From 817820b0226a1376f0fc68827ab8e42d86431117 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Wed, 24 Jun 2015 15:25:31 +1000 Subject: [PATCH] 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 Signed-off-by: Michael Ellerman --- arch/powerpc/Kconfig | 4 ++ arch/powerpc/include/asm/dma-mapping.h | 10 +-- arch/powerpc/kernel/dma-iommu.c | 2 +- arch/powerpc/kernel/dma-swiotlb.c | 4 +- arch/powerpc/kernel/dma.c | 111 +++++++++++++++++++++++++++------ 5 files changed, 105 insertions(+), 26 deletions(-) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 5ef2711..fe2f2c5 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -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 diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h index 9cbbc9e..710f60e 100644 --- a/arch/powerpc/include/asm/dma-mapping.h +++ b/arch/powerpc/include/asm/dma-mapping.h @@ -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, diff --git a/arch/powerpc/kernel/dma-iommu.c b/arch/powerpc/kernel/dma-iommu.c index 4c68bfe..41a7d9d 100644 --- a/arch/powerpc/kernel/dma-iommu.c +++ b/arch/powerpc/kernel/dma-iommu.c @@ -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); diff --git a/arch/powerpc/kernel/dma-swiotlb.c b/arch/powerpc/kernel/dma-swiotlb.c index 6e8d764..c6689f6 100644 --- a/arch/powerpc/kernel/dma-swiotlb.c +++ b/arch/powerpc/kernel/dma-swiotlb.c @@ -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, diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c index 35e4dcc..1558f81 100644 --- a/arch/powerpc/kernel/dma.c +++ b/arch/powerpc/kernel/dma.c @@ -16,6 +16,7 @@ #include #include #include +#include /* * 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) -- 2.7.4