嵌入式Linux LED字符设备驱动，基于平台驱动实现，使用设备树定义LED灯资源，引入pinctrl和gpio子系统

#include <linux/init.h> #include <linux/module.h> #include <linux/kernel.h> #include <linux/types.h> #include <linux/cdev.h> #include <linux/ide.h> #include <linux/of.h> #include <linux/platform_device.h> #include <linux/gpio/consumer.h> #include "chrdev_led.h" #include "imx6ull_led.h" static int imx6ull_led_probe(struct platform_device *pdev) { int ret; struct imx6ull_led_info *led_info; if(!of_device_is_available(pdev->dev.of_node)) return -ENODEV; //申请内存用于存放LED设备的资源 led_info = devm_kzalloc(&pdev->dev, sizeof(struct imx6ull_led_info), GFP_KERNEL); if(!led_info) { dev_err(&pdev->dev, "Failed to allocate memory for imx6ull led platform driver\n"); return -ENOMEM; } //将LED设备信息绑定到平台设备 platform_set_drvdata(pdev, led_info); //获取节点信息(不对引脚进行初始化) led_info->desc = devm_gpiod_get(&pdev->dev, "led", GPIOD_ASIS); if(IS_ERR(led_info->desc)) { dev_err(&pdev->dev, "Failed to get GPIO pin for led\n"); return PTR_ERR(led_info->desc); } ret = of_property_read_u32(pdev->dev.of_node, "id", &led_info->id); if(ret) return ret; //往内核注册一个LED字符设备 return led_chrdev_register(&led_info->led_cdev, led_info->id, 1, "imx6ull led"); } static int imx6ull_led_remove(struct platform_device *pdev) { struct imx6ull_led_info *led_info = platform_get_drvdata(pdev); return led_chrdev_unregister(&led_info->led_cdev, led_info->id, 1, "imx6ull led"); } static const struct of_device_id imx6ull_led_of_match[] = { { .compatible = "imx6ull-led" }, {} }; static struct platform_driver imx6ull_led_driver = { .probe = imx6ull_led_probe, .remove = imx6ull_led_remove, .driver = { .name = "imx6ull-led", .of_match_table = imx6ull_led_of_match, }, }; //------------------------------------------------------ static struct led_drv_func func_list; static int imx6ull_init_led_gpio(struct cdev *led_cdev, void **private) { int ret; struct imx6ull_led_info *led_info = container_of(led_cdev, struct imx6ull_led_info, led_cdev); //初始化引脚(无效逻辑值) ret = gpiod_direction_output(led_info->desc, 0); if(ret) return ret; *private = led_info; return 0; } static int imx6ull_set_led_gpio(void *private, char valid) { struct imx6ull_led_info *led_info = (struct imx6ull_led_info *)private; gpiod_set_value(led_info->desc, (int)valid); return 0; } static int imx6ull_close_led_gpio(void *private) { struct imx6ull_led_info *led_info = (struct imx6ull_led_info *)private; gpiod_set_value(led_info->desc, 0); return 0; } static int __init led_platform_driver_init(void) { func_list.func_init_led_gpio = imx6ull_init_led_gpio; func_list.func_set_led_gpio = imx6ull_set_led_gpio; func_list.func_close_led_gpio = imx6ull_close_led_gpio; led_chrdev_register_func(&func_list); return platform_driver_register(&imx6ull_led_driver); } static void __exit led_platform_driver_exit(void) { func_list.func_init_led_gpio = NULL; func_list.func_set_led_gpio = NULL; func_list.func_close_led_gpio = NULL; led_chrdev_unregister_func(); platform_driver_unregister(&imx6ull_led_driver); } module_init(led_platform_driver_init); module_exit(led_platform_driver_exit); //------------------------------------------------------- MODULE_LICENSE("GPL"); MODULE_AUTHOR("David.Tang");