Root/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
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");
508

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