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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/openrisc/kernel/dma.c
Initial import
Diffstat (limited to 'arch/openrisc/kernel/dma.c')
-rw-r--r--arch/openrisc/kernel/dma.c254
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diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c
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+/*
+ * 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 <linux/export.h>
+#include <linux/dma-attrs.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.
+ *
+ * If the NON_CONSISTENT attribute is set, then this function just
+ * returns "normal", cachable memory.
+ *
+ * There are additional flags WEAK_ORDERING and WRITE_COMBINE to take
+ * into consideration here, too. All current known implementations of
+ * the OR1K support only strongly ordered memory accesses, so that flag
+ * is being ignored for now; uncached but write-combined memory is a
+ * missing feature of the OR1K.
+ */
+static void *
+or1k_dma_alloc(struct device *dev, size_t size,
+ dma_addr_t *dma_handle, gfp_t gfp,
+ struct dma_attrs *attrs)
+{
+ 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;
+
+ if (!dma_get_attr(DMA_ATTR_NON_CONSISTENT, attrs)) {
+ /*
+ * 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;
+}
+
+static void
+or1k_dma_free(struct device *dev, size_t size, void *vaddr,
+ dma_addr_t dma_handle, struct dma_attrs *attrs)
+{
+ unsigned long va = (unsigned long)vaddr;
+ struct mm_walk walk = {
+ .pte_entry = page_clear_nocache,
+ .mm = &init_mm
+ };
+
+ if (!dma_get_attr(DMA_ATTR_NON_CONSISTENT, attrs)) {
+ /* walk_page_range shouldn't be able to fail here */
+ WARN_ON(walk_page_range(va, va + size, &walk));
+ }
+
+ free_pages_exact(vaddr, size);
+}
+
+static 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;
+}
+
+static 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... */
+}
+
+static int
+or1k_map_sg(struct device *dev, struct scatterlist *sg,
+ int nents, enum dma_data_direction dir,
+ struct dma_attrs *attrs)
+{
+ struct scatterlist *s;
+ int i;
+
+ for_each_sg(sg, s, nents, i) {
+ s->dma_address = or1k_map_page(dev, sg_page(s), s->offset,
+ s->length, dir, NULL);
+ }
+
+ return nents;
+}
+
+static void
+or1k_unmap_sg(struct device *dev, struct scatterlist *sg,
+ int nents, enum dma_data_direction dir,
+ struct dma_attrs *attrs)
+{
+ struct scatterlist *s;
+ int i;
+
+ for_each_sg(sg, s, nents, i) {
+ or1k_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir, NULL);
+ }
+}
+
+static 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);
+}
+
+static 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);
+}
+
+struct dma_map_ops or1k_dma_map_ops = {
+ .alloc = or1k_dma_alloc,
+ .free = or1k_dma_free,
+ .map_page = or1k_map_page,
+ .unmap_page = or1k_unmap_page,
+ .map_sg = or1k_map_sg,
+ .unmap_sg = or1k_unmap_sg,
+ .sync_single_for_cpu = or1k_sync_single_for_cpu,
+ .sync_single_for_device = or1k_sync_single_for_device,
+};
+EXPORT_SYMBOL(or1k_dma_map_ops);
+
+/* 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);