diff options
Diffstat (limited to 'kernel/arch/arc/mm/dma.c')
| -rw-r--r-- | kernel/arch/arc/mm/dma.c | 46 |
1 files changed, 36 insertions, 10 deletions
diff --git a/kernel/arch/arc/mm/dma.c b/kernel/arch/arc/mm/dma.c index 12cc6485b..29a46bb19 100644 --- a/kernel/arch/arc/mm/dma.c +++ b/kernel/arch/arc/mm/dma.c @@ -14,13 +14,12 @@ * Cache bit off in the TLB entry. * * The default DMA address == Phy address which is 0x8000_0000 based. - * A platform/device can make it zero based, by over-riding - * plat_{dma,kernel}_addr_to_{kernel,dma} */ #include <linux/dma-mapping.h> #include <linux/dma-debug.h> #include <linux/export.h> +#include <asm/cache.h> #include <asm/cacheflush.h> /* @@ -37,7 +36,7 @@ void *dma_alloc_noncoherent(struct device *dev, size_t size, return NULL; /* This is bus address, platform dependent */ - *dma_handle = plat_kernel_addr_to_dma(dev, paddr); + *dma_handle = (dma_addr_t)paddr; return paddr; } @@ -46,8 +45,7 @@ EXPORT_SYMBOL(dma_alloc_noncoherent); void dma_free_noncoherent(struct device *dev, size_t size, void *vaddr, dma_addr_t dma_handle) { - free_pages_exact((void *)plat_dma_addr_to_kernel(dev, dma_handle), - size); + free_pages_exact((void *)dma_handle, size); } EXPORT_SYMBOL(dma_free_noncoherent); @@ -56,6 +54,20 @@ void *dma_alloc_coherent(struct device *dev, size_t size, { void *paddr, *kvaddr; + /* + * IOC relies on all data (even coherent DMA data) being in cache + * Thus allocate normal cached memory + * + * The gains with IOC are two pronged: + * -For streaming data, elides needs for cache maintenance, saving + * cycles in flush code, and bus bandwidth as all the lines of a + * buffer need to be flushed out to memory + * -For coherent data, Read/Write to buffers terminate early in cache + * (vs. always going to memory - thus are faster) + */ + if (is_isa_arcv2() && ioc_exists) + return dma_alloc_noncoherent(dev, size, dma_handle, gfp); + /* This is linear addr (0x8000_0000 based) */ paddr = alloc_pages_exact(size, gfp); if (!paddr) @@ -63,11 +75,23 @@ void *dma_alloc_coherent(struct device *dev, size_t size, /* This is kernel Virtual address (0x7000_0000 based) */ kvaddr = ioremap_nocache((unsigned long)paddr, size); - if (kvaddr != NULL) - memset(kvaddr, 0, size); + if (kvaddr == NULL) + return NULL; /* This is bus address, platform dependent */ - *dma_handle = plat_kernel_addr_to_dma(dev, paddr); + *dma_handle = (dma_addr_t)paddr; + + /* + * Evict any existing L1 and/or L2 lines for the backing page + * in case it was used earlier as a normal "cached" page. + * Yeah this bit us - STAR 9000898266 + * + * Although core does call flush_cache_vmap(), it gets kvaddr hence + * can't be used to efficiently flush L1 and/or L2 which need paddr + * Currently flush_cache_vmap nukes the L1 cache completely which + * will be optimized as a separate commit + */ + dma_cache_wback_inv((unsigned long)paddr, size); return kvaddr; } @@ -76,10 +100,12 @@ EXPORT_SYMBOL(dma_alloc_coherent); void dma_free_coherent(struct device *dev, size_t size, void *kvaddr, dma_addr_t dma_handle) { + if (is_isa_arcv2() && ioc_exists) + return dma_free_noncoherent(dev, size, kvaddr, dma_handle); + iounmap((void __force __iomem *)kvaddr); - free_pages_exact((void *)plat_dma_addr_to_kernel(dev, dma_handle), - size); + free_pages_exact((void *)dma_handle, size); } EXPORT_SYMBOL(dma_free_coherent); |