// SPDX-License-Identifier: GPL-2.0
/*
 * Driver for the Intel SCU IPC mechanism
 *
 * (C) Copyright 2008-2010 Intel Corporation
 * Author: Sreedhara DS (sreedhara.ds@intel.com)
 *
 * This driver provides IOCTL interfaces to call Intel SCU IPC driver API.
 */

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

#include <linux/platform_data/x86/intel_scu_ipc.h>

static int major;

static struct intel_scu_ipc_dev *scu;
static DEFINE_MUTEX(scu_lock);

/* IOCTL commands */
#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 */
};

/**
 *      scu_reg_access          -       implement register access ioctls
 *      @cmd: command we are doing (read/write/update)
 *      @data: kernel copy of ioctl data
 *
 *      Allow the user to perform register accesses on the SCU via the
 *      kernel interface
 */

static int scu_reg_access(u32 cmd, struct scu_ipc_data  *data)
{
        unsigned 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_dev_readv(scu, data->addr, data->data, count);
        case INTE_SCU_IPC_REGISTER_WRITE:
                return intel_scu_ipc_dev_writev(scu, data->addr, data->data, count);
        case INTE_SCU_IPC_REGISTER_UPDATE:
                return intel_scu_ipc_dev_update(scu, data->addr[0], data->data[0],
                                                data->mask);
        default:
                return -ENOTTY;
        }
}

/**
 *      scu_ipc_ioctl           -       control ioctls for the SCU
 *      @fp: file handle of the SCU device
 *      @cmd: ioctl coce
 *      @arg: pointer to user passed structure
 *
 *      Support the I/O and firmware flashing interfaces of the SCU
 */
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 int scu_ipc_open(struct inode *inode, struct file *file)
{
        int ret = 0;

        /* Only single open at the time */
        mutex_lock(&scu_lock);
        if (scu) {
                ret = -EBUSY;
                goto unlock;
        }

        scu = intel_scu_ipc_dev_get();
        if (!scu)
                ret = -ENODEV;

unlock:
        mutex_unlock(&scu_lock);
        return ret;
}

static int scu_ipc_release(struct inode *inode, struct file *file)
{
        mutex_lock(&scu_lock);
        intel_scu_ipc_dev_put(scu);
        scu = NULL;
        mutex_unlock(&scu_lock);

        return 0;
}

static const struct file_operations scu_ipc_fops = {
        .unlocked_ioctl = scu_ipc_ioctl,
        .open = scu_ipc_open,
        .release = scu_ipc_release,
};

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 <sreedhara.ds@intel.com>");