From: Christoph Hellwig <hch@lst.de>
To: iommu@lists.linux-foundation.org,
Marek Szyprowski <m.szyprowski@samsung.com>
Cc: linux-xtensa@linux-xtensa.org, Michal Simek <monstr@monstr.eu>,
linux-parisc@vger.kernel.org, linux-sh@vger.kernel.org,
Takashi Iwai <tiwai@suse.de>,
linuxppc-dev@lists.ozlabs.org, x86@kernel.org,
linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
Robin Murphy <robin.murphy@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/7] dma-mapping: add a dma_can_mmap helper
Date: Mon, 5 Aug 2019 12:11:55 +0300 [thread overview]
Message-ID: <20190805091159.7826-4-hch@lst.de> (raw)
In-Reply-To: <20190805091159.7826-1-hch@lst.de>
Add a helper to check if DMA allocations for a specific device can be
mapped to userspace using dma_mmap_*.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
include/linux/dma-mapping.h | 5 +++++
kernel/dma/mapping.c | 23 +++++++++++++++++++++++
2 files changed, 28 insertions(+)
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index f7d1eea32c78..17271857be5d 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -462,6 +462,7 @@ int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt,
int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size,
unsigned long attrs);
+bool dma_can_mmap(struct device *dev);
int dma_supported(struct device *dev, u64 mask);
int dma_set_mask(struct device *dev, u64 mask);
int dma_set_coherent_mask(struct device *dev, u64 mask);
@@ -552,6 +553,10 @@ static inline int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
{
return -ENXIO;
}
+static inline bool dma_can_mmap(struct device *dev)
+{
+ return false;
+}
static inline int dma_supported(struct device *dev, u64 mask)
{
return 0;
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index cdb157cd70e7..ab6aa355e1a0 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -203,6 +203,29 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
#endif /* !CONFIG_ARCH_NO_COHERENT_DMA_MMAP */
}
+/**
+ * dma_can_mmap - check if a given device supports dma_mmap_*
+ * @dev: device to check
+ *
+ * Returns %true if @dev supports dma_mmap_coherent() and dma_mmap_attrs() to
+ * map DMA allocations to userspace.
+ */
+bool dma_can_mmap(struct device *dev)
+{
+ const struct dma_map_ops *ops = get_dma_ops(dev);
+
+ if (IS_ENABLED(CONFIG_ARCH_NO_COHERENT_DMA_MMAP))
+ return false;
+
+ if (dma_is_direct(ops)) {
+ return dev_is_dma_coherent(dev) ||
+ IS_ENABLED(CONFIG_ARCH_HAS_DMA_COHERENT_TO_PFN);
+ }
+
+ return ops->mmap != NULL;
+}
+EXPORT_SYMBOL_GPL(dma_can_mmap);
+
/**
* dma_mmap_attrs - map a coherent DMA allocation into user space
* @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
--
2.20.1
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next prev parent reply other threads:[~2019-08-05 9:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-05 9:11 remove default fallbacks in dma_map_ops v2 Christoph Hellwig
2019-08-05 9:11 ` [PATCH 1/7] dma-mapping: move the dma_get_sgtable API comments from arm to common code Christoph Hellwig
2019-08-05 9:11 ` [PATCH 2/7] dma-mapping: explicitly wire up ->mmap and ->get_sgtable Christoph Hellwig
2019-08-05 9:11 ` Christoph Hellwig [this message]
2019-08-05 9:11 ` [PATCH 4/7] ALSA: pcm: use dma_can_mmap() to check if a device supports dma_mmap_* Christoph Hellwig
2019-08-05 9:22 ` Takashi Iwai
2019-08-06 5:29 ` Christoph Hellwig
2019-08-06 6:00 ` Takashi Iwai
2019-08-05 9:11 ` [PATCH 5/7] m68knommu: add a pgprot_noncached stub Christoph Hellwig
2019-08-05 9:11 ` [PATCH 6/7] dma-mapping: remove ARCH_NO_COHERENT_DMA_MMAP Christoph Hellwig
2019-08-05 9:11 ` [PATCH 7/7] dma-mapping: provide a better default ->get_required_mask Christoph Hellwig
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