[PATCH v2 1/3] gpu: nova-core: Blackwell: use absolute FBHUB0 flush registers

[John Hubbard <jhubbard@nvidia.com>]

The GB20x sysmem flush registers were defined relative to an Fbhub0Base
register window, but there is exactly one FBHUB0 base, so expressing them
as base-plus-offset only adds indirection.

Rename these to FBHUB0 and give them their fixed absolute addresses,
dropping the base struct and its RegisterBase impl.

No functional changes.

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 drivers/gpu/nova-core/fb/hal/gb202.rs | 26 +++++++-------------------
 drivers/gpu/nova-core/regs.rs         | 19 ++++++++-----------
 2 files changed, 15 insertions(+), 30 deletions(-)

diff --git a/drivers/gpu/nova-core/fb/hal/gb202.rs b/drivers/gpu/nova-core/fb/hal/gb202.rs
index 038d1278c634..6747ba6c9c13 100644
--- a/drivers/gpu/nova-core/fb/hal/gb202.rs
+++ b/drivers/gpu/nova-core/fb/hal/gb202.rs
@@ -4,13 +4,7 @@
 //! Blackwell GB20x framebuffer HAL.
 
 use kernel::{
-    io::{
-        register::{
-            RegisterBase,
-            WithBase, //
-        },
-        Io, //
-    },
+    io::Io,
     num::Bounded,
     prelude::*,
     sizes::SizeConstants, //
@@ -24,17 +18,13 @@
 
 struct Gb202;
 
-impl RegisterBase<regs::Fbhub0Base> for Gb202 {
-    const BASE: usize = 0x008a_0000;
-}
-
 fn read_sysmem_flush_page_gb202(bar: Bar0<'_>) -> u64 {
     let lo = u64::from(
-        bar.read(regs::NV_PFB_FBHUB_PCIE_FLUSH_SYSMEM_ADDR_LO::of::<Gb202>())
+        bar.read(regs::NV_PFB_FBHUB0_PCIE_FLUSH_SYSMEM_ADDR_LO)
             .adr(),
     );
     let hi = u64::from(
-        bar.read(regs::NV_PFB_FBHUB_PCIE_FLUSH_SYSMEM_ADDR_HI::of::<Gb202>())
+        bar.read(regs::NV_PFB_FBHUB0_PCIE_FLUSH_SYSMEM_ADDR_HI)
             .adr(),
     );
 
@@ -44,15 +34,13 @@ fn read_sysmem_flush_page_gb202(bar: Bar0<'_>) -> u64 {
 /// Write the sysmem flush page address through the GB20x FBHUB0 registers.
 fn write_sysmem_flush_page_gb202(bar: Bar0<'_>, addr: Bounded<u64, 52>) {
     // Write HI first. The hardware will trigger the flush on the LO write.
-    bar.write(
-        regs::NV_PFB_FBHUB_PCIE_FLUSH_SYSMEM_ADDR_HI::of::<Gb202>(),
-        regs::NV_PFB_FBHUB_PCIE_FLUSH_SYSMEM_ADDR_HI::zeroed()
+    bar.write_reg(
+        regs::NV_PFB_FBHUB0_PCIE_FLUSH_SYSMEM_ADDR_HI::zeroed()
             .with_adr(addr.shr::<32, 20>().cast::<u32>()),
     );
-    bar.write(
-        regs::NV_PFB_FBHUB_PCIE_FLUSH_SYSMEM_ADDR_LO::of::<Gb202>(),
+    bar.write_reg(
         // CAST: lower 32 bits. Hardware ignores bits 7:0.
-        regs::NV_PFB_FBHUB_PCIE_FLUSH_SYSMEM_ADDR_LO::zeroed().with_adr(*addr as u32),
+        regs::NV_PFB_FBHUB0_PCIE_FLUSH_SYSMEM_ADDR_LO::zeroed().with_adr(*addr as u32),
     );
 }
 
diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs
index 73339a0cff99..5ab7ccfb9855 100644
--- a/drivers/gpu/nova-core/regs.rs
+++ b/drivers/gpu/nova-core/regs.rs
@@ -153,11 +153,6 @@ fn fmt(&self, f: &mut kernel::fmt::Formatter<'_>) -> kernel::fmt::Result {
 /// The base is provided by the GB10x framebuffer HAL.
 pub(crate) struct Hshub0Base(());
 
-/// Base of the GB20x FBHUB0 register window (`NV_FBHUB0_PRI_BASE` in Open RM).
-///
-/// The base is provided by the GB20x framebuffer HAL.
-pub(crate) struct Fbhub0Base(());
-
 register! {
     // GB10x sysmem flush registers, relative to the HSHUB0 base. GB10x routes sysmembar
     // through a primary and an EG (egress) pair that must both be programmed to the same
@@ -178,16 +173,18 @@ fn fmt(&self, f: &mut kernel::fmt::Formatter<'_>) -> kernel::fmt::Result {
     pub(crate) NV_PFB_HSHUB_EG_PCIE_FLUSH_SYSMEM_ADDR_HI(u32) @ Hshub0Base + 0x000006c4 {
         19:0    adr;
     }
+}
 
-    // GB20x sysmem flush registers, relative to the FBHUB0 base. Unlike the older
-    // NV_PFB_NISO_FLUSH_SYSMEM_ADDR registers which encode the address with an 8-bit
-    // right-shift, these take the raw address split into lower and upper halves. Hardware
-    // ignores bits 7:0 of the LO register.
-    pub(crate) NV_PFB_FBHUB_PCIE_FLUSH_SYSMEM_ADDR_LO(u32) @ Fbhub0Base + 0x00001d58 {
+register! {
+    // GB20x FBHUB0 sysmem flush registers. Unlike the older
+    // NV_PFB_NISO_FLUSH_SYSMEM_ADDR registers, which encode the address with an
+    // 8-bit right-shift, these take the raw address split into lower and upper
+    // halves. Hardware ignores bits 7:0 of the LO register.
+    pub(crate) NV_PFB_FBHUB0_PCIE_FLUSH_SYSMEM_ADDR_LO(u32) @ 0x008a1d58 {
         31:0    adr => u32;
     }
 
-    pub(crate) NV_PFB_FBHUB_PCIE_FLUSH_SYSMEM_ADDR_HI(u32) @ Fbhub0Base + 0x00001d5c {
+    pub(crate) NV_PFB_FBHUB0_PCIE_FLUSH_SYSMEM_ADDR_HI(u32) @ 0x008a1d5c {
         19:0    adr;
     }
 }
-- 
2.54.0