1.6 LS2K0300-misc+platform-点灯（推荐）（修订1）-优快云博客

本文链接：https://blog.youkuaiyun.com/pointer_NULL/article/details/145763293

注：misc+platform组合，相对于字符设备驱动，更简便。

三步骤：驱动模块+设备树配置、驱动测试、编译模块

1、驱动模块+设备树配置

上述代码和图片标注处，要符合，才能正常使用。（重点：在虚拟机可以查看该节点的属性，是因为已经编译内核并更新了内核--参考1.6之前的编译内核，记住，需要正常关闭龙芯，不然板子就坏了）

//ls2k0300_led_drv.c

#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/gpio.h>
#include <linux/uaccess.h>
#include <linux/ioctl.h>
#include <linux/platform_device.h>
#include <linux/of_gpio.h>

// IOCTL 控制命令定义
#define LED_MAGIC 'L'
#define LED_ON _IOW(LED_MAGIC, 0, int)
#define LED_OFF _IOW(LED_MAGIC, 1, int)

// Misc设备名称
#define DEVICE_NAME "loongson_led"

static int led_gpio_num; // 保存从设备树获取的GPIO编号

// 函数前向声明
static int led_open(struct inode *inode, struct file *filp);
static int led_release(struct inode *inode, struct file *filp);
static long led_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);

// 文件操作结构体
static const struct file_operations led_fops = {
.owner = THIS_MODULE,
.open = led_open,
.release = led_release,
.unlocked_ioctl = led_ioctl, // 新增此行
};

// Misc设备定义
static struct miscdevice led_misc = {
.minor = MISC_DYNAMIC_MINOR,
.name = DEVICE_NAME,
.fops = &led_fops,
.mode = 0666,
};

// ********** 核心函数实现 **********
static int led_open(struct inode *inode, struct file *filp) {
// GPIO申请已在probe阶段完成，此处无需操作
return 0;
}

static int led_release(struct inode *inode, struct file *filp) {
// GPIO资源通过devm自动释放，此处无需操作
return 0;
}

// I/O 控制函数实现
static long led_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) {
switch (cmd) {
case LED_ON:
gpio_set_value(led_gpio_num, 1);
break;
case LED_OFF:
gpio_set_value(led_gpio_num, 0);
break;
default:
return -ENOTTY;
}
return 0;
}
// ********** 平台驱动函数 **********
static int led_probe(struct platform_device *pdev) {
struct device *dev = &pdev->dev;
int ret;

// 从设备树获取GPIO编号
led_gpio_num = of_get_named_gpio(dev->of_node, "led-gpios", 0);
if (led_gpio_num < 0) {
dev_err(dev, "无法从设备树获取 'led-gpios' 属性\n");
return led_gpio_num;
}

// 申请并配置GPIO（使用devm自动释放）
ret = devm_gpio_request_one(dev, led_gpio_num, GPIOF_OUT_INIT_LOW, "led_gpio");
if (ret) {
dev_err(dev, "无法申请GPIO %d\n", led_gpio_num);
return ret;
}

// 注册Misc设备
ret = misc_register(&led_misc);
if (ret) {
dev_err(dev, "无法注册Misc设备\n");
return ret;
}

dev_info(dev, "LED驱动已加载 (GPIO%d)\n", led_gpio_num);
return 0;
}

static int led_remove(struct platform_device *pdev) {
misc_deregister(&led_misc);
dev_info(&pdev->dev, "驱动已卸载\n");
return 0;
}

// 设备树匹配表
static const struct of_device_id led_dt_ids[] = {
{ .compatible = "loongson,ls2k0300_led" },
{ /* 结束标记 */ }
};
MODULE_DEVICE_TABLE(of, led_dt_ids);

// 平台驱动结构体
static struct platform_driver led_driver = {
.driver = {
.name = "ls2k-led",
.of_match_table = led_dt_ids,
},
.probe = led_probe,
.remove = led_remove,
};

module_platform_driver(led_driver); // 自动注册/注销驱动

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("Loongson LS2K0300 LED Platform Driver");

2、驱动测试

//ls2k0300_led_test.c

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h> // 添加 usleep 函数所需头文件
#include <sys/ioctl.h>

#define LED_MAGIC 'L'
#define LED_ON _IOW(LED_MAGIC, 0, int)
#define LED_OFF _IOW(LED_MAGIC, 1, int)

int main() {
int fd;
const char *device = "/dev/loongson_led";

// 打开设备
fd = open(device, O_RDWR);
if (fd < 0) {
perror("无法打开设备");
exit(EXIT_FAILURE);
}

printf("LED开始闪烁(500ms周期)\n");

while (1) {
// 亮灯
ioctl(fd, LED_ON, 0);
usleep(500000); // 500ms

// 灭灯
ioctl(fd, LED_OFF, 0);
usleep(500000);
}

close(fd);
return 0;
}