1 Kernel CAPI Interface to Hardware Drivers
2 -----------------------------------------
6 Kernel CAPI operates as a dispatching layer between CAPI applications and CAPI
7 hardware drivers. Hardware drivers register ISDN devices (controllers, in CAPI
8 lingo) with Kernel CAPI to indicate their readiness to provide their service
9 to CAPI applications. CAPI applications also register with Kernel CAPI,
10 requesting association with a CAPI device. Kernel CAPI then dispatches the
11 application registration to an available device, forwarding it to the
12 corresponding hardware driver. Kernel CAPI then forwards CAPI messages in both
13 directions between the application and the hardware driver.
16 2. Driver and Device Registration
18 CAPI drivers optionally register themselves with Kernel CAPI by calling the
19 Kernel CAPI function register_capi_driver() with a pointer to a struct
20 capi_driver. This structure must be filled with the name and revision of the
21 driver, and optionally a pointer to a callback function, add_card(). The
22 registration can be revoked by calling the function unregister_capi_driver()
23 with a pointer to the same struct capi_driver.
25 CAPI drivers must register each of the ISDN devices they control with Kernel
26 CAPI by calling the Kernel CAPI function attach_capi_ctr() with a pointer to a
27 struct capi_ctr before they can be used. This structure must be filled with
28 the names of the driver and controller, and a number of callback function
29 pointers which are subsequently used by Kernel CAPI for communicating with the
30 driver. The registration can be revoked by calling the function
31 detach_capi_ctr() with a pointer to the same struct capi_ctr.
33 Before the device can be actually used, the driver must fill in the device
34 information fields 'manu', 'version', 'profile' and 'serial' in the capi_ctr
35 structure of the device, and signal its readiness by calling capi_ctr_ready().
36 From then on, Kernel CAPI may call the registered callback functions for the
39 If the device becomes unusable for any reason (shutdown, disconnect ...), the
40 driver has to call capi_ctr_reseted(). This will prevent further calls to the
41 callback functions by Kernel CAPI.
44 3. Application Registration and Communication
46 Kernel CAPI forwards registration requests from applications (calls to CAPI
47 operation CAPI_REGISTER) to an appropriate hardware driver by calling its
48 register_appl() callback function. A unique Application ID (ApplID, u16) is
49 allocated by Kernel CAPI and passed to register_appl() along with the
50 parameter structure provided by the application. This is analogous to the
51 open() operation on regular files or character devices.
53 After a successful return from register_appl(), CAPI messages from the
54 application may be passed to the driver for the device via calls to the
55 send_message() callback function. The CAPI message to send is stored in the
56 data portion of a skb. Conversely, the driver may call Kernel CAPI's
57 capi_ctr_handle_message() function to pass a received CAPI message to Kernel
58 CAPI for forwarding to an application, specifying its ApplID.
60 Format and semantics of CAPI messages are specified in the CAPI 2.0 standard.
62 Deregistration requests (CAPI operation CAPI_RELEASE) from applications are
63 forwarded as calls to the release_appl() callback function, passing the same
64 ApplID as with register_appl(). After return from release_appl(), no CAPI
65 messages for that application may be passed to or from the device anymore.
70 4.1 struct capi_driver
72 This structure describes a Kernel CAPI driver itself. It is used in the
73 register_capi_driver() and unregister_capi_driver() functions, and contains
74 the following non-private fields, all to be set by the driver before calling
75 register_capi_driver():
78 the name of the driver, as a zero terminated ASCII string
80 the revision number of the driver, as a zero terminated ASCII string
81 int (*add_card)(struct capi_driver *driver, capicardparams *data)
82 a callback function pointer (may be NULL)
87 This structure describes an ISDN device (controller) handled by a Kernel CAPI
88 driver. After registration via the attach_capi_ctr() function it is passed to
89 all controller specific lower layer interface and callback functions to
90 identify the controller to operate on.
92 It contains the following non-private fields:
94 - to be set by the driver before calling attach_capi_ctr():
97 pointer to the driver module owning the device
100 an opaque pointer to driver specific data, not touched by Kernel CAPI
103 the name of the controller, as a zero terminated ASCII string
106 the name of the driver, as a zero terminated ASCII string
108 int (*load_firmware)(struct capi_ctr *ctrlr, capiloaddata *ldata)
109 (optional) pointer to a callback function for sending firmware and
110 configuration data to the device
112 void (*reset_ctr)(struct capi_ctr *ctrlr)
113 pointer to a callback function for performing a reset on the device,
114 releasing all registered applications
116 void (*register_appl)(struct capi_ctr *ctrlr, u16 applid,
117 capi_register_params *rparam)
118 void (*release_appl)(struct capi_ctr *ctrlr, u16 applid)
119 pointers to callback functions for registration and deregistration of
120 applications with the device
122 u16 (*send_message)(struct capi_ctr *ctrlr, struct sk_buff *skb)
123 pointer to a callback function for sending a CAPI message to the
126 char *(*procinfo)(struct capi_ctr *ctrlr)
127 pointer to a callback function returning the entry for the device in
128 the CAPI controller info table, /proc/capi/controller
130 read_proc_t *ctr_read_proc
131 pointer to the read_proc callback function for the device's proc file
132 system entry, /proc/capi/controllers/<n>; will be called with a
133 pointer to the device's capi_ctr structure as the last (data) argument
135 - to be filled in before calling capi_ctr_ready():
137 u8 manu[CAPI_MANUFACTURER_LEN]
138 value to return for CAPI_GET_MANUFACTURER
141 value to return for CAPI_GET_VERSION
144 value to return for CAPI_GET_PROFILE
146 u8 serial[CAPI_SERIAL_LEN]
147 value to return for CAPI_GET_SERIAL
150 5. Lower Layer Interface Functions
152 (declared in <linux/isdn/capilli.h>)
154 void register_capi_driver(struct capi_driver *drvr)
155 void unregister_capi_driver(struct capi_driver *drvr)
156 register/unregister a driver with Kernel CAPI
158 int attach_capi_ctr(struct capi_ctr *ctrlr)
159 int detach_capi_ctr(struct capi_ctr *ctrlr)
160 register/unregister a device (controller) with Kernel CAPI
162 void capi_ctr_ready(struct capi_ctr *ctrlr)
163 void capi_ctr_reseted(struct capi_ctr *ctrlr)
164 signal controller ready/not ready
166 void capi_ctr_suspend_output(struct capi_ctr *ctrlr)
167 void capi_ctr_resume_output(struct capi_ctr *ctrlr)
168 signal suspend/resume
170 void capi_ctr_handle_message(struct capi_ctr * ctrlr, u16 applid,
172 pass a received CAPI message to Kernel CAPI
173 for forwarding to the specified application
176 6. Helper Functions and Macros
178 Library functions (from <linux/isdn/capilli.h>):
180 void capilib_new_ncci(struct list_head *head, u16 applid,
181 u32 ncci, u32 winsize)
182 void capilib_free_ncci(struct list_head *head, u16 applid, u32 ncci)
183 void capilib_release_appl(struct list_head *head, u16 applid)
184 void capilib_release(struct list_head *head)
185 void capilib_data_b3_conf(struct list_head *head, u16 applid,
187 u16 capilib_data_b3_req(struct list_head *head, u16 applid,
191 Macros to extract/set element values from/in a CAPI message header
192 (from <linux/isdn/capiutil.h>):
194 Get Macro Set Macro Element (Type)
196 CAPIMSG_LEN(m) CAPIMSG_SETLEN(m, len) Total Length (u16)
197 CAPIMSG_APPID(m) CAPIMSG_SETAPPID(m, applid) ApplID (u16)
198 CAPIMSG_COMMAND(m) CAPIMSG_SETCOMMAND(m,cmd) Command (u8)
199 CAPIMSG_SUBCOMMAND(m) CAPIMSG_SETSUBCOMMAND(m, cmd) Subcommand (u8)
200 CAPIMSG_CMD(m) - Command*256
202 CAPIMSG_MSGID(m) CAPIMSG_SETMSGID(m, msgid) Message Number (u16)
204 CAPIMSG_CONTROL(m) CAPIMSG_SETCONTROL(m, contr) Controller/PLCI/NCCI
206 CAPIMSG_DATALEN(m) CAPIMSG_SETDATALEN(m, len) Data Length (u16)