freebsd_hello_driver.c

#include <sys/types.h>
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/errno.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/uio.h>

static d_open_t hello_open;
static d_close_t hello_close;
static d_read_t hello_read;
static  d_write_t hello_write;

static struct make_dev_args args;
static struct cdevsw hello_cdevsw = {
	.d_version = D_VERSION,
	.d_open = hello_open,
	.d_read = hello_read,
	.d_write = hello_write,
	.d_close = hello_close,
	.d_name = "hello"
};
static struct cdev *hello_dev = NULL;

static char buffer[1024];

static int hello_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
{
	uprintf("Open hello device\n");
	return 0;
}

static int hello_read(struct cdev *dev, struct uio *uio, int ioflag)
{
	int error = 0;

	uprintf("Read: %p,%p,%d,%ld,%zd,%d,%d,%p\n", uio, uio->uio_iov, uio->uio_iovcnt, uio->uio_offset, uio->uio_resid, uio->uio_segflg, uio->uio_rw, uio->uio_td);
	uiomove("Hello", strlen("Hello") + 1, uio);
	uprintf("Read: %p,%p,%d,%ld,%zd,%d,%d,%p\n", uio, uio->uio_iov, uio->uio_iovcnt, uio->uio_offset, uio->uio_resid, uio->uio_segflg, uio->uio_rw, uio->uio_td);

	return error;
}

static int hello_write(struct cdev *dev, struct uio *uio, int ioflag)
{
	int error = 0;

	uprintf("Write: %p,%p,%d,%ld,%zd,%d,%d,%p\n", uio, uio->uio_iov, uio->uio_iovcnt, uio->uio_offset, uio->uio_resid, uio->uio_segflg, uio->uio_rw, uio->uio_td);
	error = copyin(uio->uio_iov->iov_base, buffer, MIN(sizeof(buffer) - 1, uio->uio_iov->iov_len));
		
	if (error != 0)
	{
		uprintf("Write to hello device failed, error code is %d\n", error);
	}
	else 
	{
		buffer[MIN(sizeof(buffer) - 1, uio->uio_iov->iov_len)] = 0;
		uprintf("Write to hello device successfully, string is %s\n", buffer);
	}
	
	return error;		
}

static int hello_close(struct cdev *dev, int fflag, int devtype, struct thread *td)
{
	uprintf("Close hello device\n");
	return 0;
}

static int hello_modevent(module_t mod __unused, int /* modeventtype_t */ event, void *arg __unused)
{
	int error = 0;
	
	
	switch (event) 
	{
		case MOD_LOAD:
		{
			make_dev_args_init(&args);
			args.mda_devsw = &hello_cdevsw;
			args.mda_uid = UID_ROOT;
			args.mda_gid = GID_WHEEL;
			args.mda_mode = 0600;
			uprintf("Hello is loaded:%d\n", make_dev_s(&args, &hello_dev, "%s", hello_cdevsw.d_name));
			break;
		}
		case MOD_UNLOAD:
		{
			destroy_dev(hello_dev);
			uprintf("Hello is unloaded\n");
			break;
		}
		default:
		{
			error = EOPNOTSUPP;
			break;
		}	
	}
	return error;
}

static moduledata_t hello_mod = 
{
	"hello",
	hello_modevent,
	NULL
};

DECLARE_MODULE(hello, hello_mod, SI_SUB_DRIVERS, SI_ORDER_ANY);