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1 /* SPDX-License-Identifier: GPL-2.0-only */
4 * Kernel space API for accessing WiMAX devices
6 * Copyright (C) 2007-2008 Intel Corporation <linux-wimax@intel.com>
7 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
9 * The WiMAX stack provides an API for controlling and managing the
10 * system's WiMAX devices. This API affects the control plane; the
11 * data plane is accessed via the network stack (netdev).
13 * Parts of the WiMAX stack API and notifications are exported to
14 * user space via Generic Netlink. In user space, libwimax (part of
15 * the wimax-tools package) provides a shim layer for accessing those
18 * The API is standarized for all WiMAX devices and different drivers
19 * implement the backend support for it. However, device-specific
20 * messaging pipes are provided that can be used to issue commands and
21 * receive notifications in free form.
23 * Currently the messaging pipes are the only means of control as it
24 * is not known (due to the lack of more devices in the market) what
25 * will be a good abstraction layer. Expect this to change as more
26 * devices show in the market. This API is designed to be growable in
27 * order to address this problem.
31 * Embed a `struct wimax_dev` at the beginning of the the device's
32 * private structure, initialize and register it. For details, see
33 * `struct wimax_dev`s documentation.
35 * Once this is done, wimax-tools's libwimaxll can be used to
36 * communicate with the driver from user space. You user space
37 * application does not have to forcibily use libwimaxll and can talk
38 * the generic netlink protocol directly if desired.
40 * Remember this is a very low level API that will to provide all of
41 * WiMAX features. Other daemons and services running in user space
42 * are the expected clients of it. They offer a higher level API that
43 * applications should use (an example of this is the Intel's WiMAX
44 * Network Service for the i2400m).
48 * Although not set on final stone, this very basic interface is
49 * mostly completed. Remember this is meant to grow as new common
50 * operations are decided upon. New operations will be added to the
51 * interface, intent being on keeping backwards compatibility as much
54 * This layer implements a set of calls to control a WiMAX device,
55 * exposing a frontend to the rest of the kernel and user space (via
56 * generic netlink) and a backend implementation in the driver through
59 * WiMAX devices have a state, and a kernel-only API allows the
60 * drivers to manipulate that state. State transitions are atomic, and
61 * only some of them are allowed (see `enum wimax_st`).
63 * Most API calls will set the state automatically; in most cases
64 * drivers have to only report state changes due to external
67 * All API operations are 'atomic', serialized through a mutex in the
70 * EXPORTING TO USER SPACE THROUGH GENERIC NETLINK
72 * The API is exported to user space using generic netlink (other
73 * methods can be added as needed).
75 * There is a Generic Netlink Family named "WiMAX", where interfaces
76 * supporting the WiMAX interface receive commands and broadcast their
77 * signals over a multicast group named "msg".
79 * Mapping to the source/destination interface is done by an interface
82 * For user-to-kernel traffic (commands) we use a function call
83 * marshalling mechanism, where a message X with attributes A, B, C
84 * sent from user space to kernel space means executing the WiMAX API
85 * call wimax_X(A, B, C), sending the results back as a message.
87 * Kernel-to-user (notifications or signals) communication is sent
88 * over multicast groups. This allows to have multiple applications
91 * Each command/signal gets assigned it's own attribute policy. This
92 * way the validator will verify that all the attributes in there are
93 * only the ones that should be for each command/signal. Thing of an
94 * attribute mapping to a type+argumentname for each command/signal.
96 * If we had a single policy for *all* commands/signals, after running
97 * the validator we'd have to check "does this attribute belong in
98 * here"? for each one. It can be done manually, but it's just easier
99 * to have the validator do that job with multiple policies. As well,
100 * it makes it easier to later expand each command/signal signature
101 * without affecting others and keeping the namespace more or less
102 * sane. Not that it is too complicated, but it makes it even easier.
104 * No state information is maintained in the kernel for each user
105 * space connection (the connection is stateless).
107 * TESTING FOR THE INTERFACE AND VERSIONING
109 * If network interface X is a WiMAX device, there will be a Generic
110 * Netlink family named "WiMAX X" and the device will present a
111 * "wimax" directory in it's network sysfs directory
112 * (/sys/class/net/DEVICE/wimax) [used by HAL].
114 * The inexistence of any of these means the device does not support
117 * By querying the generic netlink controller, versioning information
118 * and the multicast groups available can be found. Applications using
119 * the interface can either rely on that or use the generic netlink
120 * controller to figure out which generic netlink commands/signals are
123 * NOTE: this versioning is a last resort to avoid hard
124 * incompatibilities. It is the intention of the design of this
125 * stack not to introduce backward incompatible changes.
127 * The version code has to fit in one byte (restrictions imposed by
128 * generic netlink); we use `version / 10` for the major version and
129 * `version % 10` for the minor. This gives 9 minors for each major
132 * The version change protocol is as follow:
134 * - Major versions: needs to be increased if an existing message/API
135 * call is changed or removed. Doesn't need to be changed if a new
138 * - Minor version: needs to be increased if new messages/API calls are
139 * being added or some other consideration that doesn't impact the
140 * user-kernel interface too much (like some kind of bug fix) and
141 * that is kind of left up in the air to common sense.
143 * User space code should not try to work if the major version it was
144 * compiled for differs from what the kernel offers. As well, if the
145 * minor version of the kernel interface is lower than the one user
146 * space is expecting (the one it was compiled for), the kernel
147 * might be missing API calls; user space shall be ready to handle
148 * said condition. Use the generic netlink controller operations to
149 * find which ones are supported and which not.
151 * libwimaxll:wimaxll_open() takes care of checking versions.
155 * Each operation is defined in its on file (drivers/net/wimax/op-*.c)
156 * for clarity. The parts needed for an operation are:
158 * - a function pointer in `struct wimax_dev`: optional, as the
159 * operation might be implemented by the stack and not by the
162 * All function pointers are named wimax_dev->op_*(), and drivers
163 * must implement them except where noted otherwise.
165 * - When exported to user space, a `struct nla_policy` to define the
166 * attributes of the generic netlink command and a `struct genl_ops`
167 * to define the operation.
169 * All the declarations for the operation codes (WIMAX_GNL_OP_<NAME>)
170 * and generic netlink attributes (WIMAX_GNL_<NAME>_*) are declared in
171 * include/linux/wimax.h; this file is intended to be cloned by user
172 * space to gain access to those declarations.
174 * A few caveats to remember:
176 * - Need to define attribute numbers starting in 1; otherwise it
179 * - the `struct genl_family` requires a maximum attribute id; when
180 * defining the `struct nla_policy` for each message, it has to have
181 * an array size of WIMAX_GNL_ATTR_MAX+1.
183 * The op_*() function pointers will not be called if the wimax_dev is
184 * in a state <= %WIMAX_ST_UNINITIALIZED. The exception is:
186 * - op_reset: can be called at any time after wimax_dev_add() has
189 * THE PIPE INTERFACE:
191 * This interface is kept intentionally simple. The driver can send
192 * and receive free-form messages to/from user space through a
193 * pipe. See drivers/net/wimax/op-msg.c for details.
195 * The kernel-to-user messages are sent with
196 * wimax_msg(). user-to-kernel messages are delivered via
197 * wimax_dev->op_msg_from_user().
201 * RFKILL support is built into the wimax_dev layer; the driver just
202 * needs to call wimax_report_rfkill_{hw,sw}() to inform of changes in
203 * the hardware or software RF kill switches. When the stack wants to
204 * turn the radio off, it will call wimax_dev->op_rfkill_sw_toggle(),
205 * which the driver implements.
207 * User space can set the software RF Kill switch by calling
210 * The code for now only supports devices that don't require polling;
211 * If the device needs to be polled, create a self-rearming delayed
212 * work struct for polling or look into adding polled support to the
215 * When initializing the hardware (_probe), after calling
216 * wimax_dev_add(), query the device for it's RF Kill switches status
217 * and feed it back to the WiMAX stack using
218 * wimax_report_rfkill_{hw,sw}(). If any switch is missing, always
221 * NOTE: the wimax stack uses an inverted terminology to that of the
224 * - ON: radio is ON, RFKILL is DISABLED or OFF.
225 * - OFF: radio is OFF, RFKILL is ENABLED or ON.
229 * wimax_reset() can be used to reset the device to power on state; by
230 * default it issues a warm reset that maintains the same device
231 * node. If that is not possible, it falls back to a cold reset
232 * (device reconnect). The driver implements the backend to this
233 * through wimax_dev->op_reset().
236 #ifndef __NET__WIMAX_H__
237 #define __NET__WIMAX_H__
239 #include <linux/wimax.h>
240 #include <net/genetlink.h>
241 #include <linux/netdevice.h>
248 * struct wimax_dev - Generic WiMAX device
250 * @net_dev: [fill] Pointer to the &struct net_device this WiMAX
253 * @op_msg_from_user: [fill] Driver-specific operation to
254 * handle a raw message from user space to the driver. The
255 * driver can send messages to user space using with
256 * wimax_msg_to_user().
258 * @op_rfkill_sw_toggle: [fill] Driver-specific operation to act on
259 * userspace (or any other agent) requesting the WiMAX device to
260 * change the RF Kill software switch (WIMAX_RF_ON or
262 * If such hardware support is not present, it is assumed the
263 * radio cannot be switched off and it is always on (and the stack
264 * will error out when trying to switch it off). In such case,
265 * this function pointer can be left as NULL.
267 * @op_reset: [fill] Driver specific operation to reset the
269 * This operation should always attempt first a warm reset that
270 * does not disconnect the device from the bus and return 0.
271 * If that fails, it should resort to some sort of cold or bus
272 * reset (even if it implies a bus disconnection and device
273 * disappearance). In that case, -ENODEV should be returned to
274 * indicate the device is gone.
275 * This operation has to be synchronous, and return only when the
276 * reset is complete. In case of having had to resort to bus/cold
277 * reset implying a device disconnection, the call is allowed to
278 * return immediately.
279 * NOTE: wimax_dev->mutex is NOT locked when this op is being
280 * called; however, wimax_dev->mutex_reset IS locked to ensure
281 * serialization of calls to wimax_reset().
282 * See wimax_reset()'s documentation.
284 * @name: [fill] A way to identify this device. We need to register a
285 * name with many subsystems (rfkill, workqueue creation, etc).
286 * We can't use the network device name as that
287 * might change and in some instances we don't know it yet (until
288 * we don't call register_netdev()). So we generate an unique one
289 * using the driver name and device bus id, place it here and use
290 * it across the board. Recommended naming:
291 * DRIVERNAME-BUSNAME:BUSID (dev->bus->name, dev->bus_id).
293 * @id_table_node: [private] link to the list of wimax devices kept by
294 * id-table.c. Protected by it's own spinlock.
296 * @mutex: [private] Serializes all concurrent access and execution of
299 * @mutex_reset: [private] Serializes reset operations. Needs to be a
300 * different mutex because as part of the reset operation, the
301 * driver has to call back into the stack to do things such as
302 * state change, that require wimax_dev->mutex.
304 * @state: [private] Current state of the WiMAX device.
306 * @rfkill: [private] integration into the RF-Kill infrastructure.
308 * @rf_sw: [private] State of the software radio switch (OFF/ON)
310 * @rf_hw: [private] State of the hardware radio switch (OFF/ON)
312 * @debugfs_dentry: [private] Used to hook up a debugfs entry. This
313 * shows up in the debugfs root as wimax\:DEVICENAME.
316 * This structure defines a common interface to access all WiMAX
317 * devices from different vendors and provides a common API as well as
318 * a free-form device-specific messaging channel.
321 * 1. Embed a &struct wimax_dev at *the beginning* the network
322 * device structure so that netdev_priv() points to it.
324 * 2. memset() it to zero
326 * 3. Initialize with wimax_dev_init(). This will leave the WiMAX
327 * device in the %__WIMAX_ST_NULL state.
329 * 4. Fill all the fields marked with [fill]; once called
330 * wimax_dev_add(), those fields CANNOT be modified.
332 * 5. Call wimax_dev_add() *after* registering the network
333 * device. This will leave the WiMAX device in the %WIMAX_ST_DOWN
335 * Protect the driver's net_device->open() against succeeding if
336 * the wimax device state is lower than %WIMAX_ST_DOWN.
338 * 6. Select when the device is going to be turned on/initialized;
339 * for example, it could be initialized on 'ifconfig up' (when the
340 * netdev op 'open()' is called on the driver).
342 * When the device is initialized (at `ifconfig up` time, or right
343 * after calling wimax_dev_add() from _probe(), make sure the
344 * following steps are taken
346 * a. Move the device to %WIMAX_ST_UNINITIALIZED. This is needed so
347 * some API calls that shouldn't work until the device is ready
350 * b. Initialize the device. Make sure to turn the SW radio switch
351 * off and move the device to state %WIMAX_ST_RADIO_OFF when
352 * done. When just initialized, a device should be left in RADIO
353 * OFF state until user space devices to turn it on.
355 * c. Query the device for the state of the hardware rfkill switch
356 * and call wimax_rfkill_report_hw() and wimax_rfkill_report_sw()
357 * as needed. See below.
359 * wimax_dev_rm() undoes before unregistering the network device. Once
360 * wimax_dev_add() is called, the driver can get called on the
361 * wimax_dev->op_* function pointers
365 * The stack provides a mutex for each device that will disallow API
366 * calls happening concurrently; thus, op calls into the driver
367 * through the wimax_dev->op*() function pointers will always be
368 * serialized and *never* concurrent.
370 * For locking, take wimax_dev->mutex is taken; (most) operations in
371 * the API have to check for wimax_dev_is_ready() to return 0 before
372 * continuing (this is done internally).
374 * REFERENCE COUNTING:
376 * The WiMAX device is reference counted by the associated network
377 * device. The only operation that can be used to reference the device
378 * is wimax_dev_get_by_genl_info(), and the reference it acquires has
379 * to be released with dev_put(wimax_dev->net_dev).
383 * At startup, both HW and SW radio switchess are assumed to be off.
385 * At initialization time [after calling wimax_dev_add()], have the
386 * driver query the device for the status of the software and hardware
387 * RF kill switches and call wimax_report_rfkill_hw() and
388 * wimax_rfkill_report_sw() to indicate their state. If any is
389 * missing, just call it to indicate it is ON (radio always on).
391 * Whenever the driver detects a change in the state of the RF kill
392 * switches, it should call wimax_report_rfkill_hw() or
393 * wimax_report_rfkill_sw() to report it to the stack.
396 struct net_device
*net_dev
;
397 struct list_head id_table_node
;
398 struct mutex mutex
; /* Protects all members and API calls */
399 struct mutex mutex_reset
;
402 int (*op_msg_from_user
)(struct wimax_dev
*wimax_dev
,
404 const void *, size_t,
405 const struct genl_info
*info
);
406 int (*op_rfkill_sw_toggle
)(struct wimax_dev
*wimax_dev
,
407 enum wimax_rf_state
);
408 int (*op_reset
)(struct wimax_dev
*wimax_dev
);
410 struct rfkill
*rfkill
;
415 struct dentry
*debugfs_dentry
;
421 * WiMAX stack public API for device drivers
422 * -----------------------------------------
424 * These functions are not exported to user space.
426 void wimax_dev_init(struct wimax_dev
*);
427 int wimax_dev_add(struct wimax_dev
*, struct net_device
*);
428 void wimax_dev_rm(struct wimax_dev
*);
431 struct wimax_dev
*net_dev_to_wimax(struct net_device
*net_dev
)
433 return netdev_priv(net_dev
);
437 struct device
*wimax_dev_to_dev(struct wimax_dev
*wimax_dev
)
439 return wimax_dev
->net_dev
->dev
.parent
;
442 void wimax_state_change(struct wimax_dev
*, enum wimax_st
);
443 enum wimax_st
wimax_state_get(struct wimax_dev
*);
446 * Radio Switch state reporting.
448 * enum wimax_rf_state is declared in linux/wimax.h so the exports
449 * to user space can use it.
451 void wimax_report_rfkill_hw(struct wimax_dev
*, enum wimax_rf_state
);
452 void wimax_report_rfkill_sw(struct wimax_dev
*, enum wimax_rf_state
);
456 * Free-form messaging to/from user space
460 * wimax_msg(wimax_dev, pipe_name, buf, buf_size, GFP_KERNEL);
464 * skb = wimax_msg_alloc(wimax_dev, pipe_name, buf_size, GFP_KERNEL);
466 * wimax_msg_send(wimax_dev, pipe_name, skb);
468 * Be sure not to modify skb->data in the middle (ie: don't use
469 * skb_push()/skb_pull()/skb_reserve() on the skb).
471 * "pipe_name" is any string, that can be interpreted as the name of
472 * the pipe or recipient; the interpretation of it is driver
473 * specific, so the recipient can multiplex it as wished. It can be
474 * NULL, it won't be used - an example is using a "diagnostics" tag to
475 * send diagnostics information that a device-specific diagnostics
476 * tool would be interested in.
478 struct sk_buff
*wimax_msg_alloc(struct wimax_dev
*, const char *, const void *,
480 int wimax_msg_send(struct wimax_dev
*, struct sk_buff
*);
481 int wimax_msg(struct wimax_dev
*, const char *, const void *, size_t, gfp_t
);
483 const void *wimax_msg_data_len(struct sk_buff
*, size_t *);
484 const void *wimax_msg_data(struct sk_buff
*);
485 ssize_t
wimax_msg_len(struct sk_buff
*);
489 * WiMAX stack user space API
490 * --------------------------
492 * This API is what gets exported to user space for general
493 * operations. As well, they can be called from within the kernel,
494 * (with a properly referenced `struct wimax_dev`).
496 * Properly referenced means: the 'struct net_device' that embeds the
497 * device's control structure and (as such) the 'struct wimax_dev' is
498 * referenced by the caller.
500 int wimax_rfkill(struct wimax_dev
*, enum wimax_rf_state
);
501 int wimax_reset(struct wimax_dev
*);
503 #endif /* #ifndef __NET__WIMAX_H__ */