[RFC PATCH v2 1/5] drm/amdgpu: add typed helpers for ring writeback slots

[Runyu Xiao]

AMDGPU ring writeback slots are currently accessed with a mix of direct
pointer dereferences, casted u64 accesses, READ_ONCE()/WRITE_ONCE() on
casted pointers, and atomic64_t casts.

Add small typed helpers for reading and writing 32-bit and 64-bit ring
writeback slots. This makes the intended slot width explicit at each
call site and provides a single access model for the later cleanup
patches in this series.

This patch only introduces the helpers and does not change any existing
call site behavior.

Signed-off-by: Runyu Xiao <runyu.xiao@xxxxxxxxxx>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
index 8f28b3bd7..cdc855285 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
@@ -457,6 +457,26 @@ struct amdgpu_ring {
 #define amdgpu_ring_patch_de(r, o) ((r)->funcs->patch_de((r), (o)))
 #define amdgpu_ring_reset(r, v, f) (r)->funcs->reset((r), (v), (f))
 
+static inline u32 amdgpu_ring_wb_read32(const void *cpu_addr)
+{
+	return READ_ONCE(*(const u32 *)cpu_addr);
+}
+
+static inline void amdgpu_ring_wb_write32(void *cpu_addr, u32 value)
+{
+	WRITE_ONCE(*(u32 *)cpu_addr, value);
+}
+
+static inline u64 amdgpu_ring_wb_read64(const void *cpu_addr)
+{
+	return READ_ONCE(*(const u64 *)cpu_addr);
+}
+
+static inline void amdgpu_ring_wb_write64(void *cpu_addr, u64 value)
+{
+	WRITE_ONCE(*(u64 *)cpu_addr, value);
+}
+
 unsigned int amdgpu_ring_max_ibs(enum amdgpu_ring_type type);
 int amdgpu_ring_alloc(struct amdgpu_ring *ring, unsigned ndw);
 void amdgpu_ring_ib_begin(struct amdgpu_ring *ring);
-- 
2.34.1