LXR linux/drivers/platform/x86/intel_scu

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Driver for the Intel SCU IPC mechanism
   4 *
   5 * (C) Copyright 2008-2010 Intel Corporation
   6 * Author: Sreedhara DS (sreedhara.ds@intel.com)
   7 *
   8 * This driver provides IOCTL interfaces to call Intel SCU IPC driver API.
   9 */
  10
  11#include <linux/errno.h>
  12#include <linux/fcntl.h>
  13#include <linux/fs.h>
  14#include <linux/kernel.h>
  15#include <linux/module.h>
  16#include <linux/sched.h>
  17#include <linux/slab.h>
  18#include <linux/types.h>
  19#include <linux/uaccess.h>
  20
  21#include <asm/intel_scu_ipc.h>
  22
  23static int major;
  24
  25struct intel_scu_ipc_dev *scu;
  26static DEFINE_MUTEX(scu_lock);
  27
  28/* IOCTL commands */
  29#define INTE_SCU_IPC_REGISTER_READ      0
  30#define INTE_SCU_IPC_REGISTER_WRITE     1
  31#define INTE_SCU_IPC_REGISTER_UPDATE    2
  32
  33struct scu_ipc_data {
  34        u32     count;  /* No. of registers */
  35        u16     addr[5]; /* Register addresses */
  36        u8      data[5]; /* Register data */
  37        u8      mask; /* Valid for read-modify-write */
  38};
  39
  40/**
  41 *      scu_reg_access          -       implement register access ioctls
  42 *      @cmd: command we are doing (read/write/update)
  43 *      @data: kernel copy of ioctl data
  44 *
  45 *      Allow the user to perform register accesses on the SCU via the
  46 *      kernel interface
  47 */
  48
  49static int scu_reg_access(u32 cmd, struct scu_ipc_data  *data)
  50{
  51        unsigned int count = data->count;
  52
  53        if (count == 0 || count == 3 || count > 4)
  54                return -EINVAL;
  55
  56        switch (cmd) {
  57        case INTE_SCU_IPC_REGISTER_READ:
  58                return intel_scu_ipc_dev_readv(scu, data->addr, data->data, count);
  59        case INTE_SCU_IPC_REGISTER_WRITE:
  60                return intel_scu_ipc_dev_writev(scu, data->addr, data->data, count);
  61        case INTE_SCU_IPC_REGISTER_UPDATE:
  62                return intel_scu_ipc_dev_update(scu, data->addr[0], data->data[0],
  63                                                data->mask);
  64        default:
  65                return -ENOTTY;
  66        }
  67}
  68
  69/**
  70 *      scu_ipc_ioctl           -       control ioctls for the SCU
  71 *      @fp: file handle of the SCU device
  72 *      @cmd: ioctl coce
  73 *      @arg: pointer to user passed structure
  74 *
  75 *      Support the I/O and firmware flashing interfaces of the SCU
  76 */
  77static long scu_ipc_ioctl(struct file *fp, unsigned int cmd,
  78                                                        unsigned long arg)
  79{
  80        int ret;
  81        struct scu_ipc_data  data;
  82        void __user *argp = (void __user *)arg;
  83
  84        if (!capable(CAP_SYS_RAWIO))
  85                return -EPERM;
  86
  87        if (copy_from_user(&data, argp, sizeof(struct scu_ipc_data)))
  88                return -EFAULT;
  89        ret = scu_reg_access(cmd, &data);
  90        if (ret < 0)
  91                return ret;
  92        if (copy_to_user(argp, &data, sizeof(struct scu_ipc_data)))
  93                return -EFAULT;
  94        return 0;
  95}
  96
  97static int scu_ipc_open(struct inode *inode, struct file *file)
  98{
  99        int ret = 0;
 100
 101        /* Only single open at the time */
 102        mutex_lock(&scu_lock);
 103        if (scu) {
 104                ret = -EBUSY;
 105                goto unlock;
 106        }
 107
 108        scu = intel_scu_ipc_dev_get();
 109        if (!scu)
 110                ret = -ENODEV;
 111
 112unlock:
 113        mutex_unlock(&scu_lock);
 114        return ret;
 115}
 116
 117static int scu_ipc_release(struct inode *inode, struct file *file)
 118{
 119        mutex_lock(&scu_lock);
 120        intel_scu_ipc_dev_put(scu);
 121        scu = NULL;
 122        mutex_unlock(&scu_lock);
 123
 124        return 0;
 125}
 126
 127static const struct file_operations scu_ipc_fops = {
 128        .unlocked_ioctl = scu_ipc_ioctl,
 129        .open = scu_ipc_open,
 130        .release = scu_ipc_release,
 131};
 132
 133static int __init ipc_module_init(void)
 134{
 135        major = register_chrdev(0, "intel_mid_scu", &scu_ipc_fops);
 136        if (major < 0)
 137                return major;
 138
 139        return 0;
 140}
 141
 142static void __exit ipc_module_exit(void)
 143{
 144        unregister_chrdev(major, "intel_mid_scu");
 145}
 146
 147module_init(ipc_module_init);
 148module_exit(ipc_module_exit);
 149
 150MODULE_LICENSE("GPL v2");
 151MODULE_DESCRIPTION("Utility driver for intel scu ipc");
 152MODULE_AUTHOR("Sreedhara <sreedhara.ds@intel.com>");
 153