[PATCH v4 11/13] gpu: nova-core: sequencer: Implement core resume operation

[Joel Fernandes <joelagnelf@nvidia.com>]

Implement core resume operation. This is the last step of the sequencer
resulting in resume of the GSP and proceeding to INIT_DONE stage of GSP
boot.

Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
 drivers/gpu/nova-core/falcon/gsp.rs    |  1 -
 drivers/gpu/nova-core/gsp/sequencer.rs | 44 ++++++++++++++++++++++++--
 2 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/nova-core/falcon/gsp.rs b/drivers/gpu/nova-core/falcon/gsp.rs
index 9ef1fbae141f..67edef3636c1 100644
--- a/drivers/gpu/nova-core/falcon/gsp.rs
+++ b/drivers/gpu/nova-core/falcon/gsp.rs
@@ -45,7 +45,6 @@ pub(crate) fn clear_swgen0_intr(&self, bar: &Bar0) {
     }
 
     /// Checks if GSP reload/resume has completed during the boot process.
-    #[expect(dead_code)]
     pub(crate) fn check_reload_completed(&self, bar: &Bar0, timeout: Delta) -> Result<bool> {
         read_poll_timeout(
             || Ok(regs::NV_PGC6_BSI_SECURE_SCRATCH_14::read(bar)),
diff --git a/drivers/gpu/nova-core/gsp/sequencer.rs b/drivers/gpu/nova-core/gsp/sequencer.rs
index 93c8f84e032b..a10758ffa5e8 100644
--- a/drivers/gpu/nova-core/gsp/sequencer.rs
+++ b/drivers/gpu/nova-core/gsp/sequencer.rs
@@ -93,6 +93,7 @@ pub(crate) enum GspSeqCmd {
     CoreReset,
     CoreStart,
     CoreWaitForHalt,
+    CoreResume,
 }
 
 impl GspSeqCmd {
@@ -130,7 +131,7 @@ pub(crate) fn new(data: &[u8], dev: &device::Device) -> Result<(Self, usize)> {
             fw::SeqBufOpcode::CoreReset => (GspSeqCmd::CoreReset, opcode_size),
             fw::SeqBufOpcode::CoreStart => (GspSeqCmd::CoreStart, opcode_size),
             fw::SeqBufOpcode::CoreWaitForHalt => (GspSeqCmd::CoreWaitForHalt, opcode_size),
-            _ => return Err(EINVAL),
+            fw::SeqBufOpcode::CoreResume => (GspSeqCmd::CoreResume, opcode_size),
         };
 
         if data.len() < size {
@@ -143,7 +144,6 @@ pub(crate) fn new(data: &[u8], dev: &device::Device) -> Result<(Self, usize)> {
 }
 
 /// GSP Sequencer for executing firmware commands during boot.
-#[expect(dead_code)]
 pub(crate) struct GspSequencer<'a> {
     /// Sequencer information with command data.
     seq_info: GspSequencerInfo,
@@ -251,6 +251,46 @@ fn run(&self, seq: &GspSequencer<'_>) -> Result {
                 seq.gsp_falcon.wait_till_halted(seq.bar)?;
                 Ok(())
             }
+            GspSeqCmd::CoreResume => {
+                // At this point, 'SEC2-RTOS' has been loaded into SEC2 by the sequencer
+                // but neither SEC2-RTOS nor GSP-RM is running yet. This part of the
+                // sequencer will start both.
+
+                // Reset the GSP to prepare it for resuming.
+                seq.gsp_falcon.reset(seq.bar)?;
+
+                // Write the libOS DMA handle to GSP mailboxes.
+                seq.gsp_falcon.write_mailboxes(
+                    seq.bar,
+                    Some(seq.libos_dma_handle as u32),
+                    Some((seq.libos_dma_handle >> 32) as u32),
+                )?;
+
+                // Start the SEC2 falcon which will trigger GSP-RM to resume on the GSP.
+                seq.sec2_falcon.start(seq.bar)?;
+
+                // Poll until GSP-RM reload/resume has completed (up to 2 seconds).
+                seq.gsp_falcon
+                    .check_reload_completed(seq.bar, Delta::from_secs(2))?;
+
+                // Verify SEC2 completed successfully by checking its mailbox for errors.
+                let mbox0 = seq.sec2_falcon.read_mailbox0(seq.bar)?;
+                if mbox0 != 0 {
+                    dev_err!(seq.dev, "Sequencer: sec2 errors: {:?}\n", mbox0);
+                    return Err(EIO);
+                }
+
+                // Configure GSP with the bootloader version.
+                seq.gsp_falcon
+                    .write_os_version(seq.bar, seq.bootloader_app_version);
+
+                // Verify the GSP's RISC-V core is active indicating successful GSP boot.
+                if !seq.gsp_falcon.is_riscv_active(seq.bar) {
+                    dev_err!(seq.dev, "Sequencer: RISC-V core is not active\n");
+                    return Err(EIO);
+                }
+                Ok(())
+            }
         }
     }
 }
-- 
2.34.1