Question

我试图通过ioctl将struct pwmData类型变量传递给我的驱动程序。但在我的应用程序中，我通过perror获得了无效的参数错误。有人可以告诉我为什么我得到这个？我的.h文件：

typedef struct
 {
      unsigned int pwmChannel;
      unsigned int pwmDutyCycle;
      unsigned int pwmPeriod;
  }pwmData;  

#define PWM_MAGIC '0xF2'  //Is not used in kernel, hence used here
#define ENABLE_PWM _IOW(PWM_MAGIC, 1,pwmData*)
#define DISABLE_PWM _IOW(PWM_MAGIC, 2,pwmData*)

我的应用（其中fd是我的文件描述符）：

pwmData param;
param.pwmPeriod = 1000;
param.pwmDutyCycle = 500;
param.pwmChannel = 1;

  ret = ioctl(fd, ENABLE_PWM, &param); // Check casting
  if(ret<0){
    printf("ENABLE IOCTL failed %d.\n", ret);
    perror("Error:");
    exit(-1);
  }

我的司机的ioctl部分：

static long pwm_device_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
{
    printk(KERN_DEBUG "Entered IOCTL\n");
    int retval;
    static pwmData* data;
    data = (void *)kmalloc(sizeof(pwmData)+1,GFP_KERNEL);

    switch (cmd)
    {
        case ENABLE_PWM:
        if(copy_from_user((void*)data, (void*)arg, sizeof(pwmData)))
        {
            return -EFAULT;
        }

printk(KERN_DEBUG "%d %d %d\n",data->pwmChannel,data->pwmDutyCycle,data->pwmPeriod);

    retval = pwm_config(&cpwm1->chip.pwms[(data->pwmChannel) - 1], data->pwmDutyCycle, data->pwmPeriod);
    if(retval == 0)
    {
        retval = pwm_enable(&cpwm1->chip.pwms[(data->pwmChannel) - 1]);
        return retval;
    }
    else
    {
        return retval;
    }
    break;

类似于PWM_DISABLE。我刚刚启动了linux驱动程序开发。所以任何建议都会被提升。

将struct传递给驱动程序时出现IOCTL错误

0 个答案: