1 /* SPDX-License-Identifier: GPL-2.0+ */
2 /*
3 * Surface System Aggregator Module (SSAM) bus and client-device subsystem.
4 *
5 * Main interface for the surface-aggregator bus, surface-aggregator client
6 * devices, and respective drivers building on top of the SSAM controller.
7 * Provides support for non-platform/non-ACPI SSAM clients via dedicated
8 * subsystem.
9 *
10 * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>
11 */
12
13 #ifndef _LINUX_SURFACE_AGGREGATOR_DEVICE_H
14 #define _LINUX_SURFACE_AGGREGATOR_DEVICE_H
15
16 #include <linux/device.h>
17 #include <linux/mod_devicetable.h>
18 #include <linux/property.h>
19 #include <linux/types.h>
20
21 #include <linux/surface_aggregator/controller.h>
22
23
24 /* -- Surface System Aggregator Module bus. --------------------------------- */
25
26 /**
27 * enum ssam_device_domain - SAM device domain.
28 * @SSAM_DOMAIN_VIRTUAL: Virtual device.
29 * @SSAM_DOMAIN_SERIALHUB: Physical device connected via Surface Serial Hub.
30 */
31 enum ssam_device_domain {
32 SSAM_DOMAIN_VIRTUAL = 0x00,
33 SSAM_DOMAIN_SERIALHUB = 0x01,
34 };
35
36 /**
37 * enum ssam_virtual_tc - Target categories for the virtual SAM domain.
38 * @SSAM_VIRTUAL_TC_HUB: Device hub category.
39 */
40 enum ssam_virtual_tc {
41 SSAM_VIRTUAL_TC_HUB = 0x00,
42 };
43
44 /**
45 * struct ssam_device_uid - Unique identifier for SSAM device.
46 * @domain: Domain of the device.
47 * @category: Target category of the device.
48 * @target: Target ID of the device.
49 * @instance: Instance ID of the device.
50 * @function: Sub-function of the device. This field can be used to split a
51 * single SAM device into multiple virtual subdevices to separate
52 * different functionality of that device and allow one driver per
53 * such functionality.
54 */
55 struct ssam_device_uid {
56 u8 domain;
57 u8 category;
58 u8 target;
59 u8 instance;
60 u8 function;
61 };
62
63 /*
64 * Special values for device matching.
65 *
66 * These values are intended to be used with SSAM_DEVICE(), SSAM_VDEV(), and
67 * SSAM_SDEV() exclusively. Specifically, they are used to initialize the
68 * match_flags member of the device ID structure. Do not use them directly
69 * with struct ssam_device_id or struct ssam_device_uid.
70 */
71 #define SSAM_SSH_TID_ANY 0xffff
72 #define SSAM_SSH_IID_ANY 0xffff
73 #define SSAM_SSH_FUN_ANY 0xffff
74
75 /**
76 * SSAM_DEVICE() - Initialize a &struct ssam_device_id with the given
77 * parameters.
78 * @d: Domain of the device.
79 * @cat: Target category of the device.
80 * @tid: Target ID of the device.
81 * @iid: Instance ID of the device.
82 * @fun: Sub-function of the device.
83 *
84 * Initializes a &struct ssam_device_id with the given parameters. See &struct
85 * ssam_device_uid for details regarding the parameters. The special values
86 * %SSAM_SSH_TID_ANY, %SSAM_SSH_IID_ANY, and %SSAM_SSH_FUN_ANY can be used to specify that
87 * matching should ignore target ID, instance ID, and/or sub-function,
88 * respectively. This macro initializes the ``match_flags`` field based on the
89 * given parameters.
90 *
91 * Note: The parameters @d and @cat must be valid &u8 values, the parameters
92 * @tid, @iid, and @fun must be either valid &u8 values or %SSAM_SSH_TID_ANY,
93 * %SSAM_SSH_IID_ANY, or %SSAM_SSH_FUN_ANY, respectively. Other non-&u8 values are not
94 * allowed.
95 */
96 #define SSAM_DEVICE(d, cat, tid, iid, fun) \
97 .match_flags = (((tid) != SSAM_SSH_TID_ANY) ? SSAM_MATCH_TARGET : 0) \
98 | (((iid) != SSAM_SSH_IID_ANY) ? SSAM_MATCH_INSTANCE : 0) \
99 | (((fun) != SSAM_SSH_FUN_ANY) ? SSAM_MATCH_FUNCTION : 0), \
100 .domain = d, \
101 .category = cat, \
102 .target = __builtin_choose_expr((tid) != SSAM_SSH_TID_ANY, (tid), 0), \
103 .instance = __builtin_choose_expr((iid) != SSAM_SSH_IID_ANY, (iid), 0), \
104 .function = __builtin_choose_expr((fun) != SSAM_SSH_FUN_ANY, (fun), 0)
105
106 /**
107 * SSAM_VDEV() - Initialize a &struct ssam_device_id as virtual device with
108 * the given parameters.
109 * @cat: Target category of the device.
110 * @tid: Target ID of the device.
111 * @iid: Instance ID of the device.
112 * @fun: Sub-function of the device.
113 *
114 * Initializes a &struct ssam_device_id with the given parameters in the
115 * virtual domain. See &struct ssam_device_uid for details regarding the
116 * parameters. The special values %SSAM_SSH_TID_ANY, %SSAM_SSH_IID_ANY, and
117 * %SSAM_SSH_FUN_ANY can be used to specify that matching should ignore target ID,
118 * instance ID, and/or sub-function, respectively. This macro initializes the
119 * ``match_flags`` field based on the given parameters.
120 *
121 * Note: The parameter @cat must be a valid &u8 value, the parameters @tid,
122 * @iid, and @fun must be either valid &u8 values or %SSAM_SSH_TID_ANY,
123 * %SSAM_SSH_IID_ANY, or %SSAM_SSH_FUN_ANY, respectively. Other non-&u8 values are not
124 * allowed.
125 */
126 #define SSAM_VDEV(cat, tid, iid, fun) \
127 SSAM_DEVICE(SSAM_DOMAIN_VIRTUAL, SSAM_VIRTUAL_TC_##cat, SSAM_SSH_TID_##tid, iid, fun)
128
129 /**
130 * SSAM_SDEV() - Initialize a &struct ssam_device_id as physical SSH device
131 * with the given parameters.
132 * @cat: Target category of the device.
133 * @tid: Target ID of the device.
134 * @iid: Instance ID of the device.
135 * @fun: Sub-function of the device.
136 *
137 * Initializes a &struct ssam_device_id with the given parameters in the SSH
138 * domain. See &struct ssam_device_uid for details regarding the parameters.
139 * The special values %SSAM_SSH_TID_ANY, %SSAM_SSH_IID_ANY, and
140 * %SSAM_SSH_FUN_ANY can be used to specify that matching should ignore target
141 * ID, instance ID, and/or sub-function, respectively. This macro initializes
142 * the ``match_flags`` field based on the given parameters.
143 *
144 * Note: The parameter @cat must be a valid &u8 value, the parameters @tid,
145 * @iid, and @fun must be either valid &u8 values or %SSAM_SSH_TID_ANY,
146 * %SSAM_SSH_IID_ANY, or %SSAM_SSH_FUN_ANY, respectively. Other non-&u8 values
147 * are not allowed.
148 */
149 #define SSAM_SDEV(cat, tid, iid, fun) \
150 SSAM_DEVICE(SSAM_DOMAIN_SERIALHUB, SSAM_SSH_TC_##cat, SSAM_SSH_TID_##tid, iid, fun)
151
152 /*
153 * enum ssam_device_flags - Flags for SSAM client devices.
154 * @SSAM_DEVICE_HOT_REMOVED_BIT:
155 * The device has been hot-removed. Further communication with it may time
156 * out and should be avoided.
157 */
158 enum ssam_device_flags {
159 SSAM_DEVICE_HOT_REMOVED_BIT = 0,
160 };
161
162 /**
163 * struct ssam_device - SSAM client device.
164 * @dev: Driver model representation of the device.
165 * @ctrl: SSAM controller managing this device.
166 * @uid: UID identifying the device.
167 * @flags: Device state flags, see &enum ssam_device_flags.
168 */
169 struct ssam_device {
170 struct device dev;
171 struct ssam_controller *ctrl;
172
173 struct ssam_device_uid uid;
174
175 unsigned long flags;
176 };
177
178 /**
179 * struct ssam_device_driver - SSAM client device driver.
180 * @driver: Base driver model structure.
181 * @match_table: Match table specifying which devices the driver should bind to.
182 * @probe: Called when the driver is being bound to a device.
183 * @remove: Called when the driver is being unbound from the device.
184 */
185 struct ssam_device_driver {
186 struct device_driver driver;
187
188 const struct ssam_device_id *match_table;
189
190 int (*probe)(struct ssam_device *sdev);
191 void (*remove)(struct ssam_device *sdev);
192 };
193
194 #ifdef CONFIG_SURFACE_AGGREGATOR_BUS
195
196 extern struct bus_type ssam_bus_type;
197 extern const struct device_type ssam_device_type;
198
199 /**
200 * is_ssam_device() - Check if the given device is a SSAM client device.
201 * @d: The device to test the type of.
202 *
203 * Return: Returns %true if the specified device is of type &struct
204 * ssam_device, i.e. the device type points to %ssam_device_type, and %false
205 * otherwise.
206 */
is_ssam_device(struct device * d)207 static inline bool is_ssam_device(struct device *d)
208 {
209 return d->type == &ssam_device_type;
210 }
211
212 #else /* CONFIG_SURFACE_AGGREGATOR_BUS */
213
is_ssam_device(struct device * d)214 static inline bool is_ssam_device(struct device *d)
215 {
216 return false;
217 }
218
219 #endif /* CONFIG_SURFACE_AGGREGATOR_BUS */
220
221 /**
222 * to_ssam_device() - Casts the given device to a SSAM client device.
223 * @d: The device to cast.
224 *
225 * Casts the given &struct device to a &struct ssam_device. The caller has to
226 * ensure that the given device is actually enclosed in a &struct ssam_device,
227 * e.g. by calling is_ssam_device().
228 *
229 * Return: Returns a pointer to the &struct ssam_device wrapping the given
230 * device @d.
231 */
232 #define to_ssam_device(d) container_of_const(d, struct ssam_device, dev)
233
234 /**
235 * to_ssam_device_driver() - Casts the given device driver to a SSAM client
236 * device driver.
237 * @d: The driver to cast.
238 *
239 * Casts the given &struct device_driver to a &struct ssam_device_driver. The
240 * caller has to ensure that the given driver is actually enclosed in a
241 * &struct ssam_device_driver.
242 *
243 * Return: Returns the pointer to the &struct ssam_device_driver wrapping the
244 * given device driver @d.
245 */
246 static inline
to_ssam_device_driver(struct device_driver * d)247 struct ssam_device_driver *to_ssam_device_driver(struct device_driver *d)
248 {
249 return container_of(d, struct ssam_device_driver, driver);
250 }
251
252 const struct ssam_device_id *ssam_device_id_match(const struct ssam_device_id *table,
253 const struct ssam_device_uid uid);
254
255 const struct ssam_device_id *ssam_device_get_match(const struct ssam_device *dev);
256
257 const void *ssam_device_get_match_data(const struct ssam_device *dev);
258
259 struct ssam_device *ssam_device_alloc(struct ssam_controller *ctrl,
260 struct ssam_device_uid uid);
261
262 int ssam_device_add(struct ssam_device *sdev);
263 void ssam_device_remove(struct ssam_device *sdev);
264
265 /**
266 * ssam_device_mark_hot_removed() - Mark the given device as hot-removed.
267 * @sdev: The device to mark as hot-removed.
268 *
269 * Mark the device as having been hot-removed. This signals drivers using the
270 * device that communication with the device should be avoided and may lead to
271 * timeouts.
272 */
ssam_device_mark_hot_removed(struct ssam_device * sdev)273 static inline void ssam_device_mark_hot_removed(struct ssam_device *sdev)
274 {
275 dev_dbg(&sdev->dev, "marking device as hot-removed\n");
276 set_bit(SSAM_DEVICE_HOT_REMOVED_BIT, &sdev->flags);
277 }
278
279 /**
280 * ssam_device_is_hot_removed() - Check if the given device has been
281 * hot-removed.
282 * @sdev: The device to check.
283 *
284 * Checks if the given device has been marked as hot-removed. See
285 * ssam_device_mark_hot_removed() for more details.
286 *
287 * Return: Returns ``true`` if the device has been marked as hot-removed.
288 */
ssam_device_is_hot_removed(struct ssam_device * sdev)289 static inline bool ssam_device_is_hot_removed(struct ssam_device *sdev)
290 {
291 return test_bit(SSAM_DEVICE_HOT_REMOVED_BIT, &sdev->flags);
292 }
293
294 /**
295 * ssam_device_get() - Increment reference count of SSAM client device.
296 * @sdev: The device to increment the reference count of.
297 *
298 * Increments the reference count of the given SSAM client device by
299 * incrementing the reference count of the enclosed &struct device via
300 * get_device().
301 *
302 * See ssam_device_put() for the counter-part of this function.
303 *
304 * Return: Returns the device provided as input.
305 */
ssam_device_get(struct ssam_device * sdev)306 static inline struct ssam_device *ssam_device_get(struct ssam_device *sdev)
307 {
308 return sdev ? to_ssam_device(get_device(&sdev->dev)) : NULL;
309 }
310
311 /**
312 * ssam_device_put() - Decrement reference count of SSAM client device.
313 * @sdev: The device to decrement the reference count of.
314 *
315 * Decrements the reference count of the given SSAM client device by
316 * decrementing the reference count of the enclosed &struct device via
317 * put_device().
318 *
319 * See ssam_device_get() for the counter-part of this function.
320 */
ssam_device_put(struct ssam_device * sdev)321 static inline void ssam_device_put(struct ssam_device *sdev)
322 {
323 if (sdev)
324 put_device(&sdev->dev);
325 }
326
327 /**
328 * ssam_device_get_drvdata() - Get driver-data of SSAM client device.
329 * @sdev: The device to get the driver-data from.
330 *
331 * Return: Returns the driver-data of the given device, previously set via
332 * ssam_device_set_drvdata().
333 */
ssam_device_get_drvdata(struct ssam_device * sdev)334 static inline void *ssam_device_get_drvdata(struct ssam_device *sdev)
335 {
336 return dev_get_drvdata(&sdev->dev);
337 }
338
339 /**
340 * ssam_device_set_drvdata() - Set driver-data of SSAM client device.
341 * @sdev: The device to set the driver-data of.
342 * @data: The data to set the device's driver-data pointer to.
343 */
ssam_device_set_drvdata(struct ssam_device * sdev,void * data)344 static inline void ssam_device_set_drvdata(struct ssam_device *sdev, void *data)
345 {
346 dev_set_drvdata(&sdev->dev, data);
347 }
348
349 int __ssam_device_driver_register(struct ssam_device_driver *d, struct module *o);
350 void ssam_device_driver_unregister(struct ssam_device_driver *d);
351
352 /**
353 * ssam_device_driver_register() - Register a SSAM client device driver.
354 * @drv: The driver to register.
355 */
356 #define ssam_device_driver_register(drv) \
357 __ssam_device_driver_register(drv, THIS_MODULE)
358
359 /**
360 * module_ssam_device_driver() - Helper macro for SSAM device driver
361 * registration.
362 * @drv: The driver managed by this module.
363 *
364 * Helper macro to register a SSAM device driver via module_init() and
365 * module_exit(). This macro may only be used once per module and replaces the
366 * aforementioned definitions.
367 */
368 #define module_ssam_device_driver(drv) \
369 module_driver(drv, ssam_device_driver_register, \
370 ssam_device_driver_unregister)
371
372
373 /* -- Helpers for controller and hub devices. ------------------------------- */
374
375 #ifdef CONFIG_SURFACE_AGGREGATOR_BUS
376
377 int __ssam_register_clients(struct device *parent, struct ssam_controller *ctrl,
378 struct fwnode_handle *node);
379 void ssam_remove_clients(struct device *dev);
380
381 #else /* CONFIG_SURFACE_AGGREGATOR_BUS */
382
__ssam_register_clients(struct device * parent,struct ssam_controller * ctrl,struct fwnode_handle * node)383 static inline int __ssam_register_clients(struct device *parent, struct ssam_controller *ctrl,
384 struct fwnode_handle *node)
385 {
386 return 0;
387 }
388
ssam_remove_clients(struct device * dev)389 static inline void ssam_remove_clients(struct device *dev) {}
390
391 #endif /* CONFIG_SURFACE_AGGREGATOR_BUS */
392
393 /**
394 * ssam_register_clients() - Register all client devices defined under the
395 * given parent device.
396 * @dev: The parent device under which clients should be registered.
397 * @ctrl: The controller with which client should be registered.
398 *
399 * Register all clients that have via firmware nodes been defined as children
400 * of the given (parent) device. The respective child firmware nodes will be
401 * associated with the correspondingly created child devices.
402 *
403 * The given controller will be used to instantiate the new devices. See
404 * ssam_device_add() for details.
405 *
406 * Return: Returns zero on success, nonzero on failure.
407 */
ssam_register_clients(struct device * dev,struct ssam_controller * ctrl)408 static inline int ssam_register_clients(struct device *dev, struct ssam_controller *ctrl)
409 {
410 return __ssam_register_clients(dev, ctrl, dev_fwnode(dev));
411 }
412
413 /**
414 * ssam_device_register_clients() - Register all client devices defined under
415 * the given SSAM parent device.
416 * @sdev: The parent device under which clients should be registered.
417 *
418 * Register all clients that have via firmware nodes been defined as children
419 * of the given (parent) device. The respective child firmware nodes will be
420 * associated with the correspondingly created child devices.
421 *
422 * The controller used by the parent device will be used to instantiate the new
423 * devices. See ssam_device_add() for details.
424 *
425 * Return: Returns zero on success, nonzero on failure.
426 */
ssam_device_register_clients(struct ssam_device * sdev)427 static inline int ssam_device_register_clients(struct ssam_device *sdev)
428 {
429 return ssam_register_clients(&sdev->dev, sdev->ctrl);
430 }
431
432
433 /* -- Helpers for client-device requests. ----------------------------------- */
434
435 /**
436 * SSAM_DEFINE_SYNC_REQUEST_CL_N() - Define synchronous client-device SAM
437 * request function with neither argument nor return value.
438 * @name: Name of the generated function.
439 * @spec: Specification (&struct ssam_request_spec_md) defining the request.
440 *
441 * Defines a function executing the synchronous SAM request specified by
442 * @spec, with the request having neither argument nor return value. Device
443 * specifying parameters are not hard-coded, but instead are provided via the
444 * client device, specifically its UID, supplied when calling this function.
445 * The generated function takes care of setting up the request struct, buffer
446 * allocation, as well as execution of the request itself, returning once the
447 * request has been fully completed. The required transport buffer will be
448 * allocated on the stack.
449 *
450 * The generated function is defined as ``static int name(struct ssam_device
451 * *sdev)``, returning the status of the request, which is zero on success and
452 * negative on failure. The ``sdev`` parameter specifies both the target
453 * device of the request and by association the controller via which the
454 * request is sent.
455 *
456 * Refer to ssam_request_do_sync_onstack() for more details on the behavior of
457 * the generated function.
458 */
459 #define SSAM_DEFINE_SYNC_REQUEST_CL_N(name, spec...) \
460 SSAM_DEFINE_SYNC_REQUEST_MD_N(__raw_##name, spec) \
461 static int name(struct ssam_device *sdev) \
462 { \
463 return __raw_##name(sdev->ctrl, sdev->uid.target, \
464 sdev->uid.instance); \
465 }
466
467 /**
468 * SSAM_DEFINE_SYNC_REQUEST_CL_W() - Define synchronous client-device SAM
469 * request function with argument.
470 * @name: Name of the generated function.
471 * @atype: Type of the request's argument.
472 * @spec: Specification (&struct ssam_request_spec_md) defining the request.
473 *
474 * Defines a function executing the synchronous SAM request specified by
475 * @spec, with the request taking an argument of type @atype and having no
476 * return value. Device specifying parameters are not hard-coded, but instead
477 * are provided via the client device, specifically its UID, supplied when
478 * calling this function. The generated function takes care of setting up the
479 * request struct, buffer allocation, as well as execution of the request
480 * itself, returning once the request has been fully completed. The required
481 * transport buffer will be allocated on the stack.
482 *
483 * The generated function is defined as ``static int name(struct ssam_device
484 * *sdev, const atype *arg)``, returning the status of the request, which is
485 * zero on success and negative on failure. The ``sdev`` parameter specifies
486 * both the target device of the request and by association the controller via
487 * which the request is sent. The request's argument is specified via the
488 * ``arg`` pointer.
489 *
490 * Refer to ssam_request_do_sync_onstack() for more details on the behavior of
491 * the generated function.
492 */
493 #define SSAM_DEFINE_SYNC_REQUEST_CL_W(name, atype, spec...) \
494 SSAM_DEFINE_SYNC_REQUEST_MD_W(__raw_##name, atype, spec) \
495 static int name(struct ssam_device *sdev, const atype *arg) \
496 { \
497 return __raw_##name(sdev->ctrl, sdev->uid.target, \
498 sdev->uid.instance, arg); \
499 }
500
501 /**
502 * SSAM_DEFINE_SYNC_REQUEST_CL_R() - Define synchronous client-device SAM
503 * request function with return value.
504 * @name: Name of the generated function.
505 * @rtype: Type of the request's return value.
506 * @spec: Specification (&struct ssam_request_spec_md) defining the request.
507 *
508 * Defines a function executing the synchronous SAM request specified by
509 * @spec, with the request taking no argument but having a return value of
510 * type @rtype. Device specifying parameters are not hard-coded, but instead
511 * are provided via the client device, specifically its UID, supplied when
512 * calling this function. The generated function takes care of setting up the
513 * request struct, buffer allocation, as well as execution of the request
514 * itself, returning once the request has been fully completed. The required
515 * transport buffer will be allocated on the stack.
516 *
517 * The generated function is defined as ``static int name(struct ssam_device
518 * *sdev, rtype *ret)``, returning the status of the request, which is zero on
519 * success and negative on failure. The ``sdev`` parameter specifies both the
520 * target device of the request and by association the controller via which
521 * the request is sent. The request's return value is written to the memory
522 * pointed to by the ``ret`` parameter.
523 *
524 * Refer to ssam_request_do_sync_onstack() for more details on the behavior of
525 * the generated function.
526 */
527 #define SSAM_DEFINE_SYNC_REQUEST_CL_R(name, rtype, spec...) \
528 SSAM_DEFINE_SYNC_REQUEST_MD_R(__raw_##name, rtype, spec) \
529 static int name(struct ssam_device *sdev, rtype *ret) \
530 { \
531 return __raw_##name(sdev->ctrl, sdev->uid.target, \
532 sdev->uid.instance, ret); \
533 }
534
535 /**
536 * SSAM_DEFINE_SYNC_REQUEST_CL_WR() - Define synchronous client-device SAM
537 * request function with argument and return value.
538 * @name: Name of the generated function.
539 * @atype: Type of the request's argument.
540 * @rtype: Type of the request's return value.
541 * @spec: Specification (&struct ssam_request_spec_md) defining the request.
542 *
543 * Defines a function executing the synchronous SAM request specified by @spec,
544 * with the request taking an argument of type @atype and having a return value
545 * of type @rtype. Device specifying parameters are not hard-coded, but instead
546 * are provided via the client device, specifically its UID, supplied when
547 * calling this function. The generated function takes care of setting up the
548 * request struct, buffer allocation, as well as execution of the request
549 * itself, returning once the request has been fully completed. The required
550 * transport buffer will be allocated on the stack.
551 *
552 * The generated function is defined as ``static int name(struct ssam_device
553 * *sdev, const atype *arg, rtype *ret)``, returning the status of the request,
554 * which is zero on success and negative on failure. The ``sdev`` parameter
555 * specifies both the target device of the request and by association the
556 * controller via which the request is sent. The request's argument is
557 * specified via the ``arg`` pointer. The request's return value is written to
558 * the memory pointed to by the ``ret`` parameter.
559 *
560 * Refer to ssam_request_do_sync_onstack() for more details on the behavior of
561 * the generated function.
562 */
563 #define SSAM_DEFINE_SYNC_REQUEST_CL_WR(name, atype, rtype, spec...) \
564 SSAM_DEFINE_SYNC_REQUEST_MD_WR(__raw_##name, atype, rtype, spec) \
565 static int name(struct ssam_device *sdev, const atype *arg, rtype *ret) \
566 { \
567 return __raw_##name(sdev->ctrl, sdev->uid.target, \
568 sdev->uid.instance, arg, ret); \
569 }
570
571
572 /* -- Helpers for client-device notifiers. ---------------------------------- */
573
574 /**
575 * ssam_device_notifier_register() - Register an event notifier for the
576 * specified client device.
577 * @sdev: The device the notifier should be registered on.
578 * @n: The event notifier to register.
579 *
580 * Register an event notifier. Increment the usage counter of the associated
581 * SAM event if the notifier is not marked as an observer. If the event is not
582 * marked as an observer and is currently not enabled, it will be enabled
583 * during this call. If the notifier is marked as an observer, no attempt will
584 * be made at enabling any event and no reference count will be modified.
585 *
586 * Notifiers marked as observers do not need to be associated with one specific
587 * event, i.e. as long as no event matching is performed, only the event target
588 * category needs to be set.
589 *
590 * Return: Returns zero on success, %-ENOSPC if there have already been
591 * %INT_MAX notifiers for the event ID/type associated with the notifier block
592 * registered, %-ENOMEM if the corresponding event entry could not be
593 * allocated, %-ENODEV if the device is marked as hot-removed. If this is the
594 * first time that a notifier block is registered for the specific associated
595 * event, returns the status of the event-enable EC-command.
596 */
ssam_device_notifier_register(struct ssam_device * sdev,struct ssam_event_notifier * n)597 static inline int ssam_device_notifier_register(struct ssam_device *sdev,
598 struct ssam_event_notifier *n)
599 {
600 /*
601 * Note that this check does not provide any guarantees whatsoever as
602 * hot-removal could happen at any point and we can't protect against
603 * it. Nevertheless, if we can detect hot-removal, bail early to avoid
604 * communication timeouts.
605 */
606 if (ssam_device_is_hot_removed(sdev))
607 return -ENODEV;
608
609 return ssam_notifier_register(sdev->ctrl, n);
610 }
611
612 /**
613 * ssam_device_notifier_unregister() - Unregister an event notifier for the
614 * specified client device.
615 * @sdev: The device the notifier has been registered on.
616 * @n: The event notifier to unregister.
617 *
618 * Unregister an event notifier. Decrement the usage counter of the associated
619 * SAM event if the notifier is not marked as an observer. If the usage counter
620 * reaches zero, the event will be disabled.
621 *
622 * In case the device has been marked as hot-removed, the event will not be
623 * disabled on the EC, as in those cases any attempt at doing so may time out.
624 *
625 * Return: Returns zero on success, %-ENOENT if the given notifier block has
626 * not been registered on the controller. If the given notifier block was the
627 * last one associated with its specific event, returns the status of the
628 * event-disable EC-command.
629 */
ssam_device_notifier_unregister(struct ssam_device * sdev,struct ssam_event_notifier * n)630 static inline int ssam_device_notifier_unregister(struct ssam_device *sdev,
631 struct ssam_event_notifier *n)
632 {
633 return __ssam_notifier_unregister(sdev->ctrl, n,
634 !ssam_device_is_hot_removed(sdev));
635 }
636
637 #endif /* _LINUX_SURFACE_AGGREGATOR_DEVICE_H */
638