[U-Boot] [PATCH 14/22] mmc: add power cyle support in mmc core

[Jean-Jacques Hiblot]

mmc/sd specification requires vdd to be disabled for 1 ms
and then enabled again during power cycle. Add a
function in mmc core to perform power cycle and set
the io signal to it's initial state.

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 | 50 +++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 41 insertions(+), 9 deletions(-)

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index d40a22b..032260b 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -30,6 +30,7 @@ static const unsigned int sd_au_size[] = {
 	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);
+static void mmc_power_cycle(struct mmc *mmc);
 
 #if CONFIG_IS_ENABLED(MMC_TINY)
 static struct mmc mmc_static;
@@ -1915,6 +1916,45 @@ static int mmc_power_init(struct mmc *mmc)
 	return 0;
 }
 
+static void mmc_set_initial_state(struct mmc *mmc)
+{
+	int err;
+
+	/* 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);
+	mmc_select_mode(mmc, MMC_LEGACY);
+}
+
+static void mmc_power_up(struct mmc *mmc)
+{
+	mmc_set_initial_state(mmc);
+	mmc_set_vdd(mmc, true);
+	udelay(10000);
+}
+
+static void mmc_power_off(struct mmc *mmc)
+{
+	mmc_set_vdd(mmc, false);
+}
+
+static void mmc_power_cycle(struct mmc *mmc)
+{
+	mmc_power_off(mmc);
+	/*
+	 * SD spec recommends at least 1ms of delay. Let's wait for 2ms
+	 * to be on the safer side.
+	 */
+	udelay(2000);
+	mmc_power_up(mmc);
+}
+
 int mmc_start_init(struct mmc *mmc)
 {
 	bool no_card;
@@ -1952,16 +1992,8 @@ int mmc_start_init(struct mmc *mmc)
 		return err;
 #endif
 	mmc->ddr_mode = 0;
-	mmc_set_vdd(mmc, true);
-	/* 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);
+	mmc_power_cycle(mmc);
 
 	/* Reset the Card */
 	err = mmc_go_idle(mmc);
-- 
1.9.1