Add BAR1_SIZE constant and Bar1 type alias for the 256MB BAR1 aperture.
These are prerequisites for BAR1 memory access functionality.

Cc: Nikola Djukic <ndjukic@nvidia.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
 drivers/gpu/nova-core/driver.rs          | 8 +++++++-
 drivers/gpu/nova-core/gsp/commands.rs    | 4 ++++
 drivers/gpu/nova-core/gsp/fw/commands.rs | 8 ++++++++
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index 84b0e1703150..b4311adf4cef 100644
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -13,7 +13,10 @@
         Vendor, //
     },
     prelude::*,
-    sizes::SZ_16M,
+    sizes::{
+        SZ_16M,
+        SZ_256M, //
+    },
     sync::{
         atomic::{
             Atomic,
@@ -37,6 +40,7 @@ pub(crate) struct NovaCore {
 }
 
 const BAR0_SIZE: usize = SZ_16M;
+pub(crate) const BAR1_SIZE: usize = SZ_256M;
 
 // For now we only support Ampere which can use up to 47-bit DMA addresses.
 //
@@ -47,6 +51,8 @@ pub(crate) struct NovaCore {
 const GPU_DMA_BITS: u32 = 47;
 
 pub(crate) type Bar0 = pci::Bar<BAR0_SIZE>;
+#[expect(dead_code)]
+pub(crate) type Bar1 = pci::Bar<BAR1_SIZE>;
 
 kernel::pci_device_table!(
     PCI_TABLE,
diff --git a/drivers/gpu/nova-core/gsp/commands.rs b/drivers/gpu/nova-core/gsp/commands.rs
index ec03bf94b34e..5a85478f2ba3 100644
--- a/drivers/gpu/nova-core/gsp/commands.rs
+++ b/drivers/gpu/nova-core/gsp/commands.rs
@@ -193,6 +193,9 @@ fn init(&self) -> impl Init<Self::Command, Self::InitError> {
 /// The reply from the GSP to the [`GetGspStaticInfo`] command.
 pub(crate) struct GetGspStaticInfoReply {
     gpu_name: [u8; 64],
+    /// BAR1 Page Directory Entry base address.
+    #[expect(dead_code)]
+    pub(crate) bar1_pde_base: u64,
     /// Usable FB (VRAM) region for driver memory allocation.
     pub(crate) usable_fb_region: Range<u64>,
     /// End of VRAM.
@@ -214,6 +217,7 @@ fn read(
 
         Ok(GetGspStaticInfoReply {
             gpu_name: msg.gpu_name_str(),
+            bar1_pde_base: msg.bar1_pde_base(),
             usable_fb_region: base..base.saturating_add(size),
             total_fb_end,
         })
diff --git a/drivers/gpu/nova-core/gsp/fw/commands.rs b/drivers/gpu/nova-core/gsp/fw/commands.rs
index 46932d5c8c1d..25f230254d8f 100644
--- a/drivers/gpu/nova-core/gsp/fw/commands.rs
+++ b/drivers/gpu/nova-core/gsp/fw/commands.rs
@@ -125,6 +125,14 @@ impl GspStaticConfigInfo {
         self.0.gpuNameString
     }
 
+    /// Returns the BAR1 Page Directory Entry base address.
+    ///
+    /// This is the root page table address for BAR1 virtual memory,
+    /// set up by GSP-RM firmware.
+    pub(crate) fn bar1_pde_base(&self) -> u64 {
+        self.0.bar1PdeBase
+    }
+
     /// Returns an iterator over valid FB regions from GSP firmware data.
     fn fb_regions(
         &self,
-- 
2.34.1