如何从驱动程序的 ioctl() 中的文件 object 获取 pci_dev？

Question

I'm working on a linux driver for a PCIE hardware. The kernel is v4.13 . For each device object, there is a bunch of data stored with pci_set_drvdata(struct pci_dev *pdev, void *data) .

In IOCtl() service routine, how can I get the data back using struct file * pFile ?

long IOCtlService(struct file * pFile, unsigned int cmd, unsigned long arg)

thanks

Answer 1

Using ioctl() driver will take command & work on those commands as

 ioctl(fd, cmd , INPARAM or OUTPARAM);

how can I get the data back using struct file * pFile ? what operation you want to perform ? you can use commands which are available in ioctl.h for this. for eg IOR (If the command needs to read some thing from the kernel space)

Answer 2

If you have more then one device you are likely using an IDR to allocate and track minor dev node IDs. The call to idr_alloc accepts a pointer to store with the ID for future use.

In your ioctl handler you can then lookup the pointer from the idr using idr_find . For example:

Allocate an IDR and store info with it

Global defines

DEFINE_MUTEX(minor_lock);
DEFINE_IDR(mydev_idr);

In your PCI probe handler

struct my_dev * info;

info = kzalloc(sizeof(struct mydev_info), GFP_KERNEL);
if (!info)
  return -ENOMEM;

mutex_lock(&minor_lock);
info->minor = idr_alloc(&mydev_idr, info, 0, MYDEV_MAX_DEVICES, GFP_KERNEL);
if (info->minor < 0)
{
  mutex_unlock(&minor_lock);
  goto out_unreg;
}
mutex_unlock(&minor_lock);

pci_set_drvdata(dev, info);

Lookup the stored pointer from the IDR

unsigned minor = iminor(flip->f_inode);
struct my_dev * dev = (struct my_dev *)idr_find(&my_idr, minor);
if (!dev)
  return -EINVAL;

Make sure to free your IDRs on device removal

mutex_lock(&minor_lock);
idr_remove(&mydev_idr, info->minor);
mutex_unlock(&minor_lock);

Answer 3

struct file also have private_data , so you can store pci_dev there, just like what struct miscdev does:

static int misc_open(struct inode *inode, struct file *file)
{
    ......
    struct miscdevice *c;

    ......

    /*
     * Place the miscdevice in the file's
     * private_data so it can be used by the
     * file operations, including f_op->open below
     */
    file->private_data = c;
}