intel_scu_ipcutil.c

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/*
 * intel_scu_ipc.c: Driver for the Intel SCU IPC mechanism
 *
 * (C) Copyright 2008-2010 Intel Corporation
 * Author: Sreedhara DS ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 2
 * of the License.
 *
 * This driver provides ioctl interfaces to call intel scu ipc driver api
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/fcntl.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <asm/intel_scu_ipc.h>

static int major;

/* ioctl commnds */
#define INTE_SCU_IPC_REGISTER_READ  0
#define INTE_SCU_IPC_REGISTER_WRITE 1
#define INTE_SCU_IPC_REGISTER_UPDATE    2

struct scu_ipc_data {
    u32     count;  /* No. of registers */
    u16     addr[5]; /* Register addresses */
    u8      data[5]; /* Register data */
    u8      mask; /* Valid for read-modify-write */
};

static int scu_reg_access(u32 cmd, struct scu_ipc_data  *data)
{
    int count = data->count;

    if (count == 0 || count == 3 || count > 4)
        return -EINVAL;

    switch (cmd) {
    case INTE_SCU_IPC_REGISTER_READ:
        return intel_scu_ipc_readv(data->addr, data->data, count);
    case INTE_SCU_IPC_REGISTER_WRITE:
        return intel_scu_ipc_writev(data->addr, data->data, count);
    case INTE_SCU_IPC_REGISTER_UPDATE:
        return intel_scu_ipc_update_register(data->addr[0],
                            data->data[0], data->mask);
    default:
        return -ENOTTY;
    }
}

static long scu_ipc_ioctl(struct file *fp, unsigned int cmd,
                            unsigned long arg)
{
    int ret;
    struct scu_ipc_data  data;
    void __user *argp = (void __user *)arg;

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

    if (copy_from_user(&data, argp, sizeof(struct scu_ipc_data)))
        return -EFAULT;
    ret = scu_reg_access(cmd, &data);
    if (ret < 0)
        return ret;
    if (copy_to_user(argp, &data, sizeof(struct scu_ipc_data)))
        return -EFAULT;
    return 0;
}

static const struct file_operations scu_ipc_fops = {
    .unlocked_ioctl = scu_ipc_ioctl,
};

static int __init ipc_module_init(void)
{
    major = register_chrdev(0, "intel_mid_scu", &scu_ipc_fops);
    if (major < 0)
        return major;

    return 0;
}

static void __exit ipc_module_exit(void)
{
    unregister_chrdev(major, "intel_mid_scu");
}

module_init(ipc_module_init);
module_exit(ipc_module_exit);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Utility driver for intel scu ipc");
MODULE_AUTHOR("Sreedhara <[email protected]>");