[PATCH V17 09/13] MIPS: Loongson: Add swiotlb to support big memory (>4GB)

[Huacai Chen <chenhc@lemote.com>]

This is probably a workaround because Loongson doesn't support DMA
address above 4GB. If memory is more than 4GB, CONFIG_SWIOTLB and
ZONE_DMA32 should be selected. In this way, DMA pages are allocated
below 4GB preferably.

However, CONFIG_SWIOTLB+ZONE_DMA32 is not enough, so, we provide a
platform-specific dma_map_ops::set_dma_mask() to make sure each
driver's dma_mask and coherent_dma_mask is below 32-bit.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Hongliang Tao <taohl@lemote.com>
Signed-off-by: Hua Yan <yanh@lemote.com>
---
 arch/mips/include/asm/dma-mapping.h                |    5 +
 .../mips/include/asm/mach-loongson/dma-coherence.h |   22 +++-
 arch/mips/loongson/common/Makefile                 |    5 +
 arch/mips/loongson/common/dma-swiotlb.c            |  137 ++++++++++++++++++++
 4 files changed, 168 insertions(+), 1 deletions(-)
 create mode 100644 arch/mips/loongson/common/dma-swiotlb.c

diff --git a/arch/mips/include/asm/dma-mapping.h b/arch/mips/include/asm/dma-mapping.h
index 84238c5..06412aa 100644
--- a/arch/mips/include/asm/dma-mapping.h
+++ b/arch/mips/include/asm/dma-mapping.h
@@ -49,9 +49,14 @@ static inline int dma_mapping_error(struct device *dev, u64 mask)
 static inline int
 dma_set_mask(struct device *dev, u64 mask)
 {
+	struct dma_map_ops *ops = get_dma_ops(dev);
+
 	if(!dev->dma_mask || !dma_supported(dev, mask))
 		return -EIO;
 
+	if (ops->set_dma_mask)
+		return ops->set_dma_mask(dev, mask);
+
 	*dev->dma_mask = mask;
 
 	return 0;
diff --git a/arch/mips/include/asm/mach-loongson/dma-coherence.h b/arch/mips/include/asm/mach-loongson/dma-coherence.h
index aeb2c05..6a90275 100644
--- a/arch/mips/include/asm/mach-loongson/dma-coherence.h
+++ b/arch/mips/include/asm/mach-loongson/dma-coherence.h
@@ -11,24 +11,40 @@
 #ifndef __ASM_MACH_LOONGSON_DMA_COHERENCE_H
 #define __ASM_MACH_LOONGSON_DMA_COHERENCE_H
 
+#ifdef CONFIG_SWIOTLB
+#include <linux/swiotlb.h>
+#endif
+
 struct device;
 
+extern dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr);
+extern phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr);
 static inline dma_addr_t plat_map_dma_mem(struct device *dev, void *addr,
 					  size_t size)
 {
+#ifdef CONFIG_CPU_LOONGSON3
+	return virt_to_phys(addr);
+#else
 	return virt_to_phys(addr) | 0x80000000;
+#endif
 }
 
 static inline dma_addr_t plat_map_dma_mem_page(struct device *dev,
 					       struct page *page)
 {
+#ifdef CONFIG_CPU_LOONGSON3
+	return page_to_phys(page);
+#else
 	return page_to_phys(page) | 0x80000000;
+#endif
 }
 
 static inline unsigned long plat_dma_addr_to_phys(struct device *dev,
 	dma_addr_t dma_addr)
 {
-#if defined(CONFIG_CPU_LOONGSON2F) && defined(CONFIG_64BIT)
+#if defined(CONFIG_CPU_LOONGSON3) && defined(CONFIG_64BIT)
+	return dma_addr;
+#elif defined(CONFIG_CPU_LOONGSON2F) && defined(CONFIG_64BIT)
 	return (dma_addr > 0x8fffffff) ? dma_addr : (dma_addr & 0x0fffffff);
 #else
 	return dma_addr & 0x7fffffff;
@@ -55,7 +71,11 @@ static inline int plat_dma_supported(struct device *dev, u64 mask)
 
 static inline int plat_device_is_coherent(struct device *dev)
 {
+#ifdef CONFIG_DMA_NONCOHERENT
 	return 0;
+#else
+	return 1;
+#endif /* CONFIG_DMA_NONCOHERENT */
 }
 
 #endif /* __ASM_MACH_LOONGSON_DMA_COHERENCE_H */
diff --git a/arch/mips/loongson/common/Makefile b/arch/mips/loongson/common/Makefile
index 9e4484c..0bb9cc9 100644
--- a/arch/mips/loongson/common/Makefile
+++ b/arch/mips/loongson/common/Makefile
@@ -26,3 +26,8 @@ obj-$(CONFIG_CS5536) += cs5536/
 #
 
 obj-$(CONFIG_LOONGSON_SUSPEND) += pm.o
+
+#
+# Big Memory (SWIOTLB) Support
+#
+obj-$(CONFIG_SWIOTLB) += dma-swiotlb.o
diff --git a/arch/mips/loongson/common/dma-swiotlb.c b/arch/mips/loongson/common/dma-swiotlb.c
new file mode 100644
index 0000000..dcf7d0b
--- /dev/null
+++ b/arch/mips/loongson/common/dma-swiotlb.c
@@ -0,0 +1,137 @@
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/dma-mapping.h>
+#include <linux/scatterlist.h>
+#include <linux/swiotlb.h>
+#include <linux/bootmem.h>
+
+#include <asm/bootinfo.h>
+#include <dma-coherence.h>
+
+static void *loongson_dma_alloc_coherent(struct device *dev, size_t size,
+		dma_addr_t *dma_handle, gfp_t gfp, struct dma_attrs *attrs)
+{
+	void *ret;
+
+	if (dma_alloc_from_coherent(dev, size, dma_handle, &ret))
+		return ret;
+
+	/* ignore region specifiers */
+	gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM);
+
+#ifdef CONFIG_ISA
+	if (dev == NULL)
+		gfp |= __GFP_DMA;
+	else
+#endif
+#ifdef CONFIG_ZONE_DMA
+	if (dev->coherent_dma_mask < DMA_BIT_MASK(32))
+		gfp |= __GFP_DMA;
+	else
+#endif
+#ifdef CONFIG_ZONE_DMA32
+	 /* Loongson-3 only support DMA in the memory below 4GB now */
+	if (dev->coherent_dma_mask < DMA_BIT_MASK(40))
+		gfp |= __GFP_DMA32;
+	else
+#endif
+	;
+	gfp |= __GFP_NORETRY;
+
+	ret = swiotlb_alloc_coherent(dev, size, dma_handle, gfp);
+	mb();
+	return ret;
+}
+
+static void loongson_dma_free_coherent(struct device *dev, size_t size,
+		void *vaddr, dma_addr_t dma_handle, struct dma_attrs *attrs)
+{
+	int order = get_order(size);
+
+	if (dma_release_from_coherent(dev, order, vaddr))
+		return;
+
+	swiotlb_free_coherent(dev, size, vaddr, dma_handle);
+}
+
+static dma_addr_t loongson_dma_map_page(struct device *dev, struct page *page,
+				unsigned long offset, size_t size,
+				enum dma_data_direction dir,
+				struct dma_attrs *attrs)
+{
+	dma_addr_t daddr = swiotlb_map_page(dev, page, offset, size,
+					dir, attrs);
+	mb();
+	return daddr;
+}
+
+static int loongson_dma_map_sg(struct device *dev, struct scatterlist *sg,
+				int nents, enum dma_data_direction dir,
+				struct dma_attrs *attrs)
+{
+	int r = swiotlb_map_sg_attrs(dev, sg, nents, dir, NULL);
+	mb();
+
+	return r;
+}
+
+static void loongson_dma_sync_single_for_device(struct device *dev,
+				dma_addr_t dma_handle, size_t size,
+				enum dma_data_direction dir)
+{
+	swiotlb_sync_single_for_device(dev, dma_handle, size, dir);
+	mb();
+}
+
+static void loongson_dma_sync_sg_for_device(struct device *dev,
+				struct scatterlist *sg, int nents,
+				enum dma_data_direction dir)
+{
+	swiotlb_sync_sg_for_device(dev, sg, nents, dir);
+	mb();
+}
+
+static int loongson_dma_set_mask(struct device *dev, u64 mask)
+{
+	/* Loongson doesn't support DMA above 32-bit */
+	if (mask > DMA_BIT_MASK(32)) {
+		*dev->dma_mask = DMA_BIT_MASK(32);
+		return -EIO;
+	}
+
+	*dev->dma_mask = mask;
+
+	return 0;
+}
+
+dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
+{
+	return paddr;
+}
+
+phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
+{
+	return daddr;
+}
+
+static struct dma_map_ops loongson_dma_map_ops = {
+	.alloc = loongson_dma_alloc_coherent,
+	.free = loongson_dma_free_coherent,
+	.map_page = loongson_dma_map_page,
+	.unmap_page = swiotlb_unmap_page,
+	.map_sg = loongson_dma_map_sg,
+	.unmap_sg = swiotlb_unmap_sg_attrs,
+	.sync_single_for_cpu = swiotlb_sync_single_for_cpu,
+	.sync_single_for_device = loongson_dma_sync_single_for_device,
+	.sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
+	.sync_sg_for_device = loongson_dma_sync_sg_for_device,
+	.mapping_error = swiotlb_dma_mapping_error,
+	.dma_supported = swiotlb_dma_supported,
+	.set_dma_mask = loongson_dma_set_mask
+};
+
+void __init plat_swiotlb_setup(void)
+{
+	swiotlb_init(1);
+	mips_dma_map_ops = &loongson_dma_map_ops;
+}
-- 
1.7.7.3