syscall.c

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/*
 *  pci_syscall.c
 *
 * 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 <asm/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_bus_and_slot(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;

error:
    /* ??? XFree86 doesn't even check the return value.  They
       just look for 0xffffffff in the output, since that's what
       they get instead of a machine check on x86.  */
    switch (len) {
    case 1:
        put_user(-1, (unsigned char __user *)buf);
        break;
    case 2:
        put_user(-1, (unsigned short __user *)buf);
        break;
    case 4:
        put_user(-1, (unsigned int __user *)buf);
        break;
    }
    pci_dev_put(dev);
    return err;
}

SYSCALL_DEFINE5(pciconfig_write, 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;
    int err = 0;

    if (!capable(CAP_SYS_ADMIN))
        return -EPERM;

    dev = pci_get_bus_and_slot(bus, dfn);
    if (!dev)
        return -ENODEV;

    switch(len) {
    case 1:
        err = get_user(byte, (u8 __user *)buf);
        if (err)
            break;
        err = pci_user_write_config_byte(dev, off, byte);
        if (err != PCIBIOS_SUCCESSFUL)
            err = -EIO;
        break;

    case 2:
        err = get_user(word, (u16 __user *)buf);
        if (err)
            break;
        err = pci_user_write_config_word(dev, off, word);
        if (err != PCIBIOS_SUCCESSFUL)
            err = -EIO;
        break;

    case 4:
        err = get_user(dword, (u32 __user *)buf);
        if (err)
            break;
        err = pci_user_write_config_dword(dev, off, dword);
        if (err != PCIBIOS_SUCCESSFUL)
            err = -EIO;
        break;

    default:
        err = -EINVAL;
        break;
    }
    pci_dev_put(dev);
    return err;
}