mmc: SDHC 3.0: support 10-bit divided clock mode

Signed-off-by: Zhangfei Gao <zgao6@marvell.com>
Cc: Michał Mirosław <mirqus@gmail.com>
Cc: David Vrabel <david.vrabel@csr.com>
Reviewed-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci.c

@@ -1001,13 +1001,28 @@ static void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
 	if (clock == 0)
 		goto out;
 
-	for (div = 1;div < 256;div *= 2) {
-		if ((host->max_clk / div) <= clock)
-			break;
+	if (host->version >= SDHCI_SPEC_300) {
+		/* Version 3.00 divisors must be a multiple of 2. */
+		if (host->max_clk <= clock)
+			div = 1;
+		else {
+			for (div = 2; div < 2046; div += 2) {
+				if ((host->max_clk / div) <= clock)
+					break;
+			}
+		}
+	} else {
+		/* Version 2.00 divisors must be a power of 2. */
+		for (div = 1; div < 256; div *= 2) {
+			if ((host->max_clk / div) <= clock)
+				break;
+		}
 	}
 	div >>= 1;
 
-	clk = div << SDHCI_DIVIDER_SHIFT;
+	clk = (div & SDHCI_DIV_MASK) << SDHCI_DIVIDER_SHIFT;
+	clk |= ((div & SDHCI_DIV_HI_MASK) >> SDHCI_DIV_MASK_LEN)
+		<< SDHCI_DIVIDER_HI_SHIFT;
 	clk |= SDHCI_CLOCK_INT_EN;
 	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
 
@@ -1708,7 +1723,7 @@ int sdhci_add_host(struct sdhci_host *host)
 	host->version = sdhci_readw(host, SDHCI_HOST_VERSION);
 	host->version = (host->version & SDHCI_SPEC_VER_MASK)
 				>> SDHCI_SPEC_VER_SHIFT;
-	if (host->version > SDHCI_SPEC_200) {
+	if (host->version > SDHCI_SPEC_300) {
 		printk(KERN_ERR "%s: Unknown controller version (%d). "
 			"You may experience problems.\n", mmc_hostname(mmc),
 			host->version);

drivers/mmc/host/sdhci.h

@@ -86,6 +86,10 @@
 
 #define SDHCI_CLOCK_CONTROL	0x2C
 #define  SDHCI_DIVIDER_SHIFT	8
+#define  SDHCI_DIVIDER_HI_SHIFT	6
+#define  SDHCI_DIV_MASK	0xFF
+#define  SDHCI_DIV_MASK_LEN	8
+#define  SDHCI_DIV_HI_MASK	0x300
 #define  SDHCI_CLOCK_CARD_EN	0x0004
 #define  SDHCI_CLOCK_INT_STABLE	0x0002
 #define  SDHCI_CLOCK_INT_EN	0x0001
@@ -178,6 +182,7 @@
 #define  SDHCI_SPEC_VER_SHIFT	0
 #define   SDHCI_SPEC_100	0
 #define   SDHCI_SPEC_200	1
+#define   SDHCI_SPEC_300	2
 
 struct sdhci_ops;