[MMC] MMCI: Add SG support to PIO data transfers

This allows us to transfer a whole request for multiple pages in one
transaction with the MMC card, resulting in higher overall throughput.

diff --git a/drivers/mmc/mmci.c b/drivers/mmc/mmci.c
index 559cea6eaa852830311a3f000a11f2103c46a37a..70cc162af9ef0aa7a8d5cb9747dca715184dc9c6 100644 (file)
--- a/drivers/mmc/mmci.c
+++ b/drivers/mmc/mmci.c
@@ -197,6 +197,7 @@ static int mmci_pio_read(struct mmci_host *host, struct request *req, u32 status
 
        do {
                unsigned long flags;
+               unsigned int bio_remain;
                char *buffer;
 
                /*
@@ -208,23 +209,44 @@ static int mmci_pio_read(struct mmci_host *host, struct request *req, u32 status
                /*
                 * Map the BIO buffer.
                 */
-               buffer = bio_kmap_irq(req->bio, &flags);
+               buffer = bio_kmap_irq(req->cbio, &flags);
+               bio_remain = (req->current_nr_sectors << 9) - host->offset;
 
                do {
                        int count = host->size - (readl(base + MMCIFIFOCNT) << 2);
 
+                       if (count > bio_remain)
+                               count = bio_remain;
+
                        if (count > 0) {
                                ret = 1;
                                readsl(base + MMCIFIFO, buffer + host->offset, count >> 2);
                                host->offset += count;
                                host->size -= count;
+                               bio_remain -= count;
+                               if (bio_remain == 0)
+                                       goto next_bio;
                        }
 
                        status = readl(base + MMCISTATUS);
-               } while (status & MCI_RXDATAAVLBL && host->size);
+               } while (status & MCI_RXDATAAVLBL);
 
                bio_kunmap_irq(buffer, &flags);
                break;
+
+        next_bio:
+               bio_kunmap_irq(buffer, &flags);
+
+               /*
+                * Ok, we've completed that BIO, move on to next
+                * BIO in the chain.  Note: this doesn't actually
+                * complete the BIO!
+                */
+               if (!process_that_request_first(req, req->current_nr_sectors))
+                       break;
+
+               host->offset = 0;
+               status = readl(base + MMCISTATUS);
        } while (1);
 
        return ret;
@@ -237,6 +259,7 @@ static int mmci_pio_write(struct mmci_host *host, struct request *req, u32 statu
 
        do {
                unsigned long flags;
+               unsigned int bio_remain;
                char *buffer;
 
                /*
@@ -250,26 +273,45 @@ static int mmci_pio_write(struct mmci_host *host, struct request *req, u32 statu
                /*
                 * Map the BIO buffer.
                 */
-               buffer = bio_kmap_irq(req->bio, &flags);
+               buffer = bio_kmap_irq(req->cbio, &flags);
+               bio_remain = (req->current_nr_sectors << 9) - host->offset;
 
                do {
                        unsigned int count, maxcnt;
 
                        maxcnt = status & MCI_TXFIFOEMPTY ?
                                 MCI_FIFOSIZE : MCI_FIFOHALFSIZE;
-                       count = min(host->size, maxcnt);
+                       count = min(bio_remain, maxcnt);
 
                        writesl(base + MMCIFIFO, buffer + host->offset, count >> 2);
                        host->offset += count;
                        host->size -= count;
+                       bio_remain -= count;
 
                        ret = 1;
 
+                       if (bio_remain == 0)
+                               goto next_bio;
+
                        status = readl(base + MMCISTATUS);
-               } while (status & MCI_TXFIFOHALFEMPTY && host->size);
+               } while (status & MCI_TXFIFOHALFEMPTY);
 
                bio_kunmap_irq(buffer, &flags);
                break;
+
+        next_bio:
+               bio_kunmap_irq(buffer, &flags);
+
+               /*
+                * Ok, we've completed that BIO, move on to next
+                * BIO in the chain.  Note: this doesn't actually
+                * complete the BIO!
+                */
+               if (!process_that_request_first(req, req->current_nr_sectors))
+                       break;
+
+               host->offset = 0;
+               status = readl(base + MMCISTATUS);
        } while (1);
 
        return ret;
@@ -483,6 +525,25 @@ static int mmci_probe(struct amba_device *dev, void *id)
        mmc->f_max = min(host->mclk, fmax);
        mmc->ocr_avail = plat->ocr_mask;
 
+       /*
+        * We can do SGIO
+        */
+       mmc->max_hw_segs = 16;
+       mmc->max_phys_segs = 16;
+
+       /*
+        * Since we only have a 16-bit data length register, we must
+        * ensure that we don't exceed 2^16-1 bytes in a single request.
+        * Choose 64 (512-byte) sectors as the limit.
+        */
+       mmc->max_sectors = 64;
+
+       /*
+        * Set the maximum segment size.  Since we aren't doing DMA
+        * (yet) we are only limited by the data length register.
+        */
+       mmc->max_seg_size = mmc->max_sectors << 9;
+
        spin_lock_init(&host->lock);
 
        writel(0, host->base + MMCIMASK0);