mmc: at91_mci: use DMA buffer for read

Convert the read to use the DMA buffer as well.  The old code was doing
double-buffering DMA with the PDC; no way to make it work.  Replace it
with a single-PDC approach.  It also simplify things removing the need for
a pre_dma_read() function.

[nicolas.ferre@atmel.com coding style modifications]
Signed-off-by: Wolfgang Muees <wolfgang.mues@auerswald.de>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Andrew Victor <avictor.za@gmail.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/mmc/host/at91_mci.c b/drivers/mmc/host/at91_mci.c
index 76cb05a..818b4e7 100644 (file)
--- a/drivers/mmc/host/at91_mci.c
+++ b/drivers/mmc/host/at91_mci.c
@@ -250,74 +250,6 @@ static inline void at91_mci_sg_to_dma(struct at91mci_host *host, struct mmc_data
        BUG_ON(size != 0);
 }
 
-/*
- * Prepare a dma read
- */
-static void at91_mci_pre_dma_read(struct at91mci_host *host)
-{
-       int i;
-       struct scatterlist *sg;
-       struct mmc_command *cmd;
-       struct mmc_data *data;
-
-       pr_debug("pre dma read\n");
-
-       cmd = host->cmd;
-       if (!cmd) {
-               pr_debug("no command\n");
-               return;
-       }
-
-       data = cmd->data;
-       if (!data) {
-               pr_debug("no data\n");
-               return;
-       }
-
-       for (i = 0; i < 2; i++) {
-               /* nothing left to transfer */
-               if (host->transfer_index >= data->sg_len) {
-                       pr_debug("Nothing left to transfer (index = %d)\n", host->transfer_index);
-                       break;
-               }
-
-               /* Check to see if this needs filling */
-               if (i == 0) {
-                       if (at91_mci_read(host, ATMEL_PDC_RCR) != 0) {
-                               pr_debug("Transfer active in current\n");
-                               continue;
-                       }
-               }
-               else {
-                       if (at91_mci_read(host, ATMEL_PDC_RNCR) != 0) {
-                               pr_debug("Transfer active in next\n");
-                               continue;
-                       }
-               }
-
-               /* Setup the next transfer */
-               pr_debug("Using transfer index %d\n", host->transfer_index);
-
-               sg = &data->sg[host->transfer_index++];
-               pr_debug("sg = %p\n", sg);
-
-               sg->dma_address = dma_map_page(NULL, sg_page(sg), sg->offset, sg->length, DMA_FROM_DEVICE);
-
-               pr_debug("dma address = %08X, length = %d\n", sg->dma_address, sg->length);
-
-               if (i == 0) {
-                       at91_mci_write(host, ATMEL_PDC_RPR, sg->dma_address);
-                       at91_mci_write(host, ATMEL_PDC_RCR, (data->blksz & 0x3) ? sg->length : sg->length / 4);
-               }
-               else {
-                       at91_mci_write(host, ATMEL_PDC_RNPR, sg->dma_address);
-                       at91_mci_write(host, ATMEL_PDC_RNCR, (data->blksz & 0x3) ? sg->length : sg->length / 4);
-               }
-       }
-
-       pr_debug("pre dma read done\n");
-}
-
 /*
  * Handle after a dma read
  */
@@ -325,6 +257,8 @@ static void at91_mci_post_dma_read(struct at91mci_host *host)
 {
        struct mmc_command *cmd;
        struct mmc_data *data;
+       unsigned int len, i, size;
+       unsigned *dmabuf = host->buffer;
 
        pr_debug("post dma read\n");
 
@@ -340,42 +274,39 @@ static void at91_mci_post_dma_read(struct at91mci_host *host)
                return;
        }
 
-       while (host->in_use_index < host->transfer_index) {
-               struct scatterlist *sg;
+       size = data->blksz * data->blocks;
+       len = data->sg_len;
 
-               pr_debug("finishing index %d\n", host->in_use_index);
+       at91_mci_write(host, AT91_MCI_IDR, AT91_MCI_ENDRX);
+       at91_mci_write(host, AT91_MCI_IER, AT91_MCI_RXBUFF);
 
-               sg = &data->sg[host->in_use_index++];
+       for (i = 0; i < len; i++) {
+               struct scatterlist *sg;
+               int amount;
+               unsigned int *sgbuffer;
 
-               pr_debug("Unmapping page %08X\n", sg->dma_address);
+               sg = &data->sg[i];
 
-               dma_unmap_page(NULL, sg->dma_address, sg->length, DMA_FROM_DEVICE);
+               sgbuffer = kmap_atomic(sg_page(sg), KM_BIO_SRC_IRQ) + sg->offset;
+               amount = min(size, sg->length);
+               size -= amount;
 
                if (cpu_is_at91rm9200()) {      /* AT91RM9200 errata */
-                       unsigned int *buffer;
                        int index;
-
-                       /* Swap the contents of the buffer */
-                       buffer = kmap_atomic(sg_page(sg), KM_BIO_SRC_IRQ) + sg->offset;
-                       pr_debug("buffer = %p, length = %d\n", buffer, sg->length);
-
-                       for (index = 0; index < (sg->length / 4); index++)
-                               buffer[index] = swab32(buffer[index]);
-
-                       kunmap_atomic(buffer, KM_BIO_SRC_IRQ);
+                       for (index = 0; index < (amount / 4); index++)
+                               sgbuffer[index] = swab32(*dmabuf++);
+               } else {
+                       char *tmpv = (char *)dmabuf;
+                       memcpy(sgbuffer, tmpv, amount);
+                       tmpv += amount;
+                       dmabuf = (unsigned *)tmpv;
                }
 
-               flush_dcache_page(sg_page(sg));
-
-               data->bytes_xfered += sg->length;
-       }
-
-       /* Is there another transfer to trigger? */
-       if (host->transfer_index < data->sg_len)
-               at91_mci_pre_dma_read(host);
-       else {
-               at91_mci_write(host, AT91_MCI_IDR, AT91_MCI_ENDRX);
-               at91_mci_write(host, AT91_MCI_IER, AT91_MCI_RXBUFF);
+               kunmap_atomic(((void *)sgbuffer)-sg->offset, KM_BIO_SRC_IRQ);
+               dmac_flush_range((void *)sgbuffer, ((void *)sgbuffer) + amount);
+               data->bytes_xfered += amount;
+               if (size == 0)
+                       break;
        }
 
        pr_debug("post dma read done\n");
@@ -610,7 +541,12 @@ static void at91_mci_send_command(struct at91mci_host *host, struct mmc_command
                                 */
                                host->total_length = 0;
 
-                               at91_mci_pre_dma_read(host);
+                               at91_mci_write(host, ATMEL_PDC_RPR, host->physical_address);
+                               at91_mci_write(host, ATMEL_PDC_RCR, (data->blksz & 0x3) ?
+                                       (blocks * block_length) : (blocks * block_length) / 4);
+                               at91_mci_write(host, ATMEL_PDC_RNPR, 0);
+                               at91_mci_write(host, ATMEL_PDC_RNCR, 0);
+
                                ier = AT91_MCI_ENDRX /* | AT91_MCI_RXBUFF */;
                        }
                        else {