ARM: 7724/1: mmc: mmci: Support signal voltage switch for UHS cards

Add .start_signal_voltage_switch callback to be able to support UHS cards.
The voltage switch requires the optional vqmmc regulator to exist since
the actual voltage switch will be performed directly on it.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/mmc/host/mmci.c

@@ -1266,6 +1266,39 @@ static int mmci_get_cd(struct mmc_host *mmc)
 	return status;
 }
 
+static int mmci_sig_volt_switch(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+	int ret = 0;
+
+	if (!IS_ERR(mmc->supply.vqmmc)) {
+
+		pm_runtime_get_sync(mmc_dev(mmc));
+
+		switch (ios->signal_voltage) {
+		case MMC_SIGNAL_VOLTAGE_330:
+			ret = regulator_set_voltage(mmc->supply.vqmmc,
+						2700000, 3600000);
+			break;
+		case MMC_SIGNAL_VOLTAGE_180:
+			ret = regulator_set_voltage(mmc->supply.vqmmc,
+						1700000, 1950000);
+			break;
+		case MMC_SIGNAL_VOLTAGE_120:
+			ret = regulator_set_voltage(mmc->supply.vqmmc,
+						1100000, 1300000);
+			break;
+		}
+
+		if (ret)
+			dev_warn(mmc_dev(mmc), "Voltage switch failed\n");
+
+		pm_runtime_mark_last_busy(mmc_dev(mmc));
+		pm_runtime_put_autosuspend(mmc_dev(mmc));
+	}
+
+	return ret;
+}
+
 static irqreturn_t mmci_cd_irq(int irq, void *dev_id)
 {
 	struct mmci_host *host = dev_id;
@@ -1282,6 +1315,7 @@ static const struct mmc_host_ops mmci_ops = {
 	.set_ios	= mmci_set_ios,
 	.get_ro		= mmci_get_ro,
 	.get_cd		= mmci_get_cd,
+	.start_signal_voltage_switch = mmci_sig_volt_switch,
 };
 
 #ifdef CONFIG_OF