[PATCH v2 7/9] gpu: nova-core: gsp: add RM control command infrastructure

[Eliot Courtney <ecourtney@nvidia.com>]

Add `RmControl` which implements CommandToGsp for sending RM control
RPCs.

Add `RmControlReply` which implements MessageFromGsp for getting the
reply back.

Add `send_rm_control` 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 and adding
its bindings wrappers and writing a helper function to send it via
`send_rm_control`.

Tested-by: Zhi Wang <zhiw@nvidia.com>
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 | 118 +++++++++++++++++++++++++++++++
 4 files changed, 122 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/nova-core/gsp.rs b/drivers/gpu/nova-core/gsp.rs
index 72f173726f87..14c734c53e7c 100644
--- a/drivers/gpu/nova-core/gsp.rs
+++ b/drivers/gpu/nova-core/gsp.rs
@@ -17,6 +17,7 @@
 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..5a3ac7bd415a
--- /dev/null
+++ b/drivers/gpu/nova-core/gsp/rm/commands.rs
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use core::{
+    array,
+    convert::Infallible, //
+};
+
+use kernel::prelude::*;
+
+use crate::{
+    driver::Bar0,
+    gsp::{
+        cmdq::{
+            Cmdq,
+            CommandToGsp,
+            MessageFromGsp, //
+        },
+        commands::{
+            Client,
+            Handle, //
+        },
+        fw::{
+            rm::*,
+            MsgFunction,
+            NvStatus, //
+        },
+    },
+    sbuffer::SBufferIter,
+};
+
+/// 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.
+struct RmControl<'a, T> {
+    /// The client handle under which `object` is allocated.
+    client: Handle<Client>,
+    /// The RM object handle to query or control.
+    object: Handle<T>,
+    /// The specific control message to send.
+    cmd: RmControlMsgFunction,
+    /// The raw parameter bytes to send with the control message. Interpretation of these bytes is
+    /// specific to the control message being sent.
+    params: &'a [u8],
+}
+
+impl<'a, T> RmControl<'a, T> {
+    /// Creates a new RM control command.
+    #[expect(dead_code)]
+    fn new(
+        client: Handle<Client>,
+        object: Handle<T>,
+        cmd: RmControlMsgFunction,
+        params: &'a [u8],
+    ) -> Self {
+        Self {
+            client,
+            object,
+            cmd,
+            params,
+        }
+    }
+}
+
+impl<T> CommandToGsp for RmControl<'_, T> {
+    const FUNCTION: MsgFunction = MsgFunction::GspRmControl;
+    type Command = GspRmControl;
+    type Reply = RmControlReply;
+    type InitError = Infallible;
+
+    fn init(&self) -> impl Init<Self::Command, Self::InitError> {
+        GspRmControl::new(self.client, self.object, self.cmd, self.params.len() as u32)
+    }
+
+    fn variable_payload_len(&self) -> usize {
+        self.params.len()
+    }
+
+    fn init_variable_payload(
+        &self,
+        dst: &mut SBufferIter<array::IntoIter<&mut [u8], 2>>,
+    ) -> Result {
+        dst.write_all(self.params)
+    }
+}
+
+/// Response from an RM control message.
+pub(crate) 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)?,
+        })
+    }
+}
+
+/// Sends an RM control command, checks the reply status, and returns the raw parameter bytes.
+#[expect(dead_code)]
+fn send_rm_control<T>(cmdq: &Cmdq, bar: &Bar0, cmd: RmControl<'_, T>) -> Result<KVVec<u8>> {
+    let reply = cmdq.send_command(bar, cmd)?;
+
+    Result::from(reply.status)?;
+
+    Ok(reply.params)
+}

-- 
2.53.0