[PATCH v6 08/23] mfd: max77686: Add Dynamic Voltage Scaling (DVS) support

diff --git a/drivers/mfd/max77686.c b/drivers/mfd/max77686.c
index 8650832..648d564 100644
--- a/drivers/mfd/max77686.c
+++ b/drivers/mfd/max77686.c

@@ -32,8 +32,10 @@
 #include <linux/mfd/core.h>
 #include <linux/mfd/max77686.h>
 #include <linux/mfd/max77686-private.h>
+#include <linux/gpio/consumer.h>
 #include <linux/err.h>
 #include <linux/of.h>
+#include <linux/export.h>
 
 #define I2C_ADDR_RTC	(0x0C >> 1)
 

@@ -101,9 +103,115 @@ static const struct of_device_id max77686_pmic_dt_match[] = {
 	{},
 };
 
+static void max77686_dt_parse_dvs_gpio(struct device *dev)
+{
+	struct max77686_platform_data *pd = dev_get_platdata(dev);
+	int i;
+
+	/*
+	 * NOTE: we don't consider GPIO errors fatal; board may have some lines
+	 * directly pulled high or low and thus doesn't specify them.
+	 */
+	for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_dvs); i++)
+		pd->buck_gpio_dvs[i] =
+			devm_gpiod_get_index(dev, "max77686,pmic-buck-dvs", i);
+
+	for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_selb); i++)
+		pd->buck_gpio_selb[i] =
+			devm_gpiod_get_index(dev, "max77686,pmic-buck-selb", i);
+}
+
+/**
+ * max77686_setup_gpios - init DVS-related GPIOs
+ *
+ * This function claims / initalizations GPIOs related to DVS if they are
+ * defined. This may have the effect of switching voltages if the
+ * pdata->buck_default_idx does not match the boot time state of pins.
+ */
+int max77686_setup_gpios(struct device *dev)
+{
+	struct max77686_platform_data *pd = dev_get_platdata(dev);
+	int buck_default_idx = pd->buck_default_idx;
+	int ret;
+	int i;
+
+	/* Set all SELB high to avoid glitching while DVS is changing */
+	for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_selb); i++) {
+		struct gpio_desc *gpio = pd->buck_gpio_selb[i];
+
+		/* OK if some GPIOs aren't defined */
+		if (IS_ERR(gpio))
+			continue;
+
+		ret = gpiod_direction_output_raw(gpio, 1);
+		if (ret) {
+			dev_err(dev, "can't set gpio[%d] dir: %d\n", i, ret);
+			return ret;
+		}
+	}
+
+	/* Set our initial setting */
+	for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_dvs); i++) {
+		struct gpio_desc *gpio = pd->buck_gpio_dvs[i];
+
+		/* OK if some GPIOs aren't defined */
+		if (IS_ERR(gpio))
+			continue;
+
+		/* If a GPIO is valid, set it */
+		gpiod_direction_output(gpio, (buck_default_idx >> i) & 1);
+		if (ret) {
+			dev_err(dev, "can't set gpio[%d]: dir %d\n", i, ret);
+			return ret;
+		}
+	}
+
+	/* Now set SELB low to take effect */
+	for (i = 0; i < ARRAY_SIZE(pd->buck_gpio_selb); i++) {
+		struct gpio_desc *gpio = pd->buck_gpio_selb[i];
+
+		if (!IS_ERR(gpio))
+			gpiod_set_value(gpio, 0);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(max77686_setup_gpios);
+
+/**
+ * max77686_read_gpios - read the current state of the dvs GPIOs
+ *
+ * We call this function at bootup to detect what slot the firmware was
+ * using for the DVS GPIOs.  That way we can properly preserve the firmware's
+ * voltage settings
+ */
+int max77686_read_gpios(struct max77686_platform_data *pdata)
+{