1 /* -*- Mode: C; indent-tabs-mode:t ; c-basic-offset:8 -*- */
3 * Hotplug functions for libusbx
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 LIBUSBX_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.
64 * Callbacks for a particular context are automatically deregistered by libusb_exit().
66 * As of 1.0.16 there are two supported hotplug events:
67 * - LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED: A device has arrived and is ready to use
68 * - LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT: A device has left and is no longer available
70 * A hotplug event can listen for either or both of these events.
72 * Note: If you receive notification that a device has left and you have any
73 * a libusb_device_handles for the device it is up to you to call libusb_close()
74 * on each handle to free up any remaining resources associated with the device.
75 * Once a device has left any libusb_device_handle associated with the device
76 * are invalid and will remain so even if the device comes back.
78 * When handling a LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED event it is considered
79 * safe to call any libusbx function that takes a libusb_device. On the other hand,
80 * when handling a LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT event the only safe function
81 * is libusb_get_device_descriptor().
83 * The following code provides an example of the usage of the hotplug interface:
87 int hotplug_callback(struct libusb_context *ctx, struct libusb_device *dev,
88 libusb_hotplug_event event, void *user_data) {
89 static libusb_device_handle *handle = NULL;
90 struct libusb_device_descriptor desc;
93 (void)libusb_get_device_descriptor(dev, &desc);
95 if (LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED == event) {
96 rc = libusb_open(dev, &handle);
97 if (LIBUSB_SUCCESS != rc) {
98 printf("Could not open USB device\n");
100 } else if (LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT == event) {
102 libusb_close(handle);
106 printf("Unhandled event %d\n", event);
114 libusb_hotplug_callback_handle handle;
119 rc = libusb_hotplug_register_callback(NULL, LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED |
120 LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT, 0, 0x045a, 0x5005,
121 LIBUSB_HOTPLUG_MATCH_ANY, hotplug_callback, NULL,
123 if (LIBUSB_SUCCESS != rc) {
124 printf("Error creating a hotplug callback\n");
133 libusb_hotplug_deregister_callback(handle);
141 static int usbi_hotplug_match_cb (struct libusb_context *ctx,
142 struct libusb_device *dev, libusb_hotplug_event event,
143 struct libusb_hotplug_callback *hotplug_cb)
145 /* Handle lazy deregistration of callback */
146 if (hotplug_cb->needs_free) {
151 if (!(hotplug_cb->events & event)) {
155 if (LIBUSB_HOTPLUG_MATCH_ANY != hotplug_cb->vendor_id &&
156 hotplug_cb->vendor_id != dev->device_descriptor.idVendor) {
160 if (LIBUSB_HOTPLUG_MATCH_ANY != hotplug_cb->product_id &&
161 hotplug_cb->product_id != dev->device_descriptor.idProduct) {
165 if (LIBUSB_HOTPLUG_MATCH_ANY != hotplug_cb->dev_class &&
166 hotplug_cb->dev_class != dev->device_descriptor.bDeviceClass) {
170 return hotplug_cb->cb (ctx, dev, event, hotplug_cb->user_data);
173 void usbi_hotplug_match(struct libusb_context *ctx, struct libusb_device *dev,
174 libusb_hotplug_event event)
176 struct libusb_hotplug_callback *hotplug_cb, *next;
179 usbi_mutex_lock(&ctx->hotplug_cbs_lock);
181 list_for_each_entry_safe(hotplug_cb, next, &ctx->hotplug_cbs, list, struct libusb_hotplug_callback) {
182 usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
183 ret = usbi_hotplug_match_cb (ctx, dev, event, hotplug_cb);
184 usbi_mutex_lock(&ctx->hotplug_cbs_lock);
187 list_del(&hotplug_cb->list);
192 usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
194 /* the backend is expected to call the callback for each active transfer */
197 int API_EXPORTED libusb_hotplug_register_callback(libusb_context *ctx,
198 libusb_hotplug_event events, libusb_hotplug_flag flags,
199 int vendor_id, int product_id, int dev_class,
200 libusb_hotplug_callback_fn cb_fn, void *user_data,
201 libusb_hotplug_callback_handle *handle)
203 libusb_hotplug_callback *new_callback;
204 static int handle_id = 1;
206 /* check for hotplug support */
207 if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
208 return LIBUSB_ERROR_NOT_SUPPORTED;
211 /* check for sane values */
212 if ((LIBUSB_HOTPLUG_MATCH_ANY != vendor_id && (~0xffff & vendor_id)) ||
213 (LIBUSB_HOTPLUG_MATCH_ANY != product_id && (~0xffff & product_id)) ||
214 (LIBUSB_HOTPLUG_MATCH_ANY != dev_class && (~0xff & dev_class)) ||
216 return LIBUSB_ERROR_INVALID_PARAM;
219 USBI_GET_CONTEXT(ctx);
221 new_callback = (libusb_hotplug_callback *)calloc(1, sizeof (*new_callback));
223 return LIBUSB_ERROR_NO_MEM;
226 new_callback->ctx = ctx;
227 new_callback->vendor_id = vendor_id;
228 new_callback->product_id = product_id;
229 new_callback->dev_class = dev_class;
230 new_callback->flags = flags;
231 new_callback->events = events;
232 new_callback->cb = cb_fn;
233 new_callback->user_data = user_data;
234 new_callback->needs_free = 0;
236 usbi_mutex_lock(&ctx->hotplug_cbs_lock);
238 /* protect the handle by the context hotplug lock. it doesn't matter if the same handle
239 * is used for different contexts only that the handle is unique for this context */
240 new_callback->handle = handle_id++;
242 list_add(&new_callback->list, &ctx->hotplug_cbs);
244 if (flags & LIBUSB_HOTPLUG_ENUMERATE) {
245 struct libusb_device *dev;
247 usbi_mutex_lock(&ctx->usb_devs_lock);
249 list_for_each_entry(dev, &ctx->usb_devs, list, struct libusb_device) {
250 (void) usbi_hotplug_match_cb (ctx, dev, LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED, new_callback);
253 usbi_mutex_unlock(&ctx->usb_devs_lock);
256 usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
259 *handle = new_callback->handle;
262 return LIBUSB_SUCCESS;
265 void API_EXPORTED libusb_hotplug_deregister_callback (struct libusb_context *ctx,
266 libusb_hotplug_callback_handle handle)
268 struct libusb_hotplug_callback *hotplug_cb;
269 libusb_hotplug_message message;
272 /* check for hotplug support */
273 if (!libusb_has_capability(LIBUSB_CAP_HAS_HOTPLUG)) {
277 USBI_GET_CONTEXT(ctx);
279 usbi_mutex_lock(&ctx->hotplug_cbs_lock);
280 list_for_each_entry(hotplug_cb, &ctx->hotplug_cbs, list,
281 struct libusb_hotplug_callback) {
282 if (handle == hotplug_cb->handle) {
283 /* Mark this callback for deregistration */
284 hotplug_cb->needs_free = 1;
287 usbi_mutex_unlock(&ctx->hotplug_cbs_lock);
289 /* wakeup handle_events to do the actual free */
290 memset(&message, 0, sizeof(message));
291 ret = usbi_write(ctx->hotplug_pipe[1], &message, sizeof(message));
292 if (sizeof(message) != ret) {
293 usbi_err(ctx, "error writing hotplug message");
297 void usbi_hotplug_deregister_all(struct libusb_context *ctx) {
298 struct libusb_hotplug_callback *hotplug_cb, *next;
300 usbi_mutex_lock(&ctx->hotplug_cbs_lock);
301 list_for_each_entry_safe(hotplug_cb, next, &ctx->hotplug_cbs, list,
302 struct libusb_hotplug_callback) {
303 list_del(&hotplug_cb->list);
307 usbi_mutex_unlock(&ctx->hotplug_cbs_lock);