[PATCH v2] mmc: sdhci-sirf: fix 8bit width enable by overwriting set_bus_width

[Barry Song]

From: Minda Chen <Minda.Chen at csr.com>

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 CSR mmc
controllers and improve performance for mmc0 a lot.

Signed-off-by: Minda Chen <Minda.Chen at csr.com>
Signed-off-by: Barry Song <Baohua.Song at csr.com>
---
 -v2: check for host->version >= SDHCI_SPEC_300

 drivers/mmc/host/sdhci-sirf.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci-sirf.c b/drivers/mmc/host/sdhci-sirf.c
index 1700453..a7224e5 100644
--- a/drivers/mmc/host/sdhci-sirf.c
+++ b/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 +29,34 @@ 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);
+	if (width == MMC_BUS_WIDTH_8) {
+		ctrl &= ~SDHCI_CTRL_4BITBUS;
+		/*
+		 * 8bit-width enable bit of CSR MMC hosts is 3,
+		 * while stardard hosts use bit 5
+		 */
+		if (host->version >= SDHCI_SPEC_300)
+			ctrl |= SDHCI_SIRF_8BITBUS;
+	} else {
+		if (host->version >= SDHCI_SPEC_300)
+			ctrl &= ~SDHCI_SIRF_8BITBUS;
+		if (width == MMC_BUS_WIDTH_4)
+			ctrl |= SDHCI_CTRL_4BITBUS;
+		else
+			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,
 };
-- 
2.0.4