.\"	$OpenBSD: radio.9,v 1.2 2001/10/08 08:52:50 mpech Exp $
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.\" Copyright (c) Maxim Tsyplakov <tm@oganer.net>
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.Dd September 29, 2001
.Dt RADIO 9
.Os
.Sh NAME
.Nm radio
.Nd interface between low and high level radio drivers
.Sh DESCRIPTION
The radio device driver is divided into a high level,
hardware independent layer, and a low level hardware
dependent layer.
The interface between these is the
.Va radio_hw_if
structure.
.Bd -literal
struct radio_hw_if {
	int	*open(dev_t, int, int, struct proc *);
	void	*close(dev_t, int, int, struct proc *);
	int	*ioctl(dev_t, u_long, caddr_t, int, struct proc *);
};
.Ed
.Pp
The high level radio driver attaches to the low level driver
when the latter calls
.Va radio_attach_mi .
This call should be
.Bd -literal
    void
    radio_attach_mi(rhwp, hdlp, dev)
	struct radio_hw_if *rhwp;
	void *hdlp;
	struct device *dev;
.Ed
.Pp
The
.Va radio_hw_if
struct is as shown above.
The
.Va hdlp
argument is a handle to some low level data structure.
It is reserved field for future usage, and actually not used in any 
low-level driver functions. 
.Va radio_hw_if
when the high level driver calls them.
.Va dev
is the device struct for the hardware device.
.Pp
The fields of
.Va radio_hw_if
are described in some more detail below.
.Bd -literal
int open (dev_t dev, int flags, int fmt, struct proc *p);
  Is called when the radio device is opened.
  Returns 0 on success, otherwise an error code.

int close (dev_t dev, int flags, int fmt, struct proc *p);
  Is called when the radio device is closed.
  Returns 0 on success, otherwise an error code.

int ioctl (dev_t dev, u_long cmd, caddr_t data, int flags, struct proc *p);
  Is ioctl requests handler function.
  Returns 0 on success, otherwise an error code.
.Ed
.Sh SEE ALSO
.Xr radio 4