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Date: Wed, 13 Oct 2010 16:57:35 -0700
From: Kevin Cernekee <cernekee@...il.com>
To: Ralf Baechle <ralf@...ux-mips.org>
Cc: <dediao@...co.com>, <ddaney@...iumnetworks.com>,
<dvomlehn@...co.com>, <sshtylyov@...sta.com>,
<linux-mips@...ux-mips.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v4] MIPS: HIGHMEM DMA on noncoherent MIPS32 processors
[v4: Patch applies to linux-queue.git with kmap_atomic patches:
https://patchwork.kernel.org/patch/189932/
https://patchwork.kernel.org/patch/194552/
https://patchwork.kernel.org/patch/189912/ ]
The MIPS DMA coherency functions do not work properly (i.e. kernel oops)
when HIGHMEM pages are passed in as arguments. Use kmap_atomic() to
temporarily map high pages for cache maintenance operations.
Tested on a 2.6.36-rc7 1GB HIGHMEM SMP no-alias system.
Signed-off-by: Dezhong Diao <dediao@...co.com>
Signed-off-by: Kevin Cernekee <cernekee@...il.com>
---
arch/mips/mm/dma-default.c | 114 ++++++++++++++++++++++++++------------------
1 files changed, 68 insertions(+), 46 deletions(-)
diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
index 4fc1a0f..1e20758 100644
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -15,18 +15,18 @@
#include <linux/scatterlist.h>
#include <linux/string.h>
#include <linux/gfp.h>
+#include <linux/highmem.h>
#include <asm/cache.h>
#include <asm/io.h>
#include <dma-coherence.h>
-static inline unsigned long dma_addr_to_virt(struct device *dev,
+static inline struct page *dma_addr_to_page(struct device *dev,
dma_addr_t dma_addr)
{
- unsigned long addr = plat_dma_addr_to_phys(dev, dma_addr);
-
- return (unsigned long)phys_to_virt(addr);
+ return pfn_to_page(
+ plat_dma_addr_to_phys(dev, dma_addr) >> PAGE_SHIFT);
}
/*
@@ -148,20 +148,20 @@ static void mips_dma_free_coherent(struct device *dev, size_t size, void *vaddr,
free_pages(addr, get_order(size));
}
-static inline void __dma_sync(unsigned long addr, size_t size,
+static inline void __dma_sync_virtual(void *addr, size_t size,
enum dma_data_direction direction)
{
switch (direction) {
case DMA_TO_DEVICE:
- dma_cache_wback(addr, size);
+ dma_cache_wback((unsigned long)addr, size);
break;
case DMA_FROM_DEVICE:
- dma_cache_inv(addr, size);
+ dma_cache_inv((unsigned long)addr, size);
break;
case DMA_BIDIRECTIONAL:
- dma_cache_wback_inv(addr, size);
+ dma_cache_wback_inv((unsigned long)addr, size);
break;
default:
@@ -169,12 +169,49 @@ static inline void __dma_sync(unsigned long addr, size_t size,
}
}
+/*
+ * A single sg entry may refer to multiple physically contiguous
+ * pages. But we still need to process highmem pages individually.
+ * If highmem is not configured then the bulk of this loop gets
+ * optimized out.
+ */
+static inline void __dma_sync(struct page *page,
+ unsigned long offset, size_t size, enum dma_data_direction direction)
+{
+ size_t left = size;
+
+ do {
+ size_t len = left;
+
+ if (PageHighMem(page)) {
+ void *addr;
+
+ if (offset + len > PAGE_SIZE) {
+ if (offset >= PAGE_SIZE) {
+ page += offset >> PAGE_SHIFT;
+ offset &= ~PAGE_MASK;
+ }
+ len = PAGE_SIZE - offset;
+ }
+
+ addr = kmap_atomic(page);
+ __dma_sync_virtual(addr + offset, len, direction);
+ kunmap_atomic(addr);
+ } else
+ __dma_sync_virtual(page_address(page) + offset,
+ size, direction);
+ offset = 0;
+ page++;
+ left -= len;
+ } while (left);
+}
+
static void mips_dma_unmap_page(struct device *dev, dma_addr_t dma_addr,
size_t size, enum dma_data_direction direction, struct dma_attrs *attrs)
{
if (cpu_is_noncoherent_r10000(dev))
- __dma_sync(dma_addr_to_virt(dev, dma_addr), size,
- direction);
+ __dma_sync(dma_addr_to_page(dev, dma_addr),
+ dma_addr & ~PAGE_MASK, size, direction);
plat_unmap_dma_mem(dev, dma_addr, size, direction);
}
@@ -185,13 +222,11 @@ static int mips_dma_map_sg(struct device *dev, struct scatterlist *sg,
int i;
for (i = 0; i < nents; i++, sg++) {
- unsigned long addr;
-
- addr = (unsigned long) sg_virt(sg);
- if (!plat_device_is_coherent(dev) && addr)
- __dma_sync(addr, sg->length, direction);
- sg->dma_address = plat_map_dma_mem(dev,
- (void *)addr, sg->length);
+ if (!plat_device_is_coherent(dev))
+ __dma_sync(sg_page(sg), sg->offset, sg->length,
+ direction);
+ sg->dma_address = plat_map_dma_mem_page(dev, sg_page(sg)) +
+ sg->offset;
}
return nents;
@@ -201,30 +236,23 @@ static dma_addr_t mips_dma_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size, enum dma_data_direction direction,
struct dma_attrs *attrs)
{
- unsigned long addr;
-
- addr = (unsigned long) page_address(page) + offset;
-
if (!plat_device_is_coherent(dev))
- __dma_sync(addr, size, direction);
+ __dma_sync(page, offset, size, direction);
- return plat_map_dma_mem(dev, (void *)addr, size);
+ return plat_map_dma_mem_page(dev, page) + offset;
}
static void mips_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
int nhwentries, enum dma_data_direction direction,
struct dma_attrs *attrs)
{
- unsigned long addr;
int i;
for (i = 0; i < nhwentries; i++, sg++) {
if (!plat_device_is_coherent(dev) &&
- direction != DMA_TO_DEVICE) {
- addr = (unsigned long) sg_virt(sg);
- if (addr)
- __dma_sync(addr, sg->length, direction);
- }
+ direction != DMA_TO_DEVICE)
+ __dma_sync(sg_page(sg), sg->offset, sg->length,
+ direction);
plat_unmap_dma_mem(dev, sg->dma_address, sg->length, direction);
}
}
@@ -232,24 +260,18 @@ static void mips_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
static void mips_dma_sync_single_for_cpu(struct device *dev,
dma_addr_t dma_handle, size_t size, enum dma_data_direction direction)
{
- if (cpu_is_noncoherent_r10000(dev)) {
- unsigned long addr;
-
- addr = dma_addr_to_virt(dev, dma_handle);
- __dma_sync(addr, size, direction);
- }
+ if (cpu_is_noncoherent_r10000(dev))
+ __dma_sync(dma_addr_to_page(dev, dma_handle),
+ dma_handle & ~PAGE_MASK, size, direction);
}
static void mips_dma_sync_single_for_device(struct device *dev,
dma_addr_t dma_handle, size_t size, enum dma_data_direction direction)
{
plat_extra_sync_for_device(dev);
- if (!plat_device_is_coherent(dev)) {
- unsigned long addr;
-
- addr = dma_addr_to_virt(dev, dma_handle);
- __dma_sync(addr, size, direction);
- }
+ if (!plat_device_is_coherent(dev))
+ __dma_sync(dma_addr_to_page(dev, dma_handle),
+ dma_handle & ~PAGE_MASK, size, direction);
}
static void mips_dma_sync_sg_for_cpu(struct device *dev,
@@ -260,8 +282,8 @@ static void mips_dma_sync_sg_for_cpu(struct device *dev,
/* Make sure that gcc doesn't leave the empty loop body. */
for (i = 0; i < nelems; i++, sg++) {
if (cpu_is_noncoherent_r10000(dev))
- __dma_sync((unsigned long)page_address(sg_page(sg)),
- sg->length, direction);
+ __dma_sync(sg_page(sg), sg->offset, sg->length,
+ direction);
}
}
@@ -273,8 +295,8 @@ static void mips_dma_sync_sg_for_device(struct device *dev,
/* Make sure that gcc doesn't leave the empty loop body. */
for (i = 0; i < nelems; i++, sg++) {
if (!plat_device_is_coherent(dev))
- __dma_sync((unsigned long)page_address(sg_page(sg)),
- sg->length, direction);
+ __dma_sync(sg_page(sg), sg->offset, sg->length,
+ direction);
}
}
@@ -295,7 +317,7 @@ void mips_dma_cache_sync(struct device *dev, void *vaddr, size_t size,
plat_extra_sync_for_device(dev);
if (!plat_device_is_coherent(dev))
- __dma_sync((unsigned long)vaddr, size, direction);
+ __dma_sync_virtual(vaddr, size, direction);
}
static struct dma_map_ops mips_default_dma_map_ops = {
--
1.7.0.4
--
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