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From: Julian Elischer <julian@whistle.com>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: writting device drivers..
Date: Sat, 01 Feb 1997 22:58:26 -0800
Organization: Whistle Communications
Lines: 445
Message-ID: <32F43B12.52BFA1D7@whistle.com>
References: <5cjbuv$6bp@epsilon.qmw.ac.uk>
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eng-jon Ong wrote:
>
> Hi there..
> Can anyone tell me if writting device drivers for the
> FreeBSD kernel is more or less similar to writting device
> drivers for Linux? Is there any major differences or lots
> of minor things here and there? Is there any document or somesort
> of HOWTO to point out or get a person started for writting
> device drivers and installing interrupt handlers for freeBSD?
>
> Thanks in advance..
>
> ongej
here is a script that makes a skeleton device driver for freeBSD
2.2.
run it as
sh make_device_driver.sh foo
to ad a foo driver to the kernel
and then edit it to do what you want..
I have a differnt script for pseudo device drivers (ones that
dont have specific hardware (e.g /dev/null)
let me know if you want a copy of that...
julian
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#!/bin/sh
# This writes a skeleton driver and puts it into the kernel tree for you
#arg1 is lowercase "foo"
#
# Trust me, RUN THIS SCRIPT :)
#
#-------cut here------------------
cd /sys/i386/conf
if [ "${1}X" = "X" ]
then
echo "Hey , how about some help here.. give me a device name!"
exit 1
fi
UPPER=`echo ${1} |tr "[:lower:]" "[:upper:]"`
cat >files.${UPPER} <<DONE
i386/isa/${1}.c optional ${1} device-driver
DONE
cat >${UPPER} <<DONE
# Configuration file for kernel type: ${UPPER}
ident ${UPPER}
# \$Id:\$"
DONE
grep -v GENERIC < GENERIC >>${UPPER}
cat >>${UPPER} <<DONE
# trust me, you'll need this
options DDB
device ${1}0 at isa? port 0x234 bio irq 5 vector ${1}intr
DONE
cat >../isa/${1}.c <<DONE
/*
* Copyright ME
*
* ${1} driver
* \$Id:\$
*/
#include "${1}.h" /* generated file.. defines N${UPPER} */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h> /* SYSINIT stuff */
#include <sys/conf.h> /* cdevsw stuff */
#include <sys/malloc.h> /* malloc region definitions */
#include <machine/clock.h> /* DELAY() */
#include <i386/isa/isa.h> /* ISA bus port definitions etc. */
#include <i386/isa/isa_device.h>/* ISA bus configuration structures */
#include <sys/${1}io.h> /* ${1} IOCTL definitions */
#ifdef DEVFS
#include <sys/devfsext.h> /* DEVFS defintitions */
#endif /* DEVFS */
/* Function prototypes (these should all be static except for ${1}intr()) */
static d_open_t ${1}open;
static d_close_t ${1}close;
static d_read_t ${1}read;
static d_write_t ${1}write;
static d_ioctl_t ${1}ioctl;
static d_mmap_t ${1}mmap;
static d_select_t ${1}select;
static int ${1}probe (struct isa_device *);
static int ${1}attach (struct isa_device *);
/* void ${1}intr(int unit);*//* actually defined in ioconf.h (generated file) */
#define CDEV_MAJOR 20
static struct cdevsw ${1}_cdevsw = {
${1}open,
${1}close,
${1}read,
${1}write,
${1}ioctl,
nullstop,
nullreset,
nodevtotty,
${1}select,
${1}mmap,
NULL,
"${1}",
NULL,
-1 };
struct isa_driver ${1}driver = {
${1}probe,
${1}attach,
"${1}" };
/*
* device specific Misc defines
*/
#define BUFFERSIZE 1024
#define NUMPORTS 4
#define UNIT(dev) minor(dev) /* assume one minor number per unit */
/*
* One of these per allocated device
*/
struct ${1}_softc {
struct isa_device *dev;
char buffer[BUFFERSIZE];
#ifdef DEVFS
static void *devfs_token;
#endif
} ;
typedef struct ${1}_softc *sc_p;
static sc_p sca[N${UPPER}];
/* add your own test to see if it exists */
/* should return the number of ports needed */
static int
${1}probe (struct isa_device *dev)
{
char val;
int unit = dev->id_unit;
sc_p scp = sca[unit];
/*
* Check the unit makes sense.
*/
if (unit > N${UPPER}) {
printf("bad unit (%d)\n", unit);
return (0);
}
if (scp) {
printf("unit $d already attached\n", unit);
return (0);
}
/*
* try see if the device is there.
*/
val = inb (dev->id_iobase);
if ( val != 42 ) {
return (0);
}
/*
* ok, we got one we think
* do some further (this time possibly destructive) tests.
*/
outb (dev->id_iobase, 0xff);
DELAY (10000); /* 10 ms delay */
val = inb (dev->id_iobase) & 0x0f;
return ((val & 0x0f) == 0x0f)? NUMPORTS : 0 ;
}
/*
* Called if the probe succeeded.
* We can be destructive here as we know we have the device.
* we can also trust the unit number.
*/
static int
${1}attach (struct isa_device *dev)
{
int unit = dev->id_unit;
sc_p scp = sca[unit];
/*
* Allocate storage for this instance .
*/
scp = malloc(sizeof(*scp), M_DEVBUF, M_NOWAIT);
if( scp == NULL) {
printf("${1}%d failed to allocage driver strorage\n", unit);
return (0);
}
bzero(scp, sizeof(*scp));
sca[unit] = scp;
/*
* Store whatever seems wise.
*/
scp->dev = dev;
#if DEVFS
scp->devfs_token = devfs_add_devswf(&${1}_cdevsw, unit, DV_CHR,
UID_ROOT, GID_KMEM, 0600, "${1}%d", unit);
#endif
return 1;
}
/*
* Macro to check that the unit number is valid
* Often this isn't needed as once the open() is performed,
* the unit number is pretty much safe.. The exception would be if we
* implemented devices that could "go away". in which case all these routines
* would be wise to check the number, DIAGNOSTIC or not.
*/
#define CHECKUNIT(RETVAL) \
do { /* the do-while is a safe way to do this grouping */ \
if (unit > N${UPPER}) { \
printf(__FUNCTION__ ":bad unit $d\n", unit); \
return (RETVAL); \
} \
if (scp == NULL) { \
printf( __FUNCTION__ ": unit $d not attached\n", unit);\
return (RETVAL); \
} \
} while (0)
#ifdef DIAGNOSTIC
#define CHECKUNIT_DIAG(RETVAL) CHECKUNIT(RETVAL)
#else /* DIAGNOSTIC */
#define CHECKUNIT_DIAG(RETVAL)
#endif /* DIAGNOSTIC */
void
${1}intr(int unit)
{
sc_p scp = sca[unit];
/*
* well we got an interupt, now what?
* Theoretically we don't need to check the unit.
*/
return;
}
int ${1}ioctl (dev_t dev, int cmd, caddr_t data, int flag, struct proc *p)
{
int unit = UNIT (dev);
sc_p scp = sca[unit];
CHECKUNIT_DIAG(ENXIO);
switch (cmd) {
case DHIOCRESET:
/* whatever resets it */
outb(scp->dev->id_iobase, 0xff);
break;
default:
return ENXIO;
}
return (0);
}
/*
* You also need read, write, open, close routines.
* This should get you started
*/
static int
${1}open(dev_t dev, int oflags, int devtype, struct proc *p)
{
int unit = UNIT (dev);
sc_p scp = sca[unit];
CHECKUNIT(ENXIO);
/*
* Do processing
*/
return (0);
}
static int
${1}close(dev_t dev, int fflag, int devtype, struct proc *p)
{
int unit = UNIT (dev);
sc_p scp = sca[unit];
CHECKUNIT_DIAG(ENXIO);
/*
* Do processing
*/
return (0);
}
static int
${1}read(dev_t dev, struct uio *uio, int ioflag)
{
int unit = UNIT (dev);
sc_p scp = sca[unit];
int toread;
CHECKUNIT_DIAG(ENXIO);
/*
* Do processing
* read from buffer
*/
toread = (min(uio->uio_resid, sizeof(scp->buffer)));
return(uiomove(scp->buffer, toread, uio));
}
static int
${1}write(dev_t dev, struct uio *uio, int ioflag)
{
int unit = UNIT (dev);
sc_p scp = sca[unit];
int towrite;
CHECKUNIT_DIAG(ENXIO);
/*
* Do processing
* write to buffer
*/
towrite = (min(uio->uio_resid, sizeof(scp->buffer)));
return(uiomove(scp->buffer, towrite, uio));
}
static int
${1}mmap(dev_t dev, int offset, int nprot)
{
int unit = UNIT (dev);
sc_p scp = sca[unit];
CHECKUNIT_DIAG(-1);
/*
* Do processing
*/
#if 0 /* if we had a frame buffer or whatever.. do this */
if (offset > FRAMEBUFFERSIZE - PAGE_SIZE) {
return (-1);
}
return i386_btop((FRAMEBASE + offset));
#else
return (-1);
#endif
}
static int
${1}select(dev_t dev, int which, struct proc *p)
{
int unit = UNIT (dev);
sc_p scp = sca[unit];
CHECKUNIT_DIAG(ENXIO);
/*
* Do processing
*/
return (0); /* this is the wrong value I'm sure */
}
/*
* Now for some driver initialisation.
* Occurs ONCE during boot (very early).
*/
static void
${1}_drvinit(void *unused)
{
dev_t dev;
dev = makedev(CDEV_MAJOR, 0);
cdevsw_add(&dev, &${1}_cdevsw, NULL);
}
SYSINIT(${1}dev, SI_SUB_DRIVERS, SI_ORDER_MIDDLE+CDEV_MAJOR,
${1}_drvinit, NULL)
DONE
cat >../../sys/${1}io.h <<DONE
/*
* Definitions needed to access the ${1} device (ioctls etc)
* see mtio.h , ioctl.h as examples
*/
#ifndef SYS_DHIO_H
#define SYS_DHIO_H
#ifndef KERNEL
#include <sys/types.h>
#endif
#include <sys/ioccom.h>
/*
* define an ioctl here
*/
#define DHIOCRESET _IO('D', 0) /* reset the ${1} device */
#endif
DONE
config ${UPPER}
cd ../../compile/${UPPER}
make depend
make ${1}.o
make
exit
#--------------end of script---------------
#
#you also need to add an entry into the cdevsw[]
#array in conf.c, but it's too hard to do in a script..
#
#edit to your taste..
#
#
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