RK3568(六)——led设备驱动（GPIO子系统）

修改设备树文件

先关闭心跳灯功能，也就是在图 10.4.1.2 中第 167 行添加 status 改为 disabled，也就是禁止 work 这个节点，那么禁止心跳灯功能。

我们后面需要禁止哪个功能，只需要将其 status 属性改为 disabled 就可以了。

	gpioled{compatible = "zxk, led";led-gpio = <&gpio0 RK_PC0 GPIO_ACTIVE_HIGH>;status = "okay";};

编译内核并烧写boot.img

// 1. 编译
./bulid.sh kernel
// 2. 烧写

驱动编写

/* 设置LED所使用的GPIO *//* 1. 获取设备节点：gpioled */gpioled.nd = of_find_node_by_path("/gpioled");if (gpioled.nd == NULL){printk("gpioled node not found!\n");return -EINVAL;}/* 2. 读取status属性 */ret = of_property_read_string(gpioled.nd, "status", &str);if (ret < 0){printk("gpioled status not found!\n");return -EINVAL;}if (strcmp(str, "okay") != 0){printk("gpioled status not okay!\n");return -EINVAL;}/* 3. 获取compatible属性值并进行匹配 */ret = of_property_read_string(gpioled.nd, "compatible", &str);if (ret < 0){printk("compatible property not found!\n");return -EINVAL;}if (strcmp(str, "zxk, led")!= 0){printk("compatible property not match!\n");return -EINVAL;}/* 4. 获取gpio属性值并转换为gpio */ gpioled.led_gpio =  of_get_named_gpio(gpioled.nd, "led-gpio", 0);if (gpioled.led_gpio < 0){printk("led-gpio property not found!\n");return -EINVAL;}printk("led-gpio = %d\n", gpioled.led_gpio);/* 5. 向gpio子系统申请使用GPIO */ret = gpio_request(gpioled.led_gpio, "led-gpio");if (ret < 0){printk("gpio_request failed!\n");return -EINVAL;}/* 6. 设置GPIO为输出模式，并输出为低电平，默认led关闭 */ret = gpio_direction_output(gpioled.led_gpio, 0);if (ret < 0){printk("gpio_direction_output failed!\n");return -EINVAL;}

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/gpio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_gpio.h>
//#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>/**************************************************************** 文件名   : gpioled.c* 功能     : 这是一个led设备驱动程序文件* 作者     : zxk* 创建日期: 2024年11月28日* 其他     
***************************************************************/#define GPIOLED_CNT     1               /* 设备号个数 */
#define GPIOLED_NAME    "gpioled"       /* 设备名 */
#define LED_ON          1       /* 开灯 */
#define LED_OFF         0       /* 关灯 *//* gpioled 设备结构体 */
struct gpioled_dev
{dev_t devid;                /* 设备号 */struct cdev cdev;               /* cdev */struct class *class;        /* 类 */struct device *device;      /* 设备 */int major;                  /* 主设备号 */int minor;                  /* 次设备号 */struct device_node *nd;     /* 设备节点 */int led_gpio;               /* led对应的gpio */
};struct gpioled_dev gpioled;/**************************************************************** led_open - 函数名* description  : 打开设备* @param-inode : 传递给驱动的 inode* @param-filp  : 设备文件，file 结构体有个叫做 private_data 的成员变量* 一般在 open 的时候将 private_data 指向设备结构体。** 返回值       : 0 成功
***************************************************************/
static int led_open(struct inode *inode, struct file *filp)
{filp->private_data = &gpioled; /* 设置私有数据 */return 0;
}/**************************************************************** led_reads - 函数名* @description   : 从设备读取数据* @param-filp   : 要打开的文件设备* @param-buf    : 返回给用户空间的数据缓冲区* @param-cnt    : 读取的数据长度* @param-off_t  : 相对于文件首地址的偏移* @return       ：读取的字节数
***************************************************************/
static ssize_t led_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off_t)
{    return 0;
}/**************************************************************** led_write - 函数名* @description   : 向设备写入数据* @param-filp   : 设备文件，要打开的文件设备* @param-buf    : 要写入设备的数据* @param-cnt    : 写入的数据长度* @param-off_t  : 相对于文件首地址的偏移* @return       ：写入的文件数 
***************************************************************/
static ssize_t led_write(struct file *filp, const char __user *buf, size_t cnt, loff_t *off_t)
{int retvalue;unsigned char databuf[1];unsigned char ledstat;struct gpioled_dev *dev = filp->private_data;retvalue = copy_from_user(databuf, buf, cnt);if(retvalue < 0) {printk("kernel write failed!\r\n");return -EFAULT;}ledstat = databuf[0];       /* 获取状态值 */if(ledstat == LED_ON) { gpio_set_value(dev->led_gpio, 1);       /* 打开LED灯 */} else if(ledstat == LED_OFF) {gpio_set_value(dev->led_gpio, 0);       /* 关闭LED灯 */}return 0;
}/**************************************************************** led_release - 函数名* description  : 关闭释放设备* @param-inode : 传递给驱动的 inode* @param-filp  : 设备文件，要关闭的文件设备描述符** 返回值       : 0 成功
***************************************************************/
static int led_release(struct inode *inode, struct file *filp)
{return 0;
}/*
* 设备操作函数结构体
* 将驱动函数映射为系统调用
*/static struct file_operations gpioled_fops = 
{.owner = THIS_MODULE,.open = led_open,.read = led_read,.write = led_write,.release = led_release,
};/**************************************************************** led_init - 函数名* description  : 驱动入口函数* @param       : 无* 返回值        : 0 成功
***************************************************************/
static int __init led_init(void)
{int ret;const char *str;/* 设置LED所使用的GPIO *//* 1. 获取设备节点：gpioled */gpioled.nd = of_find_node_by_path("/gpioled");if (gpioled.nd == NULL){printk("gpioled node not found!\n");return -EINVAL;}/* 2. 读取status属性 */ret = of_property_read_string(gpioled.nd, "status", &str);if (ret < 0){printk("gpioled status not found!\n");return -EINVAL;}if (strcmp(str, "okay") != 0){printk("gpioled status not okay!\n");return -EINVAL;}/* 3. 获取compatible属性值并进行匹配 */ret = of_property_read_string(gpioled.nd, "compatible", &str);if (ret < 0){printk("compatible property not found!\n");return -EINVAL;}if (strcmp(str, "zxk, led")!= 0){printk("compatible property not match!\n");return -EINVAL;}/* 4. 获取gpio属性值并转换为gpio */ gpioled.led_gpio =  of_get_named_gpio(gpioled.nd, "led-gpio", 0);if (gpioled.led_gpio < 0){printk("led-gpio property not found!\n");return -EINVAL;}printk("led-gpio = %d\n", gpioled.led_gpio);/* 5. 向gpio子系统申请使用GPIO */ret = gpio_request(gpioled.led_gpio, "led-gpio");if (ret < 0){printk("gpio_request failed!\n");return -EINVAL;}/* 6. 设置GPIO为输出模式，并输出为低电平，默认led关闭 */ret = gpio_direction_output(gpioled.led_gpio, 0);if (ret < 0){printk("gpio_direction_output failed!\n");return -EINVAL;}/* 注册字符设备驱动 *//* 1.创建设备号 */if (gpioled.major){gpioled.devid = MKDEV(gpioled.major, 0);ret = register_chrdev_region(gpioled.devid, GPIOLED_CNT, GPIOLED_NAME);if (ret < 0){printk("cannot register %s char driver [ret=%d]\n",GPIOLED_NAME, GPIOLED_CNT);goto free_gpio;}}else{ret = alloc_chrdev_region(&gpioled.devid, 0, GPIOLED_CNT, GPIOLED_NAME);if (ret < 0){printk("cannot register %s char driver [ret=%d]\n",GPIOLED_NAME, GPIOLED_CNT);goto free_gpio;}gpioled.major = MAJOR(gpioled.devid);/* 获取主设备号 */gpioled.minor = MINOR(gpioled.devid);/* 获取次设备号 */}printk("gpioled major=%d,minor=%d\r\n",gpioled.major,gpioled.minor);/*  2.初始化cdev */gpioled.cdev.owner = THIS_MODULE;cdev_init(&gpioled.cdev, &gpioled_fops);/* 3.添加一个cdev字符设备 */ret = cdev_add(&gpioled.cdev, gpioled.devid, GPIOLED_CNT);if (ret < 0){goto del_unregister;}/* 4. 创建类 */gpioled.class = class_create(THIS_MODULE, GPIOLED_NAME);if (IS_ERR(gpioled.class)){goto del_cdev;}/* 5.创建设备 */gpioled.device = device_create(gpioled.class, NULL, gpioled.devid, NULL, GPIOLED_NAME);if (IS_ERR(gpioled.device)){goto destroy_class;}printk("led_init() \r\n");return 0;destroy_class:class_destroy(gpioled.class);
del_cdev:cdev_del(&gpioled.cdev);
del_unregister:unregister_chrdev_region(gpioled.devid, GPIOLED_CNT);
free_gpio:gpio_free(gpioled.led_gpio);return -EIO;
}/**************************************************************** led_exit - 函数名* description  : 驱动出口函数* @param       : 无* 返回值        : 0 成功
***************************************************************/
static void __exit led_exit(void)
{/* 注销字符设备驱动 */cdev_del(&gpioled.cdev);    /* 删除 cdev */unregister_chrdev_region(gpioled.devid, GPIOLED_CNT);/* 删除类 */device_destroy(gpioled.class, gpioled.devid);class_destroy(gpioled.class);/* 释放GPIO */gpio_free(gpioled.led_gpio);printk("led_exit() \r\n");
}/* 将上面两个函数指定为驱动的入口和出口函数 */
module_init(led_init);
module_exit(led_exit);MODULE_LICENSE("GPL");
MODULE_AUTHOR("zxk");
MODULE_INFO(intree, "Y");

ARCH = arm64
KERNELDIR := /home/zxk/work/rk3568_linux_sdk/kernel
CURRENT_PATH := /home/zxk/linux_driver/05_gpioled/obj-m := gpioled.obulid: kernel_moduleskernel_modules:$(MAKE) -C $(KERNELDIR) M=$(CURRENT_PATH) modules
clean:$(MAKE) -C $(KERNELDIR) M=$(CURRENT_PATH) cleana

编译测试

// 1.编译
make ARCH=arm64 //ARCH=arm64 必须指定，否则编译会失败
/opt/atk-dlrk356x-toolchain/bin/aarch64-buildroot-linux-gnu-gcc ledApp.c -o ledApp
// 2.上传
scp ./01_chrdevbase/chrdevbase.ko root@192.168.137.65:/lib/modules/4.19.232/
scp ./01_chrdevbase/chrdevbaseAPP root@192.168.137.65:/lib/modules/4.19.232/