1 files changed, 98 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/pci-dma.c b/arch/xtensa/kernel/pci-dma.c
new file mode 100644
index 000000000..94955caa4
--- /dev/null
+++ b/arch/xtensa/kernel/pci-dma.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * DMA coherent memory allocation.
+ *
+ * Copyright (C) 2002 - 2005 Tensilica Inc.
+ * Copyright (C) 2015 Cadence Design Systems Inc.
+ *
+ * Based on version for i386.
+ *
+ * Chris Zankel <chris@zankel.net>
+ * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
+ */
+
+#include <linux/dma-map-ops.h>
+#include <linux/dma-direct.h>
+#include <linux/gfp.h>
+#include <linux/highmem.h>
+#include <linux/mm.h>
+#include <linux/types.h>
+#include <asm/cacheflush.h>
+#include <asm/io.h>
+#include <asm/platform.h>
+
+static void do_cache_op(phys_addr_t paddr, size_t size,
+			void (*fn)(unsigned long, unsigned long))
+{
+	unsigned long off = paddr & (PAGE_SIZE - 1);
+	unsigned long pfn = PFN_DOWN(paddr);
+	struct page *page = pfn_to_page(pfn);
+
+	if (!PageHighMem(page))
+		fn((unsigned long)phys_to_virt(paddr), size);
+	else
+		while (size > 0) {
+			size_t sz = min_t(size_t, size, PAGE_SIZE - off);
+			void *vaddr = kmap_atomic(page);
+
+			fn((unsigned long)vaddr + off, sz);
+			kunmap_atomic(vaddr);
+			off = 0;
+			++page;
+			size -= sz;
+		}
+}
+
+void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
+		enum dma_data_direction dir)
+{
+	switch (dir) {
+	case DMA_BIDIRECTIONAL:
+	case DMA_FROM_DEVICE:
+		do_cache_op(paddr, size, __invalidate_dcache_range);
+		break;
+
+	case DMA_NONE:
+		BUG();
+		break;
+
+	default:
+		break;
+	}
+}
+
+void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
+		enum dma_data_direction dir)
+{
+	switch (dir) {
+	case DMA_BIDIRECTIONAL:
+	case DMA_TO_DEVICE:
+		if (XCHAL_DCACHE_IS_WRITEBACK)
+			do_cache_op(paddr, size, __flush_dcache_range);
+		break;
+
+	case DMA_NONE:
+		BUG();
+		break;
+
+	default:
+		break;
+	}
+}
+
+void arch_dma_prep_coherent(struct page *page, size_t size)
+{
+	__invalidate_dcache_range((unsigned long)page_address(page), size);
+}
+
+/*
+ * Memory caching is platform-dependent in noMMU xtensa configurations.
+ * This function should be implemented in platform code in order to enable
+ * coherent DMA memory operations when CONFIG_MMU is not enabled.
+ */
+#ifdef CONFIG_MMU
+void *arch_dma_set_uncached(void *p, size_t size)
+{
+	return p + XCHAL_KSEG_BYPASS_VADDR - XCHAL_KSEG_CACHED_VADDR;
+}
+#endif /* CONFIG_MMU */