[PATCH 2/9] mmc: sdhci: add a callback for signal voltage switching

[Yangbo Lu]

Add a callback for signal voltage switching to let host driver
switch signal voltage in its own way.

Signed-off-by: Yangbo Lu <yangbo.lu at nxp.com>
---
 drivers/mmc/host/sdhci.c | 6 ++++++
 drivers/mmc/host/sdhci.h | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 6fdd7a7..3c9a924 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1852,6 +1852,12 @@ static int sdhci_start_signal_voltage_switch(struct mmc_host *mmc,
 	if (host->version < SDHCI_SPEC_300)
 		return 0;
 
+	if (host->ops->start_signal_voltage_switch) {
+		ret = host->ops->start_signal_voltage_switch(
+					host, ios->signal_voltage);
+		return ret;
+	}
+
 	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
 
 	switch (ios->signal_voltage) {
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index edf3adf..04af687 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -566,6 +566,8 @@ struct sdhci_ops {
 					 struct mmc_card *card,
 					 unsigned int max_dtr, int host_drv,
 					 int card_drv, int *drv_type);
+	int	(*start_signal_voltage_switch)(struct sdhci_host *host,
+					       unsigned char signal_voltage);
 };
 
 #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
-- 
2.1.0.27.g96db324