[PATCH 2/2] arm64: mm: Remove assembly DMA cache maintenance wrappers

From: Will Deacon <will@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
	Christoph Hellwig <hch@lst.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Russell King <linux@armlinux.org.uk>
Subject: [PATCH 2/2] arm64: mm: Remove assembly DMA cache maintenance wrappers
Date: Fri, 10 Jun 2022 16:12:28 +0100	[thread overview]
Message-ID: <20220610151228.4562-3-will@kernel.org> (raw)
In-Reply-To: <20220610151228.4562-1-will@kernel.org>

Remove the __dma_{flush,map,unmap}_area assembly wrappers and call the
appropriate cache maintenance functions directly from the DMA mapping
callbacks.

Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/include/asm/cacheflush.h |  7 -----
 arch/arm64/mm/cache.S               | 41 -----------------------------
 arch/arm64/mm/dma-mapping.c         | 19 +++++++++----
 3 files changed, 14 insertions(+), 53 deletions(-)

diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
index 5a228e203ef9..37185e978aeb 100644
--- a/arch/arm64/include/asm/cacheflush.h
+++ b/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
diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S
index 21c907987080..081058d4e436 100644
--- a/arch/arm64/mm/cache.S
+++ b/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)
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 6719f9efea09..df0c488ae643 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -14,20 +14,29 @@
 #include <asm/cacheflush.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
-- 
2.36.1.476.g0c4daa206d-goog


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