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