[PATCH 05/12] gpu: nova-core: mm: Implement Alignable and Debug for VramAddress

Later patches align VRAM addresses down to the PRAMIN window. Implement
`Alignable` trait for `VramAddress` and plus add a `ZERO` constant.

Also print the address in hex under `{:?}`, so it reads well in debug
output.

Signed-off-by: Eliot Courtney <[email protected]>
---
 drivers/gpu/nova-core/mm.rs | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/nova-core/mm.rs b/drivers/gpu/nova-core/mm.rs
index dcd5e5e919bf..f9d80ffbe01d 100644
--- a/drivers/gpu/nova-core/mm.rs
+++ b/drivers/gpu/nova-core/mm.rs
@@ -10,7 +10,14 @@
     ops, //
 };
 
-use kernel::fmt;
+use kernel::{
+    fmt,
+    prelude::*,
+    ptr::{
+        Alignable,
+        Alignment, //
+    },
+};
 
 /// Physical VRAM address in GPU video memory.
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
@@ -18,6 +25,9 @@
 pub(crate) struct VramAddress(u64);
 
 impl VramAddress {
+    /// The zero address.
+    pub(crate) const ZERO: Self = Self::from_raw(0);
+
     /// Creates an address from a raw value.
     pub(crate) const fn from_raw(addr: u64) -> Self {
         Self(addr)
@@ -37,12 +47,28 @@ pub(crate) const fn checked_add(self, rhs: u64) -> Option<Self> {
     }
 }
 
+impl Alignable for VramAddress {
+    fn align_down(self, alignment: Alignment) -> Self {
+        Self::from_raw(self.into_raw().align_down(alignment))
+    }
+
+    fn align_up(self, alignment: Alignment) -> Option<Self> {
+        self.into_raw().align_up(alignment).map(Self::from_raw)
+    }
+}
+
 impl LowerHex for VramAddress {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         LowerHex::fmt(&self.into_raw(), f)
     }
 }
 
+impl fmt::Debug for VramAddress {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_fmt(fmt!("{:#x}", self))
+    }
+}
+
 impl ops::Add<u64> for VramAddress {
     type Output = Self;
 

-- 
2.55.0