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Documentation/isdn/INTERFACE.CAPI

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isdn: document Kernel CAPI driver interface

Create a file Documentation/isdn/INTERFACE.CAPI describing the
interface between the kernel CAPI subsystem and ISDN device drivers,
analogous to the existing Documentation/isdn/INTERFACE for the old
isdn4linux subsystem. Also add kerneldoc comments to the exported
functions in drivers/isdn/capi/kcapi.c.

Impact: Documentation
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Karsten Keil <keil@b1-systems.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tilman Schmidt 2009-04-23 02:24:21 +00:00 committed by David S. Miller
parent 7ced70c47f
commit 554f200e22
3 changed files with 380 additions and 0 deletions
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2
Documentation/isdn/00-INDEX
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@ -8,6 +8,8 @@ INTERFACE
- description of isdn4linux Link Level and Hardware Level interfaces.
INTERFACE.fax
- description of the fax subinterface of isdn4linux.
INTERFACE.CAPI
- description of kernel CAPI Link Level to Hardware Level interface.
README
- general info on what you need and what to do for Linux ISDN.
README.FAQ

207
Documentation/isdn/INTERFACE.CAPI Normal file
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@ -0,0 +1,207 @@
Kernel CAPI Interface to Hardware Drivers
-----------------------------------------
1. Overview
Kernel CAPI operates as a dispatching layer between CAPI applications and CAPI
hardware drivers. Hardware drivers register ISDN devices (controllers, in CAPI
lingo) with Kernel CAPI to indicate their readiness to provide their service
to CAPI applications. CAPI applications also register with Kernel CAPI,
requesting association with a CAPI device. Kernel CAPI then dispatches the
application registration to an available device, forwarding it to the
corresponding hardware driver. Kernel CAPI then forwards CAPI messages in both
directions between the application and the hardware driver.
2. Driver and Device Registration
CAPI drivers optionally register themselves with Kernel CAPI by calling the
Kernel CAPI function register_capi_driver() with a pointer to a struct
capi_driver. This structure must be filled with the name and revision of the
driver, and optionally a pointer to a callback function, add_card(). The
registration can be revoked by calling the function unregister_capi_driver()
with a pointer to the same struct capi_driver.
CAPI drivers must register each of the ISDN devices they control with Kernel
CAPI by calling the Kernel CAPI function attach_capi_ctr() with a pointer to a
struct capi_ctr before they can be used. This structure must be filled with
the names of the driver and controller, and a number of callback function
pointers which are subsequently used by Kernel CAPI for communicating with the
driver. The registration can be revoked by calling the function
detach_capi_ctr() with a pointer to the same struct capi_ctr.
Before the device can be actually used, the driver must fill in the device
information fields 'manu', 'version', 'profile' and 'serial' in the capi_ctr
structure of the device, and signal its readiness by calling capi_ctr_ready().
From then on, Kernel CAPI may call the registered callback functions for the
device.
If the device becomes unusable for any reason (shutdown, disconnect ...), the
driver has to call capi_ctr_reseted(). This will prevent further calls to the
callback functions by Kernel CAPI.
3. Application Registration and Communication
Kernel CAPI forwards registration requests from applications (calls to CAPI
operation CAPI_REGISTER) to an appropriate hardware driver by calling its
register_appl() callback function. A unique Application ID (ApplID, u16) is
allocated by Kernel CAPI and passed to register_appl() along with the
parameter structure provided by the application. This is analogous to the
open() operation on regular files or character devices.
After a successful return from register_appl(), CAPI messages from the
application may be passed to the driver for the device via calls to the
send_message() callback function. The CAPI message to send is stored in the
data portion of a skb. Conversely, the driver may call Kernel CAPI's
capi_ctr_handle_message() function to pass a received CAPI message to Kernel
CAPI for forwarding to an application, specifying its ApplID.
Format and semantics of CAPI messages are specified in the CAPI 2.0 standard.
Deregistration requests (CAPI operation CAPI_RELEASE) from applications are
forwarded as calls to the release_appl() callback function, passing the same
ApplID as with register_appl(). After return from release_appl(), no CAPI
messages for that application may be passed to or from the device anymore.
4. Data Structures
4.1 struct capi_driver
This structure describes a Kernel CAPI driver itself. It is used in the
register_capi_driver() and unregister_capi_driver() functions, and contains
the following non-private fields, all to be set by the driver before calling
register_capi_driver():
char name[32]
the name of the driver, as a zero terminated ASCII string
char revision[32]
the revision number of the driver, as a zero terminated ASCII string
int (*add_card)(struct capi_driver *driver, capicardparams *data)
a callback function pointer (may be NULL)
4.2 struct capi_ctr
This structure describes an ISDN device (controller) handled by a Kernel CAPI
driver. After registration via the attach_capi_ctr() function it is passed to
all controller specific lower layer interface and callback functions to
identify the controller to operate on.
It contains the following non-private fields:
- to be set by the driver before calling attach_capi_ctr():
struct module *owner
pointer to the driver module owning the device
void *driverdata
an opaque pointer to driver specific data, not touched by Kernel CAPI
char name[32]
the name of the controller, as a zero terminated ASCII string
char *driver_name
the name of the driver, as a zero terminated ASCII string
int (*load_firmware)(struct capi_ctr *ctrlr, capiloaddata *ldata)
(optional) pointer to a callback function for sending firmware and
configuration data to the device
void (*reset_ctr)(struct capi_ctr *ctrlr)
pointer to a callback function for performing a reset on the device,
releasing all registered applications
void (*register_appl)(struct capi_ctr *ctrlr, u16 applid,
capi_register_params *rparam)
void (*release_appl)(struct capi_ctr *ctrlr, u16 applid)
pointers to callback functions for registration and deregistration of
applications with the device
u16 (*send_message)(struct capi_ctr *ctrlr, struct sk_buff *skb)
pointer to a callback function for sending a CAPI message to the
device
char *(*procinfo)(struct capi_ctr *ctrlr)
pointer to a callback function returning the entry for the device in
the CAPI controller info table, /proc/capi/controller
read_proc_t *ctr_read_proc
pointer to the read_proc callback function for the device's proc file
system entry, /proc/capi/controllers/<n>; will be called with a
pointer to the device's capi_ctr structure as the last (data) argument
- to be filled in before calling capi_ctr_ready():
u8 manu[CAPI_MANUFACTURER_LEN]
value to return for CAPI_GET_MANUFACTURER
capi_version version
value to return for CAPI_GET_VERSION
capi_profile profile
value to return for CAPI_GET_PROFILE
u8 serial[CAPI_SERIAL_LEN]
value to return for CAPI_GET_SERIAL
5. Lower Layer Interface Functions
(declared in <linux/isdn/capilli.h>)
void register_capi_driver(struct capi_driver *drvr)
void unregister_capi_driver(struct capi_driver *drvr)
register/unregister a driver with Kernel CAPI
int attach_capi_ctr(struct capi_ctr *ctrlr)
int detach_capi_ctr(struct capi_ctr *ctrlr)
register/unregister a device (controller) with Kernel CAPI
void capi_ctr_ready(struct capi_ctr *ctrlr)
void capi_ctr_reseted(struct capi_ctr *ctrlr)
signal controller ready/not ready
void capi_ctr_suspend_output(struct capi_ctr *ctrlr)
void capi_ctr_resume_output(struct capi_ctr *ctrlr)
signal suspend/resume
void capi_ctr_handle_message(struct capi_ctr * ctrlr, u16 applid,
struct sk_buff *skb)
pass a received CAPI message to Kernel CAPI
for forwarding to the specified application
6. Helper Functions and Macros
Library functions (from <linux/isdn/capilli.h>):
void capilib_new_ncci(struct list_head *head, u16 applid,
u32 ncci, u32 winsize)
void capilib_free_ncci(struct list_head *head, u16 applid, u32 ncci)
void capilib_release_appl(struct list_head *head, u16 applid)
void capilib_release(struct list_head *head)
void capilib_data_b3_conf(struct list_head *head, u16 applid,
u32 ncci, u16 msgid)
u16 capilib_data_b3_req(struct list_head *head, u16 applid,
u32 ncci, u16 msgid)
Macros to extract/set element values from/in a CAPI message header
(from <linux/isdn/capiutil.h>):
Get Macro Set Macro Element (Type)
CAPIMSG_LEN(m) CAPIMSG_SETLEN(m, len) Total Length (u16)
CAPIMSG_APPID(m) CAPIMSG_SETAPPID(m, applid) ApplID (u16)
CAPIMSG_COMMAND(m) CAPIMSG_SETCOMMAND(m,cmd) Command (u8)
CAPIMSG_SUBCOMMAND(m) CAPIMSG_SETSUBCOMMAND(m, cmd) Subcommand (u8)
CAPIMSG_CMD(m) - Command*256
+ Subcommand (u16)
CAPIMSG_MSGID(m) CAPIMSG_SETMSGID(m, msgid) Message Number (u16)
CAPIMSG_CONTROL(m) CAPIMSG_SETCONTROL(m, contr) Controller/PLCI/NCCI
(u32)
CAPIMSG_DATALEN(m) CAPIMSG_SETDATALEN(m, len) Data Length (u16)

171
drivers/isdn/capi/kcapi.c
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@ -270,6 +270,15 @@ static void recv_handler(struct work_struct *work)
mutex_unlock(&ap->recv_mtx);
}
/**
* capi_ctr_handle_message() - handle incoming CAPI message
* @card: controller descriptor structure.
* @appl: application ID.
* @skb: message.
*
* Called by hardware driver to pass a CAPI message to the application.
*/
void capi_ctr_handle_message(struct capi_ctr * card, u16 appl, struct sk_buff *skb)
{
struct capi20_appl *ap;
@ -348,6 +357,13 @@ error:
EXPORT_SYMBOL(capi_ctr_handle_message);
/**
* capi_ctr_ready() - signal CAPI controller ready
* @card: controller descriptor structure.
*
* Called by hardware driver to signal that the controller is up and running.
*/
void capi_ctr_ready(struct capi_ctr * card)
{
card->cardstate = CARD_RUNNING;
@ -360,6 +376,14 @@ void capi_ctr_ready(struct capi_ctr * card)
EXPORT_SYMBOL(capi_ctr_ready);
/**
* capi_ctr_reseted() - signal CAPI controller reset
* @card: controller descriptor structure.
*
* Called by hardware driver to signal that the controller is down and
* unavailable for use.
*/
void capi_ctr_reseted(struct capi_ctr * card)
{
u16 appl;
@ -391,6 +415,13 @@ void capi_ctr_reseted(struct capi_ctr * card)
EXPORT_SYMBOL(capi_ctr_reseted);
/**
* capi_ctr_suspend_output() - suspend controller
* @card: controller descriptor structure.
*
* Called by hardware driver to stop data flow.
*/
void capi_ctr_suspend_output(struct capi_ctr *card)
{
if (!card->blocked) {
@ -401,6 +432,13 @@ void capi_ctr_suspend_output(struct capi_ctr *card)
EXPORT_SYMBOL(capi_ctr_suspend_output);
/**
* capi_ctr_resume_output() - resume controller
* @card: controller descriptor structure.
*
* Called by hardware driver to resume data flow.
*/
void capi_ctr_resume_output(struct capi_ctr *card)
{
if (card->blocked) {
@ -413,6 +451,14 @@ EXPORT_SYMBOL(capi_ctr_resume_output);
/* ------------------------------------------------------------- */
/**
* attach_capi_ctr() - register CAPI controller
* @card: controller descriptor structure.
*
* Called by hardware driver to register a controller with the CAPI subsystem.
* Return value: 0 on success, error code < 0 on error
*/
int
attach_capi_ctr(struct capi_ctr *card)
{
@ -459,6 +505,15 @@ attach_capi_ctr(struct capi_ctr *card)
EXPORT_SYMBOL(attach_capi_ctr);
/**
* detach_capi_ctr() - unregister CAPI controller
* @card: controller descriptor structure.
*
* Called by hardware driver to remove the registration of a controller
* with the CAPI subsystem.
* Return value: 0 on success, error code < 0 on error
*/
int detach_capi_ctr(struct capi_ctr *card)
{
if (card->cardstate != CARD_DETECTED)
@ -479,6 +534,13 @@ int detach_capi_ctr(struct capi_ctr *card)
EXPORT_SYMBOL(detach_capi_ctr);
/**
* register_capi_driver() - register CAPI driver
* @driver: driver descriptor structure.
*
* Called by hardware driver to register itself with the CAPI subsystem.
*/
void register_capi_driver(struct capi_driver *driver)
{
unsigned long flags;
@ -490,6 +552,13 @@ void register_capi_driver(struct capi_driver *driver)
EXPORT_SYMBOL(register_capi_driver);
/**
* unregister_capi_driver() - unregister CAPI driver
* @driver: driver descriptor structure.
*
* Called by hardware driver to unregister itself from the CAPI subsystem.
*/
void unregister_capi_driver(struct capi_driver *driver)
{
unsigned long flags;
@ -505,6 +574,13 @@ EXPORT_SYMBOL(unregister_capi_driver);
/* -------- CAPI2.0 Interface ---------------------------------- */
/* ------------------------------------------------------------- */
/**
* capi20_isinstalled() - CAPI 2.0 operation CAPI_INSTALLED
*
* Return value: CAPI result code (CAPI_NOERROR if at least one ISDN controller
* is ready for use, CAPI_REGNOTINSTALLED otherwise)
*/
u16 capi20_isinstalled(void)
{
int i;
@ -517,6 +593,18 @@ u16 capi20_isinstalled(void)
EXPORT_SYMBOL(capi20_isinstalled);
/**
* capi20_register() - CAPI 2.0 operation CAPI_REGISTER
* @ap: CAPI application descriptor structure.
*
* Register an application's presence with CAPI.
* A unique application ID is assigned and stored in @ap->applid.
* After this function returns successfully, the message receive
* callback function @ap->recv_message() may be called at any time
* until capi20_release() has been called for the same @ap.
* Return value: CAPI result code
*/
u16 capi20_register(struct capi20_appl *ap)
{
int i;
@ -571,6 +659,16 @@ u16 capi20_register(struct capi20_appl *ap)
EXPORT_SYMBOL(capi20_register);
/**
* capi20_release() - CAPI 2.0 operation CAPI_RELEASE
* @ap: CAPI application descriptor structure.
*
* Terminate an application's registration with CAPI.
* After this function returns successfully, the message receive
* callback function @ap->recv_message() will no longer be called.
* Return value: CAPI result code
*/
u16 capi20_release(struct capi20_appl *ap)
{
int i;
@ -603,6 +701,15 @@ u16 capi20_release(struct capi20_appl *ap)
EXPORT_SYMBOL(capi20_release);
/**
* capi20_put_message() - CAPI 2.0 operation CAPI_PUT_MESSAGE
* @ap: CAPI application descriptor structure.
* @skb: CAPI message.
*
* Transfer a single message to CAPI.
* Return value: CAPI result code
*/
u16 capi20_put_message(struct capi20_appl *ap, struct sk_buff *skb)
{
struct capi_ctr *card;
@ -668,6 +775,16 @@ u16 capi20_put_message(struct capi20_appl *ap, struct sk_buff *skb)
EXPORT_SYMBOL(capi20_put_message);
/**
* capi20_get_manufacturer() - CAPI 2.0 operation CAPI_GET_MANUFACTURER
* @contr: controller number.
* @buf: result buffer (64 bytes).
*
* Retrieve information about the manufacturer of the specified ISDN controller
* or (for @contr == 0) the driver itself.
* Return value: CAPI result code
*/
u16 capi20_get_manufacturer(u32 contr, u8 *buf)
{
struct capi_ctr *card;
@ -685,6 +802,16 @@ u16 capi20_get_manufacturer(u32 contr, u8 *buf)
EXPORT_SYMBOL(capi20_get_manufacturer);
/**
* capi20_get_version() - CAPI 2.0 operation CAPI_GET_VERSION
* @contr: controller number.
* @verp: result structure.
*
* Retrieve version information for the specified ISDN controller
* or (for @contr == 0) the driver itself.
* Return value: CAPI result code
*/
u16 capi20_get_version(u32 contr, struct capi_version *verp)
{
struct capi_ctr *card;
@ -703,6 +830,16 @@ u16 capi20_get_version(u32 contr, struct capi_version *verp)
EXPORT_SYMBOL(capi20_get_version);
/**
* capi20_get_serial() - CAPI 2.0 operation CAPI_GET_SERIAL_NUMBER
* @contr: controller number.
* @serial: result buffer (8 bytes).
*
* Retrieve the serial number of the specified ISDN controller
* or (for @contr == 0) the driver itself.
* Return value: CAPI result code
*/
u16 capi20_get_serial(u32 contr, u8 *serial)
{
struct capi_ctr *card;
@ -721,6 +858,16 @@ u16 capi20_get_serial(u32 contr, u8 *serial)
EXPORT_SYMBOL(capi20_get_serial);
/**
* capi20_get_profile() - CAPI 2.0 operation CAPI_GET_PROFILE
* @contr: controller number.
* @profp: result structure.
*
* Retrieve capability information for the specified ISDN controller
* or (for @contr == 0) the number of installed controllers.
* Return value: CAPI result code
*/
u16 capi20_get_profile(u32 contr, struct capi_profile *profp)
{
struct capi_ctr *card;
@ -903,6 +1050,15 @@ static int old_capi_manufacturer(unsigned int cmd, void __user *data)
}
#endif
/**
* capi20_manufacturer() - CAPI 2.0 operation CAPI_MANUFACTURER
* @cmd: command.
* @data: parameter.
*
* Perform manufacturer specific command.
* Return value: CAPI result code
*/
int capi20_manufacturer(unsigned int cmd, void __user *data)
{
struct capi_ctr *card;
@ -981,6 +1137,21 @@ int capi20_manufacturer(unsigned int cmd, void __user *data)
EXPORT_SYMBOL(capi20_manufacturer);
/* temporary hack */
/**
* capi20_set_callback() - set CAPI application notification callback function
* @ap: CAPI application descriptor structure.
* @callback: callback function (NULL to remove).
*
* If not NULL, the callback function will be called to notify the
* application of the addition or removal of a controller.
* The first argument (cmd) will tell whether the controller was added
* (KCI_CONTRUP) or removed (KCI_CONTRDOWN).
* The second argument (contr) will be the controller number.
* For cmd==KCI_CONTRUP the third argument (data) will be a pointer to the
* new controller's capability profile structure.
*/
void capi20_set_callback(struct capi20_appl *ap,
void (*callback) (unsigned int cmd, __u32 contr, void *data))
{