[PATCH v6 8/8] arm: dma-mapping: plumb our iommu mapping ops into arch_setup_dma_ops

Will Deacon
2014-12-01T16:57:14Z

This patch plumbs the existing ARM IOMMU DMA infrastructure (which isn't
actually called outside of a few drivers) into arch_setup_dma_ops, so
that we can use IOMMUs for DMA transfers in a more generic fashion.

Since this significantly complicates the arch_setup_dma_ops function,
it is moved out of line into dma-mapping.c. If CONFIG_ARM_DMA_USE_IOMMU
is not set, the iommu parameter is ignored and the normal ops are used
instead.

Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm/include/asm/dma-mapping.h | 12 +++---
arch/arm/mm/dma-mapping.c | 83 ++++++++++++++++++++++++++++++++++----
2 files changed, 81 insertions(+), 14 deletions(-)

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index f3c0d953f6a2..9410b7e548fc 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -121,14 +121,12 @@ static inline unsigned long dma_max_pfn(struct device *dev)
}
#define dma_max_pfn(dev) dma_max_pfn(dev)

-static inline void arch_setup_dma_ops(struct device *dev, u64 dma_base,
- u64 size, struct iommu_ops *iommu,
- bool coherent)
-{
- if (coherent)
- set_dma_ops(dev, &arm_coherent_dma_ops);
-}
#define arch_setup_dma_ops arch_setup_dma_ops
+extern void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
+ struct iommu_ops *iommu, bool coherent);
+
+#define arch_teardown_dma_ops arch_teardown_dma_ops
+extern void arch_teardown_dma_ops(struct device *dev);

static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
{
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index e8907117861e..09645f00bd17 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1947,9 +1947,8 @@ EXPORT_SYMBOL_GPL(arm_iommu_release_mapping);
* arm_iommu_create_mapping)
*
* Attaches specified io address space mapping to the provided device,
- * this replaces the dma operations (dma_map_ops pointer) with the
- * IOMMU aware version. More than one client might be attached to
- * the same io address space mapping.
+ * More than one client might be attached to the same io address space
+ * mapping.
*/
int arm_iommu_attach_device(struct device *dev,
struct dma_iommu_mapping *mapping)
@@ -1962,7 +1961,6 @@ int arm_iommu_attach_device(struct device *dev,

kref_get(&mapping->kref);
dev->archdata.mapping = mapping;
- set_dma_ops(dev, &iommu_ops);

pr_debug("Attached IOMMU controller to %s device.\n", dev_name(dev));
return 0;
@@ -1974,7 +1972,6 @@ EXPORT_SYMBOL_GPL(arm_iommu_attach_device);
* @dev: valid struct device pointer
*
* Detaches the provided device from a previously attached map.
- * This voids the dma operations (dma_map_ops pointer)
*/
void arm_iommu_detach_device(struct device *dev)
{
@@ -1989,10 +1986,82 @@ void arm_iommu_detach_device(struct device *dev)
iommu_detach_device(mapping->domain, dev);
kref_put(&mapping->kref, release_iommu_mapping);
dev->archdata.mapping = NULL;
- set_dma_ops(dev, NULL);

pr_debug("Detached IOMMU controller from %s device.\n", dev_name(dev));
}
EXPORT_SYMBOL_GPL(arm_iommu_detach_device);

-#endif
+static struct dma_map_ops *arm_get_iommu_dma_map_ops(bool coherent)
+{
+ return coherent ? &iommu_coherent_ops : &iommu_ops;
+}
+
+static bool arm_setup_iommu_dma_ops(struct device *dev, u64 dma_base, u64 size,
+ struct iommu_ops *iommu)
+{
+ struct dma_iommu_mapping *mapping;
+
+ if (!iommu)
+ return false;
+
+ mapping = arm_iommu_create_mapping(dev->bus, dma_base, size);
+ if (IS_ERR(mapping)) {
+ pr_warn("Failed to create %llu-byte IOMMU mapping for device %s\n",
+ size, dev_name(dev));
+ return false;
+ }
+
+ if (arm_iommu_attach_device(dev, mapping)) {
+ pr_warn("Failed to attached device %s to IOMMU_mapping\n",
+ dev_name(dev));
+ arm_iommu_release_mapping(mapping);
+ return false;
+ }
+
+ return true;
+}
+
+static void arm_teardown_iommu_dma_ops(struct device *dev)
+{
+ struct dma_iommu_mapping *mapping = dev->archdata.mapping;
+
+ arm_iommu_detach_device(dev);
+ arm_iommu_release_mapping(mapping);
+}
+
+#else
+
+static bool arm_setup_iommu_dma_ops(struct device *dev, u64 dma_base, u64 size,
+ struct iommu_ops *iommu)
+{
+ return false;
+}
+
+static void arm_teardown_iommu_dma_ops(struct device *dev) { }
+
+#define arm_get_iommu_dma_map_ops arm_get_dma_map_ops
+
+#endif /* CONFIG_ARM_DMA_USE_IOMMU */
+
+static struct dma_map_ops *arm_get_dma_map_ops(bool coherent)
+{
+ return coherent ? &arm_coherent_dma_ops : &arm_dma_ops;
+}
+
+void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
+ struct iommu_ops *iommu, bool coherent)
+{
+ struct dma_map_ops *dma_ops;
+
+ if (arm_setup_iommu_dma_ops(dev, dma_base, size, iommu))
+ dma_ops = arm_get_iommu_dma_map_ops(coherent);
+ else
+ dma_ops = arm_get_dma_map_ops(coherent);
+
+ set_dma_ops(dev, dma_ops);
+}
+
+void arch_teardown_dma_ops(struct device *dev)
+{
+ arm_teardown_iommu_dma_ops(dev);
+}
--
2.1.1