mmc: sdhci: Let a driver override timeout clock frequency

Let a driver override the timeout clock frequency by
populating it before calling sdhci_add_host().  Note
the value will otherwise be zero because sdhci_host is
zeroed when allocated.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci.c

@@ -2791,6 +2791,7 @@ int sdhci_add_host(struct sdhci_host *host)
 	u32 caps[2] = {0, 0};
 	u32 max_current_caps;
 	unsigned int ocr_avail;
+	unsigned int override_timeout_clk;
 	int ret;
 
 	WARN_ON(host == NULL);
@@ -2804,6 +2805,8 @@ int sdhci_add_host(struct sdhci_host *host)
 	if (debug_quirks2)
 		host->quirks2 = debug_quirks2;
 
+	override_timeout_clk = host->timeout_clk;
+
 	sdhci_do_reset(host, SDHCI_RESET_ALL);
 
 	host->version = sdhci_readw(host, SDHCI_HOST_VERSION);
@@ -2970,6 +2973,9 @@ int sdhci_add_host(struct sdhci_host *host)
 		mmc->max_busy_timeout /= host->timeout_clk;
 	}
 
+	if (override_timeout_clk)
+		host->timeout_clk = override_timeout_clk;
+
 	mmc->caps |= MMC_CAP_SDIO_IRQ | MMC_CAP_ERASE | MMC_CAP_CMD23;
 	mmc->caps2 |= MMC_CAP2_SDIO_IRQ_NOTHREAD;