Linux ioctl 從應用到驅動

摘要： Linux ioctl 從應用到驅動 示例程式碼 驅動 將示例程式碼中n76e003_driver複製到linux/drivers/misc目錄下，修改相關Kconfig與Makefile檔案 標頭檔案中定義ioctl命...

Linux ioctl 從應用到驅動

ofollow,noindex">示例程式碼

驅動

將示例程式碼中n76e003_driver複製到linux/drivers/misc目錄下，修改相關Kconfig與Makefile檔案

1. 標頭檔案中定義ioctl命令

// ioctl cmd
#define N76E003_IOC/">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;
};

2. 實現ioctl函式

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;
}

3. 定義file_operations

static const struct file_operations n76e003_dev_fops = {
.owner = THIS_MODULE,
.open = n76e003_dev_open,
.unlocked_ioctl = n76e003_dev_ioctl
};

4. 註冊裝置

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;
}

...
}

應用程式

如果是Android工程，將示例程式碼中n76e003_app複製到external目錄下，並在Android根目錄執行：make n76e003

#include <sys/types.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>

#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;
}