ARM: 7280/1: mmc: mmci: Cache MMCICLOCK and MMCIPOWER register

Instead of reading a register value everytime we need to
apply a new value for it, maintain a cached copy for it.
This also means we are able to skip writes that are not
needed.

Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/mmc/host/mmci.c

@@ -118,6 +118,28 @@ static struct variant_data variant_ux500v2 = {
 	.signal_direction	= true,
 };
 
+/*
+ * This must be called with host->lock held
+ */
+static void mmci_write_clkreg(struct mmci_host *host, u32 clk)
+{
+	if (host->clk_reg != clk) {
+		host->clk_reg = clk;
+		writel(clk, host->base + MMCICLOCK);
+	}
+}
+
+/*
+ * This must be called with host->lock held
+ */
+static void mmci_write_pwrreg(struct mmci_host *host, u32 pwr)
+{
+	if (host->pwr_reg != pwr) {
+		host->pwr_reg = pwr;
+		writel(pwr, host->base + MMCIPOWER);
+	}
+}
+
 /*
  * This must be called with host->lock held
  */
@@ -165,7 +187,7 @@ static void mmci_set_clkreg(struct mmci_host *host, unsigned int desired)
 	if (host->mmc->ios.bus_width == MMC_BUS_WIDTH_8)
 		clk |= MCI_ST_8BIT_BUS;
 
-	writel(clk, host->base + MMCICLOCK);
+	mmci_write_clkreg(host, clk);
 }
 
 static void
@@ -846,14 +868,13 @@ static int mmci_pio_write(struct mmci_host *host, char *buffer, unsigned int rem
 		 */
 		if (variant->sdio &&
 		    mmc_card_sdio(host->mmc->card)) {
+			u32 clk;
 			if (count < 8)
-				writel(readl(host->base + MMCICLOCK) &
-					~variant->clkreg_enable,
-					host->base + MMCICLOCK);
+				clk = host->clk_reg & ~variant->clkreg_enable;
 			else
-				writel(readl(host->base + MMCICLOCK) |
-					variant->clkreg_enable,
-					host->base + MMCICLOCK);
+				clk = host->clk_reg | variant->clkreg_enable;
+
+			mmci_write_clkreg(host, clk);
 		}
 
 		/*
@@ -1114,11 +1135,7 @@ static void mmci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 	spin_lock_irqsave(&host->lock, flags);
 
 	mmci_set_clkreg(host, ios->clock);
-
-	if (host->pwr != pwr) {
-		host->pwr = pwr;
-		writel(pwr, host->base + MMCIPOWER);
-	}
+	mmci_write_pwrreg(host, pwr);
 
 	spin_unlock_irqrestore(&host->lock, flags);
 

drivers/mmc/host/mmci.h

@@ -179,7 +179,8 @@ struct mmci_host {
 
 	unsigned int		mclk;
 	unsigned int		cclk;
-	u32			pwr;
+	u32			pwr_reg;
+	u32			clk_reg;
 	struct mmci_platform_data *plat;
 	struct variant_data	*variant;