linux-kernel - [PATCH 2/2] m68k: implement arch_dma_prep

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Date:   Fri, 14 Jun 2019 12:21:26 +0200
From:   Christoph Hellwig <hch@....de>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Greg Ungerer <gerg@...ux-m68k.org>
Cc:     linux-m68k@...ts.linux-m68k.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] m68k: implement arch_dma_prep_coherent

When we remap memory as non-cached to be used as a DMA coherent buffer
we should writeback all cache and invalidate the cache lines so that
we make sure we have a clean slate.  Implement this using the
cache_push() helper.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 arch/m68k/Kconfig      | 1 +
 arch/m68k/kernel/dma.c | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 2571a8fba4b0..64b122595896 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -4,6 +4,7 @@ config M68K
 	default y
 	select ARCH_32BIT_OFF_T
 	select ARCH_HAS_DMA_MMAP_PGPROT if MMU && !COLDFIRE
+	select ARCH_HAS_DMA_PREP_COHERENT
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE if HAS_DMA
 	select ARCH_MIGHT_HAVE_PC_PARPORT if ISA
 	select ARCH_NO_COHERENT_DMA_MMAP if !MMU
diff --git a/arch/m68k/kernel/dma.c b/arch/m68k/kernel/dma.c
index 9c6a350a16d8..e720e6eed838 100644
--- a/arch/m68k/kernel/dma.c
+++ b/arch/m68k/kernel/dma.c
@@ -18,6 +18,11 @@
 #include <asm/pgalloc.h>
 
 #if defined(CONFIG_MMU) && !defined(CONFIG_COLDFIRE)
+void arch_dma_prep_coherent(struct page *page, size_t size)
+{
+	cache_push(page_to_phys(page), size);
+}
+
 pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
 		unsigned long attrs)
 {
-- 
2.20.1