mmc: tmio: Add UHS-I mode support

Based on work by Shinobu Uehara and Ben Dooks. This adds the voltage
switch operation needed for all UHS-I modes, but not the tuning needed
for SDR-104 which will come later.

Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
index b44b589..b1819c7 100644
--- a/drivers/mmc/host/tmio_mmc.h
+++ b/drivers/mmc/host/tmio_mmc.h
@@ -101,6 +101,8 @@
 	void (*clk_disable)(struct tmio_mmc_host *host);
 	int (*multi_io_quirk)(struct mmc_card *card,
 			      unsigned int direction, int blk_size);
+	int (*start_signal_voltage_switch)(struct mmc_host *mmc,
+					   struct mmc_ios *ios);
 };
 
 struct tmio_mmc_host *tmio_mmc_host_alloc(struct platform_device *pdev);