Allow the driver to work with device tree 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.fran...@nxp.com>
---
Changes since v3:
-Remove the optional properties because they are not hardware description
-Change the sensor node name

 Documentation/devicetree/bindings/hwmon/sht15.txt | 19 +++++++
 drivers/hwmon/sht15.c                             | 64 +++++++++++++++++++++--
 2 files changed, 79 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..6a80277
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/sht15.txt
@@ -0,0 +1,19 @@
+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.
+
+Example:
+
+       sensor {
+               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..69141b2 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 +912,54 @@ 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 NULL if pdev isn't a device instatiated by dt,
+ * a pointer to pdata if it could successfully get all information
+ * from dt or a negative ERR_PTR() on error.
+ */
+static struct sht15_platform_data *sht15_probe_dt(struct device *dev)
+{
+       struct device_node *np = dev->of_node;
+       struct sht15_platform_data *pdata;
+
+       /* no device tree device */
+       if (!np)
+               return NULL;
+
+       pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+       if (!pdata)
+               return ERR_PTR(-ENOMEM);
+
+       pdata->gpio_data = of_get_named_gpio(np, "data-gpios", 0);
+       if (pdata->gpio_data < 0) {
+               if (pdata->gpio_data != -EPROBE_DEFER)
+                       dev_err(dev, "data-gpios not found\n");
+               return ERR_PTR(pdata->gpio_data);
+       }
+
+       pdata->gpio_sck = of_get_named_gpio(np, "clk-gpios", 0);
+       if (pdata->gpio_sck < 0) {
+               if (pdata->gpio_sck != -EPROBE_DEFER)
+                       dev_err(dev, "clk-gpios not found\n");
+               return ERR_PTR(pdata->gpio_sck);
+       }
+
+       return pdata;
+}
+#else
+static inline struct sht15_platform_data *sht15_probe_dt(struct device *dev)
+{
+       return NULL;
+}
+#endif
+
 static int sht15_probe(struct platform_device *pdev)
 {
        int ret;
@@ -928,11 +977,17 @@ 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;
+       data->pdata = sht15_probe_dt(&pdev->dev);
+       if (IS_ERR(data->pdata))
+               return PTR_ERR(data->pdata);
+       if (data->pdata == NULL) {
+               data->pdata = dev_get_platdata(&pdev->dev);
+               if (data->pdata == NULL) {
+                       dev_err(&pdev->dev, "no platform data supplied\n");
+                       return -EINVAL;
+               }
        }
-       data->pdata = dev_get_platdata(&pdev->dev);
+
        data->supply_uv = data->pdata->supply_mv * 1000;
        if (data->pdata->checksum)
                data->checksumming = true;
@@ -1075,6 +1130,7 @@ 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

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