[PATCH v4 13/20] gpu: nova-core: register sysmem flush page

[Alexandre Courbot <acourbot@nvidia.com>]

Reserve a page of system memory so sysmembar can perform a read on it if
a system write occurred since the last flush. Do this early as it can be
required to e.g. reset the GPU falcons.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
 drivers/gpu/nova-core/gpu.rs  | 45 +++++++++++++++++++++++++++++++++++++++++--
 drivers/gpu/nova-core/regs.rs | 10 ++++++++++
 2 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 50417f608dc7b445958ae43444a13c7593204fcf..a4e2cf1b529cc25fc168f68f9eaa6f4a7a9748eb 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -2,6 +2,7 @@
 
 use kernel::{device, devres::Devres, error::code::*, pci, prelude::*};
 
+use crate::dma::DmaObject;
 use crate::driver::Bar0;
 use crate::firmware::{Firmware, FIRMWARE_VERSION};
 use crate::gfw;
@@ -158,12 +159,32 @@ fn new(bar: &Bar0) -> Result<Spec> {
 }
 
 /// Structure holding the resources required to operate the GPU.
-#[pin_data]
+#[pin_data(PinnedDrop)]
 pub(crate) struct Gpu {
     spec: Spec,
     /// MMIO mapping of PCI BAR 0
     bar: Devres<Bar0>,
     fw: Firmware,
+    /// System memory page required for flushing all pending GPU-side memory writes done through
+    /// PCIE into system memory.
+    sysmem_flush: DmaObject,
+}
+
+#[pinned_drop]
+impl PinnedDrop for Gpu {
+    fn drop(self: Pin<&mut Self>) {
+        // Unregister the sysmem flush page before we release it.
+        let _ = self.bar.try_access_with(|b| {
+            regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR::default()
+                .set_adr_39_08(0)
+                .write(b);
+            if self.spec.chipset >= Chipset::GA102 {
+                regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR_HI::default()
+                    .set_adr_63_40(0)
+                    .write(b);
+            }
+        });
+    }
 }
 
 impl Gpu {
@@ -187,10 +208,30 @@ pub(crate) fn new(
         gfw::wait_gfw_boot_completion(bar)
             .inspect_err(|_| dev_err!(pdev.as_ref(), "GFW boot did not complete"))?;
 
+        // System memory page required for sysmembar to properly flush into system memory.
+        let sysmem_flush = {
+            let page = DmaObject::new(pdev.as_ref(), kernel::bindings::PAGE_SIZE)?;
+
+            // Register the sysmem flush page.
+            let handle = page.dma_handle();
+
+            regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR::default()
+                .set_adr_39_08((handle >> 8) as u32)
+                .write(bar);
+            if spec.chipset >= Chipset::GA102 {
+                regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR_HI::default()
+                    .set_adr_63_40((handle >> 40) as u32)
+                    .write(bar);
+            }
+
+            page
+        };
+
         Ok(pin_init!(Self {
             spec,
             bar: devres_bar,
-            fw
+            fw,
+            sysmem_flush,
         }))
     }
 }
diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
index cba442da51181971f209b338249307c11ac481e3..b599e7ddad57ed8defe0324056571ba46b926cf6 100644
--- a/drivers/gpu/nova-core/regs.rs
+++ b/drivers/gpu/nova-core/regs.rs
@@ -38,6 +38,16 @@ pub(crate) fn chipset(self) -> Result<Chipset> {
     }
 }
 
+/* PFB */
+
+register!(NV_PFB_NISO_FLUSH_SYSMEM_ADDR @ 0x00100c10 {
+    31:0    adr_39_08 as u32;
+});
+
+register!(NV_PFB_NISO_FLUSH_SYSMEM_ADDR_HI @ 0x00100c40 {
+    23:0    adr_63_40 as u32;
+});
+
 /* PGC6 */
 
 register!(NV_PGC6_AON_SECURE_SCRATCH_GROUP_05_PRIV_LEVEL_MASK @ 0x00118128 {

-- 
2.49.0