[PATCH 02/25] dma-mapping: add a Kconfig symbol to indicated arch_dma_prep_coherent presence

Christoph Hellwig
2019-04-30T10:53:54Z

Add a Kconfig symbol that indicates an architecture provides a
arch_dma_prep_coherent implementation, and provide a stub otherwise.

This will allow the generic dma-iommu code to use it while still
allowing to be built for cache coherent architectures.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
---
arch/arm64/Kconfig | 1 +
arch/csky/Kconfig | 1 +
include/linux/dma-noncoherent.h | 6 ++++++
kernel/dma/Kconfig | 3 +++
4 files changed, 11 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7e34b9eba5de..adda078d6df7 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -13,6 +13,7 @@ config ARM64
select ARCH_HAS_DEVMEM_IS_ALLOWED
select ARCH_HAS_DMA_COHERENT_TO_PFN
select ARCH_HAS_DMA_MMAP_PGPROT
+ select ARCH_HAS_DMA_PREP_COHERENT
select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_FAST_MULTIPLIER
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 725a115759c9..2c3178848b7d 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -1,6 +1,7 @@
config CSKY
def_bool y
select ARCH_32BIT_OFF_T
+ select ARCH_HAS_DMA_PREP_COHERENT
select ARCH_HAS_SYNC_DMA_FOR_CPU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
select ARCH_USE_BUILTIN_BSWAP
diff --git a/include/linux/dma-noncoherent.h b/include/linux/dma-noncoherent.h
index 69b36ed31a99..9741767e400f 100644
--- a/include/linux/dma-noncoherent.h
+++ b/include/linux/dma-noncoherent.h
@@ -72,6 +72,12 @@ static inline void arch_sync_dma_for_cpu_all(struct device *dev)
}
#endif /* CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL */

+#ifdef CONFIG_ARCH_HAS_DMA_PREP_COHERENT
void arch_dma_prep_coherent(struct page *page, size_t size);
+#else
+static inline void arch_dma_prep_coherent(struct page *page, size_t size)
+{
+}
+#endif /* CONFIG_ARCH_HAS_DMA_PREP_COHERENT */

#endif /* _LINUX_DMA_NONCOHERENT_H */
diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index 52b704e2b97a..83d711f8d665 100644
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -38,6 +38,9 @@ config ARCH_HAS_SYNC_DMA_FOR_CPU
config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL
bool

+config ARCH_HAS_DMA_PREP_COHERENT
+ bool
+
config ARCH_HAS_DMA_COHERENT_TO_PFN
bool