From 43392b550e56b52274398763329f35d54109d291 Mon Sep 17 00:00:00 2001
From: Faiz Abbas <faiz_abbas@ti.com>
Date: Thu, 4 Feb 2021 15:10:46 +0530
Subject: [PATCH] mmc: sdhci: Add helper functions for UHS modes

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@ti.com>
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
---
 drivers/mmc/sdhci.c | 95 +++++++++++++++++++++++++++++++++++++++++++++
 include/sdhci.h     | 10 +++++
 2 files changed, 105 insertions(+)

diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
index 0628934312..ed0dc17325 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)
 {
@@ -509,6 +510,100 @@ void sdhci_set_uhs_timing(struct sdhci_host *host)
 	sdhci_writew(host, reg, SDHCI_HOST_CONTROL2);
 }
 
+static void sdhci_set_voltage(struct sdhci_host *host)
+{
+	if (IS_ENABLED(CONFIG_MMC_IO_VOLTAGE)) {
+		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 CONFIG_IS_ENABLED(DM_REGULATOR)
+			if (mmc->vqmmc_supply) {
+				if (regulator_set_enable_if_allowed(mmc->vqmmc_supply, false)) {
+					pr_err("failed to disable vqmmc-supply\n");
+					return;
+				}
+
+				if (regulator_set_value(mmc->vqmmc_supply, 3300000)) {
+					pr_err("failed to set vqmmc-voltage to 3.3V\n");
+					return;
+				}
+
+				if (regulator_set_enable_if_allowed(mmc->vqmmc_supply, true)) {
+					pr_err("failed to enable vqmmc-supply\n");
+					return;
+				}
+			}
+#endif
+			if (IS_SD(mmc)) {
+				ctrl &= ~SDHCI_CTRL_VDD_180;
+				sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
+			}
+
+			/* Wait for 5ms */
+			mdelay(5);
+
+			/* 3.3V regulator output should be stable within 5 ms */
+			if (IS_SD(mmc)) {
+				if (ctrl & SDHCI_CTRL_VDD_180) {
+					pr_err("3.3V regulator output did not become stable\n");
+					return;
+				}
+			}
+
+			break;
+		case MMC_SIGNAL_VOLTAGE_180:
+#if CONFIG_IS_ENABLED(DM_REGULATOR)
+			if (mmc->vqmmc_supply) {
+				if (regulator_set_enable_if_allowed(mmc->vqmmc_supply, false)) {
+					pr_err("failed to disable vqmmc-supply\n");
+					return;
+				}
+
+				if (regulator_set_value(mmc->vqmmc_supply, 1800000)) {
+					pr_err("failed to set vqmmc-voltage to 1.8V\n");
+					return;
+				}
+
+				if (regulator_set_enable_if_allowed(mmc->vqmmc_supply, true)) {
+					pr_err("failed to enable vqmmc-supply\n");
+					return;
+				}
+			}
+#endif
+			if (IS_SD(mmc)) {
+				ctrl |= SDHCI_CTRL_VDD_180;
+				sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
+			}
+
+			/* Wait for 5 ms */
+			mdelay(5);
+
+			/* 1.8V regulator output has to be stable within 5 ms */
+			if (IS_SD(mmc)) {
+				if (!(ctrl & SDHCI_CTRL_VDD_180)) {
+					pr_err("1.8V regulator output did not become stable\n");
+					return;
+				}
+			}
+
+			break;
+		default:
+			/* No signal voltage switch required */
+			return;
+		}
+	}
+}
+
+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 3e5a649818..0ae9471ad7 100644
--- a/include/sdhci.h
+++ b/include/sdhci.h
@@ -491,6 +491,16 @@ 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);
+
+/**
+ * sdhci_set_control_reg - Set control registers
+ *
+ * This is used set up control registers for voltage level and UHS speed
+ * mode.
+ *
+ * @host: SDHCI host structure
+ */
+void sdhci_set_control_reg(struct sdhci_host *host);
 extern const struct dm_mmc_ops sdhci_ops;
 #else
 #endif