// SPDX-License-Identifier: GPL-2.0
/*
 * IOCTL interface for SCLP
 *
 * Copyright IBM Corp. 2012
 *
 * Author: Michael Holzheu <holzheu@linux.vnet.ibm.com>
 */

#include <linux/uaccess.h>
#include <linux/miscdevice.h>
#include <linux/gfp.h>
#include <linux/init.h>
#include <linux/ioctl.h>
#include <linux/fs.h>
#include <asm/sclp_ctl.h>
#include <asm/sclp.h>

#include "sclp.h"

/*
 * Supported command words
 */
static unsigned int sclp_ctl_sccb_wlist[] = {
        0x00400002,
        0x00410002,
};

/*
 * Check if command word is supported
 */
static int sclp_ctl_cmdw_supported(unsigned int cmdw)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(sclp_ctl_sccb_wlist); i++) {
                if (cmdw == sclp_ctl_sccb_wlist[i])
                        return 1;
        }
        return 0;
}

static void __user *u64_to_uptr(u64 value)
{
        return (void __user *)(unsigned long)value;
}

/*
 * Start SCLP request
 */
static int sclp_ctl_ioctl_sccb(void __user *user_area)
{
        struct sclp_ctl_sccb ctl_sccb;
        struct sccb_header *sccb;
        unsigned long copied;
        int rc;

        if (copy_from_user(&ctl_sccb, user_area, sizeof(ctl_sccb)))
                return -EFAULT;
        if (!sclp_ctl_cmdw_supported(ctl_sccb.cmdw))
                return -EOPNOTSUPP;
        sccb = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
        if (!sccb)
                return -ENOMEM;
        copied = PAGE_SIZE -
                copy_from_user(sccb, u64_to_uptr(ctl_sccb.sccb), PAGE_SIZE);
        if (offsetof(struct sccb_header, length) +
            sizeof(sccb->length) > copied || sccb->length > copied) {
                rc = -EFAULT;
                goto out_free;
        }
        if (sccb->length < 8) {
                rc = -EINVAL;
                goto out_free;
        }
        rc = sclp_sync_request(ctl_sccb.cmdw, sccb);
        if (rc)
                goto out_free;
        if (copy_to_user(u64_to_uptr(ctl_sccb.sccb), sccb, sccb->length))
                rc = -EFAULT;
out_free:
        free_page((unsigned long) sccb);
        return rc;
}

/*
 * SCLP SCCB ioctl function
 */
static long sclp_ctl_ioctl(struct file *filp, unsigned int cmd,
                           unsigned long arg)
{
        void __user *argp;

        argp = (void __user *)arg;
        switch (cmd) {
        case SCLP_CTL_SCCB:
                return sclp_ctl_ioctl_sccb(argp);
        default: /* unknown ioctl number */
                return -ENOTTY;
        }
}

/*
 * File operations
 */
static const struct file_operations sclp_ctl_fops = {
        .owner = THIS_MODULE,
        .open = nonseekable_open,
        .unlocked_ioctl = sclp_ctl_ioctl,
};

/*
 * Misc device definition
 */
static struct miscdevice sclp_ctl_device = {
        .minor = MISC_DYNAMIC_MINOR,
        .name = "sclp",
        .fops = &sclp_ctl_fops,
};
builtin_misc_device(sclp_ctl_device);