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powerpc: Override dma_get_required_mask by platform hook and ops

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The hook dma_get_required_mask is supposed to return the mask required
by the platform to operate efficently.  The generic version of
dma_get_required_mask in driver/base/platform.c returns a mask based
only on max_pfn.  However, this is likely too big for iommu systems
and could be too small for platforms that require a dma offset or have
a secondary window at a high offset.

Override the default, provide a hook in ppc_md used by pseries lpar and
cell, and provide the default answer based on memblock_end_of_DRAM(),
with hooks for get_dma_offset, and provide an implementation for iommu
that looks at the defined table size.  Coverting from the end address
to the required bit mask is based on the generic implementation.

The need for this was discovered when the qla2xxx driver switched to
64 bit dma then reverted to 32 bit when dma_get_required_mask said
32 bits was sufficient.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Cc: benh@kernel.crashing.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Milton Miller
2011-06-24 09:05:22 +00:00
committed by Benjamin Herrenschmidt
parent ce39508883
commit 6a5c7be5e4
6 changed files with 96 additions and 1 deletions
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3
arch/powerpc/include/asm/dma-mapping.h
View File

@@ -20,6 +20,8 @@
#define DMA_ERROR_CODE (~(dma_addr_t)0x0)
#define ARCH_HAS_DMA_GET_REQUIRED_MASK
/* 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);
@@ -69,6 +71,7 @@ static inline unsigned long device_to_mask(struct device *dev)
*/
#ifdef CONFIG_PPC64
extern struct dma_map_ops dma_iommu_ops;
extern u64 dma_iommu_get_required_mask(struct device *dev);
#endif
extern struct dma_map_ops dma_direct_ops;

3
arch/powerpc/include/asm/machdep.h
View File

@@ -85,8 +85,9 @@ struct machdep_calls {
void (*pci_dma_dev_setup)(struct pci_dev *dev);
void (*pci_dma_bus_setup)(struct pci_bus *bus);
/* Platform set_dma_mask override */
/* Platform set_dma_mask and dma_get_required_mask overrides */
int (*dma_set_mask)(struct device *dev, u64 dma_mask);
u64 (*dma_get_required_mask)(struct device *dev);
int (*probe)(void);
void (*setup_arch)(void); /* Optional, may be NULL */