[PATCH] mmc: multi sector write transfers

SD cards extend the protocol by allowing the host to query a card how many
blocks were successfully stored on the medium.  This allows us to safely write
chunks of blocks at once.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 95 insertions, 9 deletions

diff --git a/drivers/mmc/mmc_block.c b/drivers/mmc/mmc_block.c
index c1293f1bda87..f9027c8db792 100644
--- a/drivers/mmc/mmc_block.c
+++ b/drivers/mmc/mmc_block.c
@@ -28,6 +28,7 @@
 #include <linux/kdev_t.h>
 #include <linux/blkdev.h>
 #include <linux/mutex.h>
+#include <linux/scatterlist.h>
 
 #include <linux/mmc/card.h>
 #include <linux/mmc/host.h>
@@ -154,6 +155,71 @@ static int mmc_blk_prep_rq(struct mmc_queue *mq, struct request *req)
         return stat;
 }
 
+static u32 mmc_sd_num_wr_blocks(struct mmc_card *card)
+{
+        int err;
+        u32 blocks;
+
+        struct mmc_request mrq;
+        struct mmc_command cmd;
+        struct mmc_data data;
+        unsigned int timeout_us;
+
+        struct scatterlist sg;
+
+        memset(&cmd, 0, sizeof(struct mmc_command));
+
+        cmd.opcode = MMC_APP_CMD;
+        cmd.arg = card->rca << 16;
+        cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
+
+        err = mmc_wait_for_cmd(card->host, &cmd, 0);
+        if ((err != MMC_ERR_NONE) || !(cmd.resp[0] & R1_APP_CMD))
+                return (u32)-1;
+
+        memset(&cmd, 0, sizeof(struct mmc_command));
+
+        cmd.opcode = SD_APP_SEND_NUM_WR_BLKS;
+        cmd.arg = 0;
+        cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
+
+        memset(&data, 0, sizeof(struct mmc_data));
+
+        data.timeout_ns = card->csd.tacc_ns * 100;
+        data.timeout_clks = card->csd.tacc_clks * 100;
+
+        timeout_us = data.timeout_ns / 1000;
+        timeout_us += data.timeout_clks * 1000 /
+                (card->host->ios.clock / 1000);
+
+        if (timeout_us > 100000) {
+                data.timeout_ns = 100000000;
+                data.timeout_clks = 0;
+        }
+
+        data.blksz = 4;
+        data.blocks = 1;
+        data.flags = MMC_DATA_READ;
+        data.sg = &sg;
+        data.sg_len = 1;
+
+        memset(&mrq, 0, sizeof(struct mmc_request));
+
+        mrq.cmd = &cmd;
+        mrq.data = &data;
+
+        sg_init_one(&sg, &blocks, 4);
+
+        mmc_wait_for_req(card->host, &mrq);
+
+        if (cmd.error != MMC_ERR_NONE || data.error != MMC_ERR_NONE)
+                return (u32)-1;
+
+        blocks = ntohl(blocks);
+
+        return blocks;
+}
+
 static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 {
         struct mmc_blk_data *md = mq->data;
@@ -184,10 +250,13 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
 
                 /*
                  * If the host doesn't support multiple block writes, force
-                 * block writes to single block.
+                 * block writes to single block. SD cards are excepted from
+                 * this rule as they support querying the number of
+                 * successfully written sectors.
                  */
                 if (rq_data_dir(req) != READ &&
-                    !(card->host->caps & MMC_CAP_MULTIWRITE))
+                    !(card->host->caps & MMC_CAP_MULTIWRITE) &&
+                    !mmc_card_sd(card))
                         brq.data.blocks = 1;
 
                 if (brq.data.blocks > 1) {
@@ -276,24 +345,41 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
         return 1;
 
  cmd_err:
-        mmc_card_release_host(card);
-
         ret = 1;
 
-        /*
-         * For writes and where the host claims to support proper
-         * error reporting, we first ok the successful blocks.
+        /*
+         * If this is an SD card and we're writing, we can first
+         * mark the known good sectors as ok.
+         *
+         * If the card is not SD, we can still ok written sectors
+         * if the controller can do proper error reporting.
          *
          * For reads we just fail the entire chunk as that should
          * be safe in all cases.
          */
-        if (rq_data_dir(req) != READ &&
-            (card->host->caps & MMC_CAP_MULTIWRITE)) {
+        if (rq_data_dir(req) != READ && mmc_card_sd(card)) {
+                u32 blocks;
+                unsigned int bytes;
+
+                blocks = mmc_sd_num_wr_blocks(card);
+                if (blocks != (u32)-1) {
+                        if (card->csd.write_partial)
+                                bytes = blocks << md->block_bits;
+                        else
+                                bytes = blocks << 9;
+                        spin_lock_irq(&md->lock);
+                        ret = end_that_request_chunk(req, 1, bytes);
+                        spin_unlock_irq(&md->lock);
+                }
+        } else if (rq_data_dir(req) != READ &&
+                   (card->host->caps & MMC_CAP_MULTIWRITE)) {
                 spin_lock_irq(&md->lock);
                 ret = end_that_request_chunk(req, 1, brq.data.bytes_xfered);
                 spin_unlock_irq(&md->lock);
         }
 
+        mmc_card_release_host(card);
+
         spin_lock_irq(&md->lock);
         while (ret) {
                 ret = end_that_request_chunk(req, 0,