    fn variable_payload_len(&self) -> usize {
+        T::LEN
+    }
+
+    fn init_variable_payload(
+        &self,
+        dst: &mut SBufferIter<array::IntoIter<&mut [u8], 2>>,
+    ) -> Result {
+        self.0.cmd.write_payload(dst)
+    }
+}
+
+/// Command for sending an RM control message to the GSP.
+///
+/// RM control messages are used to query or control RM objects (see [`Handle`] for more info on RM
+/// objects). It takes a client handle and an RM object handle identifying the target of the
+/// message, within the given client.
+pub(crate) struct RmControl<T>
+where
+    T: RmControlCommand,
+{
+    /// The client handle under which `object` is allocated.
+    client: Handle<Client>,
+    /// The RM object handle to query or control.
+    object: Handle<T::Target>,
+    /// The specific RM control command to send.
+    cmd: T,
+}
+
+#[expect(unused)]
+impl<T: RmControlCommand> RmControl<T> {
+    /// Creates a new RM control command.
+    pub(crate) fn new(client: Handle<Client>, object: Handle<T::Target>, cmd: T) -> Self {
+        Self {
+            client,
+            object,
+            cmd,
+        }
+    }
+
+    /// Sends an RM control command, checks the reply status, and returns the reply.
+    pub(crate) fn send(self, cmdq: &Cmdq, bar: &Bar0) -> Result<T::Reply> {
+        let reply = cmdq.send_command(bar, RawRmControl(&self))?;
+
+        Result::from(reply.status)?;
+
+        self.cmd.parse_reply(&reply.params)
+    }
+}
+
+/// Response from an RM control message.
+struct RmControlReply {
+    status: NvStatus,
+    params: KVVec<u8>,
+}
+
+impl MessageFromGsp for RmControlReply {
+    const FUNCTION: MsgFunction = MsgFunction::GspRmControl;
+    type Message = GspRmControl;
+    type InitError = Error;
+
+    fn read(
+        msg: &Self::Message,
+        sbuffer: &mut SBufferIter<array::IntoIter<&[u8], 2>>,
+    ) -> Result<Self, Self::InitError> {
+        Ok(RmControlReply {
+            status: msg.status(),
+            params: sbuffer.read_to_vec(GFP_KERNEL)?,
+        })
+    }
+}
+
+/// Trait for RM control commands that can be sent using [`RmControl`].
+pub(crate) trait RmControlCommand {
+    /// The specific RM control message kind to send.
+    const FUNCTION: RmControlMsgFunction;
+
+    /// Length of the command-specific payload to send with the RM control message.
+    const LEN: usize;
+
+    /// The type of the reply after parsing the raw bytes from the RM control reply message.
+    type Reply;
+
+    /// The type of the RM object that this command targets.
+    type Target;
+
+    /// Writes the payload of the command into `dst`.
+    fn write_payload(&self, dst: &mut SBufferIter<array::IntoIter<&mut [u8], 2>>) -> Result;
+
+    /// Parses the reply bytes from an RM control reply message into the command-specific
+    /// reply type.
+    fn parse_reply(&self, params: &[u8]) -> Result<Self::Reply>;
+}

-- 
2.53.0