1 files changed, 160 insertions, 0 deletions
diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c
new file mode 100644
index 000000000..159336adf
--- /dev/null
+++ b/arch/openrisc/kernel/dma.c
@@ -0,0 +1,160 @@
+/*
+ * 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-noncoherent.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;
+	struct cpuinfo_or1k *cpuinfo = &cpuinfo_or1k[smp_processor_id()];
+
+	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.
+ */
+void *
+arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
+		gfp_t gfp, unsigned long 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 ((attrs & DMA_ATTR_NON_CONSISTENT) == 0) {
+		/*
+		 * 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
+arch_dma_free(struct device *dev, size_t size, void *vaddr,
+		dma_addr_t dma_handle, unsigned long attrs)
+{
+	unsigned long va = (unsigned long)vaddr;
+	struct mm_walk walk = {
+		.pte_entry = page_clear_nocache,
+		.mm = &init_mm
+	};
+
+	if ((attrs & DMA_ATTR_NON_CONSISTENT) == 0) {
+		/* walk_page_range shouldn't be able to fail here */
+		WARN_ON(walk_page_range(va, va + size, &walk));
+	}
+
+	free_pages_exact(vaddr, size);
+}
+
+void arch_sync_dma_for_device(struct device *dev, phys_addr_t addr, size_t size,
+		enum dma_data_direction dir)
+{
+	unsigned long cl;
+	struct cpuinfo_or1k *cpuinfo = &cpuinfo_or1k[smp_processor_id()];
+
+	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;
+	}
+}