mmc_block: bounce buffer highmem support

Support highmem pages in the bounce buffer code by using the
sg_copy_from/to_buffer() functions.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

1 files changed, 31 insertions, 66 deletions

diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index 7731ddefdc1b..3dee97e7d165 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -148,7 +148,7 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card, spinlock_t *lock
                         printk(KERN_WARNING "%s: unable to allocate "
                                 "bounce buffer\n", mmc_card_name(card));
                 } else {
-                        blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_HIGH);
+                        blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_ANY);
                         blk_queue_max_sectors(mq->queue, bouncesz / 512);
                         blk_queue_max_phys_segments(mq->queue, bouncesz / 512);
                         blk_queue_max_hw_segments(mq->queue, bouncesz / 512);
@@ -290,55 +290,15 @@ void mmc_queue_resume(struct mmc_queue *mq)
         }
 }
 
-static void copy_sg(struct scatterlist *dst, unsigned int dst_len,
-        struct scatterlist *src, unsigned int src_len)
-{
-        unsigned int chunk;
-        char *dst_buf, *src_buf;
-        unsigned int dst_size, src_size;
-
-        dst_buf = NULL;
-        src_buf = NULL;
-        dst_size = 0;
-        src_size = 0;
-
-        while (src_len) {
-                BUG_ON(dst_len == 0);
-
-                if (dst_size == 0) {
-                        dst_buf = sg_virt(dst);
-                        dst_size = dst->length;
-                }
-
-                if (src_size == 0) {
-                        src_buf = sg_virt(src);
-                        src_size = src->length;
-                }
-
-                chunk = min(dst_size, src_size);
-
-                memcpy(dst_buf, src_buf, chunk);
-
-                dst_buf += chunk;
-                src_buf += chunk;
-                dst_size -= chunk;
-                src_size -= chunk;
-
-                if (dst_size == 0) {
-                        dst++;
-                        dst_len--;
-                }
-
-                if (src_size == 0) {
-                        src++;
-                        src_len--;
-                }
-        }
-}
-
+/*
+ * Prepare the sg list(s) to be handed of to the host driver
+ */
 unsigned int mmc_queue_map_sg(struct mmc_queue *mq)
 {
         unsigned int sg_len;
+        size_t buflen;
+        struct scatterlist *sg;
+        int i;
 
         if (!mq->bounce_buf)
                 return blk_rq_map_sg(mq->queue, mq->req, mq->sg);
@@ -349,47 +309,52 @@ unsigned int mmc_queue_map_sg(struct mmc_queue *mq)
 
         mq->bounce_sg_len = sg_len;
 
-        /*
-         * Shortcut in the event we only get a single entry.
-         */
-        if (sg_len == 1) {
-                memcpy(mq->sg, mq->bounce_sg, sizeof(struct scatterlist));
-                return 1;
-        }
+        buflen = 0;
+        for_each_sg(mq->bounce_sg, sg, sg_len, i)
+                buflen += sg->length;
 
-        sg_init_one(mq->sg, mq->bounce_buf, 0);
-
-        while (sg_len) {
-                mq->sg[0].length += mq->bounce_sg[sg_len - 1].length;
-                sg_len--;
-        }
+        sg_init_one(mq->sg, mq->bounce_buf, buflen);
 
         return 1;
 }
 
+/*
+ * If writing, bounce the data to the buffer before the request
+ * is sent to the host driver
+ */
 void mmc_queue_bounce_pre(struct mmc_queue *mq)
 {
+        unsigned long flags;
+
         if (!mq->bounce_buf)
                 return;
 
-        if (mq->bounce_sg_len == 1)
-                return;
         if (rq_data_dir(mq->req) != WRITE)
                 return;
 
-        copy_sg(mq->sg, 1, mq->bounce_sg, mq->bounce_sg_len);
+        local_irq_save(flags);
+        sg_copy_to_buffer(mq->bounce_sg, mq->bounce_sg_len,
+                mq->bounce_buf, mq->sg[0].length);
+        local_irq_restore(flags);
 }
 
+/*
+ * If reading, bounce the data from the buffer after the request
+ * has been handled by the host driver
+ */
 void mmc_queue_bounce_post(struct mmc_queue *mq)
 {
+        unsigned long flags;
+
         if (!mq->bounce_buf)
                 return;
 
-        if (mq->bounce_sg_len == 1)
-                return;
         if (rq_data_dir(mq->req) != READ)
                 return;
 
-        copy_sg(mq->bounce_sg, mq->bounce_sg_len, mq->sg, 1);
+        local_irq_save(flags);
+        sg_copy_from_buffer(mq->bounce_sg, mq->bounce_sg_len,
+                mq->bounce_buf, mq->sg[0].length);
+        local_irq_restore(flags);
 }