linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * For architectures where we want to allow direct access to the PCI config

 * stuff - it would probably be preferable on PCs too, but there people

 * just do it by hand with the magic northbridge registers.

 */

​

#include <linux/errno.h>

#include <linux/pci.h>

#include <linux/syscalls.h>

#include <linux/uaccess.h>

#include "pci.h"

​

SYSCALL_DEFINE5(pciconfig_read, unsigned long, bus, unsigned long, dfn,

        unsigned long, off, unsigned long, len, void __user *, buf)

{

    struct pci_dev *dev;

    u8 byte;

    u16 word;

    u32 dword;

    long err;

    long cfg_ret;

​

    if (!capable(CAP_SYS_ADMIN))

        return -EPERM;

​

    err = -ENODEV;

    dev = pci_get_domain_bus_and_slot(0, bus, dfn);

    if (!dev)

        goto error;

​

    switch (len) {

    case 1:

        cfg_ret = pci_user_read_config_byte(dev, off, &byte);

        break;

    case 2:

        cfg_ret = pci_user_read_config_word(dev, off, &word);

        break;

    case 4:

        cfg_ret = pci_user_read_config_dword(dev, off, &dword);

        break;

    default:

        err = -EINVAL;

        goto error;

    }

​

    err = -EIO;

    if (cfg_ret != PCIBIOS_SUCCESSFUL)

        goto error;

​

    switch (len) {

    case 1:

        err = put_user(byte, (unsigned char __user *)buf);

        break;

    case 2:

        err = put_user(word, (unsigned short __user *)buf);

        break;

    case 4:

        err = put_user(dword, (unsigned int __user *)buf);

        break;

    }

    pci_dev_put(dev);

    return err;