Description of the Interface between Linklevel and Hardwarelevel
of isdn4linux:
The Communication between Linklevel (LL) and Hardwarelevel (HL)
is based on the struct isdn_if (defined in isdnif.h).
An HL-driver can register itself at LL by calling the function
register_isdn() with a pointer to that struct. Prior to that, it has
to preset some of the fields of isdn_if. The LL sets the rest of
the fields. All further communication is done via callbacks using
the function-pointers defined in isdn_if.
ATTENTION, CHANGES since version 0.6 are marked with "***CHANGE0.6"!
ATTENTION, CHANGES since version 0.7 are marked with "***CHANGE0.7"!
ATTENTION, CHANGES since version 0.71 are marked with "***CHANGE0.7.1"!
1. Description of the fields of isdn_if:
int channels;
This field has to be set by the HL-driver to the number of channels
supported prior to calling register_isdn(). Upon return of the call,
the LL puts an id there, which has to be used by the HL-driver when
invoking the other callbacks.
int maxbufsize;
***CHANGE0.6: New since this version.
Also to be preset by the HL-driver. With this value the HL-driver
tells to the LL the maximum size of a data-packet it will accept.
unsigned long features;
To be preset by the HL-driver. Using this field, the HL-driver
announces the features supported. At the moment this is limited to
report the supported layer2 and layer3-protocols. For setting this
field the constants ISDN_FEATURE..., declared in isdnif.h have to be
used.
***CHANGE0.7.1: The line type (1TR6, EDSS1) has to be set.
unsigned short hl_hdrlen;
***CHANGED.7.4: New field.
To be preset by the HL-driver, if it supports sk_buff's. The driver
should put here the amount of additional space needed in sk-buff's for
it's internal purposes. Drivers not supporting sk_buff's should put
initialize this field to 0.
void (*rcvcallb)(int, int, u_char*, int);
This field will be set by LL. The HL-driver delivers received data-
packets by calling this function.
Parameter:
int driver-Id
int Channel-number locally to the driver. (starting with 0)
u_char Pointer to received data. (in kernel-space)
int length of data-packet.
void (*rcvcallb_skb)(int, int, struct sk_buff *)
***CHANGED.7.4: New field.
This field will be set by LL. The HL-driver delivers received data-
packets by calling this function. Upon calling, the HL-driver must
already have it's private data pulled off the head of the sk_buff.
Parameter:
int driver-Id
int Channel-number locally to the driver. (starting with 0)
struct sk_buff * Pointer to sk_buff, containing received data.
int (*statcallb)(isdn_ctrl*);
This field will be set by LL. This function has to be called by the
HL-driver for signaling status-changes or other events to the LL.
Parameter:
isdn_ctrl*
The struct isdn_ctrl also defined in isdn_if. The exact meaning of it's
fields is described together with the descriptions of the possible
events. Here is only a short description of the fields:
driver = driver Id.
command = event-type. (one of the constants ISDN_STAT_...)
arg = depends on event-type.
num = depends on event-type.
Returnvalue:
0 on success, else -1
int (*command)(isdn_ctrl*);
This field has to be preset by the HL-driver. It points to a function,
to be called by LL to perform functions like dialing, B-channel
setup, etc. The exact meaning of the parameters is described with the
descriptions of the possible commands.
Parameter:
isdn_ctrl*
driver = driver-Id
command = command to perform. (one of the constants ISDN_CMD_...)
arg = depends on command.
num = depends on command.
Returnvalue:
>=0 on success, else error-code (-ENODEV etc.)
int (*writebuf)(int, int, u_char*, int, int);
This field has to be preset by the HL-driver. The given function will
be called by the LL for delivering data to be send via B-Channel.
Parameter:
int driver-Id ***CHANGE.7.4: New parameter.
int channel-number locally to the HL-driver. (starts with 0)
u_char* pointer to data.
int length of data-packet.
int flag: 0 = call from within kernel-space. (HL-driver must use
memcpy, may NOT use schedule())
1 = call from user-space. (HL-driver must use
memcpy_fromfs, use of schedule() allowed)
Returnvalue:
Length of data accepted on success, else error-code (-EINVAL on
oversized packets etc.)
int (*writebuf_skb)(int, int, struct sk_buff *)
***CHANGED.7.4: New field.
This field has to be preset by the HL-driver. The given function will
be called by the LL for delivering data to be send via B-Channel.
Parameter:
int driver-Id ***CHANGE.7.4: New parameter.
int channel-number locally to the HL-driver. (starts with 0)
struct sk_buff * Pointer to sk_buff containing data to be send via
B-channel.
Returnvalue:
Length of data accepted on success, else error-code (-EINVAL on
oversized packets etc.)
NOTE on writebuf and writebuf_skb:
The HL-driver may initialize one of the fields to NULL, in which case
the LL will call the non-NULL function only.
int (*writecmd)(u_char*, int, int);
This field has to be preset by the HL-driver. The given function will be
called to perform write-requests on /dev/isdnctrl (i.e. sending commands
to the card) The data-format is hardware-specific. This function is
intended for debugging only. It is not necessary for normal operation
and never will be called by the tty-emulation- or network-code. If
this function is not supported, the driver has to set NULL here.
Parameter:
u_char* pointer to data.
int length of data.
int flag: 0 = call from within kernel-space. (HL-driver must use
memcpy, may NOT use schedule())
1 = call from user-space. (HL-driver must use
memcpy_fromfs, use of schedule() allowed)
Returnvalue:
Length of data accepted on success, else error-code (-EINVAL etc.)
int (*readstat)(u_char*, int, int);
This field has to be preset by the HL-driver. The given function will be
called to perform read-requests on /dev/isdnctrl (i.e. reading replies
from the card) The data-format is hardware-specific. This function is
intended for debugging only. It is not necessary for normal operation
and never will be called by the tty-emulation- or network-code. If
this function is not supported, the driver has to set NULL here.
Parameter:
u_char* pointer to data.
int length of data.
int flag: 0 = call from within kernel-space. (HL-driver must use
memcpy, may NOT use schedule())
1 = call from user-space. (HL-driver must use
memcpy_fromfs, use of schedule() allowed)
Returnvalue:
Length of data on success, else error-code (-EINVAL etc.)
char id[20];
***CHANGE0.7: New since this version.
This string has to be preset by the HL-driver. It's purpose is for
identification of the driver by the user. Eg.: it is shown in the
status-info of /dev/isdninfo. Furthermore it is used as Id for binding
net-interfaces to a specific channel. If a string of length zero is
given, upon return, isdn4linux will replace it by a generic name. (line0,
line1 etc.) It is recommended to make this string configurable during
module-load-time. (copy a global variable to this string.) For doing that,
modules 1.2.8 or newer are necessary.
2. Description of the commands, a HL-driver has to support:
All commands will be performed by calling the function command() described
above from within the LL. The field command of the struct-parameter will
contain the desired command, the field driver always is set to the
appropriate driver-Id.
Until now, the following commands are defined:
ISDN_CMD_IOCTL:
This command is intended for performing ioctl-calls for configuring
hardware or similar purposes (setting port-addresses, loading firmware
etc.) For this purpose, in the LL all ioctl-calls with an argument
>= ISDN_IOCTL_DRVIOCTL (0x100) will be handed transparently to this
function after subtracting 0x100 and placing the result in arg.
Example:
If a userlevel-program calls ioctl(0x101,...) the function gets
called with the field command set to 1.
Parameter:
driver = driver-Id.
command = ISDN_CMD_IOCTL
arg = Original ioctl-cmd - ISDN_IOCTL_DRVIOCTL
num = first bytes filled with (unsigned long)arg
Returnvalue:
Depending on driver.
ISDN_CMD_DIAL:
This command is used to tell the HL-driver it should dial a given
number.
Parameter:
driver = driver-Id.
command = ISDN_CMD_DIAL
arg = channel-number locally to the driver. (starting with 0)
num = An ASCII-String containing the number to dial, the own
EAZ or MSN, the Service-Indicator and the Additional
Info. Format:
"%s,%s,%d,%d" RemotePhoneNumber,EazOrMsn,SI,AI
If the Line has been designed as SPV (a special german
feature, meaning semi-leased-line) the number has to
start with an "S".
***CHANGE0.6: In previous versions the EAZ has been given in the
highbyte of arg.
***CHANGE0.7.1: New since this version: ServiceIndicator and AddInfo.
ISDN_CMD_ACCEPTD:
With this command, the HL-driver is told to accept a D-Channel-setup.
(Response to an incoming call)
Parameter:
driver = driver-Id.
command = ISDN_CMD_ACCEPTD
arg = channel-number locally to the driver. (starting with 0)
num = unused.
ISDN_CMD_ACCEPTB:
With this command, the HL-driver is told to perform a B-Channel-setup.
(after establishing D-Channel-Connection)
Parameter:
driver = driver-Id.
command = ISDN_CMD_ACCEPTB
arg = channel-number locally to the driver. (starting with 0)
num = unused.
ISDN_CMD_HANGUP:
With this command, the HL-driver is told to hangup (B-Channel if
established first, then D-Channel). This command is also used for
actively rejecting an incoming call.
Parameter:
driver = driver-Id.
command = ISDN_CMD_HANGUP
arg = channel-number locally to the driver. (starting with 0)
num = unused.
ISDN_CMD_CLREAZ:
With this command, the HL-driver is told not to signal incoming
calls to the LL.
Parameter:
driver = driver-Id.
command = ISDN_CMD_CLREAZ
arg = channel-number locally to the driver. (starting with 0)
num = unused.
ISDN_CMD_SETEAZ:
With this command, the HL-driver is told to signal incoming calls for
the given EAZs/MSNs to the LL.
Parameter:
driver = driver-Id.
command = ISDN_CMD_SETEAZ
arg = channel-number locally to the driver. (starting with 0)
num = ASCII-String, containing the desired EAZ's/MSN's
(comma-separated). If an empty String is given, the
HL-driver should respond to ALL incoming calls,
regardless of the destination-address.
***CHANGE0.6: New since this version the "empty-string"-feature.
ISDN_CMD_GETEAZ: (currently unused)
With this command, the HL-driver is told to report the current setting
given with ISDN_CMD_SETEAZ.
Parameter:
driver = driver-Id.
command = ISDN_CMD_GETEAZ
arg = channel-number locally to the driver. (starting with 0)
num = ASCII-String, containing the current EAZ's/MSN's
ISDN_CMD_SETSIL: (currently unused)
With this command, the HL-driver is told to signal only incoming
calls with the given Service-Indicators.
Parameter:
driver = driver-Id.
command = ISDN_CMD_SETSIL
arg = channel-number locally to the driver. (starting with 0)
num = ASCII-String, containing the desired Service-Indicators.
ISDN_CMD_GETSIL: (currently unused)
With this command, the HL-driver is told to return the current
Service-Indicators it will respond to.
Parameter:
driver = driver-Id.
command = ISDN_CMD_SETSIL
arg = channel-number locally to the driver. (starting with 0)
num = ASCII-String, containing the current Service-Indicators.
ISDN_CMD_SETL2:
With this command, the HL-driver is told to select the given Layer-2-
protocol. This command is issued by the LL prior to ISDN_CMD_DIAL or
ISDN_CMD_ACCEPTD.
Parameter:
driver = driver-Id.
command = ISDN_CMD_SETL2
arg = channel-number locally to the driver. (starting with 0)
logical or'ed with (protocol-Id << 8)
protocol-Id is one of the constants ISDN_PROTO_L2...
num = unused.
ISDN_CMD_GETL2: (currently unused)
With this command, the HL-driver is told to return the current
setting of the Layer-2-protocol.
Parameter:
driver = driver-Id.
command = ISDN_CMD_GETL2
arg = channel-number locally to the driver. (starting with 0)
num = unused.
Returnvalue:
current protocol-Id (one of the constants ISDN_L2_PROTO)
ISDN_CMD_SETL3:
With this command, the HL-driver is told to select the given Layer-3-
protocol. This command is issued by the LL prior to ISDN_CMD_DIAL or
ISDN_CMD_ACCEPTD.
Parameter:
driver = driver-Id.
command = ISDN_CMD_SETL3
arg = channel-number locally to the driver. (starting with 0)
logical or'ed with (protocol-Id << 8)
protocol-Id is one of the constants ISDN_PROTO_L3...
num = unused.
ISDN_CMD_GETL2: (currently unused)
With this command, the HL-driver is told to return the current
setting of the Layer-3-protocol.
Parameter:
driver = driver-Id.
command = ISDN_CMD_GETL3
arg = channel-number locally to the driver. (starting with 0)
num = unused.
Returnvalue:
current protocol-Id (one of the constants ISDN_L3_PROTO)
ISDN_CMD_LOCK:
With this command the HL-driver is told, that it will be used by the
LL and therefore may not be unloaded. The HL-driver should use
MOD_INC_USE_COUNT to tell that to the kernel.
Parameter:
driver = driver-Id.
command = ISDN_CMD_LOCK
arg = unused.
num = unused.
ISDN_CMD_UNLOCK:
With this command the HL-driver is told, that it is no more used by the
LL and therefore may be unloaded. The HL-driver should use
DEC_INC_USE_COUNT to tell that to the kernel.
Parameter:
driver = driver-Id.
command = ISDN_CMD_UNLOCK
arg = unused.
num = unused.
3. Description of the events to be signaled by the HL-driver to th LL.
All status-changes are signaled via calling the previously described
function statcallb(). The field command of the struct isdn_cmd has
to be set by the HL-driver with the appropriate Status-Id (event-number).
The field arg has to be set to the channel-number (locally to the driver,
starting with 0) to which this event applies. (Exception: STAVAIL-event)
Until now, the following Status-Ids are defined:
ISDN_STAT_AVAIL:
With this call, the HL-driver signals the availability of new data
for readstat(). Used only for debugging-purposes, see description
of readstat().
Parameter:
driver = driver-Id
command = ISDN_STAT_STAVAIL
arg = length of available data.
num = unused.
ISDN_STAT_ICALL:
With this call, the HL-driver signals an incoming call to the LL.
Parameter:
driver = driver-Id
command = ISDN_STAT_ICALL
arg = channel-number, locally to the driver. (starting with 0)
num = ASCII-String in the following format:
"%s,%d,%d,%s",CallerNumber,ServiceIndicator,AddInfo,
CalledNumber.
ISDN_STAT_RUN:
With this call, the HL-driver signals availability of the ISDN-card.
(after initializing, loading firmware)
Parameter:
driver = driver-Id
command = ISDN_STAT_RUN
arg = unused.
num = unused.
ISDN_STAT_STOP:
With this call, the HL-driver signals unavailability of the ISDN-card.
(before unloading, while resetting/reconfiguring the card)
Parameter:
driver = driver-Id
command = ISDN_STAT_STOP
arg = unused.
num = unused.
ISDN_STAT_DCONN:
With this call, the HL-driver signals the successful establishment of
a D-Channel-connection. (Response to ISDN_CMD_ACCEPTD or ISDN_CMD_DIAL)
Parameter:
driver = driver-Id
command = ISDN_STAT_DCONN
arg = channel-number, locally to the driver. (starting with 0)
num = unused.
ISDN_STAT_BCONN:
With this call, the HL-driver signals the successful establishment of
a B-Channel-connection. (Response to ISDN_CMD_ACCEPTB or because the
remote-station has initiated establishment)
Parameter:
driver = driver-Id
command = ISDN_STAT_BCONN
arg = channel-number, locally to the driver. (starting with 0)
num = unused.
ISDN_STAT_DHUP:
With this call, the HL-driver signals the shutdown of a
D-Channel-connection. This could be a response to a prior ISDN_CMD_HANGUP,
or caused by a remote-hangup or if the remote-station has actively
rejected a call.
Parameter:
driver = driver-Id
command = ISDN_STAT_DHUP
arg = channel-number, locally to the driver. (starting with 0)
num = unused.
ISDN_STAT_BHUP:
With this call, the HL-driver signals the shutdown of a
B-Channel-connection. This could be a response to a prior ISDN_CMD_HANGUP,
or caused by a remote-hangup.
Parameter:
driver = driver-Id
command = ISDN_STAT_BHUP
arg = channel-number, locally to the driver. (starting with 0)
num = unused.
ISDN_STAT_CINF:
With this call, the HL-driver delivers charge-unit information to the
LL.
Parameter:
driver = driver-Id
command = ISDN_STAT_CINF
arg = channel-number, locally to the driver. (starting with 0)
num = ASCII string containing charge-units (digits only).
ISDN_STAT_LOAD: (currently unused)
ISDN_STAT_UNLOAD:
With this call, the HL-driver signals that it will be unloaded now. This
tells the LL to release all corresponding data-structures.
Parameter:
driver = driver-Id
command = ISDN_STAT_UNLOAD
arg = unused.
num = unused.
ISDN_STAT_BSENT:
With this call the HL-driver signals the delivery of a data-packet.
This callback is used by the network-interfaces only, tty-Emulation
does not need this call.
Parameter:
driver = driver-Id
command = ISDN_STAT_BSENT
arg = channel-number, locally to the driver. (starting with 0)
num = unused.
ISDN_STAT_NODCH:
With this call, the driver has to respond to a prior ISDN_CMD_DIAL, if
no D-Channel is available.
Parameter:
driver = driver-Id
command = ISDN_STAT_NODCH
arg = channel-number, locally to the driver. (starting with 0)
num = unused.
ISDN_STAT_ADDCH: (currently unused)
This call is planned for HL-drivers, which are unable to check card-type
or numbers of supported channels before they have loaded any firmware
using ioctl. Those HL-driver simply set the channel-parameter to zero
or a minimum channel-number when registering, and later if they know
the real amount, perform this call, allocating additional channels.
Parameter:
driver = driver-Id
command = ISDN_STAT_ADDCH
arg = to be defined.
num = to be defined.
ISDN_STAT_CAUSE:
With this call, the HL-driver delivers CAUSE-messages to the LL.
Currently the LL does not use this messages. Their contents is simply
logged via kernel-messages. Therefore, currently the format of the
messages is currently completely free. However they should be printable.
Parameter:
driver = driver-Id
command = ISDN_STAT_NODCH
arg = channel-number, locally to the driver. (starting with 0)
num = ASCII string containing CAUSE-message.
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