omap_hsmmc: Implement scatter-gather emulation

Instead of using the bounce buffer, using scatter-gather emulation
(as in the OMAP1/2 MMC driver) removes the need of one extra memory
copy and improves performance.

Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

1 files changed, 95 insertions, 77 deletions

diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index 1f84bd4a3b27..483e591f7bbb 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -100,9 +100,6 @@
 #define OMAP_MMC1_DEVID         0
 #define OMAP_MMC2_DEVID         1
 
-#define OMAP_MMC_DATADIR_NONE   0
-#define OMAP_MMC_DATADIR_READ   1
-#define OMAP_MMC_DATADIR_WRITE  2
 #define MMC_TIMEOUT_MS          20
 #define OMAP_MMC_MASTER_CLOCK   96000000
 #define DRIVER_NAME             "mmci-omap-hs"
@@ -138,16 +135,14 @@ struct mmc_omap_host {
         resource_size_t         mapbase;
         unsigned int            id;
         unsigned int            dma_len;
-        unsigned int            dma_dir;
+        unsigned int            dma_sg_idx;
         unsigned char           bus_mode;
-        unsigned char           datadir;
         u32                     *buffer;
         u32                     bytesleft;
         int                     suspended;
         int                     irq;
         int                     carddetect;
         int                     use_dma, dma_ch;
-        int                     initstr;
         int                     slot_id;
         int                     dbclk_enabled;
         int                     response_busy;
@@ -281,6 +276,15 @@ mmc_omap_start_command(struct mmc_omap_host *host, struct mmc_command *cmd,
         OMAP_HSMMC_WRITE(host->base, CMD, cmdreg);
 }
 
+static int
+mmc_omap_get_dma_dir(struct mmc_omap_host *host, struct mmc_data *data)
+{
+        if (data->flags & MMC_DATA_WRITE)
+                return DMA_TO_DEVICE;
+        else
+                return DMA_FROM_DEVICE;
+}
+
 /*
  * Notify the transfer complete to MMC core
  */
@@ -300,9 +304,7 @@ mmc_omap_xfer_done(struct mmc_omap_host *host, struct mmc_data *data)
 
         if (host->use_dma && host->dma_ch != -1)
                 dma_unmap_sg(mmc_dev(host->mmc), data->sg, host->dma_len,
-                        host->dma_dir);
-
-        host->datadir = OMAP_MMC_DATADIR_NONE;
+                        mmc_omap_get_dma_dir(host, data));
 
         if (!data->error)
                 data->bytes_xfered += data->blocks * (data->blksz);
@@ -352,13 +354,12 @@ static void mmc_dma_cleanup(struct mmc_omap_host *host, int errno)
 
         if (host->use_dma && host->dma_ch != -1) {
                 dma_unmap_sg(mmc_dev(host->mmc), host->data->sg, host->dma_len,
-                        host->dma_dir);
+                        mmc_omap_get_dma_dir(host, host->data));
                 omap_free_dma(host->dma_ch);
                 host->dma_ch = -1;
                 up(&host->sem);
         }
         host->data = NULL;
-        host->datadir = OMAP_MMC_DATADIR_NONE;
 }
 
 /*
@@ -592,6 +593,55 @@ static irqreturn_t omap_mmc_cd_handler(int irq, void *dev_id)
         return IRQ_HANDLED;
 }
 
+static int mmc_omap_get_dma_sync_dev(struct mmc_omap_host *host,
+                                     struct mmc_data *data)
+{
+        int sync_dev;
+
+        if (data->flags & MMC_DATA_WRITE) {
+                if (host->id == OMAP_MMC1_DEVID)
+                        sync_dev = OMAP24XX_DMA_MMC1_TX;
+                else
+                        sync_dev = OMAP24XX_DMA_MMC2_TX;
+        } else {
+                if (host->id == OMAP_MMC1_DEVID)
+                        sync_dev = OMAP24XX_DMA_MMC1_RX;
+                else
+                        sync_dev = OMAP24XX_DMA_MMC2_RX;
+        }
+        return sync_dev;
+}
+
+static void mmc_omap_config_dma_params(struct mmc_omap_host *host,
+                                       struct mmc_data *data,
+                                       struct scatterlist *sgl)
+{
+        int blksz, nblk, dma_ch;
+
+        dma_ch = host->dma_ch;
+        if (data->flags & MMC_DATA_WRITE) {
+                omap_set_dma_dest_params(dma_ch, 0, OMAP_DMA_AMODE_CONSTANT,
+                        (host->mapbase + OMAP_HSMMC_DATA), 0, 0);
+                omap_set_dma_src_params(dma_ch, 0, OMAP_DMA_AMODE_POST_INC,
+                        sg_dma_address(sgl), 0, 0);
+        } else {
+                omap_set_dma_src_params(dma_ch, 0, OMAP_DMA_AMODE_CONSTANT,
+                                        (host->mapbase + OMAP_HSMMC_DATA), 0, 0);
+                omap_set_dma_dest_params(dma_ch, 0, OMAP_DMA_AMODE_POST_INC,
+                        sg_dma_address(sgl), 0, 0);
+        }
+
+        blksz = host->data->blksz;
+        nblk = sg_dma_len(sgl) / blksz;
+
+        omap_set_dma_transfer_params(dma_ch, OMAP_DMA_DATA_TYPE_S32,
+                        blksz / 4, nblk, OMAP_DMA_SYNC_FRAME,
+                        mmc_omap_get_dma_sync_dev(host, data),
+                        !(data->flags & MMC_DATA_WRITE));
+
+        omap_start_dma(dma_ch);
+}
+
 /*
  * DMA call back function
  */
@@ -605,6 +655,14 @@ static void mmc_omap_dma_cb(int lch, u16 ch_status, void *data)
         if (host->dma_ch < 0)
                 return;
 
+        host->dma_sg_idx++;
+        if (host->dma_sg_idx < host->dma_len) {
+                /* Fire up the next transfer. */
+                mmc_omap_config_dma_params(host, host->data,
+                                           host->data->sg + host->dma_sg_idx);
+                return;
+        }
+
         omap_free_dma(host->dma_ch);
         host->dma_ch = -1;
         /*
@@ -615,38 +673,28 @@ static void mmc_omap_dma_cb(int lch, u16 ch_status, void *data)
 }
 
 /*
- * Configure dma src and destination parameters
- */
-static int mmc_omap_config_dma_param(int sync_dir, struct mmc_omap_host *host,
-                                struct mmc_data *data)
-{
-        if (sync_dir == 0) {
-                omap_set_dma_dest_params(host->dma_ch, 0,
-                        OMAP_DMA_AMODE_CONSTANT,
-                        (host->mapbase + OMAP_HSMMC_DATA), 0, 0);
-                omap_set_dma_src_params(host->dma_ch, 0,
-                        OMAP_DMA_AMODE_POST_INC,
-                        sg_dma_address(&data->sg[0]), 0, 0);
-        } else {
-                omap_set_dma_src_params(host->dma_ch, 0,
-                        OMAP_DMA_AMODE_CONSTANT,
-                        (host->mapbase + OMAP_HSMMC_DATA), 0, 0);
-                omap_set_dma_dest_params(host->dma_ch, 0,
-                        OMAP_DMA_AMODE_POST_INC,
-                        sg_dma_address(&data->sg[0]), 0, 0);
-        }
-        return 0;
-}
-/*
  * Routine to configure and start DMA for the MMC card
  */
 static int
 mmc_omap_start_dma_transfer(struct mmc_omap_host *host, struct mmc_request *req)
 {
-        int sync_dev, sync_dir = 0;
-        int dma_ch = 0, ret = 0, err = 1;
+        int dma_ch = 0, ret = 0, err = 1, i;
         struct mmc_data *data = req->data;
 
+        /* Sanity check: all the SG entries must be aligned by block size. */
+        for (i = 0; i < host->dma_len; i++) {
+                struct scatterlist *sgl;
+
+                sgl = data->sg + i;
+                if (sgl->length % data->blksz)
+                        return -EINVAL;
+        }
+        if ((data->blksz % 4) != 0)
+                /* REVISIT: The MMC buffer increments only when MSB is written.
+                 * Return error for blksz which is non multiple of four.
+                 */
+                return -EINVAL;
+
         /*
          * If for some reason the DMA transfer is still active,
          * we wait for timeout period and free the dma
@@ -665,49 +713,22 @@ mmc_omap_start_dma_transfer(struct mmc_omap_host *host, struct mmc_request *req)
                         return err;
         }
 
-        if (!(data->flags & MMC_DATA_WRITE)) {
-                host->dma_dir = DMA_FROM_DEVICE;
-                if (host->id == OMAP_MMC1_DEVID)
-                        sync_dev = OMAP24XX_DMA_MMC1_RX;
-                else
-                        sync_dev = OMAP24XX_DMA_MMC2_RX;
-        } else {
-                host->dma_dir = DMA_TO_DEVICE;
-                if (host->id == OMAP_MMC1_DEVID)
-                        sync_dev = OMAP24XX_DMA_MMC1_TX;
-                else
-                        sync_dev = OMAP24XX_DMA_MMC2_TX;
-        }
-
-        ret = omap_request_dma(sync_dev, "MMC/SD", mmc_omap_dma_cb,
-                        host, &dma_ch);
+        ret = omap_request_dma(mmc_omap_get_dma_sync_dev(host, data), "MMC/SD",
+                               mmc_omap_dma_cb,host, &dma_ch);
         if (ret != 0) {
-                dev_dbg(mmc_dev(host->mmc),
+                dev_err(mmc_dev(host->mmc),
                         "%s: omap_request_dma() failed with %d\n",
                         mmc_hostname(host->mmc), ret);
                 return ret;
         }
 
         host->dma_len = dma_map_sg(mmc_dev(host->mmc), data->sg,
-                        data->sg_len, host->dma_dir);
+                        data->sg_len, mmc_omap_get_dma_dir(host, data));
         host->dma_ch = dma_ch;
+        host->dma_sg_idx = 0;
 
-        if (!(data->flags & MMC_DATA_WRITE))
-                mmc_omap_config_dma_param(1, host, data);
-        else
-                mmc_omap_config_dma_param(0, host, data);
-
-        if ((data->blksz % 4) == 0)
-                omap_set_dma_transfer_params(dma_ch, OMAP_DMA_DATA_TYPE_S32,
-                        (data->blksz / 4), data->blocks, OMAP_DMA_SYNC_FRAME,
-                        sync_dev, sync_dir);
-        else
-                /* REVISIT: The MMC buffer increments only when MSB is written.
-                 * Return error for blksz which is non multiple of four.
-                 */
-                return -EINVAL;
+        mmc_omap_config_dma_params(host, data, data->sg);
 
-        omap_start_dma(dma_ch);
         return 0;
 }
 
@@ -757,7 +778,6 @@ mmc_omap_prepare_data(struct mmc_omap_host *host, struct mmc_request *req)
         host->data = req->data;
 
         if (req->data == NULL) {
-                host->datadir = OMAP_MMC_DATADIR_NONE;
                 OMAP_HSMMC_WRITE(host->base, BLK, 0);
                 return 0;
         }
@@ -766,9 +786,6 @@ mmc_omap_prepare_data(struct mmc_omap_host *host, struct mmc_request *req)
                                         | (req->data->blocks << 16));
         set_data_timeout(host, req);
 
-        host->datadir = (req->data->flags & MMC_DATA_WRITE) ?
-                        OMAP_MMC_DATADIR_WRITE : OMAP_MMC_DATADIR_READ;
-
         if (host->use_dma) {
                 ret = mmc_omap_start_dma_transfer(host, req);
                 if (ret != 0) {
@@ -1027,10 +1044,11 @@ static int __init omap_mmc_probe(struct platform_device *pdev)
                 else
                         host->dbclk_enabled = 1;
 
-#ifdef CONFIG_MMC_BLOCK_BOUNCE
-        mmc->max_phys_segs = 1;
-        mmc->max_hw_segs = 1;
-#endif
+        /* Since we do only SG emulation, we can have as many segs
+         * as we want. */
+        mmc->max_phys_segs = 1024;
+        mmc->max_hw_segs = 1024;
+
         mmc->max_blk_size = 512;       /* Block Length at max can be 1024 */
         mmc->max_blk_count = 0xFFFF;    /* No. of Blocks is 16 bits */
         mmc->max_req_size = mmc->max_blk_size * mmc->max_blk_count;