[U-Boot] [PATCH 12/22] mmc: Enable signal voltage to be selected from mmc core

[Jean-Jacques Hiblot]

From: Kishon Vijay Abraham I <kishon at ti.com>

Add a new function *mmc_set_signal_voltage* in mmc core
which can be used during mmc initialization to select the
signal voltage. Platform driver should use the set_ios
callback function to select the signal voltage.

Signed-off-by: Kishon Vijay Abraham I <kishon at ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot at ti.com>
---
 drivers/mmc/mmc.c | 15 +++++++++++++++
 include/mmc.h     |  5 +++++
 2 files changed, 20 insertions(+)

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 2ae6f1c..10af81d 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -29,6 +29,7 @@ static const unsigned int sd_au_size[] = {
 	SZ_4M / 512,	SZ_8M / 512,		(SZ_8M + SZ_4M) / 512,
 	SZ_16M / 512,	(SZ_16M + SZ_8M) / 512,	SZ_32M / 512,	SZ_64M / 512,
 };
+static int mmc_set_signal_voltage(struct mmc *mmc, uint signal_voltage);
 
 #if CONFIG_IS_ENABLED(MMC_TINY)
 static struct mmc mmc_static;
@@ -1247,6 +1248,12 @@ struct mode_width_tuning {
 	uint widths;
 };
 
+static int mmc_set_signal_voltage(struct mmc *mmc, uint signal_voltage)
+{
+	mmc->signal_voltage = signal_voltage;
+	return mmc_set_ios(mmc);
+}
+
 static const struct mode_width_tuning sd_modes_by_pref[] = {
 	{
 		.mode = SD_HS,
@@ -1935,6 +1942,14 @@ int mmc_start_init(struct mmc *mmc)
 		return err;
 #endif
 	mmc->ddr_mode = 0;
+
+	/* First try to set 3.3V. If it fails set to 1.8V */
+	err = mmc_set_signal_voltage(mmc, MMC_SIGNAL_VOLTAGE_330);
+	if (err != 0)
+		err = mmc_set_signal_voltage(mmc, MMC_SIGNAL_VOLTAGE_180);
+	if (err != 0)
+		printf("failed to set signal voltage\n");
+
 	mmc_set_bus_width(mmc, 1);
 	mmc_set_clock(mmc, 1);
 
diff --git a/include/mmc.h b/include/mmc.h
index 9f20eb4..89cb26c 100644
--- a/include/mmc.h
+++ b/include/mmc.h
@@ -266,6 +266,10 @@
 #define ENHNCD_SUPPORT		(0x2)
 #define PART_ENH_ATTRIB		(0x1f)
 
+#define MMC_SIGNAL_VOLTAGE_330	1
+#define MMC_SIGNAL_VOLTAGE_180	2
+#define MMC_SIGNAL_VOLTAGE_120	3
+
 /* Maximum block size for MMC */
 #define MMC_MAX_BLOCK_LEN	512
 
@@ -452,6 +456,7 @@ struct mmc {
 	int high_capacity;
 	uint bus_width;
 	uint clock;
+	uint signal_voltage;
 	uint card_caps;
 	uint ocr;
 	uint dsr;
-- 
1.9.1