[RFC PATCH v2 07/11] dma-mapping: Add flags to dma_map_ops to indicate PCI P2PDMA support

Logan Gunthorpe
2021-03-11T23:48:40Z

Add a flags member to the dma_map_ops structure with one flag to
indicate support for PCI P2PDMA.

Also, add a helper to check if a device supports PCI P2PDMA.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
---
include/linux/dma-map-ops.h | 3 +++
include/linux/dma-mapping.h | 5 +++++
kernel/dma/mapping.c | 8 ++++++++
3 files changed, 16 insertions(+)

diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 51872e736e7b..481892822104 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -12,6 +12,9 @@
struct cma;

struct dma_map_ops {
+ unsigned int flags;
+#define DMA_F_PCI_P2PDMA_SUPPORTED (1 << 0)
+
void *(*alloc)(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp,
unsigned long attrs);
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 2a984cb4d1e0..a6bced004de8 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -138,6 +138,7 @@ int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
unsigned long attrs);
bool dma_can_mmap(struct device *dev);
int dma_supported(struct device *dev, u64 mask);
+int dma_pci_p2pdma_supported(struct device *dev);
int dma_set_mask(struct device *dev, u64 mask);
int dma_set_coherent_mask(struct device *dev, u64 mask);
u64 dma_get_required_mask(struct device *dev);
@@ -233,6 +234,10 @@ static inline int dma_supported(struct device *dev, u64 mask)
{
return 0;
}
+static inline int dma_pci_p2pdma_supported(struct device *dev)
+{
+ return 0;
+}
static inline int dma_set_mask(struct device *dev, u64 mask)
{
return -EIO;
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index adc1a83950be..cc1b97deb74d 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -540,6 +540,14 @@ int dma_supported(struct device *dev, u64 mask)
}
EXPORT_SYMBOL(dma_supported);

+int dma_pci_p2pdma_supported(struct device *dev)
+{
+ const struct dma_map_ops *ops = get_dma_ops(dev);
+
+ return !ops || ops->flags & DMA_F_PCI_P2PDMA_SUPPORTED;
+}
+EXPORT_SYMBOL(dma_pci_p2pdma_supported);
+
#ifdef CONFIG_ARCH_HAS_DMA_SET_MASK
void arch_dma_set_mask(struct device *dev, u64 mask);
#else
--
2.20.1