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powerpc/iommu: Support "hybrid" iommu/direct DMA ops for coherent_mask < dma_mask 

This patch adds the ability to the DMA direct ops to fallback to the IOMMU
ops for coherent alloc/free if the coherent mask of the device isn't
suitable for accessing the direct DMA space and the device also happens
to have an active IOMMU table.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Benjamin Herrenschmidt 2015-06-24 15:25:31 +10:00 committed by Michael Ellerman
parent e91c25111a
commit 817820b022
5 changed files with 105 additions and 26 deletions
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4
arch/powerpc/Kconfig
View File

@ -82,6 +82,9 @@ config GENERIC_HWEIGHT
bool
default y
config ARCH_HAS_DMA_SET_COHERENT_MASK
bool
config PPC
bool
default y
@ -155,6 +158,7 @@ config PPC
select HAVE_PERF_EVENTS_NMI if PPC64
select EDAC_SUPPORT
select EDAC_ATOMIC_SCRUB
select ARCH_HAS_DMA_SET_COHERENT_MASK
config GENERIC_CSUM
def_bool CPU_LITTLE_ENDIAN

10
arch/powerpc/include/asm/dma-mapping.h
View File

@ -21,12 +21,12 @@
#define DMA_ERROR_CODE (~(dma_addr_t)0x0)
/* Some dma direct funcs must be visible for use in other dma_ops */
extern void *dma_direct_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag,
extern void *__dma_direct_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag,
struct dma_attrs *attrs);
extern void __dma_direct_free_coherent(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_handle,
struct dma_attrs *attrs);
extern void dma_direct_free_coherent(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_handle,
struct dma_attrs *attrs);
extern int dma_direct_mmap_coherent(struct device *dev,
struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t handle,

2
arch/powerpc/kernel/dma-iommu.c
View File

@ -73,7 +73,7 @@ static void dma_iommu_unmap_sg(struct device *dev, struct scatterlist *sglist,
}
/* We support DMA to/from any memory page via the iommu */
static int dma_iommu_dma_supported(struct device *dev, u64 mask)
int dma_iommu_dma_supported(struct device *dev, u64 mask)
{
struct iommu_table *tbl = get_iommu_table_base(dev);

4
arch/powerpc/kernel/dma-swiotlb.c
View File

@ -47,8 +47,8 @@ static u64 swiotlb_powerpc_get_required(struct device *dev)
* for everything else.
*/
struct dma_map_ops swiotlb_dma_ops = {
.alloc = dma_direct_alloc_coherent,
.free = dma_direct_free_coherent,
.alloc = __dma_direct_alloc_coherent,
.free = __dma_direct_free_coherent,
.mmap = dma_direct_mmap_coherent,
.map_sg = swiotlb_map_sg_attrs,
.unmap_sg = swiotlb_unmap_sg_attrs,

111
arch/powerpc/kernel/dma.c
View File

@ -16,6 +16,7 @@
#include <asm/bug.h>
#include <asm/machdep.h>
#include <asm/swiotlb.h>
#include <asm/iommu.h>
/*
* Generic direct DMA implementation
@ -39,9 +40,31 @@ static u64 __maybe_unused get_pfn_limit(struct device *dev)
return pfn;
}
void *dma_direct_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag,
struct dma_attrs *attrs)
static int dma_direct_dma_supported(struct device *dev, u64 mask)
{
#ifdef CONFIG_PPC64
u64 limit = get_dma_offset(dev) + (memblock_end_of_DRAM() - 1);
/* Limit fits in the mask, we are good */
if (mask >= limit)
return 1;
#ifdef CONFIG_FSL_SOC
/* Freescale gets another chance via ZONE_DMA/ZONE_DMA32, however
* that will have to be refined if/when they support iommus
*/
return 1;
#endif
/* Sorry ... */
return 0;
#else
return 1;
#endif
}
void *__dma_direct_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag,
struct dma_attrs *attrs)
{
void *ret;
#ifdef CONFIG_NOT_COHERENT_CACHE
@ -96,9 +119,9 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t size,
#endif
}
void dma_direct_free_coherent(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_handle,
struct dma_attrs *attrs)
void __dma_direct_free_coherent(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_handle,
struct dma_attrs *attrs)
{
#ifdef CONFIG_NOT_COHERENT_CACHE
__dma_free_coherent(size, vaddr);
@ -107,6 +130,51 @@ void dma_direct_free_coherent(struct device *dev, size_t size,
#endif
}
static void *dma_direct_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag,
struct dma_attrs *attrs)
{
struct iommu_table *iommu;
/* The coherent mask may be smaller than the real mask, check if
* we can really use the direct ops
*/
if (dma_direct_dma_supported(dev, dev->coherent_dma_mask))
return __dma_direct_alloc_coherent(dev, size, dma_handle,
flag, attrs);
/* Ok we can't ... do we have an iommu ? If not, fail */
iommu = get_iommu_table_base(dev);
if (!iommu)
return NULL;
/* Try to use the iommu */
return iommu_alloc_coherent(dev, iommu, size, dma_handle,
dev->coherent_dma_mask, flag,
dev_to_node(dev));
}
static void dma_direct_free_coherent(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_handle,
struct dma_attrs *attrs)
{
struct iommu_table *iommu;
/* See comments in dma_direct_alloc_coherent() */
if (dma_direct_dma_supported(dev, dev->coherent_dma_mask))
return __dma_direct_free_coherent(dev, size, vaddr, dma_handle,
attrs);
/* Maybe we used an iommu ... */
iommu = get_iommu_table_base(dev);
/* If we hit that we should have never allocated in the first
* place so how come we are freeing ?
*/
if (WARN_ON(!iommu))
return;
iommu_free_coherent(iommu, size, vaddr, dma_handle);
}
int dma_direct_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t handle, size_t size,
struct dma_attrs *attrs)
@ -147,18 +215,6 @@ static void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sg,
{
}
static int dma_direct_dma_supported(struct device *dev, u64 mask)
{
#ifdef CONFIG_PPC64
/* Could be improved so platforms can set the limit in case
* they have limited DMA windows
*/
return mask >= get_dma_offset(dev) + (memblock_end_of_DRAM() - 1);
#else
return 1;
#endif
}
static u64 dma_direct_get_required_mask(struct device *dev)
{
u64 end, mask;
@ -230,6 +286,25 @@ struct dma_map_ops dma_direct_ops = {
};
EXPORT_SYMBOL(dma_direct_ops);
int dma_set_coherent_mask(struct device *dev, u64 mask)
{
if (!dma_supported(dev, mask)) {
/*
* We need to special case the direct DMA ops which can
* support a fallback for coherent allocations. There
* is no dma_op->set_coherent_mask() so we have to do
* things the hard way:
*/
if (get_dma_ops(dev) != &dma_direct_ops ||
get_iommu_table_base(dev) == NULL ||
!dma_iommu_dma_supported(dev, mask))
return -EIO;
}
dev->coherent_dma_mask = mask;
return 0;
}
EXPORT_SYMBOL_GPL(dma_set_coherent_mask);
#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
int __dma_set_mask(struct device *dev, u64 dma_mask)