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Inaky Perez-Gonzalezace22f02008-12-20 16:57:33 -08001/*
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 thorough 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 PIPE INTERFACE:
199 *
200 * This interface is kept intentionally simple. The driver can send
201 * and receive free-form messages to/from user space through a
202 * pipe. See drivers/net/wimax/op-msg.c for details.
203 *
204 * The kernel-to-user messages are sent with
205 * wimax_msg(). user-to-kernel messages are delivered via
206 * wimax_dev->op_msg_from_user().
207 *
208 * RFKILL:
209 *
210 * RFKILL support is built into the wimax_dev layer; the driver just
211 * needs to call wimax_report_rfkill_{hw,sw}() to inform of changes in
212 * the hardware or software RF kill switches. When the stack wants to
213 * turn the radio off, it will call wimax_dev->op_rfkill_sw_toggle(),
214 * which the driver implements.
215 *
216 * User space can set the software RF Kill switch by calling
217 * wimax_rfkill().
218 *
219 * The code for now only supports devices that don't require polling;
220 * If the device needs to be polled, create a self-rearming delayed
221 * work struct for polling or look into adding polled support to the
222 * WiMAX stack.
223 *
224 * When initializing the hardware (_probe), after calling
225 * wimax_dev_add(), query the device for it's RF Kill switches status
226 * and feed it back to the WiMAX stack using
227 * wimax_report_rfkill_{hw,sw}(). If any switch is missing, always
228 * report it as ON.
229 *
230 * NOTE: the wimax stack uses an inverted terminology to that of the
231 * RFKILL subsystem:
232 *
233 * - ON: radio is ON, RFKILL is DISABLED or OFF.
234 * - OFF: radio is OFF, RFKILL is ENABLED or ON.
235 *
236 * MISCELLANEOUS OPS:
237 *
238 * wimax_reset() can be used to reset the device to power on state; by
239 * default it issues a warm reset that maintains the same device
240 * node. If that is not possible, it falls back to a cold reset
241 * (device reconnect). The driver implements the backend to this
242 * through wimax_dev->op_reset().
243 */
244
245#ifndef __NET__WIMAX_H__
246#define __NET__WIMAX_H__
247#ifdef __KERNEL__
248
249#include <linux/wimax.h>
250#include <net/genetlink.h>
251#include <linux/netdevice.h>
252
253struct net_device;
254struct genl_info;
255struct wimax_dev;
256struct input_dev;
257
258/**
259 * struct wimax_dev - Generic WiMAX device
260 *
261 * @net_dev: [fill] Pointer to the &struct net_device this WiMAX
262 * device implements.
263 *
264 * @op_msg_from_user: [fill] Driver-specific operation to
265 * handle a raw message from user space to the driver. The
266 * driver can send messages to user space using with
267 * wimax_msg_to_user().
268 *
269 * @op_rfkill_sw_toggle: [fill] Driver-specific operation to act on
270 * userspace (or any other agent) requesting the WiMAX device to
271 * change the RF Kill software switch (WIMAX_RF_ON or
272 * WIMAX_RF_OFF).
273 * If such hardware support is not present, it is assumed the
274 * radio cannot be switched off and it is always on (and the stack
275 * will error out when trying to switch it off). In such case,
276 * this function pointer can be left as NULL.
277 *
278 * @op_reset: [fill] Driver specific operation to reset the
279 * device.
280 * This operation should always attempt first a warm reset that
281 * does not disconnect the device from the bus and return 0.
282 * If that fails, it should resort to some sort of cold or bus
283 * reset (even if it implies a bus disconnection and device
284 * dissapearance). In that case, -ENODEV should be returned to
285 * indicate the device is gone.
286 * This operation has to be synchronous, and return only when the
287 * reset is complete. In case of having had to resort to bus/cold
288 * reset implying a device disconnection, the call is allowed to
289 * return inmediately.
290 * NOTE: wimax_dev->mutex is NOT locked when this op is being
291 * called; however, wimax_dev->mutex_reset IS locked to ensure
292 * serialization of calls to wimax_reset().
293 * See wimax_reset()'s documentation.
294 *
295 * @name: [fill] A way to identify this device. We need to register a
296 * name with many subsystems (input for RFKILL, workqueue
297 * creation, etc). We can't use the network device name as that
298 * might change and in some instances we don't know it yet (until
299 * we don't call register_netdev()). So we generate an unique one
300 * using the driver name and device bus id, place it here and use
301 * it across the board. Recommended naming:
302 * DRIVERNAME-BUSNAME:BUSID (dev->bus->name, dev->bus_id).
303 *
304 * @id_table_node: [private] link to the list of wimax devices kept by
305 * id-table.c. Protected by it's own spinlock.
306 *
307 * @mutex: [private] Serializes all concurrent access and execution of
308 * operations.
309 *
310 * @mutex_reset: [private] Serializes reset operations. Needs to be a
311 * different mutex because as part of the reset operation, the
312 * driver has to call back into the stack to do things such as
313 * state change, that require wimax_dev->mutex.
314 *
315 * @state: [private] Current state of the WiMAX device.
316 *
317 * @rfkill: [private] integration into the RF-Kill infrastructure.
318 *
319 * @rfkill_input: [private] virtual input device to process the
320 * hardware RF Kill switches.
321 *
322 * @rf_sw: [private] State of the software radio switch (OFF/ON)
323 *
324 * @rf_hw: [private] State of the hardware radio switch (OFF/ON)
325 *
326 * Description:
327 * This structure defines a common interface to access all WiMAX
328 * devices from different vendors and provides a common API as well as
329 * a free-form device-specific messaging channel.
330 *
331 * Usage:
332 * 1. Embed a &struct wimax_dev at *the beginning* the network
333 * device structure so that netdev_priv() points to it.
334 *
335 * 2. memset() it to zero
336 *
337 * 3. Initialize with wimax_dev_init(). This will leave the WiMAX
338 * device in the %__WIMAX_ST_NULL state.
339 *
340 * 4. Fill all the fields marked with [fill]; once called
341 * wimax_dev_add(), those fields CANNOT be modified.
342 *
343 * 5. Call wimax_dev_add() *after* registering the network
344 * device. This will leave the WiMAX device in the %WIMAX_ST_DOWN
345 * state.
346 * Protect the driver's net_device->open() against succeeding if
347 * the wimax device state is lower than %WIMAX_ST_DOWN.
348 *
349 * 6. Select when the device is going to be turned on/initialized;
350 * for example, it could be initialized on 'ifconfig up' (when the
351 * netdev op 'open()' is called on the driver).
352 *
353 * When the device is initialized (at `ifconfig up` time, or right
354 * after calling wimax_dev_add() from _probe(), make sure the
355 * following steps are taken
356 *
357 * a. Move the device to %WIMAX_ST_UNINITIALIZED. This is needed so
358 * some API calls that shouldn't work until the device is ready
359 * can be blocked.
360 *
361 * b. Initialize the device. Make sure to turn the SW radio switch
362 * off and move the device to state %WIMAX_ST_RADIO_OFF when
363 * done. When just initialized, a device should be left in RADIO
364 * OFF state until user space devices to turn it on.
365 *
366 * c. Query the device for the state of the hardware rfkill switch
367 * and call wimax_rfkill_report_hw() and wimax_rfkill_report_sw()
368 * as needed. See below.
369 *
370 * wimax_dev_rm() undoes before unregistering the network device. Once
371 * wimax_dev_add() is called, the driver can get called on the
372 * wimax_dev->op_* function pointers
373 *
374 * CONCURRENCY:
375 *
376 * The stack provides a mutex for each device that will disallow API
377 * calls happening concurrently; thus, op calls into the driver
378 * through the wimax_dev->op*() function pointers will always be
379 * serialized and *never* concurrent.
380 *
381 * For locking, take wimax_dev->mutex is taken; (most) operations in
382 * the API have to check for wimax_dev_is_ready() to return 0 before
383 * continuing (this is done internally).
384 *
385 * REFERENCE COUNTING:
386 *
387 * The WiMAX device is reference counted by the associated network
388 * device. The only operation that can be used to reference the device
389 * is wimax_dev_get_by_genl_info(), and the reference it acquires has
390 * to be released with dev_put(wimax_dev->net_dev).
391 *
392 * RFKILL:
393 *
394 * At startup, both HW and SW radio switchess are assumed to be off.
395 *
396 * At initialization time [after calling wimax_dev_add()], have the
397 * driver query the device for the status of the software and hardware
398 * RF kill switches and call wimax_report_rfkill_hw() and
399 * wimax_rfkill_report_sw() to indicate their state. If any is
400 * missing, just call it to indicate it is ON (radio always on).
401 *
402 * Whenever the driver detects a change in the state of the RF kill
403 * switches, it should call wimax_report_rfkill_hw() or
404 * wimax_report_rfkill_sw() to report it to the stack.
405 */
406struct wimax_dev {
407 struct net_device *net_dev;
408 struct list_head id_table_node;
409 struct mutex mutex; /* Protects all members and API calls */
410 struct mutex mutex_reset;
411 enum wimax_st state;
412
413 int (*op_msg_from_user)(struct wimax_dev *wimax_dev,
414 const char *,
415 const void *, size_t,
416 const struct genl_info *info);
417 int (*op_rfkill_sw_toggle)(struct wimax_dev *wimax_dev,
418 enum wimax_rf_state);
419 int (*op_reset)(struct wimax_dev *wimax_dev);
420
421 struct rfkill *rfkill;
422 struct input_dev *rfkill_input;
423 unsigned rf_hw;
424 unsigned rf_sw;
425 char name[32];
426
427 struct dentry *debugfs_dentry;
428};
429
430
431
432/*
433 * WiMAX stack public API for device drivers
434 * -----------------------------------------
435 *
436 * These functions are not exported to user space.
437 */
438extern void wimax_dev_init(struct wimax_dev *);
439extern int wimax_dev_add(struct wimax_dev *, struct net_device *);
440extern void wimax_dev_rm(struct wimax_dev *);
441
442static inline
443struct wimax_dev *net_dev_to_wimax(struct net_device *net_dev)
444{
445 return netdev_priv(net_dev);
446}
447
448static inline
449struct device *wimax_dev_to_dev(struct wimax_dev *wimax_dev)
450{
451 return wimax_dev->net_dev->dev.parent;
452}
453
454extern void wimax_state_change(struct wimax_dev *, enum wimax_st);
455extern enum wimax_st wimax_state_get(struct wimax_dev *);
456
457/*
458 * Radio Switch state reporting.
459 *
460 * enum wimax_rf_state is declared in linux/wimax.h so the exports
461 * to user space can use it.
462 */
463extern void wimax_report_rfkill_hw(struct wimax_dev *, enum wimax_rf_state);
464extern void wimax_report_rfkill_sw(struct wimax_dev *, enum wimax_rf_state);
465
466
467/*
468 * Free-form messaging to/from user space
469 *
470 * Sending a message:
471 *
472 * wimax_msg(wimax_dev, pipe_name, buf, buf_size, GFP_KERNEL);
473 *
474 * Broken up:
475 *
476 * skb = wimax_msg_alloc(wimax_dev, pipe_name, buf_size, GFP_KERNEL);
477 * ...fill up skb...
478 * wimax_msg_send(wimax_dev, pipe_name, skb);
479 *
480 * Be sure not to modify skb->data in the middle (ie: don't use
481 * skb_push()/skb_pull()/skb_reserve() on the skb).
482 *
483 * "pipe_name" is any string, than can be interpreted as the name of
484 * the pipe or destinatary; the interpretation of it is driver
485 * specific, so the recipient can multiplex it as wished. It can be
486 * NULL, it won't be used - an example is using a "diagnostics" tag to
487 * send diagnostics information that a device-specific diagnostics
488 * tool would be interested in.
489 */
490extern struct sk_buff *wimax_msg_alloc(struct wimax_dev *, const char *,
491 const void *, size_t, gfp_t);
492extern int wimax_msg_send(struct wimax_dev *, struct sk_buff *);
493extern int wimax_msg(struct wimax_dev *, const char *,
494 const void *, size_t, gfp_t);
495
496extern const void *wimax_msg_data_len(struct sk_buff *, size_t *);
497extern const void *wimax_msg_data(struct sk_buff *);
498extern ssize_t wimax_msg_len(struct sk_buff *);
499
500
501/*
502 * WiMAX stack user space API
503 * --------------------------
504 *
505 * This API is what gets exported to user space for general
506 * operations. As well, they can be called from within the kernel,
507 * (with a properly referenced `struct wimax_dev`).
508 *
509 * Properly referenced means: the 'struct net_device' that embeds the
510 * device's control structure and (as such) the 'struct wimax_dev' is
511 * referenced by the caller.
512 */
513extern int wimax_rfkill(struct wimax_dev *, enum wimax_rf_state);
514extern int wimax_reset(struct wimax_dev *);
515
516#else
517/* You might be looking for linux/wimax.h */
518#error This file should not be included from user space.
519#endif /* #ifdef __KERNEL__ */
520#endif /* #ifndef __NET__WIMAX_H__ */