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author | Jonas Bonn <jonas@southpole.se> | 2011-06-04 22:56:48 +0400 |
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committer | Jonas Bonn <jonas@southpole.se> | 2011-07-22 20:46:32 +0400 |
commit | a39af6f7b806f2a52962254ea8dc635b4c240810 (patch) | |
tree | 968f71a1812f7b4e658992d16451b36ab8b49c0d /arch/openrisc/kernel/dma.c | |
parent | e5ad95ce9b8d7efc443d39a7bbc4e55b7a4593f1 (diff) | |
download | linux-a39af6f7b806f2a52962254ea8dc635b4c240810.tar.xz |
OpenRISC: DMA
Simple DMA implementation. Allows for allocation of coherent memory
(simply uncached) for DMA operations.
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'arch/openrisc/kernel/dma.c')
-rw-r--r-- | arch/openrisc/kernel/dma.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c new file mode 100644 index 000000000000..968d3ee477e3 --- /dev/null +++ b/arch/openrisc/kernel/dma.c @@ -0,0 +1,191 @@ +/* + * OpenRISC Linux + * + * Linux architectural port borrowing liberally from similar works of + * others. All original copyrights apply as per the original source + * declaration. + * + * Modifications for the OpenRISC architecture: + * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> + * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + * + * DMA mapping callbacks... + * As alloc_coherent is the only DMA callback being used currently, that's + * the only thing implemented properly. The rest need looking into... + */ + +#include <linux/dma-mapping.h> +#include <linux/dma-debug.h> + +#include <asm/cpuinfo.h> +#include <asm/spr_defs.h> +#include <asm/tlbflush.h> + +static int page_set_nocache(pte_t *pte, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + unsigned long cl; + + pte_val(*pte) |= _PAGE_CI; + + /* + * Flush the page out of the TLB so that the new page flags get + * picked up next time there's an access + */ + flush_tlb_page(NULL, addr); + + /* Flush page out of dcache */ + for (cl = __pa(addr); cl < __pa(next); cl += cpuinfo.dcache_block_size) + mtspr(SPR_DCBFR, cl); + + return 0; +} + +static int page_clear_nocache(pte_t *pte, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + pte_val(*pte) &= ~_PAGE_CI; + + /* + * Flush the page out of the TLB so that the new page flags get + * picked up next time there's an access + */ + flush_tlb_page(NULL, addr); + + return 0; +} + +/* + * Alloc "coherent" memory, which for OpenRISC means simply uncached. + * + * This function effectively just calls __get_free_pages, sets the + * cache-inhibit bit on those pages, and makes sure that the pages are + * flushed out of the cache before they are used. + * + */ +void *or1k_dma_alloc_coherent(struct device *dev, size_t size, + dma_addr_t *dma_handle, gfp_t gfp) +{ + unsigned long va; + void *page; + struct mm_walk walk = { + .pte_entry = page_set_nocache, + .mm = &init_mm + }; + + page = alloc_pages_exact(size, gfp); + if (!page) + return NULL; + + /* This gives us the real physical address of the first page. */ + *dma_handle = __pa(page); + + va = (unsigned long)page; + + /* + * We need to iterate through the pages, clearing the dcache for + * them and setting the cache-inhibit bit. + */ + if (walk_page_range(va, va + size, &walk)) { + free_pages_exact(page, size); + return NULL; + } + + return (void *)va; +} + +void or1k_dma_free_coherent(struct device *dev, size_t size, void *vaddr, + dma_addr_t dma_handle) +{ + unsigned long va = (unsigned long)vaddr; + struct mm_walk walk = { + .pte_entry = page_clear_nocache, + .mm = &init_mm + }; + + /* walk_page_range shouldn't be able to fail here */ + WARN_ON(walk_page_range(va, va + size, &walk)); + + free_pages_exact(vaddr, size); +} + +dma_addr_t or1k_map_page(struct device *dev, struct page *page, + unsigned long offset, size_t size, + enum dma_data_direction dir, + struct dma_attrs *attrs) +{ + unsigned long cl; + dma_addr_t addr = page_to_phys(page) + offset; + + switch (dir) { + case DMA_TO_DEVICE: + /* Flush the dcache for the requested range */ + for (cl = addr; cl < addr + size; + cl += cpuinfo.dcache_block_size) + mtspr(SPR_DCBFR, cl); + break; + case DMA_FROM_DEVICE: + /* Invalidate the dcache for the requested range */ + for (cl = addr; cl < addr + size; + cl += cpuinfo.dcache_block_size) + mtspr(SPR_DCBIR, cl); + break; + default: + /* + * NOTE: If dir == DMA_BIDIRECTIONAL then there's no need to + * flush nor invalidate the cache here as the area will need + * to be manually synced anyway. + */ + break; + } + + return addr; +} + +void or1k_unmap_page(struct device *dev, dma_addr_t dma_handle, + size_t size, enum dma_data_direction dir, + struct dma_attrs *attrs) +{ + /* Nothing special to do here... */ +} + +void or1k_sync_single_for_cpu(struct device *dev, + dma_addr_t dma_handle, size_t size, + enum dma_data_direction dir) +{ + unsigned long cl; + dma_addr_t addr = dma_handle; + + /* Invalidate the dcache for the requested range */ + for (cl = addr; cl < addr + size; cl += cpuinfo.dcache_block_size) + mtspr(SPR_DCBIR, cl); +} + +void or1k_sync_single_for_device(struct device *dev, + dma_addr_t dma_handle, size_t size, + enum dma_data_direction dir) +{ + unsigned long cl; + dma_addr_t addr = dma_handle; + + /* Flush the dcache for the requested range */ + for (cl = addr; cl < addr + size; cl += cpuinfo.dcache_block_size) + mtspr(SPR_DCBFR, cl); +} + +/* Number of entries preallocated for DMA-API debugging */ +#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16) + +static int __init dma_init(void) +{ + dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES); + + return 0; +} + +fs_initcall(dma_init); |