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Subject[PATCH 02/20] dma-mapping: provide a generic dma-noncoherent implementation
Date
Add a new dma_map_ops implementation that uses dma-direct for the
address mapping of streaming mappings, and which requires arch-specific
implemenations of coherent allocate/free.

Architectures have to provide flushing helpers to ownership trasnfers
to the device and/or CPU, and can provide optional implementations of
the coherent mmap functionality, and the cache_flush routines for
non-coherent long term allocations.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
MAINTAINERS | 2 +
include/asm-generic/dma-mapping.h | 9 +++
include/linux/dma-direct.h | 7 ++-
include/linux/dma-mapping.h | 1 +
include/linux/dma-noncoherent.h | 47 ++++++++++++++
lib/Kconfig | 20 ++++++
lib/Makefile | 1 +
lib/dma-direct.c | 8 +--
lib/dma-noncoherent.c | 101 ++++++++++++++++++++++++++++++
9 files changed, 191 insertions(+), 5 deletions(-)
create mode 100644 include/linux/dma-noncoherent.h
create mode 100644 lib/dma-noncoherent.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 79bb02ff812f..08d0d15d4958 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4334,12 +4334,14 @@ W: http://git.infradead.org/users/hch/dma-mapping.git
S: Supported
F: lib/dma-debug.c
F: lib/dma-direct.c
+F: lib/dma-noncoherent.c
F: lib/dma-virt.c
F: drivers/base/dma-mapping.c
F: drivers/base/dma-coherent.c
F: include/asm-generic/dma-mapping.h
F: include/linux/dma-direct.h
F: include/linux/dma-mapping.h
+F: include/linux/dma-noncoherent.h

DME1737 HARDWARE MONITOR DRIVER
M: Juerg Haefliger <juergh@gmail.com>
diff --git a/include/asm-generic/dma-mapping.h b/include/asm-generic/dma-mapping.h
index 880a292d792f..ad2868263867 100644
--- a/include/asm-generic/dma-mapping.h
+++ b/include/asm-generic/dma-mapping.h
@@ -4,7 +4,16 @@

static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
{
+ /*
+ * Use the non-coherent ops if available. If an architecture wants a
+ * more fine-grained selection of operations it will have to implement
+ * get_arch_dma_ops itself or use the per-device dma_ops.
+ */
+#ifdef CONFIG_DMA_NONCOHERENT_OPS
+ return &dma_noncoherent_ops;
+#else
return &dma_direct_ops;
+#endif
}

#endif /* _ASM_GENERIC_DMA_MAPPING_H */
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index 53ad6a47f513..8d9f33febde5 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -59,6 +59,11 @@ void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
gfp_t gfp, unsigned long attrs);
void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,
dma_addr_t dma_addr, unsigned long attrs);
+dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
+ unsigned long offset, size_t size, enum dma_data_direction dir,
+ unsigned long attrs);
+int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
+ enum dma_data_direction dir, unsigned long attrs);
int dma_direct_supported(struct device *dev, u64 mask);
-
+int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr);
#endif /* _LINUX_DMA_DIRECT_H */
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 25a9a2b04f78..4be070df5fc5 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -136,6 +136,7 @@ struct dma_map_ops {
};

extern const struct dma_map_ops dma_direct_ops;
+extern const struct dma_map_ops dma_noncoherent_ops;
extern const struct dma_map_ops dma_virt_ops;

#define DMA_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
diff --git a/include/linux/dma-noncoherent.h b/include/linux/dma-noncoherent.h
new file mode 100644
index 000000000000..10b2654d549b
--- /dev/null
+++ b/include/linux/dma-noncoherent.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_DMA_NONCOHERENT_H
+#define _LINUX_DMA_NONCOHERENT_H 1
+
+#include <linux/dma-mapping.h>
+
+void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
+ gfp_t gfp, unsigned long attrs);
+void arch_dma_free(struct device *dev, size_t size, void *cpu_addr,
+ dma_addr_t dma_addr, unsigned long attrs);
+
+#ifdef CONFIG_DMA_NONCOHERENT_MMAP
+int arch_dma_mmap(struct device *dev, struct vm_area_struct *vma,
+ void *cpu_addr, dma_addr_t dma_addr, size_t size,
+ unsigned long attrs);
+#else
+#define arch_dma_mmap NULL
+#endif /* CONFIG_DMA_NONCOHERENT_MMAP */
+
+#ifdef CONFIG_DMA_NONCOHERENT_CACHE_SYNC
+void arch_dma_cache_sync(struct device *dev, void *vaddr, size_t size,
+ enum dma_data_direction direction);
+#else
+#define arch_dma_cache_sync NULL
+#endif /* CONFIG_DMA_NONCOHERENT_CACHE_SYNC */
+
+#ifdef CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE
+void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr,
+ size_t size, enum dma_data_direction dir);
+#else
+static inline void arch_sync_dma_for_device(struct device *dev,
+ phys_addr_t paddr, size_t size, enum dma_data_direction dir)
+{
+}
+#endif /* ARCH_HAS_SYNC_DMA_FOR_DEVICE */
+
+#ifdef CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU
+void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr,
+ size_t size, enum dma_data_direction dir);
+#else
+static inline void arch_sync_dma_for_cpu(struct device *dev,
+ phys_addr_t paddr, size_t size, enum dma_data_direction dir)
+{
+}
+#endif /* ARCH_HAS_SYNC_DMA_FOR_CPU */
+
+#endif /* _LINUX_DMA_NONCOHERENT_H */
diff --git a/lib/Kconfig b/lib/Kconfig
index 6c4e9d0ce5d1..7a913937888b 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -441,10 +441,30 @@ config ARCH_DMA_ADDR_T_64BIT
config IOMMU_HELPER
bool

+config ARCH_HAS_SYNC_DMA_FOR_DEVICE
+ bool
+
+config ARCH_HAS_SYNC_DMA_FOR_CPU
+ bool
+ select NEED_DMA_MAP_STATE
+
config DMA_DIRECT_OPS
bool
depends on HAS_DMA

+config DMA_NONCOHERENT_OPS
+ bool
+ depends on HAS_DMA
+ select DMA_DIRECT_OPS
+
+config DMA_NONCOHERENT_MMAP
+ bool
+ depends on DMA_NONCOHERENT_OPS
+
+config DMA_NONCOHERENT_CACHE_SYNC
+ bool
+ depends on DMA_NONCOHERENT_OPS
+
config DMA_VIRT_OPS
bool
depends on HAS_DMA
diff --git a/lib/Makefile b/lib/Makefile
index 94203b5eecd4..9f18c8152281 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -30,6 +30,7 @@ lib-$(CONFIG_PRINTK) += dump_stack.o
lib-$(CONFIG_MMU) += ioremap.o
lib-$(CONFIG_SMP) += cpumask.o
lib-$(CONFIG_DMA_DIRECT_OPS) += dma-direct.o
+lib-$(CONFIG_DMA_NONCOHERENT_OPS) += dma-noncoherent.o
lib-$(CONFIG_DMA_VIRT_OPS) += dma-virt.o

lib-y += kobject.o klist.o
diff --git a/lib/dma-direct.c b/lib/dma-direct.c
index df9e726e0712..b824eb218782 100644
--- a/lib/dma-direct.c
+++ b/lib/dma-direct.c
@@ -128,7 +128,7 @@ void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,
free_pages((unsigned long)cpu_addr, page_order);
}

-static dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
+dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size, enum dma_data_direction dir,
unsigned long attrs)
{
@@ -139,8 +139,8 @@ static dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
return dma_addr;
}

-static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
- int nents, enum dma_data_direction dir, unsigned long attrs)
+int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
+ enum dma_data_direction dir, unsigned long attrs)
{
int i;
struct scatterlist *sg;
@@ -175,7 +175,7 @@ int dma_direct_supported(struct device *dev, u64 mask)
return 1;
}

-static int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr)
+int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr)
{
return dma_addr == DIRECT_MAPPING_ERROR;
}
diff --git a/lib/dma-noncoherent.c b/lib/dma-noncoherent.c
new file mode 100644
index 000000000000..a2c192b3508d
--- /dev/null
+++ b/lib/dma-noncoherent.c
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Christoph Hellwig.
+ *
+ * DMA operations that map physical memory directly without providing cache
+ * coherence.
+ */
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/dma-direct.h>
+#include <linux/dma-noncoherent.h>
+#include <linux/scatterlist.h>
+
+static void dma_noncoherent_sync_single_for_device(struct device *dev,
+ dma_addr_t addr, size_t size, enum dma_data_direction dir)
+{
+ arch_sync_dma_for_device(dev, dma_to_phys(dev, addr), size, dir);
+}
+
+static void dma_noncoherent_sync_sg_for_device(struct device *dev,
+ struct scatterlist *sgl, int nents, enum dma_data_direction dir)
+{
+ struct scatterlist *sg;
+ int i;
+
+ for_each_sg(sgl, sg, nents, i)
+ arch_sync_dma_for_device(dev, sg_phys(sg), sg->length, dir);
+}
+
+static dma_addr_t dma_noncoherent_map_page(struct device *dev, struct page *page,
+ unsigned long offset, size_t size, enum dma_data_direction dir,
+ unsigned long attrs)
+{
+ dma_addr_t addr;
+
+ addr = dma_direct_map_page(dev, page, offset, size, dir, attrs);
+ if (!dma_mapping_error(dev, addr) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+ arch_sync_dma_for_device(dev, page_to_phys(page), size, dir);
+ return addr;
+}
+
+static int dma_noncoherent_map_sg(struct device *dev, struct scatterlist *sgl,
+ int nents, enum dma_data_direction dir, unsigned long attrs)
+{
+ nents = dma_direct_map_sg(dev, sgl, nents, dir, attrs);
+ if (nents > 0 && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+ dma_noncoherent_sync_sg_for_device(dev, sgl, nents, dir);
+ return nents;
+}
+
+#ifdef CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU
+static void dma_noncoherent_sync_single_for_cpu(struct device *dev,
+ dma_addr_t addr, size_t size, enum dma_data_direction dir)
+{
+ arch_sync_dma_for_cpu(dev, dma_to_phys(dev, addr), size, dir);
+}
+
+static void dma_noncoherent_sync_sg_for_cpu(struct device *dev,
+ struct scatterlist *sgl, int nents, enum dma_data_direction dir)
+{
+ struct scatterlist *sg;
+ int i;
+
+ for_each_sg(sgl, sg, nents, i)
+ arch_sync_dma_for_cpu(dev, sg_phys(sg), sg->length, dir);
+}
+
+static void dma_noncoherent_unmap_page(struct device *dev, dma_addr_t addr,
+ size_t size, enum dma_data_direction dir, unsigned long attrs)
+{
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+ dma_noncoherent_sync_single_for_cpu(dev, addr, size, dir);
+}
+
+static void dma_noncoherent_unmap_sg(struct device *dev, struct scatterlist *sgl,
+ int nents, enum dma_data_direction dir, unsigned long attrs)
+{
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+ dma_noncoherent_sync_sg_for_cpu(dev, sgl, nents, dir);
+}
+#endif
+
+const struct dma_map_ops dma_noncoherent_ops = {
+ .alloc = arch_dma_alloc,
+ .free = arch_dma_free,
+ .mmap = arch_dma_mmap,
+ .sync_single_for_device = dma_noncoherent_sync_single_for_device,
+ .sync_sg_for_device = dma_noncoherent_sync_sg_for_device,
+ .map_page = dma_noncoherent_map_page,
+ .map_sg = dma_noncoherent_map_sg,
+#ifdef CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU
+ .sync_single_for_cpu = dma_noncoherent_sync_single_for_cpu,
+ .sync_sg_for_cpu = dma_noncoherent_sync_sg_for_cpu,
+ .unmap_page = dma_noncoherent_unmap_page,
+ .unmap_sg = dma_noncoherent_unmap_sg,
+#endif
+ .dma_supported = dma_direct_supported,
+ .mapping_error = dma_direct_mapping_error,
+ .cache_sync = arch_dma_cache_sync,
+};
+EXPORT_SYMBOL(dma_noncoherent_ops);
--
2.17.0
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