[PATCH 2/2] gpu: nova-core: use FromSafeCast wherever possible

`FromSafeCast` should be preferred to the `*_as_*` family of functions
when it can be used (i.e. in non-const contexts), as it requires a
single import to perform all valid conversions.

After this patch, the only remaining references to the `casts` module
are those done in const context, which means the `casts` import can be
removed once these are converted to use the `cv!` macro.

Signed-off-by: Alexandre Courbot <[email protected]>
---
 drivers/gpu/nova-core/falcon/fsp.rs   |  4 ++--
 drivers/gpu/nova-core/firmware/tlv.rs |  4 ++--
 drivers/gpu/nova-core/gsp.rs          |  4 ++--
 drivers/gpu/nova-core/gsp/cmdq.rs     | 19 +++++++++++--------
 drivers/gpu/nova-core/gsp/fw.rs       |  8 ++++----
 5 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/nova-core/falcon/fsp.rs b/drivers/gpu/nova-core/falcon/fsp.rs
index 2470ac511c98..ece95b1ea8cb 100644
--- a/drivers/gpu/nova-core/falcon/fsp.rs
+++ b/drivers/gpu/nova-core/falcon/fsp.rs
@@ -16,7 +16,7 @@
         },
         Io, //
     },
-    num::casts,
+    num::casts::FromSafeCast,
     prelude::*,
     sizes::SZ_1K,
     time::Delta,
@@ -165,7 +165,7 @@ pub(crate) fn recv_msg(&mut self) -> Result<KVec<u8>> {
             Delta::from_millis(10),
             Delta::from_millis(FSP_MSG_TIMEOUT_MS),
         )
-        .map(casts::u32_as_usize)?;
+        .map(usize::from_safe_cast)?;
 
         // Don't blindly allocate more than the maximum we expect from FSP.
         if msg_size > FSP_EMEM_CHANNEL_0_SIZE {
diff --git a/drivers/gpu/nova-core/firmware/tlv.rs b/drivers/gpu/nova-core/firmware/tlv.rs
index 6653c10e3e0a..7dff8871e338 100644
--- a/drivers/gpu/nova-core/firmware/tlv.rs
+++ b/drivers/gpu/nova-core/firmware/tlv.rs
@@ -5,7 +5,7 @@
     device,
     firmware,
     num::casts::{
-        self,
+        FromSafeCast,
         IntoSafeCast, //
     },
     prelude::*,
@@ -52,7 +52,7 @@ fn parse(hdr: &[u8]) -> Option<Self> {
             return None;
         }
         let len_arr = <[u8; 4]>::try_from(hdr.get(4..Self::SIZE)?).ok()?;
-        let length = casts::u32_as_usize(u32::from_le_bytes(len_arr));
+        let length = usize::from_safe_cast(u32::from_le_bytes(len_arr));
         Some(Self { tag, length })
     }
 }
diff --git a/drivers/gpu/nova-core/gsp.rs b/drivers/gpu/nova-core/gsp.rs
index fc8648de84c2..0f5275dcb41c 100644
--- a/drivers/gpu/nova-core/gsp.rs
+++ b/drivers/gpu/nova-core/gsp.rs
@@ -17,7 +17,7 @@
         io_write,
         Io, //
     },
-    num::casts,
+    num::casts::FromSafeCast,
     pci,
     prelude::*, //
 };
@@ -92,7 +92,7 @@ fn init(view: CoherentView<'_, Self>, start: DmaAddress) -> Result<()> {
         for i in 0..NUM_PAGES {
             io_write!(view, .0[build: i],
                 start
-                    .checked_add(casts::usize_as_u64(i) << GSP_PAGE_SHIFT)
+                    .checked_add(u64::from_safe_cast(i) << GSP_PAGE_SHIFT)
                     .ok_or(EOVERFLOW)?
             );
         }
diff --git a/drivers/gpu/nova-core/gsp/cmdq.rs b/drivers/gpu/nova-core/gsp/cmdq.rs
index f85fde09aa6e..658d0a9b2cfb 100644
--- a/drivers/gpu/nova-core/gsp/cmdq.rs
+++ b/drivers/gpu/nova-core/gsp/cmdq.rs
@@ -23,7 +23,10 @@
         Io, //
     },
     new_mutex,
-    num::casts,
+    num::casts::{
+        self,
+        FromSafeCast, //
+    },
     prelude::*,
     ptr,
     sync::{
@@ -289,10 +292,10 @@ fn new(dev: &device::Device<device::Bound>) -> Result<Self> {
         unsafe {
             (
                 core::slice::from_raw_parts_mut(
-                    data.add(casts::u32_as_usize(tx)),
-                    casts::u32_as_usize(tail_end - tx),
+                    data.add(usize::from_safe_cast(tx)),
+                    usize::from_safe_cast(tail_end - tx),
                 ),
-                core::slice::from_raw_parts_mut(data, casts::u32_as_usize(wrap_end)),
+                core::slice::from_raw_parts_mut(data, usize::from_safe_cast(wrap_end)),
             )
         }
     }
@@ -307,7 +310,7 @@ fn driver_write_area_size(&self) -> usize {
         // `cpu_write_ptr`. The minimum value case is where `rx == 0` and `tx == MSGQ_NUM_PAGES -
         // 1`, which gives `0 + MSGQ_NUM_PAGES - (MSGQ_NUM_PAGES - 1) - 1 == 0`.
         let slots = (rx + MSGQ_NUM_PAGES - tx - 1) % MSGQ_NUM_PAGES;
-        casts::u32_as_usize(slots) * GSP_PAGE_SIZE
+        usize::from_safe_cast(slots) * GSP_PAGE_SIZE
     }
 
     /// Returns the region of the GSP message queue that the driver is currently allowed to read
@@ -343,10 +346,10 @@ fn driver_write_area_size(&self) -> usize {
         unsafe {
             (
                 core::slice::from_raw_parts(
-                    data.add(casts::u32_as_usize(rx)),
-                    casts::u32_as_usize(tail_end - rx),
+                    data.add(usize::from_safe_cast(rx)),
+                    usize::from_safe_cast(tail_end - rx),
                 ),
-                core::slice::from_raw_parts(data, casts::u32_as_usize(wrap_end)),
+                core::slice::from_raw_parts(data, usize::from_safe_cast(wrap_end)),
             )
         }
     }
diff --git a/drivers/gpu/nova-core/gsp/fw.rs b/drivers/gpu/nova-core/gsp/fw.rs
index 88f083ff1f13..61064b6a251b 100644
--- a/drivers/gpu/nova-core/gsp/fw.rs
+++ b/drivers/gpu/nova-core/gsp/fw.rs
@@ -681,7 +681,7 @@ fn id8(name: &str) -> u64 {
         let init_inner = init!(bindings::LibosMemoryRegionInitArgument {
             id8: id8(name),
             pa: obj.dma_address(),
-            size: casts::usize_as_u64(obj.size()),
+            size: u64::from_safe_cast(obj.size()),
             kind: casts::u32_into_u8::<
                 { bindings::LibosMemoryRegionKind_LIBOS_MEMORY_REGION_CONTIGUOUS },
             >(),
@@ -851,7 +851,7 @@ pub(crate) fn set_checksum(&mut self, checksum: u32) {
     /// Returns the length of the message's payload.
     pub(crate) fn payload_length(&self) -> usize {
         // `rpc.length` includes the length of the RPC message header.
-        casts::u32_as_usize(self.inner.rpc.length)
+        usize::from_safe_cast(self.inner.rpc.length)
             .saturating_sub(size_of::<bindings::rpc_message_header_v>())
     }
 
@@ -948,8 +948,8 @@ fn new(cmdq: &Cmdq) -> impl Init<Self> + '_ {
         init!(MessageQueueInitArguments {
             sharedMemPhysAddr: cmdq.dma_addr,
             pageTableEntryCount: casts::usize_into_u32::<{ Cmdq::NUM_PTES }>(),
-            cmdQueueOffset: casts::usize_as_u64(Cmdq::CMDQ_OFFSET),
-            statQueueOffset: casts::usize_as_u64(Cmdq::STATQ_OFFSET),
+            cmdQueueOffset: u64::from_safe_cast(Cmdq::CMDQ_OFFSET),
+            statQueueOffset: u64::from_safe_cast(Cmdq::STATQ_OFFSET),
             ..Zeroable::init_zeroed()
         })
     }

-- 
2.55.0