上一篇文章学习编写新字符设备驱动框架代码。文章地址如下：
本文在以上这篇文章代码实现的基础上，加入涉及 Led灯的功能函数集实现。
代码实现要求：测试程序（即应用程序）通过设置 Led灯电平的高低，调用到 Led设备驱动程序，从而最终驱动 Led灯的亮灭。
上一篇文章实现了新字符设备驱动代码框架。这里在此基础上加入 Led灯的功能函数的代码。
首先，来完善字符设备Led 的 file_operations结构体，完善后如下：
//字符设备的函数集
const struct file_operations fops = {
.owner = THIS_MODULE,
.open = led_open,
.write = led_write,
.release = led_release,
};
其次，来实现 上面字符设备的 file_operations结构体对应的函数实现。可以参考前面 2_led实验的代码编写，其实代码内容是一样的。
打开 3_newchrled工程， 这里需要添加 file_operations结构体的函数操作集。代码如下：
void led_on_off(unsigned int status)
{
unsigned int reg_value = 0;
if(LED_ON == status)
{
reg_value = readl(IMX6ULL_DR);
reg_value &= ~(1 << 3); //bit3清零，低电平，打开Led
writel(reg_value, IMX6ULL_DR);
}
else if(LED_OFF == status)
{
reg_value = readl(IMX6ULL_DR);
reg_value |= (1 << 3); //bit3置1，高电平，关闭Led
writel(reg_value, IMX6ULL_DR);
}
}
static int newchrled_open(struct inode *inode, struct file *file)
{
return 0;
}
static ssize_t newchrled_write(struct file * inode, const char __user * buf, size_t count, loff_t * ppos)
{
int ret = 0;
unsigned char data_buf[1] = {0};
ret = copy_from_user(data_buf, buf, count);
if(ret < 0)
{
printk("led_write failed!\r\n");
return -EFAULT;
}
led_on_off(data_buf[0]);
return 0;
}
int newchrled_release(struct inode * inode, struct file * file)
{
printk("led_release\r\n");
return 0;
}
这里 Led的IO初始化代码，可以添加到 newchrled_init()函数，也就是模块加载接口中；也可以添加到 newchrled_open()函数中，也就是打开设备接口中。
这里我添加到 newchrled_init()接口中，将以下 Led 的IO初始化代码添加到 newchrled_init()接口 中字符设备注册之前：
unsigned int value = 0;
/*Led灯的IO初始化 */
//地址映射
IMX6ULL_CCM_CCGR1 = ioremap(CCM_CCGR1_BASE, 4);
IMX6ULL_SW_MUX_GPIO1_IO03 = ioremap(SW_MUX_GPIO1_IO03_BASE, 4);
IMX6ULL_SW_PAD_GPIO01_IO03 = ioremap(SW_PAD_GPIO1_IO03_BASE, 4);
IMX6ULL_GDIR = ioremap(GPIO1_GDIR_BASE, 4);
IMX6ULL_DR = ioremap(GPIO1_DR_BASE, 4);
//使能Led时钟
value = readl(IMX6ULL_CCM_CCGR1);
value &= ~(3 << 26);
value |= (3 << 26); //bit26~27置1
writel(value, IMX6ULL_CCM_CCGR1);
//复用为GPIO功能
writel(0X05, IMX6ULL_SW_MUX_GPIO1_IO03);
//配置电气属性
writel(0X10B0, IMX6ULL_SW_PAD_GPIO01_IO03);
//设置为输出功能
value = readl(IMX6ULL_GDIR);
value |= (1 << 3);
writel(value, IMX6ULL_GDIR);
//关闭Led灯(设置为高电平)
value = readl(IMX6ULL_DR);
value |= (1 << 3);
writel(value, IMX6ULL_DR);newchrled.c文件中代码如下：
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/cdev.h>
//寄存器的物理地址
#define CCM_CCGR1_BASE (0X020C406C)
#define SW_MUX_GPIO1_IO03_BASE (0X020E0068)
#define SW_PAD_GPIO1_IO03_BASE (0X020E02F4)
#define GPIO1_GDIR_BASE (0X0209C004)
#define GPIO1_DR_BASE (0X0209C000)
//地址映射后寄存器的虚拟地址指针
static void __iomem * IMX6ULL_CCM_CCGR1;
static void __iomem * IMX6ULL_SW_MUX_GPIO1_IO03;
static void __iomem * IMX6ULL_SW_PAD_GPIO01_IO03;
static void __iomem * IMX6ULL_GDIR;
static void __iomem * IMX6ULL_DR;
#define NEWCHRLED "newchrled" //设备名
#define NEWCHRLED_COUNT 1 //设备个数
#define LED_OFF 0 //关闭Led灯
#define LED_ON 1 //打开Led灯
//Led设备结构体
struct newchrled_dev{
struct cdev led_cdev;
dev_t dev_id; //设备号
int major; //主设备号
int minor; //次设备号
};
struct newchrled_dev newchr_led;
void led_on_off(unsigned int status)
{
unsigned int reg_value = 0;
if(LED_ON == status)
{
reg_value = readl(IMX6ULL_DR);
reg_value &= ~(1 << 3); //bit3清零，低电平，打开Led
writel(reg_value, IMX6ULL_DR);
}
else if(LED_OFF == status)
{
reg_value = readl(IMX6ULL_DR);
reg_value |= (1 << 3); //bit3置1，高电平，关闭Led
writel(reg_value, IMX6ULL_DR);
}
}
static int newchrled_open(struct inode *inode, struct file *file)
{
return 0;
}
static ssize_t newchrled_write(struct file * inode, const char __user * buf, size_t count, loff_t * ppos)
{
int ret = 0;
unsigned char data_buf[1] = {0};
ret = copy_from_user(data_buf, buf, count);
if(ret < 0)
{
printk("led_write failed!\r\n");
return -EFAULT;
}
led_on_off(data_buf[0]);
return 0;
}
int newchrled_release(struct inode * inode, struct file * file)
{
printk("led_release\r\n");
return 0;
}
//字符设备的函数集
const struct file_operations fops = {
.owner = THIS_MODULE,
.open = newchrled_open,
.write = newchrled_write,
.release = newchrled_release,
};
/*驱动模块入口函数 */
static int __init newchrled_init(void)
{
int ret = 0;
unsigned int value = 0;
printk("newchrled_init!\r\n");
/*Led灯的IO初始化 */
//地址映射
IMX6ULL_CCM_CCGR1 = ioremap(CCM_CCGR1_BASE, 4);
IMX6ULL_SW_MUX_GPIO1_IO03 = ioremap(SW_MUX_GPIO1_IO03_BASE, 4);
IMX6ULL_SW_PAD_GPIO01_IO03 = ioremap(SW_PAD_GPIO1_IO03_BASE, 4);
IMX6ULL_GDIR = ioremap(GPIO1_GDIR_BASE, 4);
IMX6ULL_DR = ioremap(GPIO1_DR_BASE, 4);
//使能Led时钟
value = readl(IMX6ULL_CCM_CCGR1);
value &= ~(3 << 26);
value |= (3 << 26); //bit26~27置1
writel(value, IMX6ULL_CCM_CCGR1);
//复用为GPIO功能
writel(0X05, IMX6ULL_SW_MUX_GPIO1_IO03);
//配置电气属性
writel(0X10B0, IMX6ULL_SW_PAD_GPIO01_IO03);
//设置为输出功能
value = readl(IMX6ULL_GDIR);
value |= (1 << 3);
writel(value, IMX6ULL_GDIR);
//关闭Led灯(设置为高电平)
value = readl(IMX6ULL_DR);
value |= (1 << 3);
writel(value, IMX6ULL_DR);
/*注册字符设备 */
//设备号的分配
if(newchr_led.major) //给定主设备号
{
newchr_led.dev_id = MKDEV(newchr_led.major, 0);
ret = register_chrdev_region(newchr_led.dev_id, NEWCHRLED_COUNT, NEWCHRLED);
}
else{ //没有给定主设备号
ret = alloc_chrdev_region(&(newchr_led.dev_id), 0, NEWCHRLED_COUNT, NEWCHRLED);
newchr_led.major = MAJOR(newchr_led.dev_id);
newchr_led.minor = MINOR(newchr_led.dev_id);
}
if (ret < 0) {
printk("register-chrdev failed!\n");
return -1;
}
//初始化设备
cdev_init(&newchr_led.led_cdev, &fops);
//注册设备
cdev_add(&newchr_led.led_cdev, newchr_led.dev_id, NEWCHRLED_COUNT);
return 0;
}
/*驱动模块出口函数 */
static void __exit newchrled_exit(void)
{
printk("newchrled_eixt!\r\n");
/*注销字符设备 */
//删除设备
cdev_del(&newchr_led.led_cdev);
//注销设备号
unregister_chrdev_region(newchr_led.dev_id, NEWCHRLED_COUNT);
}
/* 注册与卸载驱动设备 */
module_init(newchrled_init);
module_exit(newchrled_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("LingXueWu");编译驱动代码 3_newchrled，经过编译，可以正常生成 newchrled.ko 驱动文件。下一篇文章对驱动代码进行加载与测试。