[PATCH v6 04/10] regulator: fixed: add support for ACPI interface

[Lu Baolu <baolu.lu@linux.intel.com>]

Add support to retrieve fixed voltage configure information through
ACPI interface. This is needed for Intel Bay Trail devices, where a
GPIO is used to control the USB vbus.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/regulator/fixed.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/drivers/regulator/fixed.c b/drivers/regulator/fixed.c
index e6f376f..4d0cc84 100644
--- a/drivers/regulator/fixed.c
+++ b/drivers/regulator/fixed.c
@@ -30,6 +30,9 @@
 #include <linux/of_gpio.h>
 #include <linux/regulator/of_regulator.h>
 #include <linux/regulator/machine.h>
+#include <linux/acpi.h>
+#include <linux/property.h>
+#include <linux/gpio/consumer.h>
 
 struct fixed_voltage_data {
 	struct regulator_desc desc;
@@ -104,6 +107,46 @@ of_get_fixed_voltage_config(struct device *dev,
 	return config;
 }
 
+/**
+ * acpi_get_fixed_voltage_config - extract fixed_voltage_config structure info
+ * @dev: device requesting for fixed_voltage_config
+ * @desc: regulator description
+ *
+ * Populates fixed_voltage_config structure by extracting data through ACPI
+ * interface, returns a pointer to the populated structure of NULL if memory
+ * alloc fails.
+ */
+static struct fixed_voltage_config *
+acpi_get_fixed_voltage_config(struct device *dev,
+			      const struct regulator_desc *desc)
+{
+	struct fixed_voltage_config *config;
+	const char *supply_name, *gpio_name;
+	struct gpio_desc *gpiod;
+	int ret;
+
+	config = devm_kzalloc(dev, sizeof(*config), GFP_KERNEL);
+	if (!config)
+		return ERR_PTR(-ENOMEM);
+
+	ret = device_property_read_string(dev, "supply-name", &supply_name);
+	if (!ret)
+		config->supply_name = supply_name;
+
+	ret = device_property_read_string(dev, "gpio-name", &gpio_name);
+	if (!ret) {
+		gpiod = gpiod_get(dev, gpio_name, GPIOD_ASIS);
+		if (!IS_ERR(gpiod)) {
+			config->gpio = desc_to_gpio(gpiod);
+			config->enable_high = device_property_read_bool(dev,
+							"enable-active-high");
+			gpiod_put(gpiod);
+		}
+	}
+
+	return config;
+}
+
 static struct regulator_ops fixed_voltage_ops = {
 };
 
@@ -124,6 +167,11 @@ static int reg_fixed_voltage_probe(struct platform_device *pdev)
 						     &drvdata->desc);
 		if (IS_ERR(config))
 			return PTR_ERR(config);
+	} else if (ACPI_HANDLE(&pdev->dev)) {
+		config = acpi_get_fixed_voltage_config(&pdev->dev,
+						       &drvdata->desc);
+		if (IS_ERR(config))
+			return PTR_ERR(config);
 	} else {
 		config = dev_get_platdata(&pdev->dev);
 	}
-- 
2.1.4