C6X: memory management and DMA support

Original port to early 2.6 kernel using TI COFF toolchain.
Brought up to date by Mark Salter <msalter@redhat.com>

The C6X architecture currently lacks an MMU so memory management is relatively
simple. There is no bus snooping between L2 and main memory but coherent DMA
memory is supported by making regions of main memory uncached. If such a region
is desired, it can be specified on the commandline with a "memdma=" argument.

Signed-off-by: Aurelien Jacquiot <a-jacquiot@ti.com>
Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 153 insertions, 0 deletions

diff --git a/arch/c6x/kernel/dma.c b/arch/c6x/kernel/dma.c
new file mode 100644
index 00000000000..ab7b12de144
--- /dev/null
+++ b/arch/c6x/kernel/dma.c
@@ -0,0 +1,153 @@
+/*
+ *  Copyright (C) 2011 Texas Instruments Incorporated
+ *  Author: Mark Salter <msalter@redhat.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.
+ */
+#include <linux/module.h>
+#include <linux/dma-mapping.h>
+#include <linux/mm.h>
+#include <linux/mm_types.h>
+#include <linux/scatterlist.h>
+
+#include <asm/cacheflush.h>
+
+static void c6x_dma_sync(dma_addr_t handle, size_t size,
+			 enum dma_data_direction dir)
+{
+	unsigned long paddr = handle;
+
+	BUG_ON(!valid_dma_direction(dir));
+
+	switch (dir) {
+	case DMA_FROM_DEVICE:
+		L2_cache_block_invalidate(paddr, paddr + size);
+		break;
+	case DMA_TO_DEVICE:
+		L2_cache_block_writeback(paddr, paddr + size);
+		break;
+	case DMA_BIDIRECTIONAL:
+		L2_cache_block_writeback_invalidate(paddr, paddr + size);
+		break;
+	default:
+		break;
+	}
+}
+
+dma_addr_t dma_map_single(struct device *dev, void *ptr, size_t size,
+			  enum dma_data_direction dir)
+{
+	dma_addr_t addr = virt_to_phys(ptr);
+
+	c6x_dma_sync(addr, size, dir);
+
+	debug_dma_map_page(dev, virt_to_page(ptr),
+			   (unsigned long)ptr & ~PAGE_MASK, size,
+			   dir, addr, true);
+	return addr;
+}
+EXPORT_SYMBOL(dma_map_single);
+
+
+void dma_unmap_single(struct device *dev, dma_addr_t handle,
+		      size_t size, enum dma_data_direction dir)
+{
+	c6x_dma_sync(handle, size, dir);
+
+	debug_dma_unmap_page(dev, handle, size, dir, true);
+}
+EXPORT_SYMBOL(dma_unmap_single);
+
+
+int dma_map_sg(struct device *dev, struct scatterlist *sglist,
+	       int nents, enum dma_data_direction dir)
+{
+	struct scatterlist *sg;
+	int i;
+
+	for_each_sg(sglist, sg, nents, i)
+		sg->dma_address = dma_map_single(dev, sg_virt(sg), sg->length,
+						 dir);
+
+	debug_dma_map_sg(dev, sglist, nents, nents, dir);
+
+	return nents;
+}
+EXPORT_SYMBOL(dma_map_sg);
+
+
+void dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
+		  int nents, enum dma_data_direction dir)
+{
+	struct scatterlist *sg;
+	int i;
+
+	for_each_sg(sglist, sg, nents, i)
+		dma_unmap_single(dev, sg_dma_address(sg), sg->length, dir);
+
+	debug_dma_unmap_sg(dev, sglist,	nents, dir);
+}
+EXPORT_SYMBOL(dma_unmap_sg);
+
+void dma_sync_single_for_cpu(struct device *dev, dma_addr_t handle,
+			     size_t size, enum dma_data_direction dir)
+{
+	c6x_dma_sync(handle, size, dir);
+
+	debug_dma_sync_single_for_cpu(dev, handle, size, dir);
+}
+EXPORT_SYMBOL(dma_sync_single_for_cpu);
+
+
+void dma_sync_single_for_device(struct device *dev, dma_addr_t handle,
+				size_t size, enum dma_data_direction dir)
+{
+	c6x_dma_sync(handle, size, dir);
+
+	debug_dma_sync_single_for_device(dev, handle, size, dir);
+}
+EXPORT_SYMBOL(dma_sync_single_for_device);
+
+
+void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sglist,
+			 int nents, enum dma_data_direction dir)
+{
+	struct scatterlist *sg;
+	int i;
+
+	for_each_sg(sglist, sg, nents, i)
+		dma_sync_single_for_cpu(dev, sg_dma_address(sg),
+					sg->length, dir);
+
+	debug_dma_sync_sg_for_cpu(dev, sglist, nents, dir);
+}
+EXPORT_SYMBOL(dma_sync_sg_for_cpu);
+
+
+void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sglist,
+			    int nents, enum dma_data_direction dir)
+{
+	struct scatterlist *sg;
+	int i;
+
+	for_each_sg(sglist, sg, nents, i)
+		dma_sync_single_for_device(dev, sg_dma_address(sg),
+					   sg->length, dir);
+
+	debug_dma_sync_sg_for_device(dev, sglist, nents, dir);
+}
+EXPORT_SYMBOL(dma_sync_sg_for_device);
+
+
+/* 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);