linux-kernel - [PATCH RFC 2/2] gpu: nova-core: demonstrate use of BoundedInt

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Message-Id: <20251002-bounded_ints-v1-2-dd60f5804ea4@nvidia.com>
Date: Thu, 02 Oct 2025 00:03:14 +0900
From: Alexandre Courbot <acourbot@...dia.com>
To: Joel Fernandes <joelagnelf@...dia.com>, 
 Yury Norov <yury.norov@...il.com>, Danilo Krummrich <dakr@...nel.org>, 
 Miguel Ojeda <ojeda@...nel.org>
Cc: rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Alexandre Courbot <acourbot@...dia.com>
Subject: [PATCH RFC 2/2] gpu: nova-core: demonstrate use of BoundedInt

Augment the register macro with two new bounded setter and getter
methods, and showcase how they can be used in the driver.

Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
---
 drivers/gpu/nova-core/falcon.rs      | 14 +++++++++-----
 drivers/gpu/nova-core/regs/macros.rs | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/nova-core/falcon.rs b/drivers/gpu/nova-core/falcon.rs
index 37e6298195e49a9a29e81226abe16cd410c9adbc..2ce2635c86d8cad6e61862d4bd1976d642090c5b 100644
--- a/drivers/gpu/nova-core/falcon.rs
+++ b/drivers/gpu/nova-core/falcon.rs
@@ -6,6 +6,7 @@
 use hal::FalconHal;
 use kernel::device;
 use kernel::dma::DmaAddress;
+use kernel::num::BoundedInt;
 use kernel::prelude::*;
 use kernel::sync::aref::ARef;
 use kernel::time::Delta;
@@ -488,24 +489,27 @@ fn dma_wr<F: FalconFirmware<Target = E>>(
         // Set up the base source DMA address.
 
         regs::NV_PFALCON_FALCON_DMATRFBASE::default()
-            .set_base((dma_start >> 8) as u32)
+            .set_base_bounded(BoundedInt::new((dma_start >> 8) as u32))
             .write(bar, &E::ID);
         regs::NV_PFALCON_FALCON_DMATRFBASE1::default()
-            .set_base((dma_start >> 40) as u16)
+            .set_base_bounded(BoundedInt::try_from((dma_start >> 40) as u32)?)
             .write(bar, &E::ID);
 
+        let r = regs::NV_PFALCON_FALCON_DMATRFBASE::read(bar, &E::ID).base_bounded();
+        pr_info!("BASE: {:x}\n", r);
+
         let cmd = regs::NV_PFALCON_FALCON_DMATRFCMD::default()
             .set_size(DmaTrfCmdSize::Size256B)
             .set_imem(target_mem == FalconMem::Imem)
-            .set_sec(if sec { 1 } else { 0 });
+            .set_sec_bounded(BoundedInt::new(if sec { 1 } else { 0 }));
 
         for pos in (0..num_transfers).map(|i| i * DMA_LEN) {
             // Perform a transfer of size `DMA_LEN`.
             regs::NV_PFALCON_FALCON_DMATRFMOFFS::default()
-                .set_offs(load_offsets.dst_start + pos)
+                .set_offs_bounded(BoundedInt::try_from(load_offsets.dst_start + pos)?)
                 .write(bar, &E::ID);
             regs::NV_PFALCON_FALCON_DMATRFFBOFFS::default()
-                .set_offs(src_start + pos)
+                .set_offs_bounded(BoundedInt::new(src_start + pos))
                 .write(bar, &E::ID);
             cmd.write(bar, &E::ID);
 
diff --git a/drivers/gpu/nova-core/regs/macros.rs b/drivers/gpu/nova-core/regs/macros.rs
index 754c14ee7f401688da51e138db71ccaa58445aa6..03a1830f492fdc1747767ed768ce2239e9ce41ec 100644
--- a/drivers/gpu/nova-core/regs/macros.rs
+++ b/drivers/gpu/nova-core/regs/macros.rs
@@ -565,6 +565,40 @@ pub(crate) fn [<set_ $field>](mut self, value: $to_type) -> Self {
             self
         }
         );
+
+        ::kernel::macros::paste!(
+        pub(crate) fn [<$field _bounded>](self) ->
+            ::kernel::num::BoundedInt<u32, { $hi + 1 - $lo }> {
+            const MASK: u32 = $name::[<$field:upper _MASK>];
+            const SHIFT: u32 = $name::[<$field:upper _SHIFT>];
+            // Ensure the returned type has the same width as the field.
+            ::kernel::static_assert!(
+                MASK >> SHIFT == ::kernel::num::BoundedInt::<u32, { $hi + 1 - $lo }>::MASK
+            );
+
+            let field = ((self.0 & MASK) >> SHIFT);
+
+            ::kernel::num::BoundedInt::<u32, { $hi + 1 - $lo }>::new(field)
+        }
+
+        pub(crate) fn [<set_ $field _bounded>](
+            mut self,
+            value: ::kernel::num::BoundedInt<u32, { $hi + 1 - $lo }>
+        ) -> Self {
+            const MASK: u32 = $name::[<$field:upper _MASK>];
+            const SHIFT: u32 = $name::[<$field:upper _SHIFT>];
+            // Ensure the returned type has the same width as the field.
+            ::kernel::static_assert!(
+                MASK >> SHIFT == ::kernel::num::BoundedInt::<u32, { $hi + 1 - $lo }>::MASK
+            );
+
+            let value = (value.get() << SHIFT) & MASK;
+            self.0 = (self.0 & !MASK) | value;
+
+            self
+        }
+        );
+
     };
 
     // Generates the `Debug` implementation for `$name`.

-- 
2.51.0