arm 驱动基础：点亮led_firt

原理图：

 

驱动程序代码实现：first_drv.c

#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>



static struct class *firstdrv_class;

static struct class_device    *firstdrv_class_dev;



volatile unsigned long *gpfcon = NULL;

volatile unsigned long *gpfdat = NULL;





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

{

    //printk("first_drv_open\n");

    /* 配置GPF4,5,6为输出 */

    *gpfcon &= ~((0x3<<(4*2)) | (0x3<<(5*2)) | (0x3<<(6*2)));

    *gpfcon |= ((0x1<<(4*2)) | (0x1<<(5*2)) | (0x1<<(6*2)));

    return 0;

}



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

{

    int val;



    //printk("first_drv_write\n");



    copy_from_user(&val, buf, count); //    copy_to_user();



    if (val == 1)

    {

        // 点灯

        *gpfdat &= ~((1<<4) | (1<<5) | (1<<6));

    }

    else

    {

        // 灭灯

        *gpfdat |= (1<<4) | (1<<5) | (1<<6);

    }

    

    return 0;

}



static struct file_operations first_drv_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   =   first_drv_open,     

    .write    =    first_drv_write,       

};





int major;

static int first_drv_init(void)

{

    major = register_chrdev(0, "first_drv", &first_drv_fops); // 注册, 告诉内核



    firstdrv_class = class_create(THIS_MODULE, "firstdrv");



    firstdrv_class_dev = class_device_create(firstdrv_class, NULL, MKDEV(major, 0), NULL, "xyz"); /* /dev/xyz */



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

    gpfdat = gpfcon + 1;



    return 0;

}



static void first_drv_exit(void)

{

    unregister_chrdev(major, "first_drv"); // 卸载



    class_device_unregister(firstdrv_class_dev);

    class_destroy(firstdrv_class);

    iounmap(gpfcon);

}



module_init(first_drv_init);

module_exit(first_drv_exit);





MODULE_LICENSE("GPL");

 

应用程序代码实现：

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <stdio.h>



/* firstdrvtest on

  * firstdrvtest off

  */

int main(int argc, char **argv)

{

    int fd;

    int val = 1;

    fd = open("/dev/xyz", O_RDWR);

    if (fd < 0)

    {

        printf("can't open!\n");

    }

    if (argc != 2)

    {

        printf("Usage :\n");

        printf("%s <on|off>\n", argv[0]);

        return 0;

    }



    if (strcmp(argv[1], "on") == 0)

    {

        val  = 1;

    }

    else

    {

        val = 0;

    }

    

    write(fd, &val, 4);

    return 0;

}