[PATCH 2/2] hwmon: (sht15) Add DTS support

[Marco Franchi <marco.franchi@nxp.com>]

Allow the driver to work with dts support.

Based on initial patch submission from Peter Fox.

Tested on a imx7d-sdb board connected to a SHT15 board via Mikro Bus.

Signed-off-by: Marco Franchi <marco.franchi@nxp.com>
---
 Documentation/devicetree/bindings/hwmon/sht15.txt | 25 ++++++++
 drivers/hwmon/sht15.c                             | 69 +++++++++++++++++++++--
 2 files changed, 90 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/hwmon/sht15.txt

diff --git a/Documentation/devicetree/bindings/hwmon/sht15.txt b/Documentation/devicetree/bindings/hwmon/sht15.txt
new file mode 100644
index 0000000..6415f52
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/sht15.txt
@@ -0,0 +1,25 @@
+Sensirion SHT15 Humidity and Temperature Sensor
+
+Required properties:
+
+ - "compatible": must be "sensirion,sht15".
+ - "data-gpios": GPIO connected to the data line.
+ - "clk-gpios": GPIO connected to the clock line.
+ - "vcc-supply": regulator that drives the VCC pin.
+
+Optional properties:
+
+ - "checksum": boolean property that when present enables the CRC validation of the readings.
+ - "no-otp-reload": boolean property that when present indicates not to reload from OTP.
+ - "low-resolution": boolean property that when present indicates that the device operates in
+ 		low-resolution mode.
+Example:
+
+	temp_humid_sensor: sht15 {
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_sensor>;
+		compatible = "sensirion,sht15";
+		clk-gpios = <&gpio4 12 0>;
+		data-gpios = <&gpio4 13 0>;
+		vcc-supply = <&reg_sht15>;
+	};
diff --git a/drivers/hwmon/sht15.c b/drivers/hwmon/sht15.c
index f16687c..608ac9e 100644
--- a/drivers/hwmon/sht15.c
+++ b/drivers/hwmon/sht15.c
@@ -34,6 +34,7 @@
 #include <linux/slab.h>
 #include <linux/atomic.h>
 #include <linux/bitrev.h>
+#include <linux/of_gpio.h>
 
 /* Commands */
 #define SHT15_MEASURE_TEMP		0x03
@@ -911,6 +912,59 @@ static int sht15_invalidate_voltage(struct notifier_block *nb,
 	return NOTIFY_OK;
 }
 
+#ifdef CONFIG_OF
+static const struct of_device_id sht15_dt_match[] = {
+	{ .compatible = "sensirion,sht15" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, sht15_dt_match);
+
+/*
+ * This function returns 1 if pdev isn't a device instatiated by dt, 0 if it
+ * could successfully get all information from dt or a negative error number.
+ */
+static int sht15_probe_dt(struct sht15_data *data, struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct sht15_platform_data *pdata;
+
+	/* no device tree device */
+	if (!np)
+		return 1;
+
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+
+	data->pdata = pdata;
+
+	data->pdata->gpio_data = of_get_named_gpio(np, "data-gpios", 0);
+	if (data->pdata->gpio_data < 0) {
+		dev_err(&pdev->dev, "data-gpios not found\n");
+		return data->pdata->gpio_data;
+	}
+
+	data->pdata->gpio_sck = of_get_named_gpio(np, "clk-gpios", 0);
+	if (data->pdata->gpio_sck < 0) {
+		dev_err(&pdev->dev, "clk-gpios not found\n");
+		return data->pdata->gpio_sck;
+	}
+
+	data->pdata->checksum = of_property_read_bool(np, "checksum");
+	data->pdata->no_otp_reload = of_property_read_bool(np, "no-otp-reload");
+	data->pdata->low_resolution = of_property_read_bool(np,
+					"low-resolution");
+
+	return 0;
+}
+#else
+static inline int sht15_probe_dt(struct sht15_data *data,
+					struct platform_device *pdev)
+{
+	return 1;
+}
+#endif
+
 static int sht15_probe(struct platform_device *pdev)
 {
 	int ret;
@@ -928,11 +982,17 @@ static int sht15_probe(struct platform_device *pdev)
 	data->dev = &pdev->dev;
 	init_waitqueue_head(&data->wait_queue);
 
-	if (dev_get_platdata(&pdev->dev) == NULL) {
-		dev_err(&pdev->dev, "no platform data supplied\n");
-		return -EINVAL;
+	ret = sht15_probe_dt(data, pdev);
+	if (ret > 0) {
+		if (dev_get_platdata(&pdev->dev) == NULL) {
+			dev_err(&pdev->dev, "no platform data supplied\n");
+			return -EINVAL;
+		}
+		data->pdata = dev_get_platdata(&pdev->dev);
+	} else if (ret < 0) {
+		return ret;
 	}
-	data->pdata = dev_get_platdata(&pdev->dev);
+
 	data->supply_uv = data->pdata->supply_mv * 1000;
 	if (data->pdata->checksum)
 		data->checksumming = true;
@@ -1075,6 +1135,7 @@ MODULE_DEVICE_TABLE(platform, sht15_device_ids);
 static struct platform_driver sht15_driver = {
 	.driver = {
 		.name = "sht15",
+		.of_match_table = of_match_ptr(sht15_dt_match),
 	},
 	.probe = sht15_probe,
 	.remove = sht15_remove,
-- 
2.7.4