ARC: I/O and DMA Mappings

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

1 files changed, 94 insertions, 0 deletions

diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c
new file mode 100644
index 0000000..12cc648
--- /dev/null
+++ b/arch/arc/mm/dma.c
@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ * DMA Coherent API Notes
+ *
+ * I/O is inherently non-coherent on ARC. So a coherent DMA buffer is
+ * implemented by accessintg it using a kernel virtual address, with
+ * 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/cacheflush.h>
+
+/*
+ * Helpers for Coherent DMA API.
+ */
+void *dma_alloc_noncoherent(struct device *dev, size_t size,
+			    dma_addr_t *dma_handle, gfp_t gfp)
+{
+	void *paddr;
+
+	/* This is linear addr (0x8000_0000 based) */
+	paddr = alloc_pages_exact(size, gfp);
+	if (!paddr)
+		return NULL;
+
+	/* This is bus address, platform dependent */
+	*dma_handle = plat_kernel_addr_to_dma(dev, paddr);
+
+	return paddr;
+}
+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);
+}
+EXPORT_SYMBOL(dma_free_noncoherent);
+
+void *dma_alloc_coherent(struct device *dev, size_t size,
+			 dma_addr_t *dma_handle, gfp_t gfp)
+{
+	void *paddr, *kvaddr;
+
+	/* This is linear addr (0x8000_0000 based) */
+	paddr = alloc_pages_exact(size, gfp);
+	if (!paddr)
+		return NULL;
+
+	/* This is kernel Virtual address (0x7000_0000 based) */
+	kvaddr = ioremap_nocache((unsigned long)paddr, size);
+	if (kvaddr != NULL)
+		memset(kvaddr, 0, size);
+
+	/* This is bus address, platform dependent */
+	*dma_handle = plat_kernel_addr_to_dma(dev, paddr);
+
+	return kvaddr;
+}
+EXPORT_SYMBOL(dma_alloc_coherent);
+
+void dma_free_coherent(struct device *dev, size_t size, void *kvaddr,
+		       dma_addr_t dma_handle)
+{
+	iounmap((void __force __iomem *)kvaddr);
+
+	free_pages_exact((void *)plat_dma_addr_to_kernel(dev, dma_handle),
+			 size);
+}
+EXPORT_SYMBOL(dma_free_coherent);
+
+/*
+ * Helper for streaming DMA...
+ */
+void __arc_dma_cache_sync(unsigned long paddr, size_t size,
+			  enum dma_data_direction dir)
+{
+	__inline_dma_cache_sync(paddr, size, dir);
+}
+EXPORT_SYMBOL(__arc_dma_cache_sync);