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>

1 files changed, 32 insertions, 96 deletions

diff --git a/drivers/mmc/host/at91_mci.c b/drivers/mmc/host/at91_mci.c
index 76cb05ab9341..818b4e75708a 100644
--- a/drivers/mmc/host/at91_mci.c
+++ b/drivers/mmc/host/at91_mci.c
@@ -251,80 +251,14 @@ static inline void at91_mci_sg_to_dma(struct at91mci_host *host, struct mmc_data
 }
 
 /*
- * 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
  */
 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 {