mmc: sdhci-sirf: fix 8bit width enable by overwriting set_bus_width

the implementation of CSR SDHCI controller is a modified version of
the one described in the 1.0 specification, and not a normal 3.0
controller.
and 8bit-width enable bit of CSR MMC hosts is 3, while stardard hosts
use bit 5.
this patch fixes the functionality of 8bit transfer in mmc controllers
and improve performance for mmc0 a lot.

Signed-off-by: Minda Chen <Minda.Chen@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Reviewed-by: Romain Izard <romain.izard.pro@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-sirf.c

@@ -15,6 +15,8 @@
 #include <linux/mmc/slot-gpio.h>
 #include "sdhci-pltfm.h"
 
+#define SDHCI_SIRF_8BITBUS BIT(3)
+
 struct sdhci_sirf_priv {
 	struct clk *clk;
 	int gpio_cd;
@@ -27,10 +29,30 @@ static unsigned int sdhci_sirf_get_max_clk(struct sdhci_host *host)
 	return clk_get_rate(priv->clk);
 }
 
+static void sdhci_sirf_set_bus_width(struct sdhci_host *host, int width)
+{
+	u8 ctrl;
+
+	ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
+	ctrl &= ~(SDHCI_CTRL_4BITBUS | SDHCI_SIRF_8BITBUS);
+
+	/*
+	 * CSR atlas7 and prima2 SD host version is not 3.0
+	 * 8bit-width enable bit of CSR SD hosts is 3,
+	 * while stardard hosts use bit 5
+	 */
+	if (width == MMC_BUS_WIDTH_8)
+		ctrl |= SDHCI_SIRF_8BITBUS;
+	else if (width == MMC_BUS_WIDTH_4)
+		ctrl |= SDHCI_CTRL_4BITBUS;
+
+	sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
+}
+
 static struct sdhci_ops sdhci_sirf_ops = {
 	.set_clock = sdhci_set_clock,
 	.get_max_clock	= sdhci_sirf_get_max_clk,
-	.set_bus_width = sdhci_set_bus_width,
+	.set_bus_width = sdhci_sirf_set_bus_width,
 	.reset = sdhci_reset,
 	.set_uhs_signaling = sdhci_set_uhs_signaling,
 };