xref: /freebsd-14.2/share/examples/kld/cdev/module/cdev.c (revision 6058f720)

/* 08 Nov 1998*/
/*-
 * cdev.c
 *
 * 08 Nov 1998	Rajesh Vaidheeswarran
 *
 * SPDX-License-Identifier: BSD-4-Clause
 *
 * Copyright (c) 1998 Rajesh Vaidheeswarran
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Rajesh Vaidheeswarran.
 * 4. The name Rajesh Vaidheeswarran may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY RAJESH VAIDHEESWARRAN ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE RAJESH VAIDHEESWARRAN BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
  * Copyright (c) 1993 Terrence R. Lambert.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Terrence R. Lambert.
 * 4. The name Terrence R. Lambert may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY TERRENCE R. LAMBERT ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE TERRENCE R. LAMBERT BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *
 * $FreeBSD$
 */
#include <sys/param.h>
#include <sys/uio.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/ioccom.h>
#include <sys/conf.h>

#include "cdev.h"

/*
 * This is the actual code for the system call... it can't be static because
 * it is exported to another part of the module... the only place it needs
 * to be referenced is the sysent we are interested in.
 *
 * To write your own system call using this as a template, you could strip
 * out this code and use the rest as a prototype module, changing only the
 * function names and the number of arguments to the call in the module
 * specific "sysent".
 *
 * You would have to use the "-R" option of "ld" to ensure a linkable file
 * if you were to do this, since you would need to combine multiple ".o"
 * files into a single ".o" file for use by "modload".
 */

#define CDEV_IOCTL1         _IOR('C', 1, u_int)

/* Stores string recv'd by _write() */
static char buf[512+1];
static size_t len;

int
mydev_open(struct cdev *dev, int flag, int otyp, struct thread *td)
{
    struct proc *procp = td->td_proc;

    printf("mydev_open: dev_t=%lu, flag=%x, otyp=%x, procp=%p\n",
	   dev2udev(dev), flag, otyp, procp);
    memset(&buf, '\0', 513);
    len = 0;
    return (0);
}

int
mydev_close(struct cdev *dev, int flag, int otyp, struct thread *td)
{
    struct proc *procp = td->td_proc;

    printf("mydev_close: dev_t=%lu, flag=%x, otyp=%x, procp=%p\n",
	      dev2udev(dev), flag, otyp, procp);
    return (0);
}

int
mydev_ioctl(struct cdev *dev, u_long cmd, caddr_t arg, int mode,
    struct thread *td)
{
    int error = 0;
    struct proc *procp = td->td_proc;

    printf("mydev_ioctl: dev_t=%lu, cmd=%lx, arg=%p, mode=%x procp=%p\n",
	   dev2udev(dev), cmd, arg, mode, procp);

    switch(cmd) {
    case CDEV_IOCTL1:
	printf("you called mydev_ioctl CDEV_IOCTL1\n");
	break;
    default:
	printf("No such ioctl for me!\n");
	error = EINVAL;
	break;
    }
    return (error);
}

/*
 * mydev_write takes in a character string and saves it
 * to buf for later accessing.
 */
int
mydev_write(struct cdev *dev, struct uio *uio, int ioflag)
{
    int err = 0;

    printf("mydev_write: dev_t=%lu, uio=%p, ioflag=%d\n",
	dev2udev(dev), uio, ioflag);

    err = copyinstr(uio->uio_iov->iov_base, &buf, 512, &len);
    if (err != 0) {
	printf("Write to \"cdev\" failed.\n");
    }
    return(err);
}

/*
 * The mydev_read function just takes the buf that was saved
 * via mydev_write() and returns it to userland for
 * accessing.
 */
int
mydev_read(struct cdev *dev, struct uio *uio, int ioflag)
{
    int err = 0;

    printf("mydev_read: dev_t=%lu, uio=%p, ioflag=%d\n",
	dev2udev(dev), uio, ioflag);

    if (len <= 0) {
	err = -1;
    } else {	/* copy buf to userland */
	copystr(&buf, uio->uio_iov->iov_base, 513, &len);
    }
    return(err);
}