mmc: sdhci: Add platform suspend/resume hooks.

Some platforms require saving/restoring registers across suspend/resume;
this hook allows them to do that inside their driver.
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci.c

@@ -2379,6 +2379,9 @@ int sdhci_suspend_host(struct sdhci_host *host)
 	int ret;
 	bool has_tuning_timer;
 
+	if (host->ops->platform_suspend)
+		host->ops->platform_suspend(host);
+
 	sdhci_disable_card_detection(host);
 
 	/* Disable tuning since we are suspending */
@@ -2429,6 +2432,9 @@ int sdhci_resume_host(struct sdhci_host *host)
 	ret = mmc_resume_host(host->mmc);
 	sdhci_enable_card_detection(host);
 
+	if (host->ops->platform_resume)
+		host->ops->platform_resume(host);
+
 	/* Set the re-tuning expiration flag */
 	if ((host->version >= SDHCI_SPEC_300) && host->tuning_count &&
 	    (host->tuning_mode == SDHCI_TUNING_MODE_1))

drivers/mmc/host/sdhci.h

@@ -275,6 +275,8 @@ struct sdhci_ops {
 	void	(*platform_reset_exit)(struct sdhci_host *host, u8 mask);
 	int	(*set_uhs_signaling)(struct sdhci_host *host, unsigned int uhs);
 	void	(*hw_reset)(struct sdhci_host *host);
+	void	(*platform_suspend)(struct sdhci_host *host);
+	void	(*platform_resume)(struct sdhci_host *host);
 };
 
 #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS