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1 | /* |
2 | * Linux WiMAX |
3 | * Kernel space API for accessing WiMAX devices |
4 | * |
5 | * |
6 | * Copyright (C) 2007-2008 Intel Corporation <linux-wimax@intel.com> |
7 | * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com> |
8 | * |
9 | * This program is free software; you can redistribute it and/or |
10 | * modify it under the terms of the GNU General Public License version |
11 | * 2 as published by the Free Software Foundation. |
12 | * |
13 | * This program is distributed in the hope that it will be useful, |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
16 | * GNU General Public License for more details. |
17 | * |
18 | * You should have received a copy of the GNU General Public License |
19 | * along with this program; if not, write to the Free Software |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
21 | * 02110-1301, USA. |
22 | * |
23 | * |
24 | * The WiMAX stack provides an API for controlling and managing the |
25 | * system's WiMAX devices. This API affects the control plane; the |
26 | * data plane is accessed via the network stack (netdev). |
27 | * |
28 | * Parts of the WiMAX stack API and notifications are exported to |
29 | * user space via Generic Netlink. In user space, libwimax (part of |
30 | * the wimax-tools package) provides a shim layer for accessing those |
31 | * calls. |
32 | * |
33 | * The API is standarized for all WiMAX devices and different drivers |
34 | * implement the backend support for it. However, device-specific |
35 | * messaging pipes are provided that can be used to issue commands and |
36 | * receive notifications in free form. |
37 | * |
38 | * Currently the messaging pipes are the only means of control as it |
39 | * is not known (due to the lack of more devices in the market) what |
40 | * will be a good abstraction layer. Expect this to change as more |
41 | * devices show in the market. This API is designed to be growable in |
42 | * order to address this problem. |
43 | * |
44 | * USAGE |
45 | * |
46 | * Embed a `struct wimax_dev` at the beginning of the the device's |
47 | * private structure, initialize and register it. For details, see |
48 | * `struct wimax_dev`s documentation. |
49 | * |
50 | * Once this is done, wimax-tools's libwimaxll can be used to |
51 | * communicate with the driver from user space. You user space |
52 | * application does not have to forcibily use libwimaxll and can talk |
53 | * the generic netlink protocol directly if desired. |
54 | * |
55 | * Remember this is a very low level API that will to provide all of |
56 | * WiMAX features. Other daemons and services running in user space |
57 | * are the expected clients of it. They offer a higher level API that |
58 | * applications should use (an example of this is the Intel's WiMAX |
59 | * Network Service for the i2400m). |
60 | * |
61 | * DESIGN |
62 | * |
63 | * Although not set on final stone, this very basic interface is |
64 | * mostly completed. Remember this is meant to grow as new common |
65 | * operations are decided upon. New operations will be added to the |
66 | * interface, intent being on keeping backwards compatibility as much |
67 | * as possible. |
68 | * |
69 | * This layer implements a set of calls to control a WiMAX device, |
70 | * exposing a frontend to the rest of the kernel and user space (via |
71 | * generic netlink) and a backend implementation in the driver through |
72 | * function pointers. |
73 | * |
74 | * WiMAX devices have a state, and a kernel-only API allows the |
75 | * drivers to manipulate that state. State transitions are atomic, and |
76 | * only some of them are allowed (see `enum wimax_st`). |
77 | * |
78 | * Most API calls will set the state automatically; in most cases |
79 | * drivers have to only report state changes due to external |
80 | * conditions. |
81 | * |
82 | * All API operations are 'atomic', serialized through a mutex in the |
83 | * `struct wimax_dev`. |
84 | * |
85 | * EXPORTING TO USER SPACE THROUGH GENERIC NETLINK |
86 | * |
87 | * The API is exported to user space using generic netlink (other |
88 | * methods can be added as needed). |
89 | * |
90 | * There is a Generic Netlink Family named "WiMAX", where interfaces |
91 | * supporting the WiMAX interface receive commands and broadcast their |
92 | * signals over a multicast group named "msg". |
93 | * |
94 | * Mapping to the source/destination interface is done by an interface |
95 | * index attribute. |
96 | * |
97 | * For user-to-kernel traffic (commands) we use a function call |
98 | * marshalling mechanism, where a message X with attributes A, B, C |
99 | * sent from user space to kernel space means executing the WiMAX API |
100 | * call wimax_X(A, B, C), sending the results back as a message. |
101 | * |
102 | * Kernel-to-user (notifications or signals) communication is sent |
103 | * over multicast groups. This allows to have multiple applications |
104 | * monitoring them. |
105 | * |
106 | * Each command/signal gets assigned it's own attribute policy. This |
107 | * way the validator will verify that all the attributes in there are |
108 | * only the ones that should be for each command/signal. Thing of an |
109 | * attribute mapping to a type+argumentname for each command/signal. |
110 | * |
111 | * If we had a single policy for *all* commands/signals, after running |
112 | * the validator we'd have to check "does this attribute belong in |
113 | * here"? for each one. It can be done manually, but it's just easier |
114 | * to have the validator do that job with multiple policies. As well, |
115 | * it makes it easier to later expand each command/signal signature |
116 | * without affecting others and keeping the namespace more or less |
117 | * sane. Not that it is too complicated, but it makes it even easier. |
118 | * |
119 | * No state information is maintained in the kernel for each user |
120 | * space connection (the connection is stateless). |
121 | * |
122 | * TESTING FOR THE INTERFACE AND VERSIONING |
123 | * |
124 | * If network interface X is a WiMAX device, there will be a Generic |
125 | * Netlink family named "WiMAX X" and the device will present a |
126 | * "wimax" directory in it's network sysfs directory |
127 | * (/sys/class/net/DEVICE/wimax) [used by HAL]. |
128 | * |
129 | * The inexistence of any of these means the device does not support |
130 | * this WiMAX API. |
131 | * |
132 | * By querying the generic netlink controller, versioning information |
133 | * and the multicast groups available can be found. Applications using |
134 | * the interface can either rely on that or use the generic netlink |
135 | * controller to figure out which generic netlink commands/signals are |
136 | * supported. |
137 | * |
138 | * NOTE: this versioning is a last resort to avoid hard |
139 | * incompatibilities. It is the intention of the design of this |
140 | * stack not to introduce backward incompatible changes. |
141 | * |
142 | * The version code has to fit in one byte (restrictions imposed by |
143 | * generic netlink); we use `version / 10` for the major version and |
144 | * `version % 10` for the minor. This gives 9 minors for each major |
145 | * and 25 majors. |
146 | * |
147 | * The version change protocol is as follow: |
148 | * |
149 | * - Major versions: needs to be increased if an existing message/API |
150 | * call is changed or removed. Doesn't need to be changed if a new |
151 | * message is added. |
152 | * |
153 | * - Minor version: needs to be increased if new messages/API calls are |
154 | * being added or some other consideration that doesn't impact the |
155 | * user-kernel interface too much (like some kind of bug fix) and |
156 | * that is kind of left up in the air to common sense. |
157 | * |
158 | * User space code should not try to work if the major version it was |
159 | * compiled for differs from what the kernel offers. As well, if the |
160 | * minor version of the kernel interface is lower than the one user |
161 | * space is expecting (the one it was compiled for), the kernel |
162 | * might be missing API calls; user space shall be ready to handle |
163 | * said condition. Use the generic netlink controller operations to |
164 | * find which ones are supported and which not. |
165 | * |
166 | * libwimaxll:wimaxll_open() takes care of checking versions. |
167 | * |
168 | * THE OPERATIONS: |
169 | * |
170 | * Each operation is defined in its on file (drivers/net/wimax/op-*.c) |
171 | * for clarity. The parts needed for an operation are: |
172 | * |
173 | * - a function pointer in `struct wimax_dev`: optional, as the |
174 | * operation might be implemented by the stack and not by the |
175 | * driver. |
176 | * |
177 | * All function pointers are named wimax_dev->op_*(), and drivers |
178 | * must implement them except where noted otherwise. |
179 | * |
180 | * - When exported to user space, a `struct nla_policy` to define the |
181 | * attributes of the generic netlink command and a `struct genl_ops` |
182 | * to define the operation. |
183 | * |
184 | * All the declarations for the operation codes (WIMAX_GNL_OP_<NAME>) |
185 | * and generic netlink attributes (WIMAX_GNL_<NAME>_*) are declared in |
186 | * include/linux/wimax.h; this file is intended to be cloned by user |
187 | * space to gain access to those declarations. |
188 | * |
189 | * A few caveats to remember: |
190 | * |
191 | * - Need to define attribute numbers starting in 1; otherwise it |
192 | * fails. |
193 | * |
194 | * - the `struct genl_family` requires a maximum attribute id; when |
195 | * defining the `struct nla_policy` for each message, it has to have |
196 | * an array size of WIMAX_GNL_ATTR_MAX+1. |
197 | * |
198 | * The op_*() function pointers will not be called if the wimax_dev is |
199 | * in a state <= %WIMAX_ST_UNINITIALIZED. The exception is: |
200 | * |
201 | * - op_reset: can be called at any time after wimax_dev_add() has |
202 | * been called. |
203 | * |
204 | * THE PIPE INTERFACE: |
205 | * |
206 | * This interface is kept intentionally simple. The driver can send |
207 | * and receive free-form messages to/from user space through a |
208 | * pipe. See drivers/net/wimax/op-msg.c for details. |
209 | * |
210 | * The kernel-to-user messages are sent with |
211 | * wimax_msg(). user-to-kernel messages are delivered via |
212 | * wimax_dev->op_msg_from_user(). |
213 | * |
214 | * RFKILL: |
215 | * |
216 | * RFKILL support is built into the wimax_dev layer; the driver just |
217 | * needs to call wimax_report_rfkill_{hw,sw}() to inform of changes in |
218 | * the hardware or software RF kill switches. When the stack wants to |
219 | * turn the radio off, it will call wimax_dev->op_rfkill_sw_toggle(), |
220 | * which the driver implements. |
221 | * |
222 | * User space can set the software RF Kill switch by calling |
223 | * wimax_rfkill(). |
224 | * |
225 | * The code for now only supports devices that don't require polling; |
226 | * If the device needs to be polled, create a self-rearming delayed |
227 | * work struct for polling or look into adding polled support to the |
228 | * WiMAX stack. |
229 | * |
230 | * When initializing the hardware (_probe), after calling |
231 | * wimax_dev_add(), query the device for it's RF Kill switches status |
232 | * and feed it back to the WiMAX stack using |
233 | * wimax_report_rfkill_{hw,sw}(). If any switch is missing, always |
234 | * report it as ON. |
235 | * |
236 | * NOTE: the wimax stack uses an inverted terminology to that of the |
237 | * RFKILL subsystem: |
238 | * |
239 | * - ON: radio is ON, RFKILL is DISABLED or OFF. |
240 | * - OFF: radio is OFF, RFKILL is ENABLED or ON. |
241 | * |
242 | * MISCELLANEOUS OPS: |
243 | * |
244 | * wimax_reset() can be used to reset the device to power on state; by |
245 | * default it issues a warm reset that maintains the same device |
246 | * node. If that is not possible, it falls back to a cold reset |
247 | * (device reconnect). The driver implements the backend to this |
248 | * through wimax_dev->op_reset(). |
249 | */ |
250 | |
251 | #ifndef __NET__WIMAX_H__ |
252 | #define __NET__WIMAX_H__ |
253 | |
254 | #include <linux/wimax.h> |
255 | #include <net/genetlink.h> |
256 | #include <linux/netdevice.h> |
257 | |
258 | struct net_device; |
259 | struct genl_info; |
260 | struct wimax_dev; |
261 | |
262 | /** |
263 | * struct wimax_dev - Generic WiMAX device |
264 | * |
265 | * @net_dev: [fill] Pointer to the &struct net_device this WiMAX |
266 | * device implements. |
267 | * |
268 | * @op_msg_from_user: [fill] Driver-specific operation to |
269 | * handle a raw message from user space to the driver. The |
270 | * driver can send messages to user space using with |
271 | * wimax_msg_to_user(). |
272 | * |
273 | * @op_rfkill_sw_toggle: [fill] Driver-specific operation to act on |
274 | * userspace (or any other agent) requesting the WiMAX device to |
275 | * change the RF Kill software switch (WIMAX_RF_ON or |
276 | * WIMAX_RF_OFF). |
277 | * If such hardware support is not present, it is assumed the |
278 | * radio cannot be switched off and it is always on (and the stack |
279 | * will error out when trying to switch it off). In such case, |
280 | * this function pointer can be left as NULL. |
281 | * |
282 | * @op_reset: [fill] Driver specific operation to reset the |
283 | * device. |
284 | * This operation should always attempt first a warm reset that |
285 | * does not disconnect the device from the bus and return 0. |
286 | * If that fails, it should resort to some sort of cold or bus |
287 | * reset (even if it implies a bus disconnection and device |
288 | * disappearance). In that case, -ENODEV should be returned to |
289 | * indicate the device is gone. |
290 | * This operation has to be synchronous, and return only when the |
291 | * reset is complete. In case of having had to resort to bus/cold |
292 | * reset implying a device disconnection, the call is allowed to |
293 | * return inmediately. |
294 | * NOTE: wimax_dev->mutex is NOT locked when this op is being |
295 | * called; however, wimax_dev->mutex_reset IS locked to ensure |
296 | * serialization of calls to wimax_reset(). |
297 | * See wimax_reset()'s documentation. |
298 | * |
299 | * @name: [fill] A way to identify this device. We need to register a |
300 | * name with many subsystems (rfkill, workqueue creation, etc). |
301 | * We can't use the network device name as that |
302 | * might change and in some instances we don't know it yet (until |
303 | * we don't call register_netdev()). So we generate an unique one |
304 | * using the driver name and device bus id, place it here and use |
305 | * it across the board. Recommended naming: |
306 | * DRIVERNAME-BUSNAME:BUSID (dev->bus->name, dev->bus_id). |
307 | * |
308 | * @id_table_node: [private] link to the list of wimax devices kept by |
309 | * id-table.c. Protected by it's own spinlock. |
310 | * |
311 | * @mutex: [private] Serializes all concurrent access and execution of |
312 | * operations. |
313 | * |
314 | * @mutex_reset: [private] Serializes reset operations. Needs to be a |
315 | * different mutex because as part of the reset operation, the |
316 | * driver has to call back into the stack to do things such as |
317 | * state change, that require wimax_dev->mutex. |
318 | * |
319 | * @state: [private] Current state of the WiMAX device. |
320 | * |
321 | * @rfkill: [private] integration into the RF-Kill infrastructure. |
322 | * |
323 | * @rf_sw: [private] State of the software radio switch (OFF/ON) |
324 | * |
325 | * @rf_hw: [private] State of the hardware radio switch (OFF/ON) |
326 | * |
327 | * @debugfs_dentry: [private] Used to hook up a debugfs entry. This |
328 | * shows up in the debugfs root as wimax\:DEVICENAME. |
329 | * |
330 | * Description: |
331 | * This structure defines a common interface to access all WiMAX |
332 | * devices from different vendors and provides a common API as well as |
333 | * a free-form device-specific messaging channel. |
334 | * |
335 | * Usage: |
336 | * 1. Embed a &struct wimax_dev at *the beginning* the network |
337 | * device structure so that netdev_priv() points to it. |
338 | * |
339 | * 2. memset() it to zero |
340 | * |
341 | * 3. Initialize with wimax_dev_init(). This will leave the WiMAX |
342 | * device in the %__WIMAX_ST_NULL state. |
343 | * |
344 | * 4. Fill all the fields marked with [fill]; once called |
345 | * wimax_dev_add(), those fields CANNOT be modified. |
346 | * |
347 | * 5. Call wimax_dev_add() *after* registering the network |
348 | * device. This will leave the WiMAX device in the %WIMAX_ST_DOWN |
349 | * state. |
350 | * Protect the driver's net_device->open() against succeeding if |
351 | * the wimax device state is lower than %WIMAX_ST_DOWN. |
352 | * |
353 | * 6. Select when the device is going to be turned on/initialized; |
354 | * for example, it could be initialized on 'ifconfig up' (when the |
355 | * netdev op 'open()' is called on the driver). |
356 | * |
357 | * When the device is initialized (at `ifconfig up` time, or right |
358 | * after calling wimax_dev_add() from _probe(), make sure the |
359 | * following steps are taken |
360 | * |
361 | * a. Move the device to %WIMAX_ST_UNINITIALIZED. This is needed so |
362 | * some API calls that shouldn't work until the device is ready |
363 | * can be blocked. |
364 | * |
365 | * b. Initialize the device. Make sure to turn the SW radio switch |
366 | * off and move the device to state %WIMAX_ST_RADIO_OFF when |
367 | * done. When just initialized, a device should be left in RADIO |
368 | * OFF state until user space devices to turn it on. |
369 | * |
370 | * c. Query the device for the state of the hardware rfkill switch |
371 | * and call wimax_rfkill_report_hw() and wimax_rfkill_report_sw() |
372 | * as needed. See below. |
373 | * |
374 | * wimax_dev_rm() undoes before unregistering the network device. Once |
375 | * wimax_dev_add() is called, the driver can get called on the |
376 | * wimax_dev->op_* function pointers |
377 | * |
378 | * CONCURRENCY: |
379 | * |
380 | * The stack provides a mutex for each device that will disallow API |
381 | * calls happening concurrently; thus, op calls into the driver |
382 | * through the wimax_dev->op*() function pointers will always be |
383 | * serialized and *never* concurrent. |
384 | * |
385 | * For locking, take wimax_dev->mutex is taken; (most) operations in |
386 | * the API have to check for wimax_dev_is_ready() to return 0 before |
387 | * continuing (this is done internally). |
388 | * |
389 | * REFERENCE COUNTING: |
390 | * |
391 | * The WiMAX device is reference counted by the associated network |
392 | * device. The only operation that can be used to reference the device |
393 | * is wimax_dev_get_by_genl_info(), and the reference it acquires has |
394 | * to be released with dev_put(wimax_dev->net_dev). |
395 | * |
396 | * RFKILL: |
397 | * |
398 | * At startup, both HW and SW radio switchess are assumed to be off. |
399 | * |
400 | * At initialization time [after calling wimax_dev_add()], have the |
401 | * driver query the device for the status of the software and hardware |
402 | * RF kill switches and call wimax_report_rfkill_hw() and |
403 | * wimax_rfkill_report_sw() to indicate their state. If any is |
404 | * missing, just call it to indicate it is ON (radio always on). |
405 | * |
406 | * Whenever the driver detects a change in the state of the RF kill |
407 | * switches, it should call wimax_report_rfkill_hw() or |
408 | * wimax_report_rfkill_sw() to report it to the stack. |
409 | */ |
410 | struct wimax_dev { |
411 | struct net_device *net_dev; |
412 | struct list_head id_table_node; |
413 | struct mutex mutex; /* Protects all members and API calls */ |
414 | struct mutex mutex_reset; |
415 | enum wimax_st state; |
416 | |
417 | int (*op_msg_from_user)(struct wimax_dev *wimax_dev, |
418 | const char *, |
419 | const void *, size_t, |
420 | const struct genl_info *info); |
421 | int (*op_rfkill_sw_toggle)(struct wimax_dev *wimax_dev, |
422 | enum wimax_rf_state); |
423 | int (*op_reset)(struct wimax_dev *wimax_dev); |
424 | |
425 | struct rfkill *rfkill; |
426 | unsigned int rf_hw; |
427 | unsigned int rf_sw; |
428 | char name[32]; |
429 | |
430 | struct dentry *debugfs_dentry; |
431 | }; |
432 | |
433 | |
434 | |
435 | /* |
436 | * WiMAX stack public API for device drivers |
437 | * ----------------------------------------- |
438 | * |
439 | * These functions are not exported to user space. |
440 | */ |
441 | extern void wimax_dev_init(struct wimax_dev *); |
442 | extern int wimax_dev_add(struct wimax_dev *, struct net_device *); |
443 | extern void wimax_dev_rm(struct wimax_dev *); |
444 | |
445 | static inline |
446 | struct wimax_dev *net_dev_to_wimax(struct net_device *net_dev) |
447 | { |
448 | return netdev_priv(net_dev); |
449 | } |
450 | |
451 | static inline |
452 | struct device *wimax_dev_to_dev(struct wimax_dev *wimax_dev) |
453 | { |
454 | return wimax_dev->net_dev->dev.parent; |
455 | } |
456 | |
457 | extern void wimax_state_change(struct wimax_dev *, enum wimax_st); |
458 | extern enum wimax_st wimax_state_get(struct wimax_dev *); |
459 | |
460 | /* |
461 | * Radio Switch state reporting. |
462 | * |
463 | * enum wimax_rf_state is declared in linux/wimax.h so the exports |
464 | * to user space can use it. |
465 | */ |
466 | extern void wimax_report_rfkill_hw(struct wimax_dev *, enum wimax_rf_state); |
467 | extern void wimax_report_rfkill_sw(struct wimax_dev *, enum wimax_rf_state); |
468 | |
469 | |
470 | /* |
471 | * Free-form messaging to/from user space |
472 | * |
473 | * Sending a message: |
474 | * |
475 | * wimax_msg(wimax_dev, pipe_name, buf, buf_size, GFP_KERNEL); |
476 | * |
477 | * Broken up: |
478 | * |
479 | * skb = wimax_msg_alloc(wimax_dev, pipe_name, buf_size, GFP_KERNEL); |
480 | * ...fill up skb... |
481 | * wimax_msg_send(wimax_dev, pipe_name, skb); |
482 | * |
483 | * Be sure not to modify skb->data in the middle (ie: don't use |
484 | * skb_push()/skb_pull()/skb_reserve() on the skb). |
485 | * |
486 | * "pipe_name" is any string, than can be interpreted as the name of |
487 | * the pipe or destinatary; the interpretation of it is driver |
488 | * specific, so the recipient can multiplex it as wished. It can be |
489 | * NULL, it won't be used - an example is using a "diagnostics" tag to |
490 | * send diagnostics information that a device-specific diagnostics |
491 | * tool would be interested in. |
492 | */ |
493 | extern struct sk_buff *wimax_msg_alloc(struct wimax_dev *, const char *, |
494 | const void *, size_t, gfp_t); |
495 | extern int wimax_msg_send(struct wimax_dev *, struct sk_buff *); |
496 | extern int wimax_msg(struct wimax_dev *, const char *, |
497 | const void *, size_t, gfp_t); |
498 | |
499 | extern const void *wimax_msg_data_len(struct sk_buff *, size_t *); |
500 | extern const void *wimax_msg_data(struct sk_buff *); |
501 | extern ssize_t wimax_msg_len(struct sk_buff *); |
502 | |
503 | |
504 | /* |
505 | * WiMAX stack user space API |
506 | * -------------------------- |
507 | * |
508 | * This API is what gets exported to user space for general |
509 | * operations. As well, they can be called from within the kernel, |
510 | * (with a properly referenced `struct wimax_dev`). |
511 | * |
512 | * Properly referenced means: the 'struct net_device' that embeds the |
513 | * device's control structure and (as such) the 'struct wimax_dev' is |
514 | * referenced by the caller. |
515 | */ |
516 | extern int wimax_rfkill(struct wimax_dev *, enum wimax_rf_state); |
517 | extern int wimax_reset(struct wimax_dev *); |
518 | |
519 | #endif /* #ifndef __NET__WIMAX_H__ */ |
520 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9