1 files changed, 66 insertions, 8 deletions

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index b5a41a7ce165..17dbc81c221e 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -36,6 +36,7 @@
 #include <linux/types.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/reset.h>
+#include <linux/gpio/consumer.h>
 
 #include <asm/div64.h>
 #include <asm/io.h>
@@ -1888,6 +1889,65 @@ static struct mmc_host_ops mmci_ops = {
 	.start_signal_voltage_switch = mmci_sig_volt_switch,
 };
 
+static void mmci_probe_level_translator(struct mmc_host *mmc)
+{
+	struct device *dev = mmc_dev(mmc);
+	struct mmci_host *host = mmc_priv(mmc);
+	struct gpio_desc *cmd_gpio;
+	struct gpio_desc *ck_gpio;
+	struct gpio_desc *ckin_gpio;
+	int clk_hi, clk_lo;
+
+	/*
+	 * Assume the level translator is present if st,use-ckin is set.
+	 * This is to cater for DTs which do not implement this test.
+	 */
+	host->clk_reg_add |= MCI_STM32_CLK_SELCKIN;
+
+	cmd_gpio = gpiod_get(dev, "st,cmd", GPIOD_OUT_HIGH);
+	if (IS_ERR(cmd_gpio))
+		goto exit_cmd;
+
+	ck_gpio = gpiod_get(dev, "st,ck", GPIOD_OUT_HIGH);
+	if (IS_ERR(ck_gpio))
+		goto exit_ck;
+
+	ckin_gpio = gpiod_get(dev, "st,ckin", GPIOD_IN);
+	if (IS_ERR(ckin_gpio))
+		goto exit_ckin;
+
+	/* All GPIOs are valid, test whether level translator works */
+
+	/* Sample CKIN */
+	clk_hi = !!gpiod_get_value(ckin_gpio);
+
+	/* Set CK low */
+	gpiod_set_value(ck_gpio, 0);
+
+	/* Sample CKIN */
+	clk_lo = !!gpiod_get_value(ckin_gpio);
+
+	/* Tristate all */
+	gpiod_direction_input(cmd_gpio);
+	gpiod_direction_input(ck_gpio);
+
+	/* Level translator is present if CK signal is propagated to CKIN */
+	if (!clk_hi || clk_lo) {
+		host->clk_reg_add &= ~MCI_STM32_CLK_SELCKIN;
+		dev_warn(dev,
+			 "Level translator inoperable, CK signal not detected on CKIN, disabling.\n");
+	}
+
+	gpiod_put(ckin_gpio);
+
+exit_ckin:
+	gpiod_put(ck_gpio);
+exit_ck:
+	gpiod_put(cmd_gpio);
+exit_cmd:
+	pinctrl_select_default_state(dev);
+}
+
 static int mmci_of_parse(struct device_node *np, struct mmc_host *mmc)
 {
 	struct mmci_host *host = mmc_priv(mmc);
@@ -1913,7 +1973,7 @@ static int mmci_of_parse(struct device_node *np, struct mmc_host *mmc)
 	if (of_get_property(np, "st,neg-edge", NULL))
 		host->clk_reg_add |= MCI_STM32_CLK_NEGEDGE;
 	if (of_get_property(np, "st,use-ckin", NULL))
-		host->clk_reg_add |= MCI_STM32_CLK_SELCKIN;
+		mmci_probe_level_translator(mmc);
 
 	if (of_get_property(np, "mmc-cap-mmc-highspeed", NULL))
 		mmc->caps |= MMC_CAP_MMC_HIGHSPEED;
@@ -1949,15 +2009,15 @@ static int mmci_probe(struct amba_device *dev,
 	if (!mmc)
 		return -ENOMEM;
 
-	ret = mmci_of_parse(np, mmc);
-	if (ret)
-		goto host_free;
-
 	host = mmc_priv(mmc);
 	host->mmc = mmc;
 	host->mmc_ops = &mmci_ops;
 	mmc->ops = &mmci_ops;
 
+	ret = mmci_of_parse(np, mmc);
+	if (ret)
+		goto host_free;
+
 	/*
 	 * Some variant (STM32) doesn't have opendrain bit, nevertheless
 	 * pins can be set accordingly using pinctrl
@@ -2195,7 +2255,7 @@ static int mmci_probe(struct amba_device *dev,
 	return ret;
 }
 
-static int mmci_remove(struct amba_device *dev)
+static void mmci_remove(struct amba_device *dev)
 {
 	struct mmc_host *mmc = amba_get_drvdata(dev);
 
@@ -2223,8 +2283,6 @@ static int mmci_remove(struct amba_device *dev)
 		clk_disable_unprepare(host->clk);
 		mmc_free_host(mmc);
 	}
-
-	return 0;
 }
 
 #ifdef CONFIG_PM