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…davem/net-2.6 Conflicts: Documentation/isdn/00-INDEX drivers/net/wireless/iwlwifi/iwl-scan.c drivers/net/wireless/rndis_wlan.c net/mac80211/main.c
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Kernel CAPI Interface to Hardware Drivers | ||
----------------------------------------- | ||
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1. Overview | ||
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From the CAPI 2.0 specification: | ||
COMMON-ISDN-API (CAPI) is an application programming interface standard used | ||
to access ISDN equipment connected to basic rate interfaces (BRI) and primary | ||
rate interfaces (PRI). | ||
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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. | ||
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Format and semantics of CAPI messages are specified in the CAPI 2.0 standard. | ||
This standard is freely available from http://www.capi.org. | ||
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2. Driver and Device Registration | ||
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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. | ||
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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. | ||
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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. | ||
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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. | ||
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3. Application Registration and Communication | ||
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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. | ||
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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 an 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. | ||
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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. | ||
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4. Data Structures | ||
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4.1 struct capi_driver | ||
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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(): | ||
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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) | ||
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4.2 struct capi_ctr | ||
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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. | ||
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It contains the following non-private fields: | ||
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- to be set by the driver before calling attach_capi_ctr(): | ||
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struct module *owner | ||
pointer to the driver module owning the device | ||
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void *driverdata | ||
an opaque pointer to driver specific data, not touched by Kernel CAPI | ||
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char name[32] | ||
the name of the controller, as a zero-terminated ASCII string | ||
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char *driver_name | ||
the name of the driver, as a zero-terminated ASCII string | ||
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int (*load_firmware)(struct capi_ctr *ctrlr, capiloaddata *ldata) | ||
(optional) pointer to a callback function for sending firmware and | ||
configuration data to the device | ||
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void (*reset_ctr)(struct capi_ctr *ctrlr) | ||
pointer to a callback function for performing a reset on the device, | ||
releasing all registered applications | ||
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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 | ||
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u16 (*send_message)(struct capi_ctr *ctrlr, struct sk_buff *skb) | ||
pointer to a callback function for sending a CAPI message to the | ||
device | ||
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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 | ||
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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 | ||
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- to be filled in before calling capi_ctr_ready(): | ||
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u8 manu[CAPI_MANUFACTURER_LEN] | ||
value to return for CAPI_GET_MANUFACTURER | ||
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capi_version version | ||
value to return for CAPI_GET_VERSION | ||
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capi_profile profile | ||
value to return for CAPI_GET_PROFILE | ||
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u8 serial[CAPI_SERIAL_LEN] | ||
value to return for CAPI_GET_SERIAL | ||
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5. Lower Layer Interface Functions | ||
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(declared in <linux/isdn/capilli.h>) | ||
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void register_capi_driver(struct capi_driver *drvr) | ||
void unregister_capi_driver(struct capi_driver *drvr) | ||
register/unregister a driver with Kernel CAPI | ||
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int attach_capi_ctr(struct capi_ctr *ctrlr) | ||
int detach_capi_ctr(struct capi_ctr *ctrlr) | ||
register/unregister a device (controller) with Kernel CAPI | ||
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void capi_ctr_ready(struct capi_ctr *ctrlr) | ||
void capi_ctr_reseted(struct capi_ctr *ctrlr) | ||
signal controller ready/not ready | ||
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void capi_ctr_suspend_output(struct capi_ctr *ctrlr) | ||
void capi_ctr_resume_output(struct capi_ctr *ctrlr) | ||
signal suspend/resume | ||
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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 | ||
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6. Helper Functions and Macros | ||
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Library functions (from <linux/isdn/capilli.h>): | ||
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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) | ||
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Macros to extract/set element values from/in a CAPI message header | ||
(from <linux/isdn/capiutil.h>): | ||
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Get Macro Set Macro Element (Type) | ||
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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) | ||
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CAPIMSG_CONTROL(m) CAPIMSG_SETCONTROL(m, contr) Controller/PLCI/NCCI | ||
(u32) | ||
CAPIMSG_DATALEN(m) CAPIMSG_SETDATALEN(m, len) Data Length (u16) | ||
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