diff mbox

[V2,2/5] arm64 : Introduce support for ACPI _CCA object

Message ID 1430838729-21572-3-git-send-email-Suravee.Suthikulpanit@amd.com
State Not Applicable, archived
Delegated to: David Miller
Headers show

Commit Message

Suravee Suthikulpanit May 5, 2015, 3:12 p.m. UTC 
From http://www.uefi.org/sites/default/files/resources/ACPI_6.0.pdf,
section 6.2.17 _CCA states that ARM platforms require ACPI _CCA
object to be specified for DMA-cabpable devices. This patch introduces
ACPI_MUST_HAVE_CCA in arm64 Kconfig to specify such requirement.

In this case of missing _CCA, arm64 would assign dummy_dma_ops
to disable DMA capability of the device.

Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
---
 arch/arm64/Kconfig                   |   2 +
 arch/arm64/include/asm/dma-mapping.h |  18 +++++-
 arch/arm64/mm/dma-mapping.c          | 104 +++++++++++++++++++++++++++++++++++
 3 files changed, 122 insertions(+), 2 deletions(-)

Comments

Robin Murphy May 6, 2015, 10:08 a.m. UTC | #1 
Hi Suravee,

On 05/05/15 16:12, Suravee Suthikulpanit wrote:
>  From http://www.uefi.org/sites/default/files/resources/ACPI_6.0.pdf,
> section 6.2.17 _CCA states that ARM platforms require ACPI _CCA
> object to be specified for DMA-cabpable devices. This patch introduces
> ACPI_MUST_HAVE_CCA in arm64 Kconfig to specify such requirement.
>
> In this case of missing _CCA, arm64 would assign dummy_dma_ops
> to disable DMA capability of the device.
>
> Signed-off-by: Mark Salter <msalter@redhat.com>
> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
> ---

[...]
> +static void __dummy_sync_single_for_cpu(struct device *dev,
> +					dma_addr_t dev_addr, size_t size,
> +					enum dma_data_direction dir)
> +{
> +}
> +
> +static void __dummy_sync_single_for_device(struct device *dev,
> +					   dma_addr_t dev_addr, size_t size,
> +					   enum dma_data_direction dir)
> +{
> +}

Minor point, but I don't see the need to have multiple dummy functions 
with identical signatures - just have a generic dummy_sync_single and 
assign it to both ops.

> +static void __dummy_sync_sg_for_cpu(struct device *dev,
> +				    struct scatterlist *sgl, int nelems,
> +				    enum dma_data_direction dir)
> +{
> +}
> +
> +static void __dummy_sync_sg_for_device(struct device *dev,
> +				       struct scatterlist *sgl, int nelems,
> +				       enum dma_data_direction dir)
> +{
> +}

Ditto here with dummy_sync_sg.

I wonder if there's any argument for putting the dummy DMA ops somewhere 
common, like drivers/base/dma-mapping.c?

Robin.

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Suravee Suthikulpanit May 6, 2015, 2:34 p.m. UTC | #2 
On 5/6/2015 5:08 AM, Robin Murphy wrote:
> [...]
>> +static void __dummy_sync_single_for_cpu(struct device *dev,
>> +                    dma_addr_t dev_addr, size_t size,
>> +                    enum dma_data_direction dir)
>> +{
>> +}
>> +
>> +static void __dummy_sync_single_for_device(struct device *dev,
>> +                       dma_addr_t dev_addr, size_t size,
>> +                       enum dma_data_direction dir)
>> +{
>> +}
>
> Minor point, but I don't see the need to have multiple dummy functions
> with identical signatures - just have a generic dummy_sync_single and
> assign it to both ops.
>
>> +static void __dummy_sync_sg_for_cpu(struct device *dev,
>> +                    struct scatterlist *sgl, int nelems,
>> +                    enum dma_data_direction dir)
>> +{
>> +}
>> +
>> +static void __dummy_sync_sg_for_device(struct device *dev,
>> +                       struct scatterlist *sgl, int nelems,
>> +                       enum dma_data_direction dir)
>> +{
>> +}
>
> Ditto here with dummy_sync_sg.

Hi Robin,

Good point. I'll take care of that in V3.

>
> I wonder if there's any argument for putting the dummy DMA ops somewhere
> common, like drivers/base/dma-mapping.c?
>
> Robin.

Hm.. If this approach will be adopted by other architectures, then it 
would make sense. Currently, this is only used by arm64. So, I think it 
is okay to leave this here for now.

Thanks,
Suravee

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diff mbox

Patch

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 4269dba..4f4bbaaf 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1,7 +1,9 @@ 
 config ARM64
 	def_bool y
 	select ACPI_GENERIC_GSI if ACPI
+	select ACPI_MUST_HAVE_CCA if ACPI
 	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
+	select ACPI_SUPPORT_CCA_ZERO if ACPI
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_GCOV_PROFILE_ALL
diff --git a/arch/arm64/include/asm/dma-mapping.h b/arch/arm64/include/asm/dma-mapping.h
index 9437e3d..f0d6d0b 100644
--- a/arch/arm64/include/asm/dma-mapping.h
+++ b/arch/arm64/include/asm/dma-mapping.h
@@ -18,6 +18,7 @@ 
 
 #ifdef __KERNEL__
 
+#include <linux/acpi.h>
 #include <linux/types.h>
 #include <linux/vmalloc.h>
 
@@ -28,13 +29,23 @@ 
 
 #define DMA_ERROR_CODE	(~(dma_addr_t)0)
 extern struct dma_map_ops *dma_ops;
+extern struct dma_map_ops dummy_dma_ops;
 
 static inline struct dma_map_ops *__generic_dma_ops(struct device *dev)
 {
-	if (unlikely(!dev) || !dev->archdata.dma_ops)
+	if (unlikely(!dev))
 		return dma_ops;
-	else
+	else if (dev->archdata.dma_ops)
 		return dev->archdata.dma_ops;
+	else if (acpi_disabled)
+		return dma_ops;
+
+	/*
+	 * When ACPI is enabled, if arch_set_dma_ops is not called,
+	 * we will disable device DMA capability by setting it
+	 * to dummy_dma_ops.
+	 */
+	return &dummy_dma_ops;
 }
 
 static inline struct dma_map_ops *get_dma_ops(struct device *dev)
@@ -48,6 +59,9 @@  static inline struct dma_map_ops *get_dma_ops(struct device *dev)
 static inline void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 				      struct iommu_ops *iommu, bool coherent)
 {
+	if (!acpi_disabled && !dev->archdata.dma_ops)
+		dev->archdata.dma_ops = dma_ops;
+
 	dev->archdata.dma_coherent = coherent;
 }
 #define arch_setup_dma_ops	arch_setup_dma_ops
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index ef7d112..31d2b52 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -415,6 +415,110 @@  out:
 	return -ENOMEM;
 }
 
+/********************************************
+ * 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,
+			   struct dma_attrs *attrs)
+{
+	return NULL;
+}
+
+static void __dummy_free(struct device *dev, size_t size,
+			 void *vaddr, dma_addr_t dma_handle,
+			 struct dma_attrs *attrs)
+{
+}
+
+static int __dummy_mmap(struct device *dev,
+			struct vm_area_struct *vma,
+			void *cpu_addr, dma_addr_t dma_addr, size_t size,
+			struct dma_attrs *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,
+				   struct dma_attrs *attrs)
+{
+	return DMA_ERROR_CODE;
+}
+
+static void __dummy_unmap_page(struct device *dev, dma_addr_t dev_addr,
+			       size_t size, enum dma_data_direction dir,
+			       struct dma_attrs *attrs)
+{
+}
+
+static int __dummy_map_sg(struct device *dev, struct scatterlist *sgl,
+			  int nelems, enum dma_data_direction dir,
+			  struct dma_attrs *attrs)
+{
+	return 0;
+}
+
+static void __dummy_unmap_sg(struct device *dev,
+			     struct scatterlist *sgl, int nelems,
+			     enum dma_data_direction dir,
+			     struct dma_attrs *attrs)
+{
+}
+
+static void __dummy_sync_single_for_cpu(struct device *dev,
+					dma_addr_t dev_addr, size_t size,
+					enum dma_data_direction dir)
+{
+}
+
+static void __dummy_sync_single_for_device(struct device *dev,
+					   dma_addr_t dev_addr, size_t size,
+					   enum dma_data_direction dir)
+{
+}
+
+static void __dummy_sync_sg_for_cpu(struct device *dev,
+				    struct scatterlist *sgl, int nelems,
+				    enum dma_data_direction dir)
+{
+}
+
+static void __dummy_sync_sg_for_device(struct device *dev,
+				       struct scatterlist *sgl, int nelems,
+				       enum dma_data_direction dir)
+{
+}
+
+static int __dummy_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
+{
+	return 1;
+}
+
+static int __dummy_dma_supported(struct device *hwdev, u64 mask)
+{
+	return 0;
+}
+
+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_for_cpu,
+	.sync_single_for_device = __dummy_sync_single_for_device,
+	.sync_sg_for_cpu        = __dummy_sync_sg_for_cpu,
+	.sync_sg_for_device     = __dummy_sync_sg_for_device,
+	.mapping_error          = __dummy_mapping_error,
+	.dma_supported          = __dummy_dma_supported,
+};
+EXPORT_SYMBOL(dummy_dma_ops);
+
 static int __init arm64_dma_init(void)
 {
 	int ret;