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