字符设备学习笔记

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,
};

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");

 #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");

#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;
}