HIL(4)                OpenBSD Programmer's Manual (HP300)               HIL(4)

NAME
     hil - Human Interface Link device driver

DESCRIPTION
     The Human Interface Link (HIL) is the interface used by the Series 300
     computers to connect devices such as keyboards, mice, control knobs, and
     ID modules to the machine.

     Special files /dev/hil[1-7] refer to physical HIL devices 1 through 7.
     /dev/hil0 refers to the ``loop'' pseudo-device and is used for the queue
     allocation commands described below.  In the current implementation,
     there can only be one keyboard and it must be the first device (hil1).

     The device file that corresponds to a particular HIL device is determined
     by the order of the devices on the loop. For instance, if the ID module
     is the second physical device on the loop, then /dev/hil2 is the special
     file that should be used for communication with the module.

     Communication with an HIL device is begun with an open system call.  A
     process may open a device already opened by another process unless the
     process is operating in HP-UX compatibility mode in which case it re-
     quires exclusive use of the device, or another process has the device
     open and is using HP-UX style device access (see HILIOCHPUX below).

     Input data from a device are obtained in one of two ways.  Processes may
     use an HP-UX style interface in which the read(2) system call is used to
     get fixed-size input packets, or they can use a shared-queue interface.
     The shared-queue interface avoids the system call overhead associated
     with the HP-UX read interface by sharing a region of memory between the
     system and a user process.  This region consists of a circular list of
     255 event packets, and a header containing the size of the queue, and its
     head and tail indices.  The system deposits event data at the tail of the
     queue, a process extracts it from the head.  Extracting an event is done
     by copying it from the queue and then updating the head appropriately
     (i.e. head = (head + 1) % qsize).  It is up to the process to ensure that
     packets are removed from the queue quickly enough to prevent the queue
     from filling.  The system, when it determines that the queue is full,
     will ignore future packets from the device.  Devices are mapped to queues
     via an ioctl(2.)  More than one device can be mapped to a single queue
     and one device can be mapped to several queues.  Queues are implicitly
     unmapped by a fork(2) and thus, cannot be shared between processes.

     Choosing the type of interface is done on a per device basis using an
     ioctl, but each device can only have one interface at any given time.

     Select may be used with either interface to detect when input data are
     present.  With the read interface, selecting indicates when there is in-
     put for a given device.  With the shared-queue interface, selecting on
     the loop pseudo-device (hil0) indicates when data are present from any
     device on any queue while selecting on an individual device indicates
     when data are present for that device on any queue.

     Close shuts down the file descriptor associated with the HIL device.  The
     last close (system-wide) of any device removes that device from all
     queues it was mapped to while the last close of the loop pseudo-device
     unmaps all devices and deallocates all queues.

     Ioctl(2) is used to control the HIL device.  The ioctl commands (see
     <hpdev/hilioctl.h>) listed below are separated into two groups.  The
     first are those which provide functions identical to HP-UX. Refer to
     hil(7) in the HP-UX documentation for more complete descriptions of these
     ioctls.  The second set of ioctls are specific to this implementation and

     are primarily related to the shared-queue interface.

     HILIOCID   Identify and Describe

                The device will return up to 11 bytes of information describ-
                ing the type and characteristics of the device.  At the very
                least, 2 bytes of information, the device ID, and the Describe
                Record Header will be returned.  Identical to the HP-UX HILID
                ioctl.

     HILIOCSC   Report Security Code

                Request the security code record from a device. The security
                code can vary from 1 byte to 15, and is only supported by some
                HIL devices.  Identical to the HP-UX HILSC ioctl.

     HILIOCRN   Report Name

                An ascii string of up to 15 bytes in length that describes the
                device is returned.  Identical to the HP-UX HILRN ioctl.

     HILIOCRS   Report Status

                An ascii string of up to 15 bytes in length that describes the
                current status of the device is returned.  Identical to the
                HP-UX HILRS ioctl.

     HILIOCED   Extended Describe

                Additional information of up to 15 bytes is returned describ-
                ing the device.  This ioctl is similar to HILIOCID, which must
                be used first to determine if the device supports extended de-
                scribe.  Identical to the HP-UX HILED ioctl.

     HILIOCAROFF
                Disable Auto Repeat

                Turn off auto repeat on the keyboard while it is in cooked
                mode.  Identical to the HP-UX HILDKR ioctl.

     HILIOCAR1  Enable Auto Repeat

                Turn on auto repeat on the keyboard while it is in raw mode.
                The repeat rate is set to 1/30th of a second.  Identical to
                the HP-UX HILER1 ioctl.

     HILIOCAR2  Enable Auto Repeat

                Turn on auto repeat on the keyboard while it is in raw mode.
                The repeat rate is set to 1/60th of a second.  Identical to
                the HP-UX HILER2 ioctl.

                The following ioctls are specific to this implementation:

     HILIOCBEEP
                Beep

                Generate a keyboard beep as defined by arg. Arg is a pointer
                to two bytes of information, the first is the duration of the
                beep (microseconds), the second is the frequency of the beep.

     HILIOCALLOCQ
                Allocate Queue

                Allocate and map into user space, an HILQ structure as defined
                in <hpdev/hilioctl.h>. Arg is a pointer to a hilqinfo struc-
                ture (also described in <hpdev/hilioctl.h>) consisting of a
                qid and an addr. If addr is non-zero it specifies where in the
                address space to map the queue.  If zero, the system will se-
                lect a convenient location and fill in addr. Qid is filled in
                by the system and is a small integer used to uniquely identify
                this queue.  This ioctl can only be issued to the loop pseudo-
                device.

     HILIOCFREEQ
                Free Queue

                Release a previously allocated HIL event queue, unmapping it
                from the user's address space.  Arg should point to a hilqinfo
                structure which contains the qid of the queue to be released.
                All devices that are currently mapped to the queue are un-
                mapped.  This ioctl can only be issued to the loop pseudo-de-
                vice.

     HILIOCMAPQ
                Map Device to Queue

                Maps this device to a previously allocated HIL event queue.
                Arg is a pointer to an integer containing the qid of the
                queue.  Once a device is mapped to a queue, all event informa-
                tion generated by the device will be placed into the event
                queue at the tail.

     HILIOCUNMAPQ
                Unmap Device from Queue

                Unmap this device from a previously allocated HIL event queue.
                Arg is a pointer to an integer containing the qid for the
                queue.  Future events from the device are no longer placed on
                the event queue.

     HILIOCHPUX
                Use HP-UX Read Interface

                Use HP-UX semantics for gathering data from this device.  In-
                stead of placing input events for the device on a queue, they
                are placed, in HP-UX format, into a buffer from which they can
                be obtained via read(2). This interface is provided for back-
                wards compatibility.  Refer to the HP-UX documentation for a
                description of the event packet.

FILES
     /dev/hil0      HIL loop pseudo device.
     /dev/hil1      HIL keyboard device.
     /dev/hil[2-7]  Individual HIL loop devices.

ERRORS
     [ENODEV]  no such HIL loop device.

     [ENXIO]   HIL loop is inoperative.

     [EBUSY]   Another HP-UX process has the device open, or another BSD pro-
               cess has the device open, and is using it in HP-UX mode.

     [EINVAL]  Invalid ioctl specification.

     [EMFILE]  No more shared queues available.

OpenBSD 2.9                    November 30, 1993                             3
