1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * Surface System Aggregator Module bus and device integration.
  4 *
  5 * Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com>
  6 */
  7
  8#include <linux/device.h>
  9#include <linux/of.h>
 10#include <linux/property.h>
 11#include <linux/slab.h>
 12
 13#include <linux/surface_aggregator/controller.h>
 14#include <linux/surface_aggregator/device.h>
 15
 16#include "bus.h"
 17#include "controller.h"
 18
 19
 20/* -- Device and bus functions. --------------------------------------------- */
 21
 22static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 23			     char *buf)
 24{
 25	struct ssam_device *sdev = to_ssam_device(dev);
 26
 27	return sysfs_emit(buf, "ssam:d%02Xc%02Xt%02Xi%02Xf%02X\n",
 28			sdev->uid.domain, sdev->uid.category, sdev->uid.target,
 29			sdev->uid.instance, sdev->uid.function);
 30}
 31static DEVICE_ATTR_RO(modalias);
 32
 33static struct attribute *ssam_device_attrs[] = {
 34	&dev_attr_modalias.attr,
 35	NULL,
 36};
 37ATTRIBUTE_GROUPS(ssam_device);
 38
 39static const struct bus_type ssam_bus_type;
 40
 41static int ssam_device_uevent(const struct device *dev, struct kobj_uevent_env *env)
 42{
 43	const struct ssam_device *sdev = to_ssam_device(dev);
 44
 45	return add_uevent_var(env, "MODALIAS=ssam:d%02Xc%02Xt%02Xi%02Xf%02X",
 46			      sdev->uid.domain, sdev->uid.category,
 47			      sdev->uid.target, sdev->uid.instance,
 48			      sdev->uid.function);
 49}
 50
 51static void ssam_device_release(struct device *dev)
 52{
 53	struct ssam_device *sdev = to_ssam_device(dev);
 54
 55	ssam_controller_put(sdev->ctrl);
 56	fwnode_handle_put(sdev->dev.fwnode);
 57	kfree(sdev);
 58}
 59
 60const struct device_type ssam_device_type = {
 61	.name    = "surface_aggregator_device",
 62	.groups  = ssam_device_groups,
 63	.uevent  = ssam_device_uevent,
 64	.release = ssam_device_release,
 65};
 66EXPORT_SYMBOL_GPL(ssam_device_type);
 67
 68/**
 69 * ssam_device_alloc() - Allocate and initialize a SSAM client device.
 70 * @ctrl: The controller under which the device should be added.
 71 * @uid:  The UID of the device to be added.
 72 *
 73 * Allocates and initializes a new client device. The parent of the device
 74 * will be set to the controller device and the name will be set based on the
 75 * UID. Note that the device still has to be added via ssam_device_add().
 76 * Refer to that function for more details.
 77 *
 78 * Return: Returns the newly allocated and initialized SSAM client device, or
 79 * %NULL if it could not be allocated.
 80 */
 81struct ssam_device *ssam_device_alloc(struct ssam_controller *ctrl,
 82				      struct ssam_device_uid uid)
 83{
 84	struct ssam_device *sdev;
 85
 86	sdev = kzalloc(sizeof(*sdev), GFP_KERNEL);
 87	if (!sdev)
 88		return NULL;
 89
 90	device_initialize(&sdev->dev);
 91	sdev->dev.bus = &ssam_bus_type;
 92	sdev->dev.type = &ssam_device_type;
 93	sdev->dev.parent = ssam_controller_device(ctrl);
 94	sdev->ctrl = ssam_controller_get(ctrl);
 95	sdev->uid = uid;
 96
 97	dev_set_name(&sdev->dev, "%02x:%02x:%02x:%02x:%02x",
 98		     sdev->uid.domain, sdev->uid.category, sdev->uid.target,
 99		     sdev->uid.instance, sdev->uid.function);
100
101	return sdev;
102}
103EXPORT_SYMBOL_GPL(ssam_device_alloc);
104
105/**
106 * ssam_device_add() - Add a SSAM client device.
107 * @sdev: The SSAM client device to be added.
108 *
109 * Added client devices must be guaranteed to always have a valid and active
110 * controller. Thus, this function will fail with %-ENODEV if the controller
111 * of the device has not been initialized yet, has been suspended, or has been
112 * shut down.
113 *
114 * The caller of this function should ensure that the corresponding call to
115 * ssam_device_remove() is issued before the controller is shut down. If the
116 * added device is a direct child of the controller device (default), it will
117 * be automatically removed when the controller is shut down.
118 *
119 * By default, the controller device will become the parent of the newly
120 * created client device. The parent may be changed before ssam_device_add is
121 * called, but care must be taken that a) the correct suspend/resume ordering
122 * is guaranteed and b) the client device does not outlive the controller,
123 * i.e. that the device is removed before the controller is being shut down.
124 * In case these guarantees have to be manually enforced, please refer to the
125 * ssam_client_link() and ssam_client_bind() functions, which are intended to
126 * set up device-links for this purpose.
127 *
128 * Return: Returns zero on success, a negative error code on failure.
129 */
130int ssam_device_add(struct ssam_device *sdev)
131{
132	int status;
133
134	/*
135	 * Ensure that we can only add new devices to a controller if it has
136	 * been started and is not going away soon. This works in combination
137	 * with ssam_controller_remove_clients to ensure driver presence for the
138	 * controller device, i.e. it ensures that the controller (sdev->ctrl)
139	 * is always valid and can be used for requests as long as the client
140	 * device we add here is registered as child under it. This essentially
141	 * guarantees that the client driver can always expect the preconditions
142	 * for functions like ssam_request_do_sync() (controller has to be
143	 * started and is not suspended) to hold and thus does not have to check
144	 * for them.
145	 *
146	 * Note that for this to work, the controller has to be a parent device.
147	 * If it is not a direct parent, care has to be taken that the device is
148	 * removed via ssam_device_remove(), as device_unregister does not
149	 * remove child devices recursively.
150	 */
151	ssam_controller_statelock(sdev->ctrl);
152
153	if (sdev->ctrl->state != SSAM_CONTROLLER_STARTED) {
154		ssam_controller_stateunlock(sdev->ctrl);
155		return -ENODEV;
156	}
157
158	status = device_add(&sdev->dev);
159
160	ssam_controller_stateunlock(sdev->ctrl);
161	return status;
162}
163EXPORT_SYMBOL_GPL(ssam_device_add);
164
165/**
166 * ssam_device_remove() - Remove a SSAM client device.
167 * @sdev: The device to remove.
168 *
169 * Removes and unregisters the provided SSAM client device.
170 */
171void ssam_device_remove(struct ssam_device *sdev)
172{
173	device_unregister(&sdev->dev);
174}
175EXPORT_SYMBOL_GPL(ssam_device_remove);
176
177/**
178 * ssam_device_id_compatible() - Check if a device ID matches a UID.
179 * @id:  The device ID as potential match.
180 * @uid: The device UID matching against.
181 *
182 * Check if the given ID is a match for the given UID, i.e. if a device with
183 * the provided UID is compatible to the given ID following the match rules
184 * described in its &ssam_device_id.match_flags member.
185 *
186 * Return: Returns %true if the given UID is compatible to the match rule
187 * described by the given ID, %false otherwise.
188 */
189static bool ssam_device_id_compatible(const struct ssam_device_id *id,
190				      struct ssam_device_uid uid)
191{
192	if (id->domain != uid.domain || id->category != uid.category)
193		return false;
194
195	if ((id->match_flags & SSAM_MATCH_TARGET) && id->target != uid.target)
196		return false;
197
198	if ((id->match_flags & SSAM_MATCH_INSTANCE) && id->instance != uid.instance)
199		return false;
200
201	if ((id->match_flags & SSAM_MATCH_FUNCTION) && id->function != uid.function)
202		return false;
203
204	return true;
205}
206
207/**
208 * ssam_device_id_is_null() - Check if a device ID is null.
209 * @id: The device ID to check.
210 *
211 * Check if a given device ID is null, i.e. all zeros. Used to check for the
212 * end of ``MODULE_DEVICE_TABLE(ssam, ...)`` or similar lists.
213 *
214 * Return: Returns %true if the given ID represents a null ID, %false
215 * otherwise.
216 */
217static bool ssam_device_id_is_null(const struct ssam_device_id *id)
218{
219	return id->match_flags == 0 &&
220		id->domain == 0 &&
221		id->category == 0 &&
222		id->target == 0 &&
223		id->instance == 0 &&
224		id->function == 0 &&
225		id->driver_data == 0;
226}
227
228/**
229 * ssam_device_id_match() - Find the matching ID table entry for the given UID.
230 * @table: The table to search in.
231 * @uid:   The UID to matched against the individual table entries.
232 *
233 * Find the first match for the provided device UID in the provided ID table
234 * and return it. Returns %NULL if no match could be found.
235 */
236const struct ssam_device_id *ssam_device_id_match(const struct ssam_device_id *table,
237						  const struct ssam_device_uid uid)
238{
239	const struct ssam_device_id *id;
240
241	for (id = table; !ssam_device_id_is_null(id); ++id)
242		if (ssam_device_id_compatible(id, uid))
243			return id;
244
245	return NULL;
246}
247EXPORT_SYMBOL_GPL(ssam_device_id_match);
248
249/**
250 * ssam_device_get_match() - Find and return the ID matching the device in the
251 * ID table of the bound driver.
252 * @dev: The device for which to get the matching ID table entry.
253 *
254 * Find the fist match for the UID of the device in the ID table of the
255 * currently bound driver and return it. Returns %NULL if the device does not
256 * have a driver bound to it, the driver does not have match_table (i.e. it is
257 * %NULL), or there is no match in the driver's match_table.
258 *
259 * This function essentially calls ssam_device_id_match() with the ID table of
260 * the bound device driver and the UID of the device.
261 *
262 * Return: Returns the first match for the UID of the device in the device
263 * driver's match table, or %NULL if no such match could be found.
264 */
265const struct ssam_device_id *ssam_device_get_match(const struct ssam_device *dev)
266{
267	const struct ssam_device_driver *sdrv;
268
269	sdrv = to_ssam_device_driver(dev->dev.driver);
270	if (!sdrv)
271		return NULL;
272
273	if (!sdrv->match_table)
274		return NULL;
275
276	return ssam_device_id_match(sdrv->match_table, dev->uid);
277}
278EXPORT_SYMBOL_GPL(ssam_device_get_match);
279
280/**
281 * ssam_device_get_match_data() - Find the ID matching the device in the
282 * ID table of the bound driver and return its ``driver_data`` member.
283 * @dev: The device for which to get the match data.
284 *
285 * Find the fist match for the UID of the device in the ID table of the
286 * corresponding driver and return its driver_data. Returns %NULL if the
287 * device does not have a driver bound to it, the driver does not have
288 * match_table (i.e. it is %NULL), there is no match in the driver's
289 * match_table, or the match does not have any driver_data.
290 *
291 * This function essentially calls ssam_device_get_match() and, if any match
292 * could be found, returns its ``struct ssam_device_id.driver_data`` member.
293 *
294 * Return: Returns the driver data associated with the first match for the UID
295 * of the device in the device driver's match table, or %NULL if no such match
296 * could be found.
297 */
298const void *ssam_device_get_match_data(const struct ssam_device *dev)
299{
300	const struct ssam_device_id *id;
301
302	id = ssam_device_get_match(dev);
303	if (!id)
304		return NULL;
305
306	return (const void *)id->driver_data;
307}
308EXPORT_SYMBOL_GPL(ssam_device_get_match_data);
309
310static int ssam_bus_match(struct device *dev, const struct device_driver *drv)
311{
312	const struct ssam_device_driver *sdrv = to_ssam_device_driver(drv);
313	struct ssam_device *sdev = to_ssam_device(dev);
314
315	if (!is_ssam_device(dev))
316		return 0;
317
318	return !!ssam_device_id_match(sdrv->match_table, sdev->uid);
319}
320
321static int ssam_bus_probe(struct device *dev)
322{
323	return to_ssam_device_driver(dev->driver)
324		->probe(to_ssam_device(dev));
325}
326
327static void ssam_bus_remove(struct device *dev)
328{
329	struct ssam_device_driver *sdrv = to_ssam_device_driver(dev->driver);
330
331	if (sdrv->remove)
332		sdrv->remove(to_ssam_device(dev));
333}
334
335static const struct bus_type ssam_bus_type = {
336	.name   = "surface_aggregator",
337	.match  = ssam_bus_match,
338	.probe  = ssam_bus_probe,
339	.remove = ssam_bus_remove,
340};
341
342/**
343 * __ssam_device_driver_register() - Register a SSAM client device driver.
344 * @sdrv:  The driver to register.
345 * @owner: The module owning the provided driver.
346 *
347 * Please refer to the ssam_device_driver_register() macro for the normal way
348 * to register a driver from inside its owning module.
349 */
350int __ssam_device_driver_register(struct ssam_device_driver *sdrv,
351				  struct module *owner)
352{
353	sdrv->driver.owner = owner;
354	sdrv->driver.bus = &ssam_bus_type;
355
356	/* force drivers to async probe so I/O is possible in probe */
357	sdrv->driver.probe_type = PROBE_PREFER_ASYNCHRONOUS;
358
359	return driver_register(&sdrv->driver);
360}
361EXPORT_SYMBOL_GPL(__ssam_device_driver_register);
362
363/**
364 * ssam_device_driver_unregister - Unregister a SSAM device driver.
365 * @sdrv: The driver to unregister.
366 */
367void ssam_device_driver_unregister(struct ssam_device_driver *sdrv)
368{
369	driver_unregister(&sdrv->driver);
370}
371EXPORT_SYMBOL_GPL(ssam_device_driver_unregister);
372
373
374/* -- Bus registration. ----------------------------------------------------- */
375
376/**
377 * ssam_bus_register() - Register and set-up the SSAM client device bus.
378 */
379int ssam_bus_register(void)
380{
381	return bus_register(&ssam_bus_type);
382}
383
384/**
385 * ssam_bus_unregister() - Unregister the SSAM client device bus.
386 */
387void ssam_bus_unregister(void)
388{
389	return bus_unregister(&ssam_bus_type);
390}
391
392
393/* -- Helpers for controller and hub devices. ------------------------------- */
394
395static int ssam_device_uid_from_string(const char *str, struct ssam_device_uid *uid)
396{
397	u8 d, tc, tid, iid, fn;
398	int n;
399
400	n = sscanf(str, "%hhx:%hhx:%hhx:%hhx:%hhx", &d, &tc, &tid, &iid, &fn);
401	if (n != 5)
402		return -EINVAL;
403
404	uid->domain = d;
405	uid->category = tc;
406	uid->target = tid;
407	uid->instance = iid;
408	uid->function = fn;
409
410	return 0;
411}
412
413static int ssam_get_uid_for_node(struct fwnode_handle *node, struct ssam_device_uid *uid)
414{
415	const char *str = fwnode_get_name(node);
416
417	/*
418	 * To simplify definitions of firmware nodes, we set the device name
419	 * based on the UID of the device, prefixed with "ssam:".
420	 */
421	if (strncmp(str, "ssam:", strlen("ssam:")) != 0)
422		return -ENODEV;
423
424	str += strlen("ssam:");
425	return ssam_device_uid_from_string(str, uid);
426}
427
428static int ssam_add_client_device(struct device *parent, struct ssam_controller *ctrl,
429				  struct fwnode_handle *node)
430{
431	struct ssam_device_uid uid;
432	struct ssam_device *sdev;
433	int status;
434
435	status = ssam_get_uid_for_node(node, &uid);
436	if (status)
437		return status;
438
439	sdev = ssam_device_alloc(ctrl, uid);
440	if (!sdev)
441		return -ENOMEM;
442
443	sdev->dev.parent = parent;
444	sdev->dev.fwnode = fwnode_handle_get(node);
445	sdev->dev.of_node = to_of_node(node);
446
447	status = ssam_device_add(sdev);
448	if (status)
449		ssam_device_put(sdev);
450
451	return status;
452}
453
454/**
455 * __ssam_register_clients() - Register client devices defined under the
456 * given firmware node as children of the given device.
457 * @parent: The parent device under which clients should be registered.
458 * @ctrl: The controller with which client should be registered.
459 * @node: The firmware node holding definitions of the devices to be added.
460 *
461 * Register all clients that have been defined as children of the given root
462 * firmware node as children of the given parent device. The respective child
463 * firmware nodes will be associated with the correspondingly created child
464 * devices.
465 *
466 * The given controller will be used to instantiate the new devices. See
467 * ssam_device_add() for details.
468 *
469 * Note that, generally, the use of either ssam_device_register_clients() or
470 * ssam_register_clients() should be preferred as they directly use the
471 * firmware node and/or controller associated with the given device. This
472 * function is only intended for use when different device specifications (e.g.
473 * ACPI and firmware nodes) need to be combined (as is done in the platform hub
474 * of the device registry).
475 *
476 * Return: Returns zero on success, nonzero on failure.
477 */
478int __ssam_register_clients(struct device *parent, struct ssam_controller *ctrl,
479			    struct fwnode_handle *node)
480{
481	struct fwnode_handle *child;
482	int status;
483
484	fwnode_for_each_child_node(node, child) {
485		/*
486		 * Try to add the device specified in the firmware node. If
487		 * this fails with -ENODEV, the node does not specify any SSAM
488		 * device, so ignore it and continue with the next one.
489		 */
490		status = ssam_add_client_device(parent, ctrl, child);
491		if (status && status != -ENODEV) {
492			fwnode_handle_put(child);
493			goto err;
494		}
495	}
496
497	return 0;
498err:
499	ssam_remove_clients(parent);
500	return status;
501}
502EXPORT_SYMBOL_GPL(__ssam_register_clients);
503
504static int ssam_remove_device(struct device *dev, void *_data)
505{
506	struct ssam_device *sdev = to_ssam_device(dev);
507
508	if (is_ssam_device(dev))
509		ssam_device_remove(sdev);
510
511	return 0;
512}
513
514/**
515 * ssam_remove_clients() - Remove SSAM client devices registered as direct
516 * children under the given parent device.
517 * @dev: The (parent) device to remove all direct clients for.
518 *
519 * Remove all SSAM client devices registered as direct children under the given
520 * device. Note that this only accounts for direct children of the device.
521 * Refer to ssam_device_add()/ssam_device_remove() for more details.
522 */
523void ssam_remove_clients(struct device *dev)
524{
525	device_for_each_child_reverse(dev, NULL, ssam_remove_device);
526}
527EXPORT_SYMBOL_GPL(ssam_remove_clients);