drm/amdgpu:implement ring_write_multiple

Write multiple dwords to the ring.
Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -1588,6 +1588,37 @@ static inline void amdgpu_ring_write(struct amdgpu_ring *ring, uint32_t v)
 	ring->count_dw--;
 }
 
+static inline void amdgpu_ring_write_multiple(struct amdgpu_ring *ring, void *src, int count_dw)
+{
+	unsigned occupied, chunk1, chunk2;
+	void *dst;
+
+	if (ring->count_dw < count_dw) {
+		DRM_ERROR("amdgpu: writing more dwords to the ring than expected!\n");
+	} else {
+		occupied = ring->wptr & ring->ptr_mask;
+		dst = (void *)&ring->ring[occupied];
+		chunk1 = ring->ptr_mask + 1 - occupied;
+		chunk1 = (chunk1 >= count_dw) ? count_dw: chunk1;
+		chunk2 = count_dw - chunk1;
+		chunk1 <<= 2;
+		chunk2 <<= 2;
+
+		if (chunk1)
+			memcpy(dst, src, chunk1);
+
+		if (chunk2) {
+			src += chunk1;
+			dst = (void *)ring->ring;
+			memcpy(dst, src, chunk2);
+		}
+
+		ring->wptr += count_dw;
+		ring->wptr &= ring->ptr_mask;
+		ring->count_dw -= count_dw;
+	}
+}
+
 static inline struct amdgpu_sdma_instance *
 amdgpu_get_sdma_instance(struct amdgpu_ring *ring)
 {