works

driver/counter.c

@@ -5,7 +5,6 @@
 #include <linux/platform_device.h>
 #include <linux/of_device.h>
 #include <linux/gpio/consumer.h>
-#include <linux/proc_fs.h>
 
 /* Meta Information */
 MODULE_LICENSE("GPL");
@@ -17,19 +16,19 @@ static int dt_probe(struct platform_device *pdev);
 static void dt_remove(struct platform_device *pdev);
 
 static struct of_device_id my_driver_ids[] = {
-	{
-		.compatible = "hottis,counter",
-	}, { /* sentinel */ }
+  {
+    .compatible = "hottis,counter",
+  }, { /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, my_driver_ids);
 
 static struct platform_driver my_driver = {
-	.probe = dt_probe,
-	.remove = dt_remove,
-	.driver = {
-		.name = "my_device_driver",
-		.of_match_table = my_driver_ids,
-	},
+  .probe = dt_probe,
+  .remove = dt_remove,
+  .driver = {
+    .name = "my_device_driver",
+    .of_match_table = my_driver_ids,
+  },
 };
 
 /* GPIO variable */
@@ -41,70 +40,70 @@ static struct gpio_desc *blue_led = NULL;
  * @brief This function is called on loading the driver 
  */
 static int dt_probe(struct platform_device *pdev) {
-	struct device *dev = &pdev->dev;
+  struct device *dev = &pdev->dev;
 
-	printk("counter - probing\n");
+  printk("counter - probing\n");
 
-	if(!device_property_present(dev, "red-led-gpio")) {
-		printk("counter - Error! Device property 'red-led-gpio' not found!\n");
-		return -1;
-	}
-	if(!device_property_present(dev, "blue-led-gpio")) {
-		printk("counter - Error! Device property 'blue-led-gpio' not found!\n");
-		return -1;
-	}
+  if(!device_property_present(dev, "red-led-gpio")) {
+    printk("counter - Error! Device property 'red-led-gpio' not found!\n");
+    return -1;
+  }
+  if(!device_property_present(dev, "blue-led-gpio")) {
+    printk("counter - Error! Device property 'blue-led-gpio' not found!\n");
+    return -1;
+  }
 
 
-	/* Init GPIO */
-	red_led = gpiod_get(dev, "red-led", GPIOD_OUT_LOW);
-	if(IS_ERR(red_led)) {
-		printk("counter - Error! Could not setup the GPIO red-led\n");
-		return -1 * IS_ERR(red_led);
-	}
-	blue_led = gpiod_get(dev, "blue-led", GPIOD_OUT_LOW);
-	if(IS_ERR(blue_led)) {
-		printk("counter - Error! Could not setup the GPIO blue-led\n");
-		return -1 * IS_ERR(blue_led);
-	}
+  /* Init GPIO */
+  red_led = gpiod_get(dev, "red-led", GPIOD_OUT_LOW);
+  if(IS_ERR(red_led)) {
+    printk("counter - Error! Could not setup the GPIO red-led\n");
+    return -1 * IS_ERR(red_led);
+  }
+  blue_led = gpiod_get(dev, "blue-led", GPIOD_OUT_LOW);
+  if(IS_ERR(blue_led)) {
+    printk("counter - Error! Could not setup the GPIO blue-led\n");
+    return -1 * IS_ERR(blue_led);
+  }
 
-	return 0;
+  return 0;
 }
 
 /**
  * @brief This function is called on unloading the driver 
  */
 static void dt_remove(struct platform_device *pdev) {
-	printk("counter - removing\n");
-	gpiod_put(red_led);
-	gpiod_put(blue_led);
+  printk("counter - removing\n");
+  gpiod_put(red_led);
+  gpiod_put(blue_led);
 }
 
 /**
  * @brief This function is called, when the module is loaded into the kernel
  */
 static int __init my_init(void) {
-	printk("counter - Loading the driver...\n");
-	if(platform_driver_register(&my_driver)) {
-		printk("dt_gpio - Error! Could not load driver\n");
-		return -1;
-	}
+  printk("counter - Loading the driver...\n");
+  if(platform_driver_register(&my_driver)) {
+    printk("dt_gpio - Error! Could not load driver\n");
+    return -1;
+  }
 
-	printk("counter - red led on\n");
-	gpiod_set_value(red_led, 1);
+  printk("counter - red led on\n");
+  gpiod_set_value(red_led, 1);
 
-	return 0;
+  return 0;
 }
 
 /**
  * @brief This function is called, when the module is removed from the kernel
  */
 static void __exit my_exit(void) {
-	printk("counter - Unload driver");
+  printk("counter - Unload driver");
 
-	printk("counter - red led off\n");
-	gpiod_set_value(red_led, 0);
+  printk("counter - red led off\n");
+  gpiod_set_value(red_led, 0);
 
-	platform_driver_unregister(&my_driver);
+  platform_driver_unregister(&my_driver);
 }
 
 module_init(my_init);

driver/counter.dts

@@ -5,6 +5,7 @@
   fragment@0 {
     target-path = "/";
     __overlay__ {
+      status = "okay";
       counter {
         compatible = "hottis,counter";
         red-led-gpio = <&gpio 26 0>;