ARM: dmabounce: separate out decision to bounce

Move the decision to perform DMA bouncing out of map_single() into its
own stand-alone function.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 28 insertions, 18 deletions

diff --git a/arch/arm/common/dmabounce.c b/arch/arm/common/dmabounce.c
index 3e0fa1548582..643e1d660677 100644
--- a/arch/arm/common/dmabounce.c
+++ b/arch/arm/common/dmabounce.c
@@ -219,36 +219,46 @@ static struct safe_buffer *find_safe_buffer_dev(struct device *dev,
         return find_safe_buffer(dev->archdata.dmabounce, dma_addr);
 }
 
-static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
-                enum dma_data_direction dir)
+static int needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size)
 {
-        struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
-        dma_addr_t dma_addr;
-        int needs_bounce = 0;
-
-        if (device_info)
-                DO_STATS ( device_info->map_op_count++ );
-
-        dma_addr = virt_to_dma(dev, ptr);
+        if (!dev || !dev->archdata.dmabounce)
+                return 0;
 
         if (dev->dma_mask) {
-                unsigned long mask = *dev->dma_mask;
-                unsigned long limit;
+                unsigned long limit, mask = *dev->dma_mask;
 
                 limit = (mask + 1) & ~mask;
                 if (limit && size > limit) {
                         dev_err(dev, "DMA mapping too big (requested %#x "
                                 "mask %#Lx)\n", size, *dev->dma_mask);
-                        return ~0;
+                        return -E2BIG;
                 }
 
-                /*
-                 * Figure out if we need to bounce from the DMA mask.
-                 */
-                needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask;
+                /* Figure out if we need to bounce from the DMA mask. */
+                if ((dma_addr | (dma_addr + size - 1)) & ~mask)
+                        return 1;
         }
 
-        if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr, size))) {
+        return dma_needs_bounce(dev, dma_addr, size) ? 1 : 0;
+}
+
+static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
+                enum dma_data_direction dir)
+{
+        struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
+        dma_addr_t dma_addr;
+        int ret;
+
+        if (device_info)
+                DO_STATS ( device_info->map_op_count++ );
+
+        dma_addr = virt_to_dma(dev, ptr);
+
+        ret = needs_bounce(dev, dma_addr, size);
+        if (ret < 0)
+                return ~0;
+
+        if (ret > 0) {
                 struct safe_buffer *buf;
 
                 buf = alloc_safe_buffer(device_info, ptr, size, dir);