sdhci: implement CAP_CLOCK_BASE_BROKEN quirk

Some hosts (e.g.  as found in CNS3xxx SOCs) report wrong value in
CLOCK_BASE capability field, and currently there is no way to force the
SDHCI core to use the platform-provided base clock value.

This patch implements CAP_CLOCK_BASE_BROKEN quirk.  When enabled, the
SDHCI core will always use base clock frequency provided by the platform.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: Richard Röjfors <richard.rojfors@pelagicore.com>
Cc: David Vrabel <david.vrabel@csr.com>
Cc: Pierre Ossman <pierre@ossman.eu>
Cc: Ben Dooks <ben@simtec.co.uk>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/mmc/host/sdhci.c

@@ -1744,7 +1744,8 @@ int sdhci_add_host(struct sdhci_host *host)
 	host->max_clk =
 		(caps & SDHCI_CLOCK_BASE_MASK) >> SDHCI_CLOCK_BASE_SHIFT;
 	host->max_clk *= 1000000;
-	if (host->max_clk == 0) {
+	if (host->max_clk == 0 || host->quirks &
+			SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN) {
 		if (!host->ops->get_max_clock) {
 			printk(KERN_ERR
 			       "%s: Hardware doesn't specify base clock "

drivers/mmc/host/sdhci.h

@@ -236,6 +236,8 @@ struct sdhci_host {
 #define SDHCI_QUIRK_DELAY_AFTER_POWER			(1<<23)
 /* Controller uses SDCLK instead of TMCLK for data timeouts */
 #define SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK		(1<<24)
+/* Controller reports wrong base clock capability */
+#define SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN		(1<<25)
 
 	int			irq;		/* Device IRQ */
 	void __iomem *		ioaddr;		/* Mapped address */