led驱动_使用次设备号来区别设备

来源：互联网发布：小受坐轮椅卖淘宝编辑：程序博客网时间：2024/06/03 19:05
上一篇文章讲解了如何自动创建设备节点. 而且通过copy_from_user来传递参数, 通过判断这个参数的值来控制设备开关. 本节将使用次设备号来区分字符设备下使用同一主设备号的多个设备.
#include <linux/module.h>#include <linux/kernel.h>#include <linux/fs.h>#include <linux/init.h>#include <linux/delay.h>#include <asm/uaccess.h>#include <asm/irq.h>#include <asm/io.h>#include <asm/arch/regs-gpio.h>#include <asm/hardware.h>#define DEVICE_NAME     "leds"  /* 加载模式后，执行”cat /proc/devices”命令看到的设备名称 */#define LED_MAJOR       231     /* 主设备号 */static struct class *leds_class;static struct class_device  *leds_class_devs[4];/*  bit0<=>D10, 0:亮, 1:灭  *  bit1<=>D11, 0:亮, 1:灭  *  bit2<=>D12, 0:亮, 1:灭  */ static char leds_status = 0x0;  static DECLARE_MUTEX(leds_lock); // 定义赋值//static int minor;static unsigned long gpio_va;#define GPIO_OFT(x) ((x) - 0x56000000)#define GPFCON  (*(volatile unsigned long *)(gpio_va + GPIO_OFT(0x56000050)))#define GPFDAT  (*(volatile unsigned long *)(gpio_va + GPIO_OFT(0x56000054)))/* 应用程序对设备文件/dev/leds执行open(...)时， * 就会调用s3c24xx_leds_open函数 */static int s3c24xx_leds_open(struct inode *inode, struct file *file){    int minor = MINOR(inode->i_rdev); //MINOR(inode->i_cdev);    switch(minor)    {        case 0: /* /dev/leds */        {            // 配置3引脚为输出            //s3c2410_gpio_cfgpin(S3C2410_GPF4, S3C2410_GPF4_OUTP);            GPFCON &= ~(0x3<<(4*2));            GPFCON |= (1<<(4*2));                        //s3c2410_gpio_cfgpin(S3C2410_GPF5, S3C2410_GPF5_OUTP);            GPFCON &= ~(0x3<<(5*2));            GPFCON |= (1<<(5*2));            //s3c2410_gpio_cfgpin(S3C2410_GPF6, S3C2410_GPF6_OUTP);            GPFCON &= ~(0x3<<(6*2));            GPFCON |= (1<<(6*2));            // 都输出0            //s3c2410_gpio_setpin(S3C2410_GPF4, 0);            GPFDAT &= ~(1<<4);                        //s3c2410_gpio_setpin(S3C2410_GPF5, 0);            GPFDAT &= ~(1<<5);            //s3c2410_gpio_setpin(S3C2410_GPF6, 0);            GPFDAT &= ~(1<<6);            down(&leds_lock);            leds_status = 0x0;            up(&leds_lock);                            break;        }        case 1: /* /dev/led1 */        {            s3c2410_gpio_cfgpin(S3C2410_GPF4, S3C2410_GPF4_OUTP);            s3c2410_gpio_setpin(S3C2410_GPF4, 0);                        down(&leds_lock);            leds_status &= ~(1<<0);            up(&leds_lock);                        break;        }        case 2: /* /dev/led2 */        {            s3c2410_gpio_cfgpin(S3C2410_GPF5, S3C2410_GPF5_OUTP);            s3c2410_gpio_setpin(S3C2410_GPF5, 0);            leds_status &= ~(1<<1);            break;        }        case 3: /* /dev/led3 */        {            s3c2410_gpio_cfgpin(S3C2410_GPF6, S3C2410_GPF6_OUTP);            s3c2410_gpio_setpin(S3C2410_GPF6, 0);            down(&leds_lock);            leds_status &= ~(1<<2);            up(&leds_lock);                        break;        }            }        return 0;}static int s3c24xx_leds_read(struct file *filp, char __user *buff, <span style="font-family: Arial, Helvetica, sans-serif;">size_t count, loff_t *offp)</span>                                     {    int minor = MINOR(filp->f_dentry->d_inode->i_rdev);    char val;    switch (minor)    {        case 0: /* /dev/leds */        {                        copy_to_user(buff, (const void *)&leds_status, 1);                                break;        }        case 1: /* /dev/led1 */        {            down(&leds_lock);            val = leds_status & 0x1;            up(&leds_lock);            copy_to_user(buff, (const void *)&val, 1);            break;        }        case 2: /* /dev/led2 */        {            down(&leds_lock);            val = (leds_status>>1) & 0x1;            up(&leds_lock);            copy_to_user(buff, (const void *)&val, 1);            break;        }        case 3: /* /dev/led3 */        {            down(&leds_lock);            val = (leds_status>>2) & 0x1;            up(&leds_lock);            copy_to_user(buff, (const void *)&val, 1);            break;        }            }    return 1;}static ssize_t s3c24xx_leds_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos){    //int minor = MINOR(inode->i_rdev); //MINOR(inode->i_cdev);    int minor = MINOR(file->f_dentry->d_inode->i_rdev);    char val;    copy_from_user(&val, buf, 1);    switch (minor)    {        case 0: /* /dev/leds */        {                        s3c2410_gpio_setpin(S3C2410_GPF4, (val & 0x1));            s3c2410_gpio_setpin(S3C2410_GPF5, (val & 0x1));            s3c2410_gpio_setpin(S3C2410_GPF6, (val & 0x1));            down(&leds_lock);            leds_status = val;            up(&leds_lock);            break;        }        case 1: /* /dev/led1 */        {            s3c2410_gpio_setpin(S3C2410_GPF4, val);            if (val == 0)            {                down(&leds_lock);                leds_status &= ~(1<<0);                up(&leds_lock);            }            else            {                down(&leds_lock);                leds_status |= (1<<0);                                up(&leds_lock);            }            break;        }        case 2: /* /dev/led2 */        {            s3c2410_gpio_setpin(S3C2410_GPF5, val);            if (val == 0)            {                down(&leds_lock);                leds_status &= ~(1<<1);                up(&leds_lock);            }            else            {                down(&leds_lock);                leds_status |= (1<<1);                                up(&leds_lock);            }            break;        }        case 3: /* /dev/led3 */        {            s3c2410_gpio_setpin(S3C2410_GPF6, val);            if (val == 0)            {                down(&leds_lock);                leds_status &= ~(1<<2);                up(&leds_lock);            }            else            {                down(&leds_lock);                leds_status |= (1<<2);                                up(&leds_lock);            }            break;        }            }    return 1;}/* 这个结构是字符设备驱动程序的核心 * 当应用程序操作设备文件时所调用的open、read、write等函数， * 最终会调用这个结构中指定的对应函数 */static struct file_operations s3c24xx_leds_fops = {    .owner  =   THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */    .open   =   s3c24xx_leds_open,         .read   =   s3c24xx_leds_read,         .write  =   s3c24xx_leds_write,    };/* * 执行insmod命令时就会调用这个函数  */static int __init s3c24xx_leds_init(void)//static int __init init_module(void){    int ret;    int minor = 0;    gpio_va = ioremap(0x56000000, 0x100000);    if (!gpio_va) {        return -EIO;    }    /* 注册字符设备     * 参数为主设备号、设备名字、file_operations结构；     * 这样，主设备号就和具体的file_operations结构联系起来了，     * 操作主设备为LED_MAJOR的设备文件时，就会调用s3c24xx_leds_fops中的相关成员函数     * LED_MAJOR可以设为0，表示由内核自动分配主设备号     */    ret = register_chrdev(LED_MAJOR, DEVICE_NAME, &s3c24xx_leds_fops);    if (ret < 0) {      printk(DEVICE_NAME " can't register major number\n");      return ret;    }    //创建设备, 然后在类下创建设备    leds_class = class_create(THIS_MODULE, "leds");    if (IS_ERR(leds_class))        return PTR_ERR(leds_class);        //这里创建了 /dev/leds,  /dev/led1,  /dev/led2, /dev/led3 四个设备    leds_class_devs[0] = class_device_create(leds_class, NULL, MKDEV(LED_MAJOR, 0), NULL, "leds"); /* /dev/leds */        for (minor = 1; minor < 4; minor++)  /* /dev/led1,2,3 */    {        leds_class_devs[minor] = class_device_create(leds_class, NULL, MKDEV(LED_MAJOR, minor), NULL, "led%d", minor);        if (unlikely(IS_ERR(leds_class_devs[minor])))            return PTR_ERR(leds_class_devs[minor]);    }            printk(DEVICE_NAME " initialized\n");    return 0;}/* * 执行rmmod命令时就会调用这个函数  */static void __exit s3c24xx_leds_exit(void){    int minor;    /* 卸载驱动程序 */    unregister_chrdev(LED_MAJOR, DEVICE_NAME);    for (minor = 0; minor < 4; minor++)    {        class_device_unregister(leds_class_devs[minor]);    }    class_destroy(leds_class);    iounmap(gpio_va);}/* 这两行指定驱动程序的初始化函数和卸载函数 */module_init(s3c24xx_leds_init);module_exit(s3c24xx_leds_exit);/* 描述驱动程序的一些信息，不是必须的 */MODULE_AUTHOR("http://www.100ask.net");MODULE_VERSION("0.1.0");MODULE_DESCRIPTION("S3C2410/S3C2440 LED Driver");MODULE_LICENSE("GPL");
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