refactor dma_cache_sync

refactor dma_cache_sync

[Christoph Hellwig]

The dma_cache_sync routines is used to flush caches for memory returned
by dma_alloc_attrs with the DMA_ATTR_NON_CONSISTENT flag (or previously
from dma_alloc_noncoherent), but the requirements for it seems to be
frequently misunderstood.  dma_cache_sync is documented to be a no-op for
allocations that do not have the DMA_ATTR_NON_CONSISTENT flag set, and
yet a lot of architectures implement it in some way despite not
implementing DMA_ATTR_NON_CONSISTENT.

This series removes a few abuses of dma_cache_sync for non-DMA API
purposes, then changes all remaining architectures that do not implement
DMA_ATTR_NON_CONSISTENT to implement dma_cache_sync as a no-op, and
then adds the struct dma_map_ops indirection we use for all other
DMA mapping operations to dma_cache_sync as well, thus removing all but
two implementations of the function.

[PATCH 03/12] frv: make dma_cache_sync a no-op

[Christoph Hellwig]

frv does not implement DMA_ATTR_NON_CONSISTENT allocations, so it doesn't
make any sense to do any work in dma_cache_sync given that it must be a
no-op when dma_alloc_attrs returns coherent memory.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/frv/include/asm/dma-mapping.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/frv/include/asm/dma-mapping.h b/arch/frv/include/asm/dma-mapping.h
index 354900917585..da0e5c9744c4 100644
--- a/arch/frv/include/asm/dma-mapping.h
+++ b/arch/frv/include/asm/dma-mapping.h
@@ -18,7 +18,6 @@ static inline
 void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
 		    enum dma_data_direction direction)
 {
-	flush_write_buffers();
 }
 
 #endif  /* _ASM_DMA_MAPPING_H */
-- 
2.11.0

[PATCH 07/12] mn10300: make dma_cache_sync a no-op

[Christoph Hellwig]

mn10300 does not implement DMA_ATTR_NON_CONSISTENT allocations, so it
doesn't make any sense to do any work in dma_cache_sync given that it must
be a no-op when dma_alloc_attrs returns coherent memory.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/mn10300/include/asm/dma-mapping.h | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/mn10300/include/asm/dma-mapping.h b/arch/mn10300/include/asm/dma-mapping.h
index 737ef574b3ea..dc24163b190f 100644
--- a/arch/mn10300/include/asm/dma-mapping.h
+++ b/arch/mn10300/include/asm/dma-mapping.h
@@ -11,9 +11,6 @@
 #ifndef _ASM_DMA_MAPPING_H
 #define _ASM_DMA_MAPPING_H
 
-#include <asm/cache.h>
-#include <asm/io.h>
-
 extern const struct dma_map_ops mn10300_dma_ops;
 
 static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
@@ -25,7 +22,6 @@ static inline
 void dma_cache_sync(void *vaddr, size_t size,
 		    enum dma_data_direction direction)
 {
-	mn10300_dcache_flush_inv();
 }
 
 #endif
-- 
2.11.0

[PATCH 09/12] unicore32: make dma_cache_sync a no-op

[Christoph Hellwig]

unicore32 does not implement DMA_ATTR_NON_CONSISTENT allocations, so it
doesn't make any sense to do any work in dma_cache_sync given that it
must be a no-op when dma_alloc_attrs returns coherent memory.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/unicore32/include/asm/cacheflush.h  |  9 ---------
 arch/unicore32/include/asm/dma-mapping.h | 17 -----------------
 arch/unicore32/mm/proc-syms.c            |  3 ---
 3 files changed, 29 deletions(-)

diff --git a/arch/unicore32/include/asm/cacheflush.h b/arch/unicore32/include/asm/cacheflush.h
index c0301e6c8b81..a5e08e2d5d6d 100644
--- a/arch/unicore32/include/asm/cacheflush.h
+++ b/arch/unicore32/include/asm/cacheflush.h
@@ -102,15 +102,6 @@ extern void __cpuc_flush_dcache_area(void *, size_t);
 extern void __cpuc_flush_kern_dcache_area(void *addr, size_t size);
 
 /*
- * These are private to the dma-mapping API.  Do not use directly.
- * Their sole purpose is to ensure that data held in the cache
- * is visible to DMA, or data written by DMA to system memory is
- * visible to the CPU.
- */
-extern void __cpuc_dma_clean_range(unsigned long, unsigned long);
-extern void __cpuc_dma_flush_range(unsigned long, unsigned long);
-
-/*
  * Copy user data from/to a page which is mapped into a different
  * processes address space.  Really, we want to allow our "user
  * space" model to handle this.
diff --git a/arch/unicore32/include/asm/dma-mapping.h b/arch/unicore32/include/asm/dma-mapping.h
index 518ba5848dd6..e949855bb794 100644
--- a/arch/unicore32/include/asm/dma-mapping.h
+++ b/arch/unicore32/include/asm/dma-mapping.h
@@ -18,9 +18,6 @@
 #include <linux/scatterlist.h>
 #include <linux/swiotlb.h>
 
-#include <asm/memory.h>
-#include <asm/cacheflush.h>
-
 extern const struct dma_map_ops swiotlb_dma_map_ops;
 
 static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
@@ -51,20 +48,6 @@ static inline void dma_mark_clean(void *addr, size_t size) {}
 static inline void dma_cache_sync(struct device *dev, void *vaddr,
 		size_t size, enum dma_data_direction direction)
 {
-	unsigned long start = (unsigned long)vaddr;
-	unsigned long end   = start + size;
-
-	switch (direction) {
-	case DMA_NONE:
-		BUG();
-	case DMA_FROM_DEVICE:
-	case DMA_BIDIRECTIONAL:	/* writeback and invalidate */
-		__cpuc_dma_flush_range(start, end);
-		break;
-	case DMA_TO_DEVICE:		/* writeback only */
-		__cpuc_dma_clean_range(start, end);
-		break;
-	}
 }
 
 #endif /* __KERNEL__ */
diff --git a/arch/unicore32/mm/proc-syms.c b/arch/unicore32/mm/proc-syms.c
index 21c00fc85c99..df215fd6d639 100644
--- a/arch/unicore32/mm/proc-syms.c
+++ b/arch/unicore32/mm/proc-syms.c
@@ -20,6 +20,3 @@ EXPORT_SYMBOL(cpu_dcache_clean_area);
 EXPORT_SYMBOL(cpu_set_pte);
 
 EXPORT_SYMBOL(__cpuc_coherent_kern_range);
-
-EXPORT_SYMBOL(__cpuc_dma_flush_range);
-EXPORT_SYMBOL(__cpuc_dma_clean_range);
-- 
2.11.0

[PATCH 01/12] floppy: consolidate the dummy fd_cacheflush definition

[Christoph Hellwig]

Only mips defines this helper, so remove all the other arch definitions.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/alpha/include/asm/floppy.h    | 2 --
 arch/powerpc/include/asm/floppy.h  | 2 --
 arch/sparc/include/asm/floppy_32.h | 1 -
 arch/sparc/include/asm/floppy_64.h | 1 -
 drivers/block/floppy.c             | 4 ++++
 5 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/arch/alpha/include/asm/floppy.h b/arch/alpha/include/asm/floppy.h
index bae97eb19d26..942924756cf2 100644
--- a/arch/alpha/include/asm/floppy.h
+++ b/arch/alpha/include/asm/floppy.h
@@ -24,7 +24,6 @@
 #define fd_set_dma_count(count) set_dma_count(FLOPPY_DMA,count)
 #define fd_enable_irq()         enable_irq(FLOPPY_IRQ)
 #define fd_disable_irq()        disable_irq(FLOPPY_IRQ)
-#define fd_cacheflush(addr,size) /* nothing */
 #define fd_request_irq()        request_irq(FLOPPY_IRQ, floppy_interrupt,\
 					    0, "floppy", NULL)
 #define fd_free_irq()           free_irq(FLOPPY_IRQ, NULL)
@@ -62,7 +61,6 @@ alpha_fd_dma_setup(char *addr, unsigned long size, int mode, int io)
 	prev_dir = dir;
 
 	fd_clear_dma_ff();
-	fd_cacheflush(addr, size);
 	fd_set_dma_mode(mode);
 	set_dma_addr(FLOPPY_DMA, bus_addr);
 	fd_set_dma_count(size);
diff --git a/arch/powerpc/include/asm/floppy.h b/arch/powerpc/include/asm/floppy.h
index 936a904ae78c..167c44b58848 100644
--- a/arch/powerpc/include/asm/floppy.h
+++ b/arch/powerpc/include/asm/floppy.h
@@ -25,7 +25,6 @@
 #define fd_get_dma_residue()    fd_ops->_get_dma_residue(FLOPPY_DMA)
 #define fd_enable_irq()         enable_irq(FLOPPY_IRQ)
 #define fd_disable_irq()        disable_irq(FLOPPY_IRQ)
-#define fd_cacheflush(addr,size) /* nothing */
 #define fd_free_irq()           free_irq(FLOPPY_IRQ, NULL);
 
 #include <linux/pci.h>
@@ -152,7 +151,6 @@ static int hard_dma_setup(char *addr, unsigned long size, int mode, int io)
 	prev_dir = dir;
 
 	fd_clear_dma_ff();
-	fd_cacheflush(addr, size);
 	fd_set_dma_mode(mode);
 	set_dma_addr(FLOPPY_DMA, bus_addr);
 	fd_set_dma_count(size);
diff --git a/arch/sparc/include/asm/floppy_32.h b/arch/sparc/include/asm/floppy_32.h
index 071b83e52f15..dab58525229e 100644
--- a/arch/sparc/include/asm/floppy_32.h
+++ b/arch/sparc/include/asm/floppy_32.h
@@ -70,7 +70,6 @@ static struct sun_floppy_ops sun_fdops;
 #define fd_set_dma_count(count)   sun_fd_set_dma_count(count)
 #define fd_enable_irq()           /* nothing... */
 #define fd_disable_irq()          /* nothing... */
-#define fd_cacheflush(addr, size) /* nothing... */
 #define fd_request_irq()          sun_fd_request_irq()
 #define fd_free_irq()             /* nothing... */
 #if 0  /* P3: added by Alain, these cause a MMU corruption. 19960524 XXX */
diff --git a/arch/sparc/include/asm/floppy_64.h b/arch/sparc/include/asm/floppy_64.h
index 625756406a7e..a1db35a22c99 100644
--- a/arch/sparc/include/asm/floppy_64.h
+++ b/arch/sparc/include/asm/floppy_64.h
@@ -72,7 +72,6 @@ static struct sun_floppy_ops sun_fdops;
 #define fd_set_dma_addr(addr)     sun_fdops.fd_set_dma_addr(addr)
 #define fd_set_dma_count(count)   sun_fdops.fd_set_dma_count(count)
 #define get_dma_residue(x)        sun_fdops.get_dma_residue()
-#define fd_cacheflush(addr, size) /* nothing... */
 #define fd_request_irq()          sun_fdops.fd_request_irq()
 #define fd_free_irq()             sun_fdops.fd_free_irq()
 #define fd_eject(drive)           sun_fdops.fd_eject(drive)
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 9c00f29e40c1..b1d896f9a227 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -275,6 +275,10 @@ static int set_next_request(void);
 #define fd_dma_mem_alloc(size) __get_dma_pages(GFP_KERNEL, get_order(size))
 #endif
 
+#ifndef fd_cacheflush
+#define fd_cacheflush(addr, size) /* nothing... */
+#endif
+
 static inline void fallback_on_nodma_alloc(char **addr, size_t l)
 {
 #ifdef FLOPPY_CAN_FALLBACK_ON_NODMA
-- 
2.11.0

[PATCH 02/12] mips: don't use dma_cache_sync to implement fd_cacheflush

[Christoph Hellwig]

The floppy drivers doesn't otherwise use the DMA API, so indirecting
through it just for cache flushing in MIPS-specific code just call
dma_cache_wback_inv directly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/mips/include/asm/floppy.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/mips/include/asm/floppy.h b/arch/mips/include/asm/floppy.h
index d75aed36480a..021d09ae5670 100644
--- a/arch/mips/include/asm/floppy.h
+++ b/arch/mips/include/asm/floppy.h
@@ -10,11 +10,11 @@
 #ifndef _ASM_FLOPPY_H
 #define _ASM_FLOPPY_H
 
-#include <linux/dma-mapping.h>
+#include <asm/io.h>
 
 static inline void fd_cacheflush(char * addr, long size)
 {
-	dma_cache_sync(NULL, addr, size, DMA_BIDIRECTIONAL);
+	dma_cache_wback_inv((unsigned long)addr, size);
 }
 
 #define MAX_BUFFER_SECTORS 24
-- 
2.11.0

[PATCH 04/12] x86: make dma_cache_sync a no-op

[Christoph Hellwig]

x86 does not implement DMA_ATTR_NON_CONSISTENT allocations, so it doesn't
make any sense to do any work in dma_cache_sync given that it must be a
no-op when dma_alloc_attrs returns coherent memory.

Signed-off-by: Christoph Hellwig <hch@lst.de
---
 arch/x86/include/asm/dma-mapping.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/asm/dma-mapping.h
index 398c79889f5c..04877267ad18 100644
--- a/arch/x86/include/asm/dma-mapping.h
+++ b/arch/x86/include/asm/dma-mapping.h
@@ -70,7 +70,6 @@ static inline void
 dma_cache_sync(struct device *dev, void *vaddr, size_t size,
 	enum dma_data_direction dir)
 {
-	flush_write_buffers();
 }
 
 static inline unsigned long dma_alloc_coherent_mask(struct device *dev,
-- 
2.11.0

Re: [PATCH 04/12] x86: make dma_cache_sync a no-op

[Thomas Gleixner]

On Sun, 27 Aug 2017, Christoph Hellwig wrote:

> x86 does not implement DMA_ATTR_NON_CONSISTENT allocations, so it doesn't
> make any sense to do any work in dma_cache_sync given that it must be a
> no-op when dma_alloc_attrs returns coherent memory.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

> ---
>  arch/x86/include/asm/dma-mapping.h | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/asm/dma-mapping.h
> index 398c79889f5c..04877267ad18 100644
> --- a/arch/x86/include/asm/dma-mapping.h
> +++ b/arch/x86/include/asm/dma-mapping.h
> @@ -70,7 +70,6 @@ static inline void
>  dma_cache_sync(struct device *dev, void *vaddr, size_t size,
>  	enum dma_data_direction dir)
>  {
> -	flush_write_buffers();
>  }
>  
>  static inline unsigned long dma_alloc_coherent_mask(struct device *dev,
> -- 
> 2.11.0
> 
> 

[PATCH 05/12] ia64: make dma_cache_sync a no-op

[Christoph Hellwig]

ia64 does not implement DMA_ATTR_NON_CONSISTENT allocations, so it doesn't
make any sense to do any work in dma_cache_sync given that it must be a
no-op when dma_alloc_attrs returns coherent memory.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/ia64/include/asm/dma-mapping.h | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/arch/ia64/include/asm/dma-mapping.h b/arch/ia64/include/asm/dma-mapping.h
index 3ce5ab4339f3..99dfc1aa9d3c 100644
--- a/arch/ia64/include/asm/dma-mapping.h
+++ b/arch/ia64/include/asm/dma-mapping.h
@@ -48,11 +48,6 @@ static inline void
 dma_cache_sync (struct device *dev, void *vaddr, size_t size,
 	enum dma_data_direction dir)
 {
-	/*
-	 * IA-64 is cache-coherent, so this is mostly a no-op.  However, we do need to
-	 * ensure that dma_cache_sync() enforces order, hence the mb().
-	 */
-	mb();
 }
 
 #endif /* _ASM_IA64_DMA_MAPPING_H */
-- 
2.11.0

[PATCH 06/12] microblaze: make dma_cache_sync a no-op

[Christoph Hellwig]

microblaze does not implement DMA_ATTR_NON_CONSISTENT allocations, so it
doesn't make any sense to do any work in dma_cache_sync given that it
must be a no-op when dma_alloc_attrs returns coherent memory.

This also allows moving __dma_sync out of the microblaze asm/dma-mapping.h
and thus greatly reduce the amount of includes there.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/microblaze/include/asm/dma-mapping.h | 34 -------------------------------
 arch/microblaze/kernel/dma.c              | 17 ++++++++++++++++
 2 files changed, 17 insertions(+), 34 deletions(-)

diff --git a/arch/microblaze/include/asm/dma-mapping.h b/arch/microblaze/include/asm/dma-mapping.h
index e15cd2f76e23..ad448e4aedb6 100644
--- a/arch/microblaze/include/asm/dma-mapping.h
+++ b/arch/microblaze/include/asm/dma-mapping.h
@@ -16,22 +16,6 @@
 #define _ASM_MICROBLAZE_DMA_MAPPING_H
 
 /*
- * See Documentation/DMA-API-HOWTO.txt and
- * Documentation/DMA-API.txt for documentation.
- */
-
-#include <linux/types.h>
-#include <linux/cache.h>
-#include <linux/mm.h>
-#include <linux/scatterlist.h>
-#include <linux/dma-debug.h>
-#include <asm/io.h>
-#include <asm/cacheflush.h>
-
-#define __dma_alloc_coherent(dev, gfp, size, handle)	NULL
-#define __dma_free_coherent(size, addr)		((void)0)
-
-/*
  * Available generic sets of operations
  */
 extern const struct dma_map_ops dma_direct_ops;
@@ -41,27 +25,9 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &dma_direct_ops;
 }
 
-static inline void __dma_sync(unsigned long paddr,
-			      size_t size, enum dma_data_direction direction)
-{
-	switch (direction) {
-	case DMA_TO_DEVICE:
-	case DMA_BIDIRECTIONAL:
-		flush_dcache_range(paddr, paddr + size);
-		break;
-	case DMA_FROM_DEVICE:
-		invalidate_dcache_range(paddr, paddr + size);
-		break;
-	default:
-		BUG();
-	}
-}
-
 static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
 		enum dma_data_direction direction)
 {
-	BUG_ON(direction = DMA_NONE);
-	__dma_sync(virt_to_phys(vaddr), size, (int)direction);
 }
 
 #endif	/* _ASM_MICROBLAZE_DMA_MAPPING_H */
diff --git a/arch/microblaze/kernel/dma.c b/arch/microblaze/kernel/dma.c
index e45ada8fb006..621902f8b0a0 100644
--- a/arch/microblaze/kernel/dma.c
+++ b/arch/microblaze/kernel/dma.c
@@ -12,6 +12,7 @@
 #include <linux/dma-debug.h>
 #include <linux/export.h>
 #include <linux/bug.h>
+#include <asm/cacheflush.h>
 
 #define NOT_COHERENT_CACHE
 
@@ -51,6 +52,22 @@ static void dma_direct_free_coherent(struct device *dev, size_t size,
 #endif
 }
 
+static inline void __dma_sync(unsigned long paddr,
+			      size_t size, enum dma_data_direction direction)
+{
+	switch (direction) {
+	case DMA_TO_DEVICE:
+	case DMA_BIDIRECTIONAL:
+		flush_dcache_range(paddr, paddr + size);
+		break;
+	case DMA_FROM_DEVICE:
+		invalidate_dcache_range(paddr, paddr + size);
+		break;
+	default:
+		BUG();
+	}
+}
+
 static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
 			     int nents, enum dma_data_direction direction,
 			     unsigned long attrs)
-- 
2.11.0

[PATCH 08/12] powerpc: make dma_cache_sync a no-op

[Christoph Hellwig]

powerpc does not implement DMA_ATTR_NON_CONSISTENT allocations, so it
doesn't make any sense to do any work in dma_cache_sync given that it
must be a no-op when dma_alloc_attrs returns coherent memory.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/powerpc/include/asm/dma-mapping.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h
index eaece3d3e225..320846442bfb 100644
--- a/arch/powerpc/include/asm/dma-mapping.h
+++ b/arch/powerpc/include/asm/dma-mapping.h
@@ -144,8 +144,6 @@ static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
 static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
 		enum dma_data_direction direction)
 {
-	BUG_ON(direction = DMA_NONE);
-	__dma_sync(vaddr, size, (int)direction);
 }
 
 #endif /* __KERNEL__ */
-- 
2.11.0

[PATCH 10/12] xtensa: make dma_cache_sync a no-op

[Christoph Hellwig]

xtensa does not implement DMA_ATTR_NON_CONSISTENT allocations, so it
doesn't make any sense to do any work in dma_cache_sync given that it
must be a no-op when dma_alloc_attrs returns coherent memory.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/xtensa/include/asm/dma-mapping.h |  6 ++++--
 arch/xtensa/kernel/pci-dma.c          | 23 -----------------------
 2 files changed, 4 insertions(+), 25 deletions(-)

diff --git a/arch/xtensa/include/asm/dma-mapping.h b/arch/xtensa/include/asm/dma-mapping.h
index 269738dc9d1d..353e0314d6ba 100644
--- a/arch/xtensa/include/asm/dma-mapping.h
+++ b/arch/xtensa/include/asm/dma-mapping.h
@@ -23,8 +23,10 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &xtensa_dma_map_ops;
 }
 
-void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-		    enum dma_data_direction direction);
+static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
+		    enum dma_data_direction direction)
+{
+}
 
 static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
diff --git a/arch/xtensa/kernel/pci-dma.c b/arch/xtensa/kernel/pci-dma.c
index cec86a1c2acc..623720a11143 100644
--- a/arch/xtensa/kernel/pci-dma.c
+++ b/arch/xtensa/kernel/pci-dma.c
@@ -26,29 +26,6 @@
 #include <asm/cacheflush.h>
 #include <asm/io.h>
 
-void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-		    enum dma_data_direction dir)
-{
-	switch (dir) {
-	case DMA_BIDIRECTIONAL:
-		__flush_invalidate_dcache_range((unsigned long)vaddr, size);
-		break;
-
-	case DMA_FROM_DEVICE:
-		__invalidate_dcache_range((unsigned long)vaddr, size);
-		break;
-
-	case DMA_TO_DEVICE:
-		__flush_dcache_range((unsigned long)vaddr, size);
-		break;
-
-	case DMA_NONE:
-		BUG();
-		break;
-	}
-}
-EXPORT_SYMBOL(dma_cache_sync);
-
 static void do_cache_op(dma_addr_t dma_handle, size_t size,
 			void (*fn)(unsigned long, unsigned long))
 {
-- 
2.11.0

[PATCH 11/12] sh: make dma_cache_sync a no-op

[Christoph Hellwig]

sh does not implement DMA_ATTR_NON_CONSISTENT allocations, so it doesn't
make any sense to do any work in dma_cache_sync given that it
must be a no-op when dma_alloc_attrs returns coherent memory.

On the other hand sh uses dma_cache_sync internally in the dma_ops
implementation and for the maple bus that does not use the DMA API,
so a the old functionality for dma_cache_sync is still provided under
the name sh_sync_dma_for_device, and without the redundant dev
argument.  While at it two of the syncing dma_ops also go the proper
_for_device postfix.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sh/include/asm/dma-mapping.h |  9 +++++++--
 arch/sh/kernel/dma-nommu.c        | 17 +++++++++--------
 arch/sh/mm/consistent.c           |  6 +++---
 drivers/sh/maple/maple.c          |  5 ++---
 4 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/arch/sh/include/asm/dma-mapping.h b/arch/sh/include/asm/dma-mapping.h
index 9b06be07db4d..b46194ecef17 100644
--- a/arch/sh/include/asm/dma-mapping.h
+++ b/arch/sh/include/asm/dma-mapping.h
@@ -9,8 +9,10 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return dma_ops;
 }
 
-void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-		    enum dma_data_direction dir);
+static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
+		    enum dma_data_direction dir)
+{
+}
 
 /* arch/sh/mm/consistent.c */
 extern void *dma_generic_alloc_coherent(struct device *dev, size_t size,
@@ -20,4 +22,7 @@ extern void dma_generic_free_coherent(struct device *dev, size_t size,
 				      void *vaddr, dma_addr_t dma_handle,
 				      unsigned long attrs);
 
+void sh_sync_dma_for_device(void *vaddr, size_t size,
+	    enum dma_data_direction dir);
+
 #endif /* __ASM_SH_DMA_MAPPING_H */
diff --git a/arch/sh/kernel/dma-nommu.c b/arch/sh/kernel/dma-nommu.c
index d24c707b2181..62b485107eae 100644
--- a/arch/sh/kernel/dma-nommu.c
+++ b/arch/sh/kernel/dma-nommu.c
@@ -9,6 +9,7 @@
  */
 #include <linux/dma-mapping.h>
 #include <linux/io.h>
+#include <asm/cacheflush.h>
 
 static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
 				 unsigned long offset, size_t size,
@@ -20,7 +21,7 @@ static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
 	WARN_ON(size = 0);
 
 	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
-		dma_cache_sync(dev, page_address(page) + offset, size, dir);
+		sh_sync_dma_for_device(page_address(page) + offset, size, dir);
 
 	return addr;
 }
@@ -38,7 +39,7 @@ static int nommu_map_sg(struct device *dev, struct scatterlist *sg,
 		BUG_ON(!sg_page(s));
 
 		if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
-			dma_cache_sync(dev, sg_virt(s), s->length, dir);
+			sh_sync_dma_for_device(sg_virt(s), s->length, dir);
 
 		s->dma_address = sg_phys(s);
 		s->dma_length = s->length;
@@ -48,20 +49,20 @@ static int nommu_map_sg(struct device *dev, struct scatterlist *sg,
 }
 
 #ifdef CONFIG_DMA_NONCOHERENT
-static void nommu_sync_single(struct device *dev, dma_addr_t addr,
+static void nommu_sync_single_for_device(struct device *dev, dma_addr_t addr,
 			      size_t size, enum dma_data_direction dir)
 {
-	dma_cache_sync(dev, phys_to_virt(addr), size, dir);
+	sh_sync_dma_for_device(phys_to_virt(addr), size, dir);
 }
 
-static void nommu_sync_sg(struct device *dev, struct scatterlist *sg,
+static void nommu_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 			  int nelems, enum dma_data_direction dir)
 {
 	struct scatterlist *s;
 	int i;
 
 	for_each_sg(sg, s, nelems, i)
-		dma_cache_sync(dev, sg_virt(s), s->length, dir);
+		sh_sync_dma_for_device(sg_virt(s), s->length, dir);
 }
 #endif
 
@@ -71,8 +72,8 @@ const struct dma_map_ops nommu_dma_ops = {
 	.map_page		= nommu_map_page,
 	.map_sg			= nommu_map_sg,
 #ifdef CONFIG_DMA_NONCOHERENT
-	.sync_single_for_device	= nommu_sync_single,
-	.sync_sg_for_device	= nommu_sync_sg,
+	.sync_single_for_device	= nommu_sync_single_for_device,
+	.sync_sg_for_device	= nommu_sync_sg_for_device,
 #endif
 	.is_phys		= 1,
 };
diff --git a/arch/sh/mm/consistent.c b/arch/sh/mm/consistent.c
index d1275adfa0ef..6ea3aab508f2 100644
--- a/arch/sh/mm/consistent.c
+++ b/arch/sh/mm/consistent.c
@@ -49,7 +49,7 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t size,
 	 * Pages from the page allocator may have data present in
 	 * cache. So flush the cache before using uncached memory.
 	 */
-	dma_cache_sync(dev, ret, size, DMA_BIDIRECTIONAL);
+	sh_sync_dma_for_device(ret, size, DMA_BIDIRECTIONAL);
 
 	ret_nocache = (void __force *)ioremap_nocache(virt_to_phys(ret), size);
 	if (!ret_nocache) {
@@ -78,7 +78,7 @@ void dma_generic_free_coherent(struct device *dev, size_t size,
 	iounmap(vaddr);
 }
 
-void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
+void sh_sync_dma_for_device(void *vaddr, size_t size,
 		    enum dma_data_direction direction)
 {
 	void *addr;
@@ -100,7 +100,7 @@ void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
 		BUG();
 	}
 }
-EXPORT_SYMBOL(dma_cache_sync);
+EXPORT_SYMBOL(sh_sync_dma_for_device);
 
 static int __init memchunk_setup(char *str)
 {
diff --git a/drivers/sh/maple/maple.c b/drivers/sh/maple/maple.c
index bec81c2404f7..7525039d812c 100644
--- a/drivers/sh/maple/maple.c
+++ b/drivers/sh/maple/maple.c
@@ -300,7 +300,7 @@ static void maple_send(void)
 	mutex_unlock(&maple_wlist_lock);
 	if (maple_packets > 0) {
 		for (i = 0; i < (1 << MAPLE_DMA_PAGES); i++)
-			dma_cache_sync(0, maple_sendbuf + i * PAGE_SIZE,
+			sh_sync_dma_for_device(maple_sendbuf + i * PAGE_SIZE,
 				       PAGE_SIZE, DMA_BIDIRECTIONAL);
 	}
 
@@ -642,8 +642,7 @@ static void maple_dma_handler(struct work_struct *work)
 		list_for_each_entry_safe(mq, nmq, &maple_sentq, list) {
 			mdev = mq->dev;
 			recvbuf = mq->recvbuf->buf;
-			dma_cache_sync(&mdev->dev, recvbuf, 0x400,
-				DMA_FROM_DEVICE);
+			sh_sync_dma_for_device(recvbuf, 0x400, DMA_FROM_DEVICE);
 			code = recvbuf[0];
 			kfree(mq->sendbuf);
 			list_del_init(&mq->list);
-- 
2.11.0

[PATCH 12/12] dma-mapping: turn dma_cache_sync into a dma_map_ops method

[Christoph Hellwig]

After we removed all the dead wood it turns out only two architectures
actually implement dma_cache_sync as a no-op: mips and parisc.  Add
a cache_sync method to struct dma_map_ops and implement it for the
mips defualt DMA ops, and the parisc pa11 ops.

Note that arm, arc and openrisc support DMA_ATTR_NON_CONSISTENT, but
never provided a functional dma_cache_sync implementations, which
seems somewhat odd.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/alpha/include/asm/dma-mapping.h      |  2 --
 arch/cris/include/asm/dma-mapping.h       |  6 ------
 arch/frv/include/asm/dma-mapping.h        |  6 ------
 arch/hexagon/include/asm/dma-mapping.h    |  3 ---
 arch/ia64/include/asm/dma-mapping.h       |  6 ------
 arch/m32r/include/asm/dma-mapping.h       |  5 -----
 arch/m68k/include/asm/dma-mapping.h       |  6 ------
 arch/metag/include/asm/dma-mapping.h      | 10 ----------
 arch/microblaze/include/asm/dma-mapping.h |  5 -----
 arch/mips/include/asm/dma-mapping.h       |  3 ---
 arch/mips/mm/dma-default.c                |  7 +++----
 arch/mn10300/include/asm/dma-mapping.h    |  6 ------
 arch/nios2/include/asm/dma-mapping.h      |  9 ---------
 arch/parisc/include/asm/dma-mapping.h     |  8 --------
 arch/parisc/kernel/pci-dma.c              |  8 ++++++++
 arch/powerpc/include/asm/dma-mapping.h    |  5 -----
 arch/s390/include/asm/dma-mapping.h       |  5 -----
 arch/sh/include/asm/dma-mapping.h         |  6 ------
 arch/sparc/include/asm/dma-mapping.h      |  8 --------
 arch/tile/include/asm/dma-mapping.h       |  9 ---------
 arch/unicore32/include/asm/dma-mapping.h  |  5 -----
 arch/x86/include/asm/dma-mapping.h        |  6 ------
 arch/xtensa/include/asm/dma-mapping.h     |  5 -----
 include/linux/dma-mapping.h               | 13 +++++++++++++
 24 files changed, 24 insertions(+), 128 deletions(-)

diff --git a/arch/alpha/include/asm/dma-mapping.h b/arch/alpha/include/asm/dma-mapping.h
index 5d53666935e6..399a4f49355e 100644
--- a/arch/alpha/include/asm/dma-mapping.h
+++ b/arch/alpha/include/asm/dma-mapping.h
@@ -8,6 +8,4 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return dma_ops;
 }
 
-#define dma_cache_sync(dev, va, size, dir)		  ((void)0)
-
 #endif	/* _ALPHA_DMA_MAPPING_H */
diff --git a/arch/cris/include/asm/dma-mapping.h b/arch/cris/include/asm/dma-mapping.h
index 256169de3743..e30adde42beb 100644
--- a/arch/cris/include/asm/dma-mapping.h
+++ b/arch/cris/include/asm/dma-mapping.h
@@ -16,10 +16,4 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 }
 #endif
 
-static inline void
-dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-	       enum dma_data_direction direction)
-{
-}
-
 #endif
diff --git a/arch/frv/include/asm/dma-mapping.h b/arch/frv/include/asm/dma-mapping.h
index da0e5c9744c4..da24ae943f02 100644
--- a/arch/frv/include/asm/dma-mapping.h
+++ b/arch/frv/include/asm/dma-mapping.h
@@ -14,10 +14,4 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &frv_dma_ops;
 }
 
-static inline
-void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-		    enum dma_data_direction direction)
-{
-}
-
 #endif  /* _ASM_DMA_MAPPING_H */
diff --git a/arch/hexagon/include/asm/dma-mapping.h b/arch/hexagon/include/asm/dma-mapping.h
index 463dbc18f853..5208de242e79 100644
--- a/arch/hexagon/include/asm/dma-mapping.h
+++ b/arch/hexagon/include/asm/dma-mapping.h
@@ -37,9 +37,6 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return dma_ops;
 }
 
-extern void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-			   enum dma_data_direction direction);
-
 static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
 {
 	if (!dev->dma_mask)
diff --git a/arch/ia64/include/asm/dma-mapping.h b/arch/ia64/include/asm/dma-mapping.h
index 99dfc1aa9d3c..9e5b5df76ff8 100644
--- a/arch/ia64/include/asm/dma-mapping.h
+++ b/arch/ia64/include/asm/dma-mapping.h
@@ -44,10 +44,4 @@ static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
 	return daddr;
 }
 
-static inline void
-dma_cache_sync (struct device *dev, void *vaddr, size_t size,
-	enum dma_data_direction dir)
-{
-}
-
 #endif /* _ASM_IA64_DMA_MAPPING_H */
diff --git a/arch/m32r/include/asm/dma-mapping.h b/arch/m32r/include/asm/dma-mapping.h
index aff3ae8b62f7..9e993daed7a0 100644
--- a/arch/m32r/include/asm/dma-mapping.h
+++ b/arch/m32r/include/asm/dma-mapping.h
@@ -13,11 +13,6 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &dma_noop_ops;
 }
 
-static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-				  enum dma_data_direction direction)
-{
-}
-
 static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
 {
 	if (!dev->dma_mask)
diff --git a/arch/m68k/include/asm/dma-mapping.h b/arch/m68k/include/asm/dma-mapping.h
index 9210e470771b..9a0d559fcc13 100644
--- a/arch/m68k/include/asm/dma-mapping.h
+++ b/arch/m68k/include/asm/dma-mapping.h
@@ -8,10 +8,4 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
         return &m68k_dma_ops;
 }
 
-static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-				  enum dma_data_direction dir)
-{
-	/* we use coherent allocation, so not much to do here. */
-}
-
 #endif  /* _M68K_DMA_MAPPING_H */
diff --git a/arch/metag/include/asm/dma-mapping.h b/arch/metag/include/asm/dma-mapping.h
index ea573be2b6d0..340265dcf839 100644
--- a/arch/metag/include/asm/dma-mapping.h
+++ b/arch/metag/include/asm/dma-mapping.h
@@ -8,14 +8,4 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &metag_dma_ops;
 }
 
-/*
- * dma_alloc_attrs() always returns non-cacheable memory, so there's no need to
- * do any flushing here.
- */
-static inline void
-dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-	       enum dma_data_direction direction)
-{
-}
-
 #endif
diff --git a/arch/microblaze/include/asm/dma-mapping.h b/arch/microblaze/include/asm/dma-mapping.h
index ad448e4aedb6..6b9ea39405b8 100644
--- a/arch/microblaze/include/asm/dma-mapping.h
+++ b/arch/microblaze/include/asm/dma-mapping.h
@@ -25,9 +25,4 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &dma_direct_ops;
 }
 
-static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-		enum dma_data_direction direction)
-{
-}
-
 #endif	/* _ASM_MICROBLAZE_DMA_MAPPING_H */
diff --git a/arch/mips/include/asm/dma-mapping.h b/arch/mips/include/asm/dma-mapping.h
index aba71385f9d1..6ea1439430a2 100644
--- a/arch/mips/include/asm/dma-mapping.h
+++ b/arch/mips/include/asm/dma-mapping.h
@@ -26,9 +26,6 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
 
 static inline void dma_mark_clean(void *addr, size_t size) {}
 
-extern void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-	       enum dma_data_direction direction);
-
 #define arch_setup_dma_ops arch_setup_dma_ops
 static inline void arch_setup_dma_ops(struct device *dev, u64 dma_base,
 				      u64 size, const struct iommu_ops *iommu,
diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
index 8e78251eccc2..e69073f32a71 100644
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -419,7 +419,7 @@ int mips_dma_supported(struct device *dev, u64 mask)
 	return plat_dma_supported(dev, mask);
 }
 
-void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
+static void mips_dma_cache_sync(struct device *dev, void *vaddr, size_t size,
 			 enum dma_data_direction direction)
 {
 	BUG_ON(direction = DMA_NONE);
@@ -428,8 +428,6 @@ void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
 		__dma_sync_virtual(vaddr, size, direction);
 }
 
-EXPORT_SYMBOL(dma_cache_sync);
-
 static const struct dma_map_ops mips_default_dma_map_ops = {
 	.alloc = mips_dma_alloc_coherent,
 	.free = mips_dma_free_coherent,
@@ -443,7 +441,8 @@ static const struct dma_map_ops mips_default_dma_map_ops = {
 	.sync_sg_for_cpu = mips_dma_sync_sg_for_cpu,
 	.sync_sg_for_device = mips_dma_sync_sg_for_device,
 	.mapping_error = mips_dma_mapping_error,
-	.dma_supported = mips_dma_supported
+	.dma_supported = mips_dma_supported,
+	.cache_sync = mips_dma_cache_sync,
 };
 
 const struct dma_map_ops *mips_dma_map_ops = &mips_default_dma_map_ops;
diff --git a/arch/mn10300/include/asm/dma-mapping.h b/arch/mn10300/include/asm/dma-mapping.h
index dc24163b190f..439e474ed6d7 100644
--- a/arch/mn10300/include/asm/dma-mapping.h
+++ b/arch/mn10300/include/asm/dma-mapping.h
@@ -18,10 +18,4 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &mn10300_dma_ops;
 }
 
-static inline
-void dma_cache_sync(void *vaddr, size_t size,
-		    enum dma_data_direction direction)
-{
-}
-
 #endif
diff --git a/arch/nios2/include/asm/dma-mapping.h b/arch/nios2/include/asm/dma-mapping.h
index f8dc62222741..6ceb92251da0 100644
--- a/arch/nios2/include/asm/dma-mapping.h
+++ b/arch/nios2/include/asm/dma-mapping.h
@@ -17,13 +17,4 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &nios2_dma_ops;
 }
 
-/*
- * dma_alloc_attrs() always returns non-cacheable memory, so there's no need to
- * do any flushing here.
- */
-static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-				  enum dma_data_direction direction)
-{
-}
-
 #endif /* _ASM_NIOS2_DMA_MAPPING_H */
diff --git a/arch/parisc/include/asm/dma-mapping.h b/arch/parisc/include/asm/dma-mapping.h
index 2b16282add69..cb26bbd71d8a 100644
--- a/arch/parisc/include/asm/dma-mapping.h
+++ b/arch/parisc/include/asm/dma-mapping.h
@@ -32,14 +32,6 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return hppa_dma_ops;
 }
 
-static inline void
-dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-	       enum dma_data_direction direction)
-{
-	if (hppa_dma_ops->sync_single_for_cpu)
-		flush_kernel_dcache_range((unsigned long)vaddr, size);
-}
-
 static inline void *
 parisc_walk_tree(struct device *dev)
 {
diff --git a/arch/parisc/kernel/pci-dma.c b/arch/parisc/kernel/pci-dma.c
index 5f0067a62738..ee43e9f73ad3 100644
--- a/arch/parisc/kernel/pci-dma.c
+++ b/arch/parisc/kernel/pci-dma.c
@@ -572,6 +572,12 @@ static void pa11_dma_sync_sg_for_device(struct device *dev, struct scatterlist *
 		flush_kernel_vmap_range(sg_virt(sg), sg->length);
 }
 
+static void pa11_dma_cache_sync(struct device *dev, void *vaddr, size_t size,
+	       enum dma_data_direction direction)
+{
+	flush_kernel_dcache_range((unsigned long)vaddr, size);
+}
+
 const struct dma_map_ops pcxl_dma_ops = {
 	.dma_supported =	pa11_dma_supported,
 	.alloc =		pa11_dma_alloc,
@@ -584,6 +590,7 @@ const struct dma_map_ops pcxl_dma_ops = {
 	.sync_single_for_device = pa11_dma_sync_single_for_device,
 	.sync_sg_for_cpu =	pa11_dma_sync_sg_for_cpu,
 	.sync_sg_for_device =	pa11_dma_sync_sg_for_device,
+	.cache_sync =		pa11_dma_cache_sync,
 };
 
 static void *pcx_dma_alloc(struct device *dev, size_t size,
@@ -620,4 +627,5 @@ const struct dma_map_ops pcx_dma_ops = {
 	.sync_single_for_device = pa11_dma_sync_single_for_device,
 	.sync_sg_for_cpu =	pa11_dma_sync_sg_for_cpu,
 	.sync_sg_for_device =	pa11_dma_sync_sg_for_device,
+	.cache_sync =		pa11_dma_cache_sync,
 };
diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h
index 320846442bfb..2e43c2ef7632 100644
--- a/arch/powerpc/include/asm/dma-mapping.h
+++ b/arch/powerpc/include/asm/dma-mapping.h
@@ -141,10 +141,5 @@ static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
 
 #define ARCH_HAS_DMA_MMAP_COHERENT
 
-static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-		enum dma_data_direction direction)
-{
-}
-
 #endif /* __KERNEL__ */
 #endif	/* _ASM_DMA_MAPPING_H */
diff --git a/arch/s390/include/asm/dma-mapping.h b/arch/s390/include/asm/dma-mapping.h
index 512ad0eaa11a..b17304b13de5 100644
--- a/arch/s390/include/asm/dma-mapping.h
+++ b/arch/s390/include/asm/dma-mapping.h
@@ -15,11 +15,6 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &dma_noop_ops;
 }
 
-static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-				  enum dma_data_direction direction)
-{
-}
-
 static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
 {
 	if (!dev->dma_mask)
diff --git a/arch/sh/include/asm/dma-mapping.h b/arch/sh/include/asm/dma-mapping.h
index b46194ecef17..e89df111c017 100644
--- a/arch/sh/include/asm/dma-mapping.h
+++ b/arch/sh/include/asm/dma-mapping.h
@@ -9,12 +9,6 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return dma_ops;
 }
 
-static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-		    enum dma_data_direction dir)
-{
-}
-
-/* arch/sh/mm/consistent.c */
 extern void *dma_generic_alloc_coherent(struct device *dev, size_t size,
 					dma_addr_t *dma_addr, gfp_t flag,
 					unsigned long attrs);
diff --git a/arch/sparc/include/asm/dma-mapping.h b/arch/sparc/include/asm/dma-mapping.h
index 60bf1633d554..b298ed45cb23 100644
--- a/arch/sparc/include/asm/dma-mapping.h
+++ b/arch/sparc/include/asm/dma-mapping.h
@@ -5,14 +5,6 @@
 #include <linux/mm.h>
 #include <linux/dma-debug.h>
 
-static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-				  enum dma_data_direction dir)
-{
-	/* Since dma_{alloc,free}_noncoherent() allocated coherent memory, this
-	 * routine can be a nop.
-	 */
-}
-
 extern const struct dma_map_ops *dma_ops;
 extern const struct dma_map_ops pci32_dma_ops;
 
diff --git a/arch/tile/include/asm/dma-mapping.h b/arch/tile/include/asm/dma-mapping.h
index 7061dc8af43a..97ad62878290 100644
--- a/arch/tile/include/asm/dma-mapping.h
+++ b/arch/tile/include/asm/dma-mapping.h
@@ -67,13 +67,4 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
 #define HAVE_ARCH_DMA_SET_MASK 1
 int dma_set_mask(struct device *dev, u64 mask);
 
-/*
- * dma_alloc_attrs() always returns non-cacheable memory, so there's no need to
- * do any flushing here.
- */
-static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-				  enum dma_data_direction direction)
-{
-}
-
 #endif /* _ASM_TILE_DMA_MAPPING_H */
diff --git a/arch/unicore32/include/asm/dma-mapping.h b/arch/unicore32/include/asm/dma-mapping.h
index e949855bb794..ac608c2f6af6 100644
--- a/arch/unicore32/include/asm/dma-mapping.h
+++ b/arch/unicore32/include/asm/dma-mapping.h
@@ -45,10 +45,5 @@ static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
 
 static inline void dma_mark_clean(void *addr, size_t size) {}
 
-static inline void dma_cache_sync(struct device *dev, void *vaddr,
-		size_t size, enum dma_data_direction direction)
-{
-}
-
 #endif /* __KERNEL__ */
 #endif
diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/asm/dma-mapping.h
index 04877267ad18..cdc1ab17eb62 100644
--- a/arch/x86/include/asm/dma-mapping.h
+++ b/arch/x86/include/asm/dma-mapping.h
@@ -66,12 +66,6 @@ static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
 }
 #endif /* CONFIG_X86_DMA_REMAP */
 
-static inline void
-dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-	enum dma_data_direction dir)
-{
-}
-
 static inline unsigned long dma_alloc_coherent_mask(struct device *dev,
 						    gfp_t gfp)
 {
diff --git a/arch/xtensa/include/asm/dma-mapping.h b/arch/xtensa/include/asm/dma-mapping.h
index 353e0314d6ba..153bf2370988 100644
--- a/arch/xtensa/include/asm/dma-mapping.h
+++ b/arch/xtensa/include/asm/dma-mapping.h
@@ -23,11 +23,6 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &xtensa_dma_map_ops;
 }
 
-static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-		    enum dma_data_direction direction)
-{
-}
-
 static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
 	return (dma_addr_t)paddr;
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 4c98cc96971f..ca73ba27ae79 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -125,6 +125,8 @@ struct dma_map_ops {
 	void (*sync_sg_for_device)(struct device *dev,
 				   struct scatterlist *sg, int nents,
 				   enum dma_data_direction dir);
+	void (*cache_sync)(struct device *dev, void *vaddr, size_t size,
+			enum dma_data_direction direction);
 	int (*mapping_error)(struct device *dev, dma_addr_t dma_addr);
 	int (*dma_supported)(struct device *dev, u64 mask);
 #ifdef ARCH_HAS_DMA_GET_REQUIRED_MASK
@@ -435,6 +437,17 @@ dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 #define dma_map_page(d, p, o, s, r) dma_map_page_attrs(d, p, o, s, r, 0)
 #define dma_unmap_page(d, a, s, r) dma_unmap_page_attrs(d, a, s, r, 0)
 
+static inline void
+dma_cache_sync(struct device *dev, void *vaddr, size_t size,
+		enum dma_data_direction dir)
+{
+	const struct dma_map_ops *ops = get_dma_ops(dev);
+
+	BUG_ON(!valid_dma_direction(dir));
+	if (ops->cache_sync)
+		ops->cache_sync(dev, vaddr, size, dir);
+}
+
 extern int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
 			   void *cpu_addr, dma_addr_t dma_addr, size_t size);
 
-- 
2.11.0

Re: [PATCH 12/12] dma-mapping: turn dma_cache_sync into a dma_map_ops method

[Geert Uytterhoeven]

Hi Christoph,

On Sun, Aug 27, 2017 at 6:10 PM, Christoph Hellwig <hch@lst.de> wrote:
> After we removed all the dead wood it turns out only two architectures
> actually implement dma_cache_sync as a no-op: mips and parisc.  Add

s/no-op/real op/

> a cache_sync method to struct dma_map_ops and implement it for the
> mips defualt DMA ops, and the parisc pa11 ops.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds