ENGR00175864 [MMC]pipeline mmc requests

the patch is based on a series of patches by Per Forlin
the patch is sdhci host side implementation.

using a toshiba SDHC3.0 card, the performance increases
from 48.5MB/s to 52.4MB/s.

cmd: dd if=/dev/mmcblk0 of=/dev/null bs=1M count=500

the performance results running@1GHz, 200MHz CPU freq are:
52.4MB/s -> 20.7MB/s

Signed-off-by: Tony Lin <tony.lin@freescale.com>

2 files changed, 77 insertions, 0 deletions

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 6137f9de67c6..82afe0522ecc 100755
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1865,8 +1865,79 @@ static void sdhci_enable_preset_value(struct mmc_host *mmc, bool enable)
 	spin_unlock_irqrestore(&host->lock, flags);
 }
 
+static void sdhci_post_req(struct mmc_host *mmc, struct mmc_request *mrq,
+				int err)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	struct mmc_data *data = mrq->data;
+
+	if (host->flags & SDHCI_REQ_USE_DMA) {
+		dma_unmap_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
+			     data->flags & MMC_DATA_WRITE ? \
+			     DMA_TO_DEVICE : DMA_FROM_DEVICE);
+		data->host_cookie = 0;
+	}
+}
+
+static int sdhci_pre_dma_transfer(struct sdhci_host *host,
+				       struct mmc_data *data,
+				       struct sdhci_host_next *next)
+{
+	int dma_len;
+
+	if (!next && data->host_cookie &&
+	    data->host_cookie != host->next_data.cookie) {
+		printk(KERN_WARNING "[%s] invalid cookie: data->host_cookie %d"
+		       " host->next_data.cookie %d\n",
+		       __func__, data->host_cookie, host->next_data.cookie);
+		data->host_cookie = 0;
+	}
+
+	/* Check if next job is already prepared */
+	if (next ||
+	    (!next && data->host_cookie != host->next_data.cookie)) {
+		dma_len = dma_map_sg(mmc_dev(host->mmc), data->sg,
+				     data->sg_len,
+				     data->flags & MMC_DATA_WRITE ? \
+				     DMA_TO_DEVICE : DMA_FROM_DEVICE);
+
+	} else {
+		dma_len = host->next_data.dma_len;
+		host->next_data.dma_len = 0;
+	}
+
+
+	if (dma_len == 0)
+		return -EINVAL;
+
+	if (next) {
+		next->dma_len = dma_len;
+		data->host_cookie = ++next->cookie < 0 ? 1 : next->cookie;
+	}
+
+	return 0;
+}
+
+static void sdhci_pre_req(struct mmc_host *mmc, struct mmc_request *mrq,
+			       bool is_first_req)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+
+	if (mrq->data->host_cookie) {
+		mrq->data->host_cookie = 0;
+		return ;
+	}
+
+	if (host->flags & SDHCI_REQ_USE_DMA)
+		if (sdhci_pre_dma_transfer(host, mrq->data,
+						&host->next_data))
+			mrq->data->host_cookie = 0;
+}
+
 static const struct mmc_host_ops sdhci_ops = {
 	.request	= sdhci_request,
+	.post_req	= sdhci_post_req,
+	.pre_req	= sdhci_pre_req,
 	.set_ios	= sdhci_set_ios,
 	.get_ro		= sdhci_get_ro,
 	.enable_sdio_irq = sdhci_enable_sdio_irq,
diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
index d73ed4622881..d9dca2739cb5 100644
--- a/include/linux/mmc/sdhci.h
+++ b/include/linux/mmc/sdhci.h
@@ -17,6 +17,11 @@
 #include <linux/io.h>
 #include <linux/mmc/host.h>
 
+struct sdhci_host_next {
+	unsigned int	dma_len;
+	s32		cookie;
+};
+
 struct sdhci_host {
 	/* Data set by hardware interface driver */
 	const char *hw_name;	/* Hardware bus name */
@@ -166,6 +171,7 @@ struct sdhci_host {
 	struct delayed_work	clk_worker;	/* Clock delayed worker */
 	unsigned int		clk_mgr_en;
 	unsigned int		clk_status;
+	struct sdhci_host_next	next_data;
 	unsigned long private[0] ____cacheline_aligned;
 };
 #endif /* __SDHCI_H */