ioctrl原形 linux_Linux ioctl 从应用到驱动

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#ioctrl原形 linux

本文介绍了Linux ioctl从应用到驱动的实现。在驱动方面，需复制示例代码到指定目录，修改相关文件，定义ioctl命令、实现ioctl函数、定义file_operations并注册设备；在应用程序方面，若为Android工程，复制代码到指定目录并编译，还给出了使用ioctl的示例代码。

Linux ioctl 从应用到驱动

驱动

将示例代码中n76e003_driver复制到linux/drivers/misc目录下，修改相关Kconfig与Makefile文件

头文件中定义ioctl命令

// ioctl cmd

#define N76E003_IOC_MAGIC 'k'

#define N76E003_IOC_HEARTBEAT _IO(N76E003_IOC_MAGIC, 1)

#define N76E003_IOC_SET_UPTIME _IOW(N76E003_IOC_MAGIC, 2, int)

#define N76E003_IOC_MAXNR 2

struct n76e003_data {

struct i2c_client *client;

struct miscdevice n76e003_device;

};

实现ioctl函数

static int n76e003_dev_open(struct inode *inode, struct file *filp)

{

int ret = 0;

struct n76e003_data *n76e003 = container_of(filp->private_data,

struct n76e003_data,

n76e003_device);

filp->private_data = n76e003;

dev_info(&n76e003->client->dev,

"device node major=%d, minor=%d\n", imajor(inode), iminor(inode));

return ret;

}

static long n76e003_dev_ioctl(struct file *pfile,

unsigned int cmd, unsigned long arg)

{

int ret = 0;

int data = 0;

struct n76e003_data *n76e003 = pfile->private_data;

if (_IOC_TYPE(cmd) != N76E003_IOC_MAGIC)

return -EINVAL;

if (_IOC_NR(cmd) > N76E003_IOC_MAXNR)

return -EINVAL;

if (_IOC_DIR(cmd) & _IOC_READ)

ret = !access_ok(VERIFY_WRITE, (void *)arg, _IOC_SIZE(cmd));

else if (_IOC_DIR(cmd) & _IOC_WRITE)

ret = !access_ok(VERIFY_READ, (void *)arg, _IOC_SIZE(cmd));

if (ret)

return -EFAULT;

dev_info(&n76e003->client->dev,

"%s, (%x, %lx):\n", __func__, cmd,

arg);

switch (cmd) {

case N76E003_IOC_HEARTBEAT:

n76e003_heartbeat(n76e003->client);

break;

case N76E003_IOC_SET_UPTIME:

if (copy_from_user(&data, (int *)arg, sizeof(int))) {

dev_err(&n76e003->client->dev,

"%s, copy from user failed\n", __func__);

return -EFAULT;

}

n76e003_set_uptime(n76e003->client, data);

break;

default:

return -EINVAL;

}

return 0;

}

定义file_operations

static const struct file_operations n76e003_dev_fops = {

.owner = THIS_MODULE,

.open = n76e003_dev_open,

.unlocked_ioctl = n76e003_dev_ioctl

};

注册设备

static int n76e003_probe(struct i2c_client * client, const struct i2c_device_id * id)

{

...

n76e003->n76e003_device.minor = MISC_DYNAMIC_MINOR;

n76e003->n76e003_device.name = "n76e003";

n76e003->n76e003_device.fops = &n76e003_dev_fops;

ret = misc_register(&n76e003->n76e003_device);

if (ret) {

dev_err(&client->dev, "Failed misc_register\n");

goto exit_misc_register;

}

...

}

应用程序

如果是Android工程，将示例代码中n76e003_app复制到external目录下，并在Android根目录执行：make n76e003

#include

#define DEV_NAME "/dev/n76e003"

// ioctl cmd

#define N76E003_IOC_MAGIC 'k'

#define N76E003_IOC_HEARTBEAT _IO(N76E003_IOC_MAGIC, 1)

#define N76E003_IOC_SET_UPTIME _IOW(N76E003_IOC_MAGIC, 2, int)

int main(int argc, char const *argv[])

{

int ret, fd, num, arg;

fd = open(DEV_NAME, O_RDWR);

if (fd < 0) {

printf("Open device fail!\n");

return -1;

}

read(fd, &num, sizeof(int));

printf("The num is: %d\n", num);

printf("Please input a number written to testdriver: \n");

scanf("%d", &num);

write(fd, &num, sizeof(int));

read(fd, &num, sizeof(int));

printf("The num is: %d\n", num);

arg = 0xff;

ret = ioctl(fd, N76E003_IOC_HEARTBEAT, &arg);

if (ret < 0) {

printf("ioctl: %d\n", ret);

}

sleep(10);

arg = 0x01020304;

ret = ioctl(fd, N76E003_IOC_SET_UPTIME, &arg);

if (ret < 0) {

printf("ioctl: %d\n", ret);

}

close(fd);

return 0;

}