2 * Synchronous I/O functions for libusb
3 * Copyright (C) 2007-2008 Daniel Drake <dsd@gentoo.org>
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
29 * @defgroup syncio Synchronous device I/O
31 * This page documents libusb's synchronous (blocking) API for USB device I/O.
32 * This interface is easy to use but has some limitations. More advanced users
33 * may wish to consider using the \ref asyncio "asynchronous I/O API" instead.
36 static void ctrl_transfer_cb(struct libusb_transfer *transfer)
38 int *completed = transfer->user_data;
40 usbi_dbg("actual_length=%d", transfer->actual_length);
41 /* caller interprets result and frees transfer */
45 * Perform a USB control transfer.
47 * The direction of the transfer is inferred from the bmRequestType field of
50 * The wValue, wIndex and wLength fields values should be given in host-endian
53 * \param dev_handle a handle for the device to communicate with
54 * \param bmRequestType the request type field for the setup packet
55 * \param bRequest the request field for the setup packet
56 * \param wValue the value field for the setup packet
57 * \param wIndex the index field for the setup packet
58 * \param data a suitably-sized data buffer for either input or output
59 * (depending on direction bits within bmRequestType)
60 * \param wLength the length field for the setup packet. The data buffer should
61 * be at least this size.
62 * \param timeout timeout (in millseconds) that this function should wait
63 * before giving up due to no response being received. For no timeout, use
65 * \returns on success, the number of bytes actually transferred
66 * \returns LIBUSB_ERROR_TIMEOUT if the transfer timed out
67 * \returns LIBUSB_ERROR_PIPE if the control request was not supported by the
69 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
70 * \returns another LIBUSB_ERROR code on other failures
72 API_EXPORTED int libusb_control_transfer(libusb_device_handle *dev_handle,
73 uint8_t bmRequestType, uint8_t bRequest, uint16_t wValue, uint16_t wIndex,
74 unsigned char *data, uint16_t wLength, unsigned int timeout)
76 struct libusb_transfer *transfer = libusb_alloc_transfer(0);
77 unsigned char *buffer;
82 return LIBUSB_ERROR_NO_MEM;
84 buffer = malloc(LIBUSB_CONTROL_SETUP_SIZE + wLength);
86 libusb_free_transfer(transfer);
87 return LIBUSB_ERROR_NO_MEM;
90 libusb_fill_control_setup(buffer, bmRequestType, bRequest, wValue, wIndex,
92 if ((bmRequestType & LIBUSB_ENDPOINT_DIR_MASK) == LIBUSB_ENDPOINT_OUT)
93 memcpy(buffer + LIBUSB_CONTROL_SETUP_SIZE, data, wLength);
95 libusb_fill_control_transfer(transfer, dev_handle, buffer,
96 ctrl_transfer_cb, &completed, timeout);
97 transfer->flags = LIBUSB_TRANSFER_FREE_BUFFER;
98 r = libusb_submit_transfer(transfer);
100 libusb_free_transfer(transfer);
105 r = libusb_handle_events();
107 libusb_cancel_transfer(transfer);
109 if (libusb_handle_events() < 0)
111 libusb_free_transfer(transfer);
116 if ((bmRequestType & LIBUSB_ENDPOINT_DIR_MASK) == LIBUSB_ENDPOINT_IN)
117 memcpy(data, libusb_control_transfer_get_data(transfer),
118 transfer->actual_length);
120 switch (transfer->status) {
121 case LIBUSB_TRANSFER_COMPLETED:
122 r = transfer->actual_length;
124 case LIBUSB_TRANSFER_TIMED_OUT:
125 r = LIBUSB_ERROR_TIMEOUT;
127 case LIBUSB_TRANSFER_STALL:
128 r = LIBUSB_ERROR_PIPE;
130 case LIBUSB_TRANSFER_NO_DEVICE:
131 r = LIBUSB_ERROR_NO_DEVICE;
134 usbi_warn("unrecognised status code %d", transfer->status);
135 r = LIBUSB_ERROR_OTHER;
138 libusb_free_transfer(transfer);
142 static void bulk_transfer_cb(struct libusb_transfer *transfer)
144 int *completed = transfer->user_data;
146 usbi_dbg("actual_length=%d", transfer->actual_length);
147 /* caller interprets results and frees transfer */
150 static int do_sync_bulk_transfer(struct libusb_device_handle *dev_handle,
151 unsigned char endpoint, unsigned char *buffer, int length,
152 int *transferred, unsigned int timeout, unsigned char type)
154 struct libusb_transfer *transfer = libusb_alloc_transfer(0);
159 return LIBUSB_ERROR_NO_MEM;
161 libusb_fill_bulk_transfer(transfer, dev_handle, endpoint, buffer, length,
162 bulk_transfer_cb, &completed, timeout);
163 transfer->type = type;
165 r = libusb_submit_transfer(transfer);
167 libusb_free_transfer(transfer);
172 r = libusb_handle_events();
174 libusb_cancel_transfer(transfer);
176 if (libusb_handle_events() < 0)
178 libusb_free_transfer(transfer);
183 *transferred = transfer->actual_length;
184 switch (transfer->status) {
185 case LIBUSB_TRANSFER_COMPLETED:
188 case LIBUSB_TRANSFER_TIMED_OUT:
189 r = LIBUSB_ERROR_TIMEOUT;
191 case LIBUSB_TRANSFER_STALL:
192 r = LIBUSB_ERROR_PIPE;
194 case LIBUSB_TRANSFER_NO_DEVICE:
195 r = LIBUSB_ERROR_NO_DEVICE;
198 usbi_warn("unrecognised status code %d", transfer->status);
199 r = LIBUSB_ERROR_OTHER;
202 libusb_free_transfer(transfer);
207 * Perform a USB bulk transfer. The direction of the transfer is inferred from
208 * the direction bits of the endpoint address.
210 * For bulk reads, the <tt>length</tt> field indicates the maximum length of
211 * data you are expecting to receive. If less data arrives than expected,
212 * this function will return that data, so be sure to check the
213 * <tt>transferred</tt> output parameter.
215 * You should also check the <tt>transferred</tt> parameter for bulk writes.
216 * Not all of the data may have been written.
218 * Also check <tt>transferred</tt> when dealing with a timeout error code.
219 * libusb may have to split your transfer into a number of chunks to satisfy
220 * underlying O/S requirements, meaning that the timeout may expire after
221 * the first few chunks have completed. libusb is careful not to lose any data
222 * that may have been transferred; do not assume that timeout conditions
223 * indicate a complete lack of I/O.
225 * \param dev_handle a handle for the device to communicate with
226 * \param endpoint the address of a valid endpoint to communicate with
227 * \param data a suitably-sized data buffer for either input or output
228 * (depending on endpoint)
229 * \param length for bulk writes, the number of bytes from data to be sent. for
230 * bulk reads, the maximum number of bytes to receive into the data buffer.
231 * \param transferred output location for the number of bytes actually
233 * \param timeout timeout (in millseconds) that this function should wait
234 * before giving up due to no response being received. For no timeout, use
237 * \returns 0 on success (and populates <tt>transferred</tt>)
238 * \returns LIBUSB_ERROR_TIMEOUT if the transfer timed out (and populates
239 * <tt>transferred</tt>)
240 * \returns LIBUSB_ERROR_PIPE if the endpoint halted
241 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
242 * \returns another LIBUSB_ERROR code on other failures
244 API_EXPORTED int libusb_bulk_transfer(struct libusb_device_handle *dev_handle,
245 unsigned char endpoint, unsigned char *data, int length, int *transferred,
246 unsigned int timeout)
248 return do_sync_bulk_transfer(dev_handle, endpoint, data, length,
249 transferred, timeout, LIBUSB_TRANSFER_TYPE_BULK);
253 * Perform a USB interrupt transfer. The direction of the transfer is inferred
254 * from the direction bits of the endpoint address.
256 * For interrupt reads, the <tt>length</tt> field indicates the maximum length
257 * of data you are expecting to receive. If less data arrives than expected,
258 * this function will return that data, so be sure to check the
259 * <tt>transferred</tt> output parameter.
261 * You should also check the <tt>transferred</tt> parameter for interrupt
262 * writes. Not all of the data may have been written.
264 * Also check <tt>transferred</tt> when dealing with a timeout error code.
265 * libusb may have to split your transfer into a number of chunks to satisfy
266 * underlying O/S requirements, meaning that the timeout may expire after
267 * the first few chunks have completed. libusb is careful not to lose any data
268 * that may have been transferred; do not assume that timeout conditions
269 * indicate a complete lack of I/O.
271 * The default endpoint bInterval value is used as the polling interval.
273 * \param dev_handle a handle for the device to communicate with
274 * \param endpoint the address of a valid endpoint to communicate with
275 * \param data a suitably-sized data buffer for either input or output
276 * (depending on endpoint)
277 * \param length for bulk writes, the number of bytes from data to be sent. for
278 * bulk reads, the maximum number of bytes to receive into the data buffer.
279 * \param transferred output location for the number of bytes actually
281 * \param timeout timeout (in millseconds) that this function should wait
282 * before giving up due to no response being received. For no timeout, use
285 * \returns 0 on success (and populates <tt>transferred</tt>)
286 * \returns LIBUSB_ERROR_TIMEOUT if the transfer timed out
287 * \returns LIBUSB_ERROR_PIPE if the endpoint halted
288 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
289 * \returns another LIBUSB_ERROR code on other error
291 API_EXPORTED int libusb_interrupt_transfer(
292 struct libusb_device_handle *dev_handle, unsigned char endpoint,
293 unsigned char *data, int length, int *transferred, unsigned int timeout)
295 return do_sync_bulk_transfer(dev_handle, endpoint, data, length,
296 transferred, timeout, LIBUSB_TRANSFER_TYPE_INTERRUPT);