use johannes4linux approach
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2
.gitignore
vendored
2
.gitignore
vendored
@ -14,6 +14,6 @@ driver/*.mod.c
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driver/*.mod.o
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driver/*.o
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driver/modules.order
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dtoverlay/*.dtbo
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driver/*.dtbo
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@ -1,11 +1,30 @@
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obj-m += counter.o
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NAME = counter
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obj-m += $(NAME).o
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KDIR := /lib/modules/$(shell uname -r)/build
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PWD := $(shell pwd)
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all: $(NAME).ko $(NAME).dtbo
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echo Builded Device Tree Overlay and kernel module
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all:
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$(MAKE) -C $(KDIR) M=$(PWD) modules
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$(NAME).ko:
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make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
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$(NAME).dtbo: $(NAME).dts
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dtc -@ -I dts -O dtb -o $@ $<
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clean:
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$(MAKE) -C $(KDIR) M=$(PWD) clean
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make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
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rm -rf $(NAME).dtbo
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load:
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sudo dtoverlay -d . $(NAME).dtbo
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@echo "Overlay loaded"
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sudo insmod ./$(NAME).ko
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@echo "LKM loaded"
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unload:
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sudo rmmod ./$(NAME).ko
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@echo "LKM unloaded"
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sudo dtoverlay -R $(NAME)
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@echo "Overlay unloaded"
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list:
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sudo dtoverlay -l
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174
driver/counter.c
174
driver/counter.c
@ -1,59 +1,147 @@
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/gpio/consumer.h>
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/mod_devicetable.h>
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#include <linux/property.h>
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#include <linux/platform_device.h>
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#include <linux/of_device.h>
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#include <linux/gpio/consumer.h>
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#include <linux/proc_fs.h>
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Du");
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MODULE_DESCRIPTION("GPIO consumer API example for two LEDs");
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/* Meta Information */
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Johannes 4 GNU/Linux");
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MODULE_DESCRIPTION("A simple LKM to parse the device tree for a specific device and its properties");
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static struct gpio_desc *led_blue;
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static struct gpio_desc *led_red;
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/* Declate the probe and remove functions */
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static int dt_probe(struct platform_device *pdev);
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static void dt_remove(struct platform_device *pdev);
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static int __init led_consumer_init(void)
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{
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struct device *dev = NULL;
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static struct of_device_id my_driver_ids[] = {
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{
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.compatible = "brightlight,mydev",
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}, { /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, my_driver_ids);
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pr_info("GPIO consumer LED module loading\n");
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static struct platform_driver my_driver = {
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.probe = dt_probe,
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.remove = dt_remove,
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.driver = {
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.name = "my_device_driver",
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.of_match_table = my_driver_ids,
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},
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};
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// GPIOs per Name aus dem Device Tree holen (via label oder node property)
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led_blue = gpiod_get(dev, "led-blue", GPIOD_OUT_LOW);
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if (IS_ERR(led_blue)) {
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pr_err("Failed to get GPIO for blue LED\n");
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return PTR_ERR(led_blue);
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}
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/* GPIO variable */
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static struct gpio_desc *my_led = NULL;
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led_red = gpiod_get(dev, "led-red", GPIOD_OUT_LOW);
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if (IS_ERR(led_red)) {
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pr_err("Failed to get GPIO for red LED\n");
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gpiod_put(led_blue);
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return PTR_ERR(led_red);
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}
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static struct proc_dir_entry *proc_file;
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// Test: LEDs einschalten
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gpiod_set_value(led_blue, 1);
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gpiod_set_value(led_red, 1);
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msleep(500);
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gpiod_set_value(led_blue, 0);
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gpiod_set_value(led_red, 0);
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pr_info("LEDs blinked using gpio/consumer\n");
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return 0;
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/**
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* @brief Write data to buffer
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*/
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static ssize_t my_write(struct file *File, const char *user_buffer, size_t count, loff_t *offs) {
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switch (user_buffer[0]) {
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case '0':
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case '1':
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gpiod_set_value(my_led, user_buffer[0] - '0');
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default:
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break;
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}
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return count;
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}
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static void __exit led_consumer_exit(void)
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{
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gpiod_set_value(led_blue, 0);
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gpiod_set_value(led_red, 0);
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static struct proc_ops fops = {
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.proc_write = my_write,
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};
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gpiod_put(led_blue);
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gpiod_put(led_red);
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/**
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* @brief This function is called on loading the driver
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*/
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static int dt_probe(struct platform_device *pdev) {
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struct device *dev = &pdev->dev;
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const char *label;
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int my_value, ret;
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pr_info("GPIO consumer LED module unloaded\n");
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printk("dt_gpio - Now I am in the probe function!\n");
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/* Check for device properties */
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if(!device_property_present(dev, "label")) {
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printk("dt_gpio - Error! Device property 'label' not found!\n");
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return -1;
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}
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if(!device_property_present(dev, "my_value")) {
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printk("dt_gpio - Error! Device property 'my_value' not found!\n");
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return -1;
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}
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if(!device_property_present(dev, "green-led-gpio")) {
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printk("dt_gpio - Error! Device property 'green-led-gpio' not found!\n");
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return -1;
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}
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/* Read device properties */
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ret = device_property_read_string(dev, "label", &label);
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if(ret) {
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printk("dt_gpio - Error! Could not read 'label'\n");
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return -1;
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}
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printk("dt_gpio - label: %s\n", label);
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ret = device_property_read_u32(dev, "my_value", &my_value);
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if(ret) {
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printk("dt_gpio - Error! Could not read 'my_value'\n");
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return -1;
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}
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printk("dt_gpio - my_value: %d\n", my_value);
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/* Init GPIO */
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my_led = gpiod_get(dev, "green-led", GPIOD_OUT_LOW);
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if(IS_ERR(my_led)) {
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printk("dt_gpio - Error! Could not setup the GPIO\n");
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return -1 * IS_ERR(my_led);
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}
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/* Creating procfs file */
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proc_file = proc_create("my-led", 0666, NULL, &fops);
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if(proc_file == NULL) {
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printk("procfs_test - Error creating /proc/my-led\n");
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gpiod_put(my_led);
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return -ENOMEM;
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}
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return 0;
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}
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module_init(led_consumer_init);
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module_exit(led_consumer_exit);
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/**
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* @brief This function is called on unloading the driver
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*/
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static void dt_remove(struct platform_device *pdev) {
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printk("dt_gpio - Now I am in the remove function\n");
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gpiod_put(my_led);
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proc_remove(proc_file);
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}
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/**
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* @brief This function is called, when the module is loaded into the kernel
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*/
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static int __init my_init(void) {
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printk("dt_gpio - Loading the driver...\n");
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if(platform_driver_register(&my_driver)) {
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printk("dt_gpio - Error! Could not load driver\n");
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return -1;
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}
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return 0;
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}
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/**
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* @brief This function is called, when the module is removed from the kernel
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*/
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static void __exit my_exit(void) {
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printk("dt_gpio - Unload driver");
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platform_driver_unregister(&my_driver);
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}
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module_init(my_init);
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module_exit(my_exit);
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17
driver/counter.dts
Normal file
17
driver/counter.dts
Normal file
@ -0,0 +1,17 @@
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/dts-v1/;
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/plugin/;
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/ {
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compatible = "brcm,bcm2835";
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fragment@0 {
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target-path = "/";
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__overlay__ {
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my_device {
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compatible = "brightlight,mydev";
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status = "okay";
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label = "Test";
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my_value = <12>;
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green-led-gpio = <&gpio 21 0>;
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};
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};
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};
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};
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@ -1,29 +0,0 @@
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# Source and target file names
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DTS = counter.dts
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DTBO = counter.dtbo
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# Installation paths
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OVERLAY_DIR = /boot/overlays
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CONFIG_TXT = /boot/firmware/config.txt
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OVERLAY_NAME = counter
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all: $(DTBO)
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$(DTBO): $(DTS)
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dtc -@ -I dts -O dtb -o $@ $<
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load: $(DTBO)
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sudo dtoverlay -d . $(OVERLAY_NAME)
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@echo "Overlay loaded"
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unload: $(DTBO)
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sudo dtoverlay -R $(OVERLAY_NAME)
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@echo "Overlay unloaded"
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list:
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sudo dtoverlay -l
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clean:
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rm -f *.dtbo
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@ -1,46 +0,0 @@
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/dts-v1/;
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/plugin/;
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/ {
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compatible = "brcm,bcm2835";
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fragment@0 {
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target = <&gpio>;
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__overlay__ {
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gpio_led_blue: gpio_led_blues@26 {
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brcm,pins = <26>;
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brcm,function = <1>; // output
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brcm,pull = <0>; // no pull
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};
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gpio_led_red: gpio_led_reds@21 {
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brcm,pins = <21>;
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brcm,function = <1>; // output
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brcm,pull = <0>; // no pull
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};
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};
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};
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fragment@1 {
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target-path = "/";
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__overlay__ {
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mygpioleds {
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compatible = "my,gpio-led-controller";
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pinctrl-names = "default";
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pinctrl-0 = <&gpio_led_blue &gpio_led_red>;
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led-blue {
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gpios = <&gpio 26 0>;
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label = "led-blue";
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};
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led-red {
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gpios = <&gpio 21 0>;
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label = "led-red";
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};
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};
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};
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};
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};
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