LXR linux/drivers/platform/x86/intel_scu

   1/*
   2 * intel_scu_ipc.c: Driver for the Intel SCU IPC mechanism
   3 *
   4 * (C) Copyright 2008-2010 Intel Corporation
   5 * Author: Sreedhara DS (sreedhara.ds@intel.com)
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License
   9 * as published by the Free Software Foundation; version 2
  10 * of the License.
  11 *
  12 * This driver provides ioctl interfaces to call intel scu ipc driver api
  13 */
  14
  15#include <linux/module.h>
  16#include <linux/kernel.h>
  17#include <linux/errno.h>
  18#include <linux/types.h>
  19#include <linux/fs.h>
  20#include <linux/fcntl.h>
  21#include <linux/sched.h>
  22#include <linux/uaccess.h>
  23#include <linux/slab.h>
  24#include <linux/init.h>
  25#include <asm/intel_scu_ipc.h>
  26
  27static int major;
  28
  29/* ioctl commnds */
  30#define INTE_SCU_IPC_REGISTER_READ      0
  31#define INTE_SCU_IPC_REGISTER_WRITE     1
  32#define INTE_SCU_IPC_REGISTER_UPDATE    2
  33
  34struct scu_ipc_data {
  35        u32     count;  /* No. of registers */
  36        u16     addr[5]; /* Register addresses */
  37        u8      data[5]; /* Register data */
  38        u8      mask; /* Valid for read-modify-write */
  39};
  40
  41/**
  42 *      scu_reg_access          -       implement register access ioctls
  43 *      @cmd: command we are doing (read/write/update)
  44 *      @data: kernel copy of ioctl data
  45 *
  46 *      Allow the user to perform register accesses on the SCU via the
  47 *      kernel interface
  48 */
  49
  50static int scu_reg_access(u32 cmd, struct scu_ipc_data  *data)
  51{
  52        unsigned int count = data->count;
  53
  54        if (count == 0 || count == 3 || count > 4)
  55                return -EINVAL;
  56
  57        switch (cmd) {
  58        case INTE_SCU_IPC_REGISTER_READ:
  59                return intel_scu_ipc_readv(data->addr, data->data, count);
  60        case INTE_SCU_IPC_REGISTER_WRITE:
  61                return intel_scu_ipc_writev(data->addr, data->data, count);
  62        case INTE_SCU_IPC_REGISTER_UPDATE:
  63                return intel_scu_ipc_update_register(data->addr[0],
  64                                                    data->data[0], data->mask);
  65        default:
  66                return -ENOTTY;
  67        }
  68}
  69
  70/**
  71 *      scu_ipc_ioctl           -       control ioctls for the SCU
  72 *      @fp: file handle of the SCU device
  73 *      @cmd: ioctl coce
  74 *      @arg: pointer to user passed structure
  75 *
  76 *      Support the I/O and firmware flashing interfaces of the SCU
  77 */
  78static long scu_ipc_ioctl(struct file *fp, unsigned int cmd,
  79                                                        unsigned long arg)
  80{
  81        int ret;
  82        struct scu_ipc_data  data;
  83        void __user *argp = (void __user *)arg;
  84
  85        if (!capable(CAP_SYS_RAWIO))
  86                return -EPERM;
  87
  88        if (copy_from_user(&data, argp, sizeof(struct scu_ipc_data)))
  89                return -EFAULT;
  90        ret = scu_reg_access(cmd, &data);
  91        if (ret < 0)
  92                return ret;
  93        if (copy_to_user(argp, &data, sizeof(struct scu_ipc_data)))
  94                return -EFAULT;
  95        return 0;
  96}
  97
  98static const struct file_operations scu_ipc_fops = {
  99        .unlocked_ioctl = scu_ipc_ioctl,
 100};
 101
 102static int __init ipc_module_init(void)
 103{
 104        major = register_chrdev(0, "intel_mid_scu", &scu_ipc_fops);
 105        if (major < 0)
 106                return major;
 107
 108        return 0;
 109}
 110
 111static void __exit ipc_module_exit(void)
 112{
 113        unregister_chrdev(major, "intel_mid_scu");
 114}
 115
 116module_init(ipc_module_init);
 117module_exit(ipc_module_exit);
 118
 119MODULE_LICENSE("GPL v2");
 120MODULE_DESCRIPTION("Utility driver for intel scu ipc");
 121MODULE_AUTHOR("Sreedhara <sreedhara.ds@intel.com>");
 122