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From: Christoph Hellwig <hch@lst.de>
To: iommu@lists.linux-foundation.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Jesper Dangaard Brouer <brouer@redhat.com>
Cc: "Tariq Toukan" <tariqt@mellanox.com>,
	"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
	"Toke Høiland-Jørgensen" <toke@toke.dk>,
	"Robin Murphy" <robin.murphy@arm.com>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"Tony Luck" <tony.luck@intel.com>,
	"Fenghua Yu" <fenghua.yu@intel.com>,
	"Marek Szyprowski" <m.szyprowski@samsung.com>,
	"Keith Busch" <keith.busch@intel.com>,
	"Jonathan Derrick" <jonathan.derrick@intel.com>,
	linux-pci@vger.kernel.org, linux-ia64@vger.kernel.org,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 12/15] dma-mapping: factor out dummy DMA ops
Date: Fri,  7 Dec 2018 11:07:17 -0800
Message-ID: <20181207190720.18517-13-hch@lst.de> (raw)
In-Reply-To: <20181207190720.18517-1-hch@lst.de>

From: Robin Murphy <robin.murphy@arm.com>

The dummy DMA ops are currently used by arm64 for any device which has
an invalid ACPI description and is thus barred from using DMA due to not
knowing whether is is cache-coherent or not. Factor these out into
general dma-mapping code so that they can be referenced from other
common code paths. In the process, we can prune all the optional
callbacks which just do the same thing as the default behaviour, and
fill in .map_resource for completeness.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[hch: moved to a separate source file]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm64/include/asm/dma-mapping.h |  4 +-
 arch/arm64/mm/dma-mapping.c          | 86 ----------------------------
 include/linux/dma-mapping.h          |  1 +
 kernel/dma/Makefile                  |  2 +-
 kernel/dma/dummy.c                   | 39 +++++++++++++
 5 files changed, 42 insertions(+), 90 deletions(-)
 create mode 100644 kernel/dma/dummy.c

diff --git a/arch/arm64/include/asm/dma-mapping.h b/arch/arm64/include/asm/dma-mapping.h
index c41f3fb1446c..273e778f7de2 100644
--- a/arch/arm64/include/asm/dma-mapping.h
+++ b/arch/arm64/include/asm/dma-mapping.h
@@ -24,15 +24,13 @@
 #include <xen/xen.h>
 #include <asm/xen/hypervisor.h>
 
-extern const struct dma_map_ops dummy_dma_ops;
-
 static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 {
 	/*
 	 * We expect no ISA devices, and all other DMA masters are expected to
 	 * have someone call arch_setup_dma_ops at device creation time.
 	 */
-	return &dummy_dma_ops;
+	return &dma_dummy_ops;
 }
 
 void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index e4effbb243b1..ab1e417204d0 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -89,92 +89,6 @@ static int __swiotlb_mmap_pfn(struct vm_area_struct *vma,
 }
 #endif /* CONFIG_IOMMU_DMA */
 
-/********************************************
- * The following APIs are for dummy DMA ops *
- ********************************************/
-
-static void *__dummy_alloc(struct device *dev, size_t size,
-			   dma_addr_t *dma_handle, gfp_t flags,
-			   unsigned long attrs)
-{
-	return NULL;
-}
-
-static void __dummy_free(struct device *dev, size_t size,
-			 void *vaddr, dma_addr_t dma_handle,
-			 unsigned long attrs)
-{
-}
-
-static int __dummy_mmap(struct device *dev,
-			struct vm_area_struct *vma,
-			void *cpu_addr, dma_addr_t dma_addr, size_t size,
-			unsigned long attrs)
-{
-	return -ENXIO;
-}
-
-static dma_addr_t __dummy_map_page(struct device *dev, struct page *page,
-				   unsigned long offset, size_t size,
-				   enum dma_data_direction dir,
-				   unsigned long attrs)
-{
-	return DMA_MAPPING_ERROR;
-}
-
-static void __dummy_unmap_page(struct device *dev, dma_addr_t dev_addr,
-			       size_t size, enum dma_data_direction dir,
-			       unsigned long attrs)
-{
-}
-
-static int __dummy_map_sg(struct device *dev, struct scatterlist *sgl,
-			  int nelems, enum dma_data_direction dir,
-			  unsigned long attrs)
-{
-	return 0;
-}
-
-static void __dummy_unmap_sg(struct device *dev,
-			     struct scatterlist *sgl, int nelems,
-			     enum dma_data_direction dir,
-			     unsigned long attrs)
-{
-}
-
-static void __dummy_sync_single(struct device *dev,
-				dma_addr_t dev_addr, size_t size,
-				enum dma_data_direction dir)
-{
-}
-
-static void __dummy_sync_sg(struct device *dev,
-			    struct scatterlist *sgl, int nelems,
-			    enum dma_data_direction dir)
-{
-}
-
-static int __dummy_dma_supported(struct device *hwdev, u64 mask)
-{
-	return 0;
-}
-
-const struct dma_map_ops dummy_dma_ops = {
-	.alloc                  = __dummy_alloc,
-	.free                   = __dummy_free,
-	.mmap                   = __dummy_mmap,
-	.map_page               = __dummy_map_page,
-	.unmap_page             = __dummy_unmap_page,
-	.map_sg                 = __dummy_map_sg,
-	.unmap_sg               = __dummy_unmap_sg,
-	.sync_single_for_cpu    = __dummy_sync_single,
-	.sync_single_for_device = __dummy_sync_single,
-	.sync_sg_for_cpu        = __dummy_sync_sg,
-	.sync_sg_for_device     = __dummy_sync_sg,
-	.dma_supported          = __dummy_dma_supported,
-};
-EXPORT_SYMBOL(dummy_dma_ops);
-
 static int __init arm64_dma_init(void)
 {
 	WARN_TAINT(ARCH_DMA_MINALIGN < cache_line_size(),
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 0f0078490df4..269ee27fc3d9 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -136,6 +136,7 @@ struct dma_map_ops {
 
 extern const struct dma_map_ops dma_direct_ops;
 extern const struct dma_map_ops dma_virt_ops;
+extern const struct dma_map_ops dma_dummy_ops;
 
 #define DMA_BIT_MASK(n)	(((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
 
diff --git a/kernel/dma/Makefile b/kernel/dma/Makefile
index a626f643cd63..72ff6e46aa86 100644
--- a/kernel/dma/Makefile
+++ b/kernel/dma/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-obj-$(CONFIG_HAS_DMA)			+= mapping.o direct.o
+obj-$(CONFIG_HAS_DMA)			+= mapping.o direct.o dummy.o
 obj-$(CONFIG_DMA_CMA)			+= contiguous.o
 obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += coherent.o
 obj-$(CONFIG_DMA_VIRT_OPS)		+= virt.o
diff --git a/kernel/dma/dummy.c b/kernel/dma/dummy.c
new file mode 100644
index 000000000000..05607642c888
--- /dev/null
+++ b/kernel/dma/dummy.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Dummy DMA ops that always fail.
+ */
+#include <linux/dma-mapping.h>
+
+static int dma_dummy_mmap(struct device *dev, struct vm_area_struct *vma,
+		void *cpu_addr, dma_addr_t dma_addr, size_t size,
+		unsigned long attrs)
+{
+	return -ENXIO;
+}
+
+static dma_addr_t dma_dummy_map_page(struct device *dev, struct page *page,
+		unsigned long offset, size_t size, enum dma_data_direction dir,
+		unsigned long attrs)
+{
+	return DMA_MAPPING_ERROR;
+}
+
+static int dma_dummy_map_sg(struct device *dev, struct scatterlist *sgl,
+		int nelems, enum dma_data_direction dir,
+		unsigned long attrs)
+{
+	return 0;
+}
+
+static int dma_dummy_supported(struct device *hwdev, u64 mask)
+{
+	return 0;
+}
+
+const struct dma_map_ops dma_dummy_ops = {
+	.mmap                   = dma_dummy_mmap,
+	.map_page               = dma_dummy_map_page,
+	.map_sg                 = dma_dummy_map_sg,
+	.dma_supported          = dma_dummy_supported,
+};
+EXPORT_SYMBOL(dma_dummy_ops);
-- 
2.19.1


  parent reply index

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-07 19:07 [RFC] avoid indirect calls for DMA direct mappings v2 Christoph Hellwig
2018-12-07 19:07 ` [PATCH 01/15] swiotlb: remove SWIOTLB_MAP_ERROR Christoph Hellwig
2018-12-07 19:07 ` [PATCH 02/15] swiotlb: remove dma_mark_clean Christoph Hellwig
2019-01-02 21:53   ` Tony Luck
2019-01-03  7:23     ` Christoph Hellwig
2019-01-03 17:35       ` Tony Luck
2019-01-04  8:09         ` Christoph Hellwig
2018-12-07 19:07 ` [PATCH 03/15] dma-direct: improve addressability error reporting Christoph Hellwig
2018-12-07 19:07 ` [PATCH 04/15] dma-direct: use dma_direct_map_page to implement dma_direct_map_sg Christoph Hellwig
2018-12-07 19:07 ` [PATCH 05/15] dma-direct: merge swiotlb_dma_ops into the dma_direct code Christoph Hellwig
2018-12-07 19:07 ` [PATCH 06/15] dma-mapping: simplify the dma_sync_single_range_for_{cpu,device} implementation Christoph Hellwig
2018-12-07 19:07 ` [PATCH 07/15] dma-mapping: merge dma_unmap_page_attrs and dma_unmap_single_attrs Christoph Hellwig
2018-12-07 19:07 ` [PATCH 08/15] dma-mapping: move dma_get_required_mask to kernel/dma Christoph Hellwig
2018-12-07 19:07 ` [PATCH 09/15] dma-mapping: move various slow path functions out of line Christoph Hellwig
2018-12-07 19:07 ` [PATCH 10/15] dma-mapping: move dma_cache_sync " Christoph Hellwig
2018-12-07 19:07 ` [PATCH 11/15] dma-mapping: always build the direct mapping code Christoph Hellwig
2018-12-07 19:07 ` Christoph Hellwig [this message]
2018-12-07 19:07 ` [PATCH 13/15] ACPI / scan: Refactor _CCA enforcement Christoph Hellwig
2018-12-14 21:15   ` Bjorn Helgaas
2018-12-07 19:07 ` [PATCH 14/15] vmd: use the proper dma_* APIs instead of direct methods calls Christoph Hellwig
2018-12-14 21:17   ` Bjorn Helgaas
2018-12-14 21:34     ` Derrick, Jonathan
2018-12-07 19:07 ` [PATCH 15/15] dma-mapping: bypass indirect calls for dma-direct Christoph Hellwig
2018-12-14 14:11   ` Marek Szyprowski
2018-12-14 14:24     ` Christoph Hellwig
2018-12-14 14:32       ` Marek Szyprowski
2018-12-15 17:46   ` [15/15] " Guenter Roeck
2018-12-16  9:02     ` Christoph Hellwig
2018-12-18 20:34   ` Guillaume Tucker
2018-12-18 20:42     ` Robin Murphy
2018-12-19  6:42       ` Christoph Hellwig
2018-12-20 16:44   ` [PATCH 15/15] " Thierry Reding
2018-12-20 16:46     ` Christoph Hellwig
2018-12-08 16:06 ` [RFC] avoid indirect calls for DMA direct mappings v2 Jesper Dangaard Brouer
2018-12-08 16:50   ` Christoph Hellwig
2018-12-10 21:51 ` Luck, Tony
2018-12-11  6:51   ` Christoph Hellwig
2018-12-11 16:42     ` Luck, Tony
2018-12-11 17:13     ` Luck, Tony
2018-12-11 17:15       ` Christoph Hellwig
2018-12-13 20:08 ` Christoph Hellwig

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