mmc: sdhci: add a voltage switch callback function

This patch adds a callback function to do
controller-specific actions when switching voltages.
It is a preparation and will be used by Fujitsu
SDHCI controller f_sdh30 driver.
Signed-off-by: Vincent Yang <Vincent.Yang@tw.fujitsu.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci.c

@@ -1829,6 +1829,10 @@ static int sdhci_do_start_signal_voltage_switch(struct sdhci_host *host,
 		ctrl |= SDHCI_CTRL_VDD_180;
 		sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
 
+		/* Some controller need to do more when switching */
+		if (host->ops->voltage_switch)
+			host->ops->voltage_switch(host);
+
 		/* 1.8V regulator output should be stable within 5 ms */
 		ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
 		if (ctrl & SDHCI_CTRL_VDD_180)

drivers/mmc/host/sdhci.h

@@ -339,6 +339,7 @@ struct sdhci_ops {
 	void    (*adma_workaround)(struct sdhci_host *host, u32 intmask);
 	void	(*platform_init)(struct sdhci_host *host);
 	void    (*card_event)(struct sdhci_host *host);
+	void	(*voltage_switch)(struct sdhci_host *host);
 };
 
 #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS