[PATCH v1] rust: conditionally compile dma abstraction based on CONFIG_HAS_DMA

[FUJITA Tomonori]

Make dma abstraction conditional on CONFIG_HAS_DMA.

This fixes the following build error on UML:

error[E0425]: cannot find function `dma_alloc_attrs` in crate `bindings`
     --> rust/kernel/dma.rs:171:23
      |
171   |               bindings::dma_alloc_attrs(
      |                         ^^^^^^^^^^^^^^^ help: a function with a similar name exists: `dma_alloc_pages`
      |
     ::: /home/fujita/build/um/rust/bindings/bindings_generated.rs:44568:5
      |
44568 | /     pub fn dma_alloc_pages(
44569 | |         dev: *mut device,
44570 | |         size: usize,
44571 | |         dma_handle: *mut dma_addr_t,
44572 | |         dir: dma_data_direction,
44573 | |         gfp: gfp_t,
44574 | |     ) -> *mut page;
      | |___________________- similarly named function `dma_alloc_pages` defined here

error[E0425]: cannot find function `dma_free_attrs` in crate `bindings`
     --> rust/kernel/dma.rs:293:23
      |
293   |               bindings::dma_free_attrs(
      |                         ^^^^^^^^^^^^^^ help: a function with a similar name exists: `dma_free_pages`
      |
     ::: /home/fujita/build/um/rust/bindings/bindings_generated.rs:44577:5
      |
44577 | /     pub fn dma_free_pages(
44578 | |         dev: *mut device,
44579 | |         size: usize,
44580 | |         page: *mut page,
44581 | |         dma_handle: dma_addr_t,
44582 | |         dir: dma_data_direction,
44583 | |     );
      | |______- similarly named function `dma_free_pages` defined here

Fixes: ad2907b4e308 ("rust: add dma coherent allocator abstraction")
Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxx>
---
 rust/kernel/lib.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index de07aadd1ff5..9d743af69dc8 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -46,6 +46,7 @@
 pub mod device;
 pub mod device_id;
 pub mod devres;
+#[cfg(CONFIG_HAS_DMA)]
 pub mod dma;
 pub mod driver;
 pub mod error;

base-commit: c59026c0570a2a97ce2e7d5ae5e9c48fc841542b
-- 
2.43.0