arm64: mm: Remove assembly DMA cache maintenance wrappers

Remove the __dma_{flush,map,unmap}_area assembly wrappers and call the
appropriate cache maintenance functions directly from the DMA mapping
callbacks.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220610151228.4562-3-will@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

arch/arm64/include/asm/cacheflush.h

@@ -104,13 +104,6 @@ static inline void flush_icache_range(unsigned long start, unsigned long end)
 }
 #define flush_icache_range flush_icache_range
 
-/*
- * Cache maintenance functions used by the DMA API. No to be used directly.
- */
-extern void __dma_map_area(const void *, size_t, int);
-extern void __dma_unmap_area(const void *, size_t, int);
-extern void __dma_flush_area(const void *, size_t);
-
 /*
  * Copy user data from/to a page which is mapped into a different
  * processes address space.  Really, we want to allow our "user

arch/arm64/mm/cache.S

@@ -194,44 +194,3 @@ SYM_FUNC_START(__pi_dcache_clean_pop)
 	ret
 SYM_FUNC_END(__pi_dcache_clean_pop)
 SYM_FUNC_ALIAS(dcache_clean_pop, __pi_dcache_clean_pop)
-
-/*
- *	__dma_flush_area(start, size)
- *
- *	clean & invalidate D / U line
- *
- *	- start   - virtual start address of region
- *	- size    - size in question
- */
-SYM_FUNC_START(__pi___dma_flush_area)
-	add	x1, x0, x1
-	dcache_by_line_op civac, sy, x0, x1, x2, x3
-	ret
-SYM_FUNC_END(__pi___dma_flush_area)
-SYM_FUNC_ALIAS(__dma_flush_area, __pi___dma_flush_area)
-
-/*
- *	__dma_map_area(start, size, dir)
- *	- start	- kernel virtual start address
- *	- size	- size of region
- *	- dir	- DMA direction
- */
-SYM_FUNC_START(__pi___dma_map_area)
-	add	x1, x0, x1
-	b	__pi_dcache_clean_poc
-SYM_FUNC_END(__pi___dma_map_area)
-SYM_FUNC_ALIAS(__dma_map_area, __pi___dma_map_area)
-
-/*
- *	__dma_unmap_area(start, size, dir)
- *	- start	- kernel virtual start address
- *	- size	- size of region
- *	- dir	- DMA direction
- */
-SYM_FUNC_START(__pi___dma_unmap_area)
-	add	x1, x0, x1
-	cmp	w2, #DMA_TO_DEVICE
-	b.ne	__pi_dcache_inval_poc
-	ret
-SYM_FUNC_END(__pi___dma_unmap_area)
-SYM_FUNC_ALIAS(__dma_unmap_area, __pi___dma_unmap_area)

arch/arm64/mm/dma-mapping.c

@@ -14,20 +14,29 @@
 #include <asm/xen/xen-ops.h>
 
 void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
-		enum dma_data_direction dir)
+			      enum dma_data_direction dir)
 {
-	__dma_map_area(phys_to_virt(paddr), size, dir);
+	unsigned long start = (unsigned long)phys_to_virt(paddr);
+
+	dcache_clean_poc(start, start + size);
 }
 
 void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
-		enum dma_data_direction dir)
+			   enum dma_data_direction dir)
 {
-	__dma_unmap_area(phys_to_virt(paddr), size, dir);
+	unsigned long start = (unsigned long)phys_to_virt(paddr);
+
+	if (dir == DMA_TO_DEVICE)
+		return;
+
+	dcache_inval_poc(start, start + size);
 }
 
 void arch_dma_prep_coherent(struct page *page, size_t size)
 {
-	__dma_flush_area(page_address(page), size);
+	unsigned long start = (unsigned long)page_address(page);
+
+	dcache_clean_inval_poc(start, start + size);
 }
 
 #ifdef CONFIG_IOMMU_DMA