add dummy led

dummy-led/.tmp_versions/dummy-led.mod

@@ -0,0 +1,2 @@
+/home/marco/projects/kernel-playground/dummy-led/dummy-led.ko
+/home/marco/projects/kernel-playground/dummy-led/dummy-led.o

dummy-led/Makefile

@@ -0,0 +1,16 @@
+obj-m := dummy-led.o
+KDIR  := /lib/modules/$(shell uname -r)/build
+PWD   := $(shell pwd)
+DEPMOD:=$(shell which depmod)
+# possible bug: maybe this will work only on debian based systems
+SYSMAP:= /boot/System.map-$(shell uname -r)
+
+default:
+	$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
+
+install:
+	$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules_install
+	$(DEPMOD) -ae -F $(SYSMAP)
+
+clean:
+	$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) clean

dummy-led/dummy-led.c

@@ -0,0 +1,47 @@
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/init.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("encrypt";)
+MODULE_DESCRIPTION("Dummy led");
+
+struct dummy_led {
+  struct led_classdev cdev;
+};
+
+static void dummy_led_set(struct led_classdev *ldev, enum led_brightness brightness) {
+  printk("dummy_led: led");
+}
+
+
+static struct dummy_led led = {
+  .cdev = {
+    .name = "dummy::led",
+    .brightness = LED_OFF,
+    .max_brightness = 1,
+    .brightness_set = dummy_led_set
+  }
+};
+
+static int __init dummy_led_init(void) {
+  int err;
+  printk("dummy_led: Hello from dummy led");
+  led.cdev.name = "dummy_led";
+  led.cdev.max_brightness = 1;
+  led.cdev.brightness_set = dummy_led_set;
+  err = led_classdev_register(NULL, &led.cdev);
+  if(err < 0)
+    return err;
+  return 0;
+}
+
+static void __exit dummy_led_exit(void) {
+  led_classdev_unregister(&led.cdev);
+  printk("dummy_led: Cya in another life");
+}
+
+module_init(dummy_led_init);
+module_exit(dummy_led_exit);