.\"	$NetBSD: ucom.9,v 1.19 2016/10/12 21:18:46 wiz Exp $
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.Dd September 12, 2016
.Dt UCOM 9
.Os
.Sh NAME
.Nm ucom
.Nd interface for USB tty like devices
.Sh DESCRIPTION
The
.Nm
driver is a (relatively) easy way to make a USB device look like
a
.Xr tty 4 .
It basically takes two bulk pipes, input and output, and makes
a tty out of them.
This is useful for a number of device types, e.g., serial ports
(see
.Xr uftdi 4 ) ,
modems (see
.Xr umodem 4 ) ,
and devices that traditionally look like a tty (see
.Xr uvisor 4 ) .
.Pp
Communication between the real driver and the
.Nm
driver is via the attachment arguments (when attached) and
via the
.Va ucom_methods
struct
.Sh ATTACHMENT
.Bd -literal
struct ucom_attach_args {
	int ucaa_portno;
	int ucaa_bulkin;
	int ucaa_bulkout;
	u_int ucaa_ibufsize;
	u_int ucaa_ibufsizepad;
	u_int ucaa_obufsize;
	u_int ucaa_opkthdrlen;
	const char *ucaa_info;
	struct usbd_device *ucaa_device;
	struct usbd_interface *ucaa_iface;
	const struct ucom_methods *ucaa_methods;
	void *ucaa_arg;
};
.Ed
.Pp
.Bl -tag -width indent
.It Dv int ucaa_portno
identifies the port if the devices should have more than one
.Nm
attached.
Use the value
.Dv UCOM_UNK_PORTNO
if there is only one port.
.It Dv int ucaa_bulkin
the number of the bulk input pipe.
.It Dv int ucaa_bulkout
the number of the bulk output pipe.
.It Dv u_int ucaa_ibufsize
the size of the read requests on the bulk in pipe.
.It Dv u_int ucaa_ibufsizepad
the size of the input buffer.
This is usually the same as
.Dv ibufsize .
.It Dv u_int ucaa_obufsize
the size of the write requests on the bulk out pipe.
.It Dv u_int ucaa_ibufsizepad
the size of the output buffer.
This is usually the same as
.Dv ucaa_obufsize .
.It Dv struct usbd_device *ucaa_device
a handle to the device.
.It struct usbd_interface *ucaa_iface
a handle to the interface that should be used.
.It struct ucom_methods *ucaa_methods
a pointer to the methods that the
.Nm
driver should use for further communication with the driver.
.It void *ucaa_arg
the value that should be passed as first argument to each method.
.El
.Sh METHODS
The
.Dv ucom_methods
struct contains a number of function pointers used by the
.Nm
driver at various stages.
If the device is not interested in being called at a particular point
it should just use a
.Dv NULL
pointer and the
.Nm
driver will use a sensible default.
.Bd -literal
struct ucom_methods {
	void (*ucom_get_status)(void *sc, int portno,
	    u_char *lsr, u_char *msr);
	void (*ucom_set)(void *sc, int portno, int reg, int onoff);
#define UCOM_SET_DTR 1
#define UCOM_SET_RTS 2
#define UCOM_SET_BREAK 3
	int (*ucom_param)(void *sc, int portno, struct termios *);
	int (*ucom_ioctl)(void *sc, int portno, u_long cmd,
	    void *data, int flag, proc_t *p);
	int (*ucom_open)(void *sc, int portno);
	void (*ucom_close)(void *sc, int portno);
	void (*ucom_read)(void *sc, int portno, u_char **ptr,
	    uint32_t *count);
	void (*ucom_write)(void *sc, int portno, u_char *to,
	    u_char *from, uint32_t *count);
};
.Ed
.Pp
.Bl -tag -width indent
.It Fn "void (*ucom_get_status)" "void *sc" "int portno" "u_char *lsr" "u_char *msr"
get the status of port
.Fa portno .
The status consists of the line status,
.Fa lsr ,
and the modem status
.Fa msr .
The contents of these two bytes is exactly as for a 16550 UART.
.It Fn "void (*ucom_set)" "void *sc" "int portno" "int reg" "int onoff"
Set (or unset) a particular feature of a port.
.It Fn "int (*ucom_param)" "void *sc" "int portno" "struct termios *t"
Set the speed, number of data bit, stop bits, and parity of a port
according to the
.Xr termios 4
struct.
.It Fn "int (*ucom_ioctl)" "void *sc" "int portno" "u_long cmd" "void *data" "int flag" "proc_t *p"
implements any non-standard
.Xr ioctl 2
that a device needs.
.It Fn "int (*ucom_open)" "void *sc" "int portno"
called just before the
.Nm
driver opens the bulk pipes for the port.
.It Fn "void (*ucom_close)" "void *sc" "int portno"
called just after the
.Nm
driver closes the bulk pipes for the port.
.It Fn "void (*ucom_read)" "void *sc" "int portno" "u_char **ptr" "uint32_t *count"
if the data delivered on the bulk pipe is not just the raw input characters
this routine needs to increment
.Fa ptr
by as many characters to skip from the start of the raw input and decrement
.Fa count
by as many characters to truncate from the end of the raw input.
.It Fn "void (*ucom_write)" "void *sc" "int portno" "u_char *dst" "u_char *src" "uint32_t *count"
if the data written to the bulk pipe is not just the raw characters then
this routine needs to copy
.Fa count
raw characters from
.Fa src
into the buffer at
.Fa dst
and do the appropriate padding.
The
.Fa count
should be updated to the new size.
The buffer at
.Fa src
is at most
.Va ibufsize
bytes and the buffer
at
.Fa dst
is
.Va ibufsizepad
bytes.
.El
.Pp
Apart from these methods there is a function
.Bl -tag -width 5n -offset 5n
.It Fn "void ucom_status_change" "struct ucom_softc *"
.El
.Pp
which should be called by the driver whenever it notices a status change.
.Sh SEE ALSO
.\" moscom
.Xr tty 4 ,
.Xr u3g 4 ,
.Xr uark 4 ,
.Xr ubsa 4 ,
.Xr uchcom 4 ,
.Xr uftdi 4 ,
.Xr ugensa 4 ,
.Xr uhmodem 4 ,
.Xr uipaq 4 ,
.Xr ukyopon 4 ,
.Xr umct 4 ,
.Xr umodem 4 ,
.Xr uplcom 4 ,
.Xr usb 4 ,
.Xr uslsa 4 ,
.Xr uvisor 4 ,
.Xr uvscom 4
.Sh HISTORY
This
.Nm
interface first appeared in
.Nx 1.5 .