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From: Christoph Hellwig <hch@lst.de>
To: iommu@lists.linux-foundation.org,
	Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Takashi Iwai <tiwai@suse.de>, Robin Murphy <robin.murphy@arm.com>,
	Michal Simek <monstr@monstr.eu>,
	linux-arm-kernel@lists.infradead.org,
	linux-m68k@lists.linux-m68k.org, linux-parisc@vger.kernel.org,
	linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org,
	linuxppc-dev@lists.ozlabs.org, x86@kernel.org,
	linux-kernel@vger.kernel.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


  parent reply	other threads:[~2019-08-05  9:13 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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