[PATCH v1 01/16] gpu: nova-core: mm: Add common types for virtual memory management

[Joel Fernandes <joelagnelf@nvidia.com>]

Add common virtual memory memory management types: `PAGE_SIZE` constant,
`VirtualAddress` bitfield type, `Vfn` (Virtual Frame Number) type.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
---
 drivers/gpu/nova-core/mm.rs | 66 +++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

diff --git a/drivers/gpu/nova-core/mm.rs b/drivers/gpu/nova-core/mm.rs
index 08d74710f790..b23667a55ecd 100644
--- a/drivers/gpu/nova-core/mm.rs
+++ b/drivers/gpu/nova-core/mm.rs
@@ -42,6 +42,7 @@ macro_rules! impl_pfn_bounded {
     num::Bounded,
     pci,
     prelude::*,
+    sizes::SZ_4K,
     sync::Arc, //
 };
 
@@ -99,6 +100,9 @@ pub(crate) fn run_mm_selftests(
     Ok(())
 }
 
+/// Page size in bytes (4 KiB).
+pub(crate) const PAGE_SIZE: usize = SZ_4K;
+
 bitfield! {
     /// Physical VRAM address in GPU video memory.
     pub(crate) struct VramAddress(u64) {
@@ -207,6 +211,29 @@ fn into_vram_range(self) -> Range<VramAddress> {
     }
 }
 
+bitfield! {
+    /// Virtual address in GPU address space.
+    pub(crate) struct VirtualAddress(u64) {
+        /// Offset within 4KB page.
+        11:0    offset;
+        /// Virtual frame number.
+        63:12   frame_number => Vfn;
+    }
+}
+
+impl VirtualAddress {
+    /// Create a new virtual address from a raw value.
+    pub(crate) const fn new(addr: u64) -> Self {
+        Self::from_raw(addr)
+    }
+}
+
+impl From<Vfn> for VirtualAddress {
+    fn from(vfn: Vfn) -> Self {
+        Self::zeroed().with_frame_number(vfn)
+    }
+}
+
 /// Physical Frame Number.
 ///
 /// Represents a physical page in VRAM.
@@ -245,3 +272,42 @@ fn from(pfn: Pfn) -> Self {
 }
 
 impl_pfn_bounded!(52);
+
+/// Virtual Frame Number.
+///
+/// Represents a virtual page in GPU address space.
+#[repr(transparent)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub(crate) struct Vfn(u64);
+
+impl Vfn {
+    /// Create a new VFN from a frame number.
+    pub(crate) const fn new(frame_number: u64) -> Self {
+        Self(frame_number)
+    }
+
+    /// Get the raw frame number.
+    pub(crate) const fn raw(self) -> u64 {
+        self.0
+    }
+}
+
+impl From<VirtualAddress> for Vfn {
+    fn from(addr: VirtualAddress) -> Self {
+        addr.frame_number()
+    }
+}
+
+impl From<u64> for Vfn {
+    fn from(val: u64) -> Self {
+        Self(val)
+    }
+}
+
+impl From<Vfn> for u64 {
+    fn from(vfn: Vfn) -> Self {
+        vfn.0
+    }
+}
+
+impl_frame_number_bounded!(Vfn, 52);
-- 
2.34.1