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skel.c
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skel.c
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/*
* Skeleton for a character device driver.
*
* Copyright (C) 2015 Serge Vakulenko
*
* Permission to use, copy, modify, and distribute this software
* and its documentation for any purpose and without fee is hereby
* granted, provided that the above copyright notice appear in all
* copies and that both that the copyright notice and this
* permission notice and warranty disclaimer appear in supporting
* documentation, and that the name of the author not be used in
* advertising or publicity pertaining to distribution of the
* software without specific, written prior permission.
*
* The author disclaim all warranties with regard to this
* software, including all implied warranties of merchantability
* and fitness. In no event shall the author be liable for any
* special, indirect or consequential damages or any damages
* whatsoever resulting from loss of use, data or profits, whether
* in an action of contract, negligence or other tortious action,
* arising out of or in connection with the use or performance of
* this software.
*/
#include <sys/param.h>
#include <sys/conf.h>
#include <sys/user.h>
#include <sys/ioctl.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/skel.h>
#define NSKEL 5 /* Ports 1...5 */
/*
* To enable debug output, uncomment the first line.
*/
#define PRINTDBG printf
#ifndef PRINTDBG
# define PRINTDBG(...) /*empty*/
#endif
/*
* Open /dev/skel# device.
*/
int skeldev_open(dev_t dev, int flag, int mode)
{
int unit = minor(dev);
if (unit >= NSKEL)
return ENXIO;
if (u.u_uid != 0)
return EPERM;
// TODO: initialize the port.
PRINTDBG("--- %s() unit=%u, flag=%d, mode=%d\n", __func__, unit, flag, mode);
return 0;
}
/*
* Close device.
*/
int skeldev_close(dev_t dev, int flag, int mode)
{
int unit = minor(dev);
if (u.u_uid != 0)
return EPERM;
// TODO: disable the port.
PRINTDBG("--- %s() unit=%u, flag=%d, mode=%d\n", __func__, unit, flag, mode);
return 0;
}
/*
* Read data from device.
*/
int skeldev_read(dev_t dev, struct uio *uio, int flag)
{
int unit = minor(dev);
// TODO: read data from port to user program.
PRINTDBG("--- %s() unit=%u, flag=%d\n", __func__, unit, flag);
return 0;
}
/*
* Write data to device.
*/
int skeldev_write(dev_t dev, struct uio *uio, int flag)
{
int unit = minor(dev);
// TODO: write data from user program to port.
PRINTDBG("--- %s() unit=%u, flag=%d\n", __func__, unit, flag);
return 0;
}
/*
* Control operations:
* SKELCTL_SETMODE - set device mode
* SKELCTL_IO(n) - perform R/W transaction of n bytes
*/
int skeldev_ioctl(dev_t dev, u_int cmd, caddr_t addr, int flag)
{
int unit = minor(dev);
int nbytes;
PRINTDBG("--- %s() unit=%u, cmd=0x%08x, addr=0x%08x, flag=%d\n", __func__, unit, cmd, addr, flag);
switch (cmd & ~(IOCPARM_MASK << 16)) {
default:
return ENODEV;
case SKELCTL_SETMODE:
// TODO: set device mode.
PRINTDBG("--- SETMODE 0x%x\n", (unsigned) addr);
return 0;
case SKELCTL_IO(0): /* transfer n bytes */
nbytes = (cmd >> 16) & IOCPARM_MASK;
if (baduaddr(addr) || baduaddr(addr + nbytes - 1))
return EFAULT;
// TODO: transfer nbytes from device to addr.
PRINTDBG("--- Transfer nbytes=%u to addr=0x%08x\n", addr);
break;
}
return 0;
}