sdhci: highmem capable PIO routines

Improve the PIO handling so that it can service highmem pages.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

2 files changed, 75 insertions, 95 deletions

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 8b1f412144cf..c3a5db72ddd7 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -173,119 +173,95 @@ static void sdhci_led_control(struct led_classdev *led,
  *                                                                           *
 \*****************************************************************************/
 
-static inline char* sdhci_sg_to_buffer(struct sdhci_host* host)
-{
-        return sg_virt(host->cur_sg);
-}
-
-static inline int sdhci_next_sg(struct sdhci_host* host)
-{
-        /*
-         * Skip to next SG entry.
-         */
-        host->cur_sg++;
-        host->num_sg--;
-
-        /*
-         * Any entries left?
-         */
-        if (host->num_sg > 0) {
-                host->offset = 0;
-                host->remain = host->cur_sg->length;
-        }
-
-        return host->num_sg;
-}
-
 static void sdhci_read_block_pio(struct sdhci_host *host)
 {
-        int blksize, chunk_remain;
-        u32 data;
-        char *buffer;
-        int size;
+        unsigned long flags;
+        size_t blksize, len, chunk;
+        u32 scratch;
+        u8 *buf;
 
         DBG("PIO reading\n");
 
         blksize = host->data->blksz;
-        chunk_remain = 0;
-        data = 0;
+        chunk = 0;
 
-        buffer = sdhci_sg_to_buffer(host) + host->offset;
+        local_irq_save(flags);
 
         while (blksize) {
-                if (chunk_remain == 0) {
-                        data = readl(host->ioaddr + SDHCI_BUFFER);
-                        chunk_remain = min(blksize, 4);
-                }
+                if (!sg_miter_next(&host->sg_miter))
+                        BUG();
 
-                size = min(host->remain, chunk_remain);
+                len = min(host->sg_miter.length, blksize);
 
-                chunk_remain -= size;
-                blksize -= size;
-                host->offset += size;
-                host->remain -= size;
+                blksize -= len;
+                host->sg_miter.consumed = len;
 
-                while (size) {
-                        *buffer = data & 0xFF;
-                        buffer++;
-                        data >>= 8;
-                        size--;
-                }
+                buf = host->sg_miter.addr;
 
-                if (host->remain == 0) {
-                        if (sdhci_next_sg(host) == 0) {
-                                BUG_ON(blksize != 0);
-                                return;
+                while (len) {
+                        if (chunk == 0) {
+                                scratch = readl(host->ioaddr + SDHCI_BUFFER);
+                                chunk = 4;
                         }
-                        buffer = sdhci_sg_to_buffer(host);
+
+                        *buf = scratch & 0xFF;
+
+                        buf++;
+                        scratch >>= 8;
+                        chunk--;
+                        len--;
                 }
         }
+
+        sg_miter_stop(&host->sg_miter);
+
+        local_irq_restore(flags);
 }
 
 static void sdhci_write_block_pio(struct sdhci_host *host)
 {
-        int blksize, chunk_remain;
-        u32 data;
-        char *buffer;
-        int bytes, size;
+        unsigned long flags;
+        size_t blksize, len, chunk;
+        u32 scratch;
+        u8 *buf;
 
         DBG("PIO writing\n");
 
         blksize = host->data->blksz;
-        chunk_remain = 4;
-        data = 0;
+        chunk = 0;
+        scratch = 0;
 
-        bytes = 0;
-        buffer = sdhci_sg_to_buffer(host) + host->offset;
+        local_irq_save(flags);
 
         while (blksize) {
-                size = min(host->remain, chunk_remain);
-
-                chunk_remain -= size;
-                blksize -= size;
-                host->offset += size;
-                host->remain -= size;
-
-                while (size) {
-                        data >>= 8;
-                        data |= (u32)*buffer << 24;
-                        buffer++;
-                        size--;
-                }
+                if (!sg_miter_next(&host->sg_miter))
+                        BUG();
 
-                if (chunk_remain == 0) {
-                        writel(data, host->ioaddr + SDHCI_BUFFER);
-                        chunk_remain = min(blksize, 4);
-                }
+                len = min(host->sg_miter.length, blksize);
+
+                blksize -= len;
+                host->sg_miter.consumed = len;
+
+                buf = host->sg_miter.addr;
 
-                if (host->remain == 0) {
-                        if (sdhci_next_sg(host) == 0) {
-                                BUG_ON(blksize != 0);
-                                return;
+                while (len) {
+                        scratch |= (u32)*buf << (chunk * 8);
+
+                        buf++;
+                        chunk++;
+                        len--;
+
+                        if ((chunk == 4) || ((len == 0) && (blksize == 0))) {
+                                writel(scratch, host->ioaddr + SDHCI_BUFFER);
+                                chunk = 0;
+                                scratch = 0;
                         }
-                        buffer = sdhci_sg_to_buffer(host);
                 }
         }
+
+        sg_miter_stop(&host->sg_miter);
+
+        local_irq_restore(flags);
 }
 
 static void sdhci_transfer_pio(struct sdhci_host *host)
@@ -294,7 +270,7 @@ static void sdhci_transfer_pio(struct sdhci_host *host)
 
         BUG_ON(!host->data);
 
-        if (host->num_sg == 0)
+        if (host->blocks == 0)
                 return;
 
         if (host->data->flags & MMC_DATA_READ)
@@ -308,7 +284,8 @@ static void sdhci_transfer_pio(struct sdhci_host *host)
                 else
                         sdhci_write_block_pio(host);
 
-                if (host->num_sg == 0)
+                host->blocks--;
+                if (host->blocks == 0)
                         break;
         }
 
@@ -713,11 +690,9 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
         }
 
         if (!(host->flags & SDHCI_REQ_USE_DMA)) {
-                host->cur_sg = data->sg;
-                host->num_sg = data->sg_len;
-
-                host->offset = 0;
-                host->remain = host->cur_sg->length;
+                sg_miter_start(&host->sg_miter,
+                        data->sg, data->sg_len, SG_MITER_ATOMIC);
+                host->blocks = data->blocks;
         }
 
         /* We do not handle DMA boundaries, so set it to max (512 KiB) */
@@ -1583,9 +1558,15 @@ int sdhci_add_host(struct sdhci_host *host)
                 }
         }
 
-        /* XXX: Hack to get MMC layer to avoid highmem */
-        if (!(host->flags & SDHCI_USE_DMA))
-                mmc_dev(host->mmc)->dma_mask = NULL;
+        /*
+         * If we use DMA, then it's up to the caller to set the DMA
+         * mask, but PIO does not need the hw shim so we set a new
+         * mask here in that case.
+         */
+        if (!(host->flags & SDHCI_USE_DMA)) {
+                host->dma_mask = DMA_BIT_MASK(64);
+                mmc_dev(host->mmc)->dma_mask = &host->dma_mask;
+        }
 
         host->max_clk =
                 (caps & SDHCI_CLOCK_BASE_MASK) >> SDHCI_CLOCK_BASE_SHIFT;
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 5bb355281765..a06bf8b89343 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -212,6 +212,7 @@ struct sdhci_host {
 
         /* Internal data */
         struct mmc_host         *mmc;           /* MMC structure */
+        u64                     dma_mask;       /* custom DMA mask */
 
 #ifdef CONFIG_LEDS_CLASS
         struct led_classdev     led;            /* LED control */
@@ -238,10 +239,8 @@ struct sdhci_host {
         struct mmc_data         *data;          /* Current data request */
         unsigned int            data_early:1;   /* Data finished before cmd */
 
-        struct scatterlist      *cur_sg;        /* We're working on this */
-        int                     num_sg;         /* Entries left */
-        int                     offset;         /* Offset into current sg */
-        int                     remain;         /* Bytes left in current */
+        struct sg_mapping_iter  sg_miter;       /* SG state for PIO */
+        unsigned int            blocks;         /* remaining PIO blocks */
 
         int                     sg_count;       /* Mapped sg entries */