[v2,3/5] ARM: dma-mapping: Implement arch_iommu_detach_device()

Message ID 20180425101051.15349-3-thierry.reding@gmail.com
State New
Headers show
Series
  • [v2,1/5] drm/nouveau: tegra: Detach from ARM DMA/IOMMU mapping
Related show

Commit Message

Thierry Reding April 25, 2018, 10:10 a.m.
From: Thierry Reding <treding@nvidia.com>

Implement this function to enable drivers from detaching from any IOMMU
domains that architecture code might have attached them to so that they
can take exclusive control of the IOMMU via the IOMMU API.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
Changes in v2:
- fix compilation

 arch/arm/include/asm/dma-mapping.h |  3 +++
 arch/arm/mm/dma-mapping-nommu.c    |  4 ++++
 arch/arm/mm/dma-mapping.c          | 17 +++++++++++++++++
 3 files changed, 24 insertions(+)

Comments

Christoph Hellwig April 25, 2018, 3:20 p.m. | #1
> +void arch_iommu_detach_device(struct device *dev)
> +{
> +#ifdef CONFIG_ARM_DMA_USE_IOMMU
> +	struct dma_iommu_mapping *mapping = to_dma_iommu_mapping(dev);
> +	const struct dma_map_ops *dma_ops;
> +
> +	if (!mapping)
> +		return;
> +
> +	arm_iommu_release_mapping(mapping);
> +	arm_iommu_detach_device(dev);
> +
> +	dma_ops = arm_get_dma_map_ops(dev->archdata.dma_coherent);
> +	set_dma_ops(dev, dma_ops);

Why not simply:

	set_dma_ops(dev, arm_get_dma_map_ops(dev->archdata.dma_coherent));
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Thierry Reding April 26, 2018, 12:14 p.m. | #2
On Wed, Apr 25, 2018 at 08:20:49AM -0700, Christoph Hellwig wrote:
> > +void arch_iommu_detach_device(struct device *dev)
> > +{
> > +#ifdef CONFIG_ARM_DMA_USE_IOMMU
> > +	struct dma_iommu_mapping *mapping = to_dma_iommu_mapping(dev);
> > +	const struct dma_map_ops *dma_ops;
> > +
> > +	if (!mapping)
> > +		return;
> > +
> > +	arm_iommu_release_mapping(mapping);
> > +	arm_iommu_detach_device(dev);
> > +
> > +	dma_ops = arm_get_dma_map_ops(dev->archdata.dma_coherent);
> > +	set_dma_ops(dev, dma_ops);
> 
> Why not simply:
> 
> 	set_dma_ops(dev, arm_get_dma_map_ops(dev->archdata.dma_coherent));

I had that initially, but it looked cluttered to me, so I split it up.
I don't care much either way, so I can revert to that if you prefer.

Thierry

Patch

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index 8436f6ade57d..d6d5bd44f962 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -103,6 +103,9 @@  extern void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 #define arch_teardown_dma_ops arch_teardown_dma_ops
 extern void arch_teardown_dma_ops(struct device *dev);
 
+#define arch_iommu_detach_device arch_iommu_detach_device
+extern void arch_iommu_detach_device(struct device *dev);
+
 /* do not use this function in a driver */
 static inline bool is_device_dma_coherent(struct device *dev)
 {
diff --git a/arch/arm/mm/dma-mapping-nommu.c b/arch/arm/mm/dma-mapping-nommu.c
index 619f24a42d09..60fef97d8452 100644
--- a/arch/arm/mm/dma-mapping-nommu.c
+++ b/arch/arm/mm/dma-mapping-nommu.c
@@ -242,6 +242,10 @@  void arch_teardown_dma_ops(struct device *dev)
 {
 }
 
+void arch_iommu_detach_device(struct device *dev)
+{
+}
+
 #define PREALLOC_DMA_DEBUG_ENTRIES	4096
 
 static int __init dma_debug_do_init(void)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 8c398fedbbb6..cc63a25bd088 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -2423,3 +2423,20 @@  void arch_teardown_dma_ops(struct device *dev)
 
 	arm_teardown_iommu_dma_ops(dev);
 }
+
+void arch_iommu_detach_device(struct device *dev)
+{
+#ifdef CONFIG_ARM_DMA_USE_IOMMU
+	struct dma_iommu_mapping *mapping = to_dma_iommu_mapping(dev);
+	const struct dma_map_ops *dma_ops;
+
+	if (!mapping)
+		return;
+
+	arm_iommu_release_mapping(mapping);
+	arm_iommu_detach_device(dev);
+
+	dma_ops = arm_get_dma_map_ops(dev->archdata.dma_coherent);
+	set_dma_ops(dev, dma_ops);
+#endif
+}