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[mirror_ubuntu-bionic-kernel.git] / drivers / hsi / hsi.c
1 /*
2 * HSI core.
3 *
4 * Copyright (C) 2010 Nokia Corporation. All rights reserved.
5 *
6 * Contact: Carlos Chinea <carlos.chinea@nokia.com>
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * version 2 as published by the Free Software Foundation.
11 *
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20 * 02110-1301 USA
21 */
22 #include <linux/hsi/hsi.h>
23 #include <linux/compiler.h>
24 #include <linux/list.h>
25 #include <linux/kobject.h>
26 #include <linux/slab.h>
27 #include <linux/string.h>
28 #include <linux/notifier.h>
29 #include "hsi_core.h"
30
31 static ssize_t modalias_show(struct device *dev,
32 struct device_attribute *a __maybe_unused, char *buf)
33 {
34 return sprintf(buf, "hsi:%s\n", dev_name(dev));
35 }
36 static DEVICE_ATTR_RO(modalias);
37
38 static struct attribute *hsi_bus_dev_attrs[] = {
39 &dev_attr_modalias.attr,
40 NULL,
41 };
42 ATTRIBUTE_GROUPS(hsi_bus_dev);
43
44 static int hsi_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
45 {
46 add_uevent_var(env, "MODALIAS=hsi:%s", dev_name(dev));
47
48 return 0;
49 }
50
51 static int hsi_bus_match(struct device *dev, struct device_driver *driver)
52 {
53 return strcmp(dev_name(dev), driver->name) == 0;
54 }
55
56 static struct bus_type hsi_bus_type = {
57 .name = "hsi",
58 .dev_groups = hsi_bus_dev_groups,
59 .match = hsi_bus_match,
60 .uevent = hsi_bus_uevent,
61 };
62
63 static void hsi_client_release(struct device *dev)
64 {
65 kfree(to_hsi_client(dev));
66 }
67
68 static void hsi_new_client(struct hsi_port *port, struct hsi_board_info *info)
69 {
70 struct hsi_client *cl;
71
72 cl = kzalloc(sizeof(*cl), GFP_KERNEL);
73 if (!cl)
74 return;
75 cl->tx_cfg = info->tx_cfg;
76 cl->rx_cfg = info->rx_cfg;
77 cl->device.bus = &hsi_bus_type;
78 cl->device.parent = &port->device;
79 cl->device.release = hsi_client_release;
80 dev_set_name(&cl->device, "%s", info->name);
81 cl->device.platform_data = info->platform_data;
82 if (info->archdata)
83 cl->device.archdata = *info->archdata;
84 if (device_register(&cl->device) < 0) {
85 pr_err("hsi: failed to register client: %s\n", info->name);
86 put_device(&cl->device);
87 }
88 }
89
90 static void hsi_scan_board_info(struct hsi_controller *hsi)
91 {
92 struct hsi_cl_info *cl_info;
93 struct hsi_port *p;
94
95 list_for_each_entry(cl_info, &hsi_board_list, list)
96 if (cl_info->info.hsi_id == hsi->id) {
97 p = hsi_find_port_num(hsi, cl_info->info.port);
98 if (!p)
99 continue;
100 hsi_new_client(p, &cl_info->info);
101 }
102 }
103
104 static int hsi_remove_client(struct device *dev, void *data __maybe_unused)
105 {
106 device_unregister(dev);
107
108 return 0;
109 }
110
111 static int hsi_remove_port(struct device *dev, void *data __maybe_unused)
112 {
113 device_for_each_child(dev, NULL, hsi_remove_client);
114 device_unregister(dev);
115
116 return 0;
117 }
118
119 static void hsi_controller_release(struct device *dev)
120 {
121 struct hsi_controller *hsi = to_hsi_controller(dev);
122
123 kfree(hsi->port);
124 kfree(hsi);
125 }
126
127 static void hsi_port_release(struct device *dev)
128 {
129 kfree(to_hsi_port(dev));
130 }
131
132 /**
133 * hsi_unregister_controller - Unregister an HSI controller
134 * @hsi: The HSI controller to register
135 */
136 void hsi_unregister_controller(struct hsi_controller *hsi)
137 {
138 device_for_each_child(&hsi->device, NULL, hsi_remove_port);
139 device_unregister(&hsi->device);
140 }
141 EXPORT_SYMBOL_GPL(hsi_unregister_controller);
142
143 /**
144 * hsi_register_controller - Register an HSI controller and its ports
145 * @hsi: The HSI controller to register
146 *
147 * Returns -errno on failure, 0 on success.
148 */
149 int hsi_register_controller(struct hsi_controller *hsi)
150 {
151 unsigned int i;
152 int err;
153
154 err = device_add(&hsi->device);
155 if (err < 0)
156 return err;
157 for (i = 0; i < hsi->num_ports; i++) {
158 hsi->port[i]->device.parent = &hsi->device;
159 err = device_add(&hsi->port[i]->device);
160 if (err < 0)
161 goto out;
162 }
163 /* Populate HSI bus with HSI clients */
164 hsi_scan_board_info(hsi);
165
166 return 0;
167 out:
168 while (i-- > 0)
169 device_del(&hsi->port[i]->device);
170 device_del(&hsi->device);
171
172 return err;
173 }
174 EXPORT_SYMBOL_GPL(hsi_register_controller);
175
176 /**
177 * hsi_register_client_driver - Register an HSI client to the HSI bus
178 * @drv: HSI client driver to register
179 *
180 * Returns -errno on failure, 0 on success.
181 */
182 int hsi_register_client_driver(struct hsi_client_driver *drv)
183 {
184 drv->driver.bus = &hsi_bus_type;
185
186 return driver_register(&drv->driver);
187 }
188 EXPORT_SYMBOL_GPL(hsi_register_client_driver);
189
190 static inline int hsi_dummy_msg(struct hsi_msg *msg __maybe_unused)
191 {
192 return 0;
193 }
194
195 static inline int hsi_dummy_cl(struct hsi_client *cl __maybe_unused)
196 {
197 return 0;
198 }
199
200 /**
201 * hsi_put_controller - Free an HSI controller
202 *
203 * @hsi: Pointer to the HSI controller to freed
204 *
205 * HSI controller drivers should only use this function if they need
206 * to free their allocated hsi_controller structures before a successful
207 * call to hsi_register_controller. Other use is not allowed.
208 */
209 void hsi_put_controller(struct hsi_controller *hsi)
210 {
211 unsigned int i;
212
213 if (!hsi)
214 return;
215
216 for (i = 0; i < hsi->num_ports; i++)
217 if (hsi->port && hsi->port[i])
218 put_device(&hsi->port[i]->device);
219 put_device(&hsi->device);
220 }
221 EXPORT_SYMBOL_GPL(hsi_put_controller);
222
223 /**
224 * hsi_alloc_controller - Allocate an HSI controller and its ports
225 * @n_ports: Number of ports on the HSI controller
226 * @flags: Kernel allocation flags
227 *
228 * Return NULL on failure or a pointer to an hsi_controller on success.
229 */
230 struct hsi_controller *hsi_alloc_controller(unsigned int n_ports, gfp_t flags)
231 {
232 struct hsi_controller *hsi;
233 struct hsi_port **port;
234 unsigned int i;
235
236 if (!n_ports)
237 return NULL;
238
239 hsi = kzalloc(sizeof(*hsi), flags);
240 if (!hsi)
241 return NULL;
242 port = kzalloc(sizeof(*port)*n_ports, flags);
243 if (!port) {
244 kfree(hsi);
245 return NULL;
246 }
247 hsi->num_ports = n_ports;
248 hsi->port = port;
249 hsi->device.release = hsi_controller_release;
250 device_initialize(&hsi->device);
251
252 for (i = 0; i < n_ports; i++) {
253 port[i] = kzalloc(sizeof(**port), flags);
254 if (port[i] == NULL)
255 goto out;
256 port[i]->num = i;
257 port[i]->async = hsi_dummy_msg;
258 port[i]->setup = hsi_dummy_cl;
259 port[i]->flush = hsi_dummy_cl;
260 port[i]->start_tx = hsi_dummy_cl;
261 port[i]->stop_tx = hsi_dummy_cl;
262 port[i]->release = hsi_dummy_cl;
263 mutex_init(&port[i]->lock);
264 ATOMIC_INIT_NOTIFIER_HEAD(&port[i]->n_head);
265 dev_set_name(&port[i]->device, "port%d", i);
266 hsi->port[i]->device.release = hsi_port_release;
267 device_initialize(&hsi->port[i]->device);
268 }
269
270 return hsi;
271 out:
272 hsi_put_controller(hsi);
273
274 return NULL;
275 }
276 EXPORT_SYMBOL_GPL(hsi_alloc_controller);
277
278 /**
279 * hsi_free_msg - Free an HSI message
280 * @msg: Pointer to the HSI message
281 *
282 * Client is responsible to free the buffers pointed by the scatterlists.
283 */
284 void hsi_free_msg(struct hsi_msg *msg)
285 {
286 if (!msg)
287 return;
288 sg_free_table(&msg->sgt);
289 kfree(msg);
290 }
291 EXPORT_SYMBOL_GPL(hsi_free_msg);
292
293 /**
294 * hsi_alloc_msg - Allocate an HSI message
295 * @nents: Number of memory entries
296 * @flags: Kernel allocation flags
297 *
298 * nents can be 0. This mainly makes sense for read transfer.
299 * In that case, HSI drivers will call the complete callback when
300 * there is data to be read without consuming it.
301 *
302 * Return NULL on failure or a pointer to an hsi_msg on success.
303 */
304 struct hsi_msg *hsi_alloc_msg(unsigned int nents, gfp_t flags)
305 {
306 struct hsi_msg *msg;
307 int err;
308
309 msg = kzalloc(sizeof(*msg), flags);
310 if (!msg)
311 return NULL;
312
313 if (!nents)
314 return msg;
315
316 err = sg_alloc_table(&msg->sgt, nents, flags);
317 if (unlikely(err)) {
318 kfree(msg);
319 msg = NULL;
320 }
321
322 return msg;
323 }
324 EXPORT_SYMBOL_GPL(hsi_alloc_msg);
325
326 /**
327 * hsi_async - Submit an HSI transfer to the controller
328 * @cl: HSI client sending the transfer
329 * @msg: The HSI transfer passed to controller
330 *
331 * The HSI message must have the channel, ttype, complete and destructor
332 * fields set beforehand. If nents > 0 then the client has to initialize
333 * also the scatterlists to point to the buffers to write to or read from.
334 *
335 * HSI controllers relay on pre-allocated buffers from their clients and they
336 * do not allocate buffers on their own.
337 *
338 * Once the HSI message transfer finishes, the HSI controller calls the
339 * complete callback with the status and actual_len fields of the HSI message
340 * updated. The complete callback can be called before returning from
341 * hsi_async.
342 *
343 * Returns -errno on failure or 0 on success
344 */
345 int hsi_async(struct hsi_client *cl, struct hsi_msg *msg)
346 {
347 struct hsi_port *port = hsi_get_port(cl);
348
349 if (!hsi_port_claimed(cl))
350 return -EACCES;
351
352 WARN_ON_ONCE(!msg->destructor || !msg->complete);
353 msg->cl = cl;
354
355 return port->async(msg);
356 }
357 EXPORT_SYMBOL_GPL(hsi_async);
358
359 /**
360 * hsi_claim_port - Claim the HSI client's port
361 * @cl: HSI client that wants to claim its port
362 * @share: Flag to indicate if the client wants to share the port or not.
363 *
364 * Returns -errno on failure, 0 on success.
365 */
366 int hsi_claim_port(struct hsi_client *cl, unsigned int share)
367 {
368 struct hsi_port *port = hsi_get_port(cl);
369 int err = 0;
370
371 mutex_lock(&port->lock);
372 if ((port->claimed) && (!port->shared || !share)) {
373 err = -EBUSY;
374 goto out;
375 }
376 if (!try_module_get(to_hsi_controller(port->device.parent)->owner)) {
377 err = -ENODEV;
378 goto out;
379 }
380 port->claimed++;
381 port->shared = !!share;
382 cl->pclaimed = 1;
383 out:
384 mutex_unlock(&port->lock);
385
386 return err;
387 }
388 EXPORT_SYMBOL_GPL(hsi_claim_port);
389
390 /**
391 * hsi_release_port - Release the HSI client's port
392 * @cl: HSI client which previously claimed its port
393 */
394 void hsi_release_port(struct hsi_client *cl)
395 {
396 struct hsi_port *port = hsi_get_port(cl);
397
398 mutex_lock(&port->lock);
399 /* Allow HW driver to do some cleanup */
400 port->release(cl);
401 if (cl->pclaimed)
402 port->claimed--;
403 BUG_ON(port->claimed < 0);
404 cl->pclaimed = 0;
405 if (!port->claimed)
406 port->shared = 0;
407 module_put(to_hsi_controller(port->device.parent)->owner);
408 mutex_unlock(&port->lock);
409 }
410 EXPORT_SYMBOL_GPL(hsi_release_port);
411
412 static int hsi_event_notifier_call(struct notifier_block *nb,
413 unsigned long event, void *data __maybe_unused)
414 {
415 struct hsi_client *cl = container_of(nb, struct hsi_client, nb);
416
417 (*cl->ehandler)(cl, event);
418
419 return 0;
420 }
421
422 /**
423 * hsi_register_port_event - Register a client to receive port events
424 * @cl: HSI client that wants to receive port events
425 * @handler: Event handler callback
426 *
427 * Clients should register a callback to be able to receive
428 * events from the ports. Registration should happen after
429 * claiming the port.
430 * The handler can be called in interrupt context.
431 *
432 * Returns -errno on error, or 0 on success.
433 */
434 int hsi_register_port_event(struct hsi_client *cl,
435 void (*handler)(struct hsi_client *, unsigned long))
436 {
437 struct hsi_port *port = hsi_get_port(cl);
438
439 if (!handler || cl->ehandler)
440 return -EINVAL;
441 if (!hsi_port_claimed(cl))
442 return -EACCES;
443 cl->ehandler = handler;
444 cl->nb.notifier_call = hsi_event_notifier_call;
445
446 return atomic_notifier_chain_register(&port->n_head, &cl->nb);
447 }
448 EXPORT_SYMBOL_GPL(hsi_register_port_event);
449
450 /**
451 * hsi_unregister_port_event - Stop receiving port events for a client
452 * @cl: HSI client that wants to stop receiving port events
453 *
454 * Clients should call this function before releasing their associated
455 * port.
456 *
457 * Returns -errno on error, or 0 on success.
458 */
459 int hsi_unregister_port_event(struct hsi_client *cl)
460 {
461 struct hsi_port *port = hsi_get_port(cl);
462 int err;
463
464 WARN_ON(!hsi_port_claimed(cl));
465
466 err = atomic_notifier_chain_unregister(&port->n_head, &cl->nb);
467 if (!err)
468 cl->ehandler = NULL;
469
470 return err;
471 }
472 EXPORT_SYMBOL_GPL(hsi_unregister_port_event);
473
474 /**
475 * hsi_event -Notifies clients about port events
476 * @port: Port where the event occurred
477 * @event: The event type
478 *
479 * Clients should not be concerned about wake line behavior. However, due
480 * to a race condition in HSI HW protocol, clients need to be notified
481 * about wake line changes, so they can implement a workaround for it.
482 *
483 * Events:
484 * HSI_EVENT_START_RX - Incoming wake line high
485 * HSI_EVENT_STOP_RX - Incoming wake line down
486 *
487 * Returns -errno on error, or 0 on success.
488 */
489 int hsi_event(struct hsi_port *port, unsigned long event)
490 {
491 return atomic_notifier_call_chain(&port->n_head, event, NULL);
492 }
493 EXPORT_SYMBOL_GPL(hsi_event);
494
495 static int __init hsi_init(void)
496 {
497 return bus_register(&hsi_bus_type);
498 }
499 postcore_initcall(hsi_init);
500
501 static void __exit hsi_exit(void)
502 {
503 bus_unregister(&hsi_bus_type);
504 }
505 module_exit(hsi_exit);
506
507 MODULE_AUTHOR("Carlos Chinea <carlos.chinea@nokia.com>");
508 MODULE_DESCRIPTION("High-speed Synchronous Serial Interface (HSI) framework");
509 MODULE_LICENSE("GPL v2");