[PATCH 01/17] mmc: sdhci: Add helper functions for UHS modes

[Faiz Abbas]

Add a set_voltage() function which handles the switch from 3.3V to 1.8V
for SD card UHS modes.

Signed-off-by: Faiz Abbas <faiz_abbas at ti.com>
---
 drivers/mmc/sdhci.c | 49 +++++++++++++++++++++++++++++++++++++++++++++
 include/sdhci.h     |  1 +
 2 files changed, 50 insertions(+)

diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
index 7673219fb3..987055d970 100644
--- a/drivers/mmc/sdhci.c
+++ b/drivers/mmc/sdhci.c
@@ -20,6 +20,7 @@
 #include <linux/delay.h>
 #include <linux/dma-mapping.h>
 #include <phys2bus.h>
+#include <power/regulator.h>
 
 static void sdhci_reset(struct sdhci_host *host, u8 mask)
 {
@@ -556,6 +557,54 @@ void sdhci_set_uhs_timing(struct sdhci_host *host)
 	sdhci_writew(host, reg, SDHCI_HOST_CONTROL2);
 }
 
+#if CONFIG_IS_ENABLED(MMC_IO_VOLTAGE)
+static void sdhci_set_voltage(struct sdhci_host *host)
+{
+	struct mmc *mmc = (struct mmc *)host->mmc;
+	u32 ctrl;
+
+	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+
+	switch (mmc->signal_voltage) {
+	case MMC_SIGNAL_VOLTAGE_330:
+		if (mmc->vqmmc_supply) {
+			regulator_set_enable(mmc->vqmmc_supply, false);
+			regulator_set_value(mmc->vqmmc_supply, 3300000);
+			regulator_set_enable(mmc->vqmmc_supply, true);
+		}
+
+		mdelay(5);
+		if (IS_SD(mmc)) {
+			ctrl &= ~SDHCI_CTRL_VDD_180;
+			sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
+		}
+		break;
+	case MMC_SIGNAL_VOLTAGE_180:
+		if (mmc->vqmmc_supply) {
+			regulator_set_enable(mmc->vqmmc_supply, false);
+			regulator_set_value(mmc->vqmmc_supply, 1800000);
+			regulator_set_enable(mmc->vqmmc_supply, true);
+		}
+
+		if (IS_SD(mmc)) {
+			ctrl |= SDHCI_CTRL_VDD_180;
+			sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
+		}
+		break;
+	default:
+		/* No signal voltage switch required */
+		return;
+	}
+}
+#else
+static void sdhci_set_voltage(struct sdhci_host *host) { }
+#endif
+void sdhci_set_control_reg(struct sdhci_host *host)
+{
+	sdhci_set_voltage(host);
+	sdhci_set_uhs_timing(host);
+}
+
 #ifdef CONFIG_DM_MMC
 static int sdhci_set_ios(struct udevice *dev)
 {
diff --git a/include/sdhci.h b/include/sdhci.h
index 94fc3ed56a..d3f8741042 100644
--- a/include/sdhci.h
+++ b/include/sdhci.h
@@ -492,6 +492,7 @@ void sdhci_set_uhs_timing(struct sdhci_host *host);
 /* Export the operations to drivers */
 int sdhci_probe(struct udevice *dev);
 int sdhci_set_clock(struct mmc *mmc, unsigned int clock);
+void sdhci_set_control_reg(struct sdhci_host *host);
 extern const struct dm_mmc_ops sdhci_ops;
 #else
 #endif
-- 
2.17.1