1 /* -*- Mode: C; indent-tabs-mode:t ; c-basic-offset:8 -*- */
3 * Hotplug functions for libusb
4 * Copyright © 2012-2013 Nathan Hjelm <hjelmn@mac.com>
5 * Copyright © 2012-2013 Peter Stuge <peter@stuge.se>
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this library; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
28 #ifdef HAVE_SYS_TYPES_H
29 #include <sys/types.h>
37 * @defgroup hotplug Device hotplug event notification
38 * This page details how to use the libusb hotplug interface, where available.
40 * Be mindful that not all platforms currently implement hotplug notification and
41 * that you should first call on \ref libusb_has_capability() with parameter
42 * \ref LIBUSB_CAP_HAS_HOTPLUG to confirm that hotplug support is available.
44 * \page hotplug Device hotplug event notification
46 * \section intro Introduction
48 * Version 1.0.16, \ref LIBUSB_API_VERSION >= 0x01000102, has added support
49 * for hotplug events on <b>some</b> platforms (you should test if your platform
50 * supports hotplug notification by calling \ref libusb_has_capability() with
51 * parameter \ref LIBUSB_CAP_HAS_HOTPLUG).
53 * This interface allows you to request notification for the arrival and departure
54 * of matching USB devices.
56 * To receive hotplug notification you register a callback by calling
57 * \ref libusb_hotplug_register_callback(). This function will optionally return
58 * a handle that can be passed to \ref libusb_hotplug_deregister_callback().
60 * A callback function must return an int (0 or 1) indicating whether the callback is
61 * expecting additional events. Returning 0 will rearm the callback and 1 will cause
62 * the callback to be deregistered. Note that when callbacks are called from
63 * libusb_hotplug_register_callback() because of the \ref LIBUSB_HOTPLUG_ENUMERATE
64 * flag, the callback return value is ignored, iow you cannot cause a callback
65 * to be deregistered by returning 1 when it is called from
66 * libusb_hotplug_register_callback().
68 * Callbacks for a particular context are automatically deregistered by libusb_exit().
70 * As of 1.0.16 there are two supported hotplug events:
71 * - LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED: A device has arrived and is ready to use
72 * - LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT: A device has left and is no longer available
74 * A hotplug event can listen for either or both of these events.
76 * Note: If you receive notification that a device has left and you have any
77 * a libusb_device_handles for the device it is up to you to call libusb_close()
78 * on each handle to free up any remaining resources associated with the device.
79 * Once a device has left any libusb_device_handle associated with the device
80 * are invalid and will remain so even if the device comes back.
82 * When handling a LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED event it is considered
83 * safe to call any libusb function that takes a libusb_device. On the other hand,
84 * when handling a LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT event the only safe function
85 * is libusb_get_device_descriptor().
87 * The following code provides an example of the usage of the hotplug interface:
95 int hotplug_callback(struct libusb_context *ctx, struct libusb_device *dev,
96 libusb_hotplug_event event, void *user_data) {
97 static libusb_device_handle *handle = NULL;
98 struct libusb_device_descriptor desc;
101 (void)libusb_get_device_descriptor(dev, &desc);
103 if (LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED == event) {
104 rc = libusb_open(dev, &handle);
105 if (LIBUSB_SUCCESS != rc) {
106 printf("Could not open USB device\n");
108 } else if (LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT == event) {
110 libusb_close(handle);
114 printf("Unhandled event %d\n", event);
122 libusb_hotplug_callback_handle handle;
127 rc = libusb_hotplug_register_callback(NULL, LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED |
128 LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT, 0, 0x045a, 0x5005,
129 LIBUSB_HOTPLUG_MATCH_ANY, hotplug_callback, NULL,
131 if (LIBUSB_SUCCESS != rc) {
132 printf("Error creating a hotplug callback\n");
138 libusb_handle_events_completed(NULL, NULL);
142 libusb_hotplug_deregister_callback(NULL, handle);
150 static int usbi_hotplug_match_cb (struct libusb_context *ctx,
151 struct libusb_device *dev, libusb_hotplug_event event,
152 struct libusb_hotplug_callback *hotplug_cb)
154 /* Handle lazy deregistration of callback */
155 if (hotplug_cb->needs_free) {
160 if (!(hotplug_cb->events & event)) {
164 if (LIBUSB_HOTPLUG_MATCH_ANY != hotplug_cb->vendor_id &&
165 hotplug_cb->vendor_id != dev->device_descriptor.idVendor) {
169 if (LIBUSB_HOTPLUG_MATCH_ANY != hotplug_cb->product_id &&
170 hotplug_cb->product_id != dev->device_descriptor.idProduct) {
174 if (LIBUSB_HOTPLUG_MATCH_ANY != hotplug_cb->dev_class &&
175 hotplug_cb->dev_class != dev->device_descriptor.bDeviceClass) {
179 return hotplug_cb->cb (ctx, dev, event, hotplug_cb->user_data);
182 void usbi_hotplug_match(struct libusb_context *ctx, struct libusb_device *dev,
183 libusb_hotplug_event event)
185 struct libusb_hotplug_callback *hotplug_cb, *next;
188 usbi_mutex_lock(&ctx->hotplug_cbs_lock);
190 list_for_each_entry_safe(hotplug_cb, next, &ctx->hotplug_cbs, list, struct libusb_hotplug_callback) {
191 usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
192 ret = usbi_hotplug_match_cb (ctx, dev, event, hotplug_cb);
193 usbi_mutex_lock(&ctx->hotplug_cbs_lock);
196 list_del(&hotplug_cb->list);
201 usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
203 /* the backend is expected to call the callback for each active transfer */
206 int API_EXPORTED libusb_hotplug_register_callback(libusb_context *ctx,
207 libusb_hotplug_event events, libusb_hotplug_flag flags,
208 int vendor_id, int product_id, int dev_class,
209 libusb_hotplug_callback_fn cb_fn, void *user_data,
210 libusb_hotplug_callback_handle *handle)
212 libusb_hotplug_callback *new_callback;
213 static int handle_id = 1;
215 /* check for hotplug support */
216 if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
217 return LIBUSB_ERROR_NOT_SUPPORTED;
220 /* check for sane values */
221 if ((LIBUSB_HOTPLUG_MATCH_ANY != vendor_id && (~0xffff & vendor_id)) ||
222 (LIBUSB_HOTPLUG_MATCH_ANY != product_id && (~0xffff & product_id)) ||
223 (LIBUSB_HOTPLUG_MATCH_ANY != dev_class && (~0xff & dev_class)) ||
225 return LIBUSB_ERROR_INVALID_PARAM;
228 USBI_GET_CONTEXT(ctx);
230 new_callback = (libusb_hotplug_callback *)calloc(1, sizeof (*new_callback));
232 return LIBUSB_ERROR_NO_MEM;
235 new_callback->ctx = ctx;
236 new_callback->vendor_id = vendor_id;
237 new_callback->product_id = product_id;
238 new_callback->dev_class = dev_class;
239 new_callback->flags = flags;
240 new_callback->events = events;
241 new_callback->cb = cb_fn;
242 new_callback->user_data = user_data;
243 new_callback->needs_free = 0;
245 usbi_mutex_lock(&ctx->hotplug_cbs_lock);
247 /* protect the handle by the context hotplug lock. it doesn't matter if the same handle
248 * is used for different contexts only that the handle is unique for this context */
249 new_callback->handle = handle_id++;
251 list_add(&new_callback->list, &ctx->hotplug_cbs);
253 usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
256 if (flags & LIBUSB_HOTPLUG_ENUMERATE) {
258 struct libusb_device **devs;
260 len = (int) libusb_get_device_list(ctx, &devs);
262 libusb_hotplug_deregister_callback(ctx,
263 new_callback->handle);
267 for (i = 0; i < len; i++) {
268 usbi_hotplug_match_cb(ctx, devs[i],
269 LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED,
273 libusb_free_device_list(devs, 1);
278 *handle = new_callback->handle;
281 return LIBUSB_SUCCESS;
284 void API_EXPORTED libusb_hotplug_deregister_callback (struct libusb_context *ctx,
285 libusb_hotplug_callback_handle handle)
287 struct libusb_hotplug_callback *hotplug_cb;
288 libusb_hotplug_message message;
291 /* check for hotplug support */
292 if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
296 USBI_GET_CONTEXT(ctx);
298 usbi_mutex_lock(&ctx->hotplug_cbs_lock);
299 list_for_each_entry(hotplug_cb, &ctx->hotplug_cbs, list,
300 struct libusb_hotplug_callback) {
301 if (handle == hotplug_cb->handle) {
302 /* Mark this callback for deregistration */
303 hotplug_cb->needs_free = 1;
306 usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
308 /* wakeup handle_events to do the actual free */
309 memset(&message, 0, sizeof(message));
310 ret = usbi_write(ctx->hotplug_pipe[1], &message, sizeof(message));
311 if (sizeof(message) != ret) {
312 usbi_err(ctx, "error writing hotplug message");
316 void usbi_hotplug_deregister_all(struct libusb_context *ctx) {
317 struct libusb_hotplug_callback *hotplug_cb, *next;
319 usbi_mutex_lock(&ctx->hotplug_cbs_lock);
320 list_for_each_entry_safe(hotplug_cb, next, &ctx->hotplug_cbs, list,
321 struct libusb_hotplug_callback) {
322 list_del(&hotplug_cb->list);
326 usbi_mutex_unlock(&ctx->hotplug_cbs_lock);