字符設備驅動-利用次設備號實現多路LED控制

驅動源碼：

#include

.

.

#include

int major;

int minor = 0;

static struct class *leddrv_class;

static struct class_device *leddrv_class_devs[4];

volatile unsigned long *gpfcon = NULL;

volatile unsigned long *gpfdat = NULL;

static int led_drv_open(struct inode *inode, struct file *file)

{

int minor = MINOR(inode->i_rdev); //MINOR(inode->i_cdev);

switch(minor)

{

case 0:

{

// 配置3引腳為輸出

//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));

// 都輸出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);

break;

}

case 1:

{

s3c2410_gpio_cfgpin(S3C2410_GPF4, S3C2410_GPF4_OUTP);

s3c2410_gpio_setpin(S3C2410_GPF4, 0);

break;

}

case 2:

{

s3c2410_gpio_cfgpin(S3C2410_GPF5, S3C2410_GPF5_OUTP);

s3c2410_gpio_setpin(S3C2410_GPF5, 0);

break;

}

case 3:

{

s3c2410_gpio_cfgpin(S3C2410_GPF6, S3C2410_GPF6_OUTP);

s3c2410_gpio_setpin(S3C2410_GPF6, 0);

break;

}

}

return 0;

}

static ssize_t led_drv_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)

{

char val;

int minor = MINOR(file->f_dentry->d_inode->i_rdev);

copy_from_user(&val, buf, 1);

switch (minor)

{

case 0:

{

s3c2410_gpio_setpin(S3C2410_GPF4, (val & 0x1));

s3c2410_gpio_setpin(S3C2410_GPF5, (val & 0x1));

s3c2410_gpio_setpin(S3C2410_GPF6, (val & 0x1));

break;

}

case 1:

{

s3c2410_gpio_setpin(S3C2410_GPF4, val);

break;

}

case 2:

{

s3c2410_gpio_setpin(S3C2410_GPF5, val);

break;

}

case 3:

{

s3c2410_gpio_setpin(S3C2410_GPF6, val);

break;

}

}

return 0;

}

static struct file_operations led_drv_fops = {

.owner = THIS_MODULE,

.open = led_drv_open,

.write = led_drv_write,

};

static int led_drv_init(void)

{

major = register_chrdev(0, "led_drv", &led_drv_fops); // 注冊字符驅動, 告訴內核

leddrv_class = class_create(THIS_MODULE, "leddrv"); //創建設備節點

leddrv_class_devs[0] = class_device_create(leddrv_class, NULL, MKDEV(major, 0), NULL, "leddrv");

for (minor = 1; minor < 4; minor++)

{

leddrv_class_devs[minor] = class_device_create(leddrv_class, NULL, MKDEV(major, minor), NULL, "leddrv%d", minor);

if (unlikely(IS_ERR(leddrv_class_devs[minor])))

return PTR_ERR(leddrv_class_devs[minor]);

}

gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);

gpfdat = gpfcon + 1;

return 0;

}

static void led_drv_exit(void)

{

unregister_chrdev(major, "led_drv"); // 卸載

for (minor = 0; minor < 4; minor++)

{

class_device_unregister(leddrv_class_devs[minor]);

}

class_destroy(leddrv_class);

iounmap(gpfcon);

}

module_init(led_drv_init);

module_exit(led_drv_exit);

MODULE_LICENSE("GPL");

==================================================================================================

測試程序：

#include

#include

#include

#include

void print_usage(char *file)

{

printf("Usage:n");

printf("%s n",file);

printf("eg. n");

printf("%s /dev/leds onn", file);

printf("%s /dev/leds offn", file);

printf("%s /dev/led1 onn", file);

printf("%s /dev/led1 offn", file);

}

int main(int argc, char **argv)

{

int fd;

char* filename;

char val;

if (argc != 3)

{

print_usage(argv[0]);

return 0;

}

filename = argv[1];

fd = open(filename, O_RDWR);

if (fd < 0)

{

printf("error, cant open %sn", filename);

return 0;

}

if (!strcmp("on", argv[2]))

{

// 亮燈

val = 0;

write(fd, &val, 1);

}

else if (!strcmp("off", argv[2]))

{

// 滅燈

val = 1;

write(fd, &val, 1);

}

else

{

print_usage(argv[0]);

return 0;

}

}

=================================================================================================

實驗：

ls -l /dev/leddrv

ls -l /dev/leddrv1

./leddrvTest /dev/leddrv on

./leddrvTest /dev/leddrv off

./leddrvTest /dev/leddrv1 on

./leddrvTest /dev/leddrv2 on

./leddrvTest /dev/leddrv2 off

./leddrvTest /dev/leddrv3 on

./leddrvTest /dev/leddrv3 off

運行程序時輸入不同的/dev/leddrv、/dev/leddrv1、/dev/leddrv2、/dev/leddrv3得到的次設備號不同，驅動程序中根據不同的次設備號控制不同的燈，輸入不同的on、off命令write時寫入的值不同，根據不同的值執行開關動作。