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https://e.coding.net/weidongshan/linux/doc_and_source_for_drivers.git
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tmp update
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weidongshan
@@ -58,9 +58,7 @@ if (r == 0 && actual_length == sizeof(data)) {
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### 2.2 主要函数
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#### 2.2.1 初始化
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### 2.2 初始化
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```c
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/** \ingroup libusb_lib
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@@ -83,7 +81,7 @@ int API_EXPORTED libusb_init(libusb_context **ctx);
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#### 2.2.2 获取设备
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### 2.3 获取设备
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可以使用`libusb_get_device_list`取出所有设备，函数接口如下：
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@@ -126,7 +124,7 @@ void API_EXPORTED libusb_free_device_list(libusb_device **list,
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int unref_devices);
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```
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#### 2.2.3 打开/关闭设备
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### 2.4 打开/关闭设备
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使用libusb_get_device_list得到设备列表后，可以选择里面的某个设备，然后调用libusb_open：
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@@ -175,7 +173,7 @@ void API_EXPORTED libusb_close(libusb_device_handle *dev_handle);
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#### 2.2.4 根据ID打开设备
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### 2.5 根据ID打开设备
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如果知道设备的VID、PID，那么可以使用libusb_open_device_with_vid_pid来找到它、打开它。这个函数的内部，先使用`libusb_get_device_list`列出所有设备，然后遍历它们根据ID选出设备，接着调用libusb_open打开它，最后调用libusb_free_device_list释放设备。
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@@ -205,7 +203,7 @@ libusb_device_handle * LIBUSB_CALL libusb_open_device_with_vid_pid(
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#### 2.2.5 detach/attach驱动
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### 2.6 detach/attach驱动
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使用libusb访问USB设备时，需要先移除(detach)设备原来的驱动程序，然后安装(attach)libusb专用的驱动程序。有两种办法：
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@@ -326,7 +324,224 @@ int API_EXPORTED libusb_release_interface(libusb_device_handle *dev_handle,
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#### 2.2.6 描述符相关函数
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### 2.7 描述符相关函数
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**获得设备描述符**：
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```c
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/** \ingroup libusb_desc
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* Get the USB device descriptor for a given device.
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*
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* This is a non-blocking function; the device descriptor is cached in memory.
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*
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* Note since libusb-1.0.16, \ref LIBUSB_API_VERSION >= 0x01000102, this
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* function always succeeds.
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*
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* \param dev the device
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* \param desc output location for the descriptor data
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* \returns 0 on success or a LIBUSB_ERROR code on failure
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*/
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int API_EXPORTED libusb_get_device_descriptor(libusb_device *dev,
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struct libusb_device_descriptor *desc);
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```
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**获得/释放配置描述符**：
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```c
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/** \ingroup libusb_desc
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* Get a USB configuration descriptor based on its index.
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* This is a non-blocking function which does not involve any requests being
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* sent to the device.
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*
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* \param dev a device
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* \param config_index the index of the configuration you wish to retrieve
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* \param config output location for the USB configuration descriptor. Only
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* valid if 0 was returned. Must be freed with libusb_free_config_descriptor()
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* after use.
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* \returns 0 on success
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* \returns LIBUSB_ERROR_NOT_FOUND if the configuration does not exist
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* \returns another LIBUSB_ERROR code on error
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* \see libusb_get_active_config_descriptor()
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* \see libusb_get_config_descriptor_by_value()
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*/
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int API_EXPORTED libusb_get_config_descriptor(libusb_device *dev,
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uint8_t config_index, struct libusb_config_descriptor **config);
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/** \ingroup libusb_desc
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* Free a configuration descriptor obtained from
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* libusb_get_active_config_descriptor() or libusb_get_config_descriptor().
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* It is safe to call this function with a NULL config parameter, in which
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* case the function simply returns.
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*
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* \param config the configuration descriptor to free
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*/
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void API_EXPORTED libusb_free_config_descriptor(
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struct libusb_config_descriptor *config);
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```
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### 2.8 同步传输函数
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#### 2.8.1 控制传输
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```c
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/** \ingroup libusb_syncio
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* Perform a USB control transfer.
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*
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* The direction of the transfer is inferred from the bmRequestType field of
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* the setup packet.
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*
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* The wValue, wIndex and wLength fields values should be given in host-endian
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* byte order.
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*
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* \param dev_handle a handle for the device to communicate with
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* \param bmRequestType the request type field for the setup packet
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* \param bRequest the request field for the setup packet
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* \param wValue the value field for the setup packet
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* \param wIndex the index field for the setup packet
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* \param data a suitably-sized data buffer for either input or output
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* (depending on direction bits within bmRequestType)
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* \param wLength the length field for the setup packet. The data buffer should
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* be at least this size.
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* \param timeout timeout (in milliseconds) that this function should wait
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* before giving up due to no response being received. For an unlimited
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* timeout, use value 0.
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* \returns on success, the number of bytes actually transferred
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* \returns LIBUSB_ERROR_TIMEOUT if the transfer timed out
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* \returns LIBUSB_ERROR_PIPE if the control request was not supported by the
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* device
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* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
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* \returns LIBUSB_ERROR_BUSY if called from event handling context
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* \returns LIBUSB_ERROR_INVALID_PARAM if the transfer size is larger than
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* the operating system and/or hardware can support (see \ref asynclimits)
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* \returns another LIBUSB_ERROR code on other failures
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*/
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int API_EXPORTED libusb_control_transfer(libusb_device_handle *dev_handle,
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uint8_t bmRequestType, uint8_t bRequest, uint16_t wValue, uint16_t wIndex,
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unsigned char *data, uint16_t wLength, unsigned int timeout);
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```
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#### 2.8.2 批量传输
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```c
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/** \ingroup libusb_syncio
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* Perform a USB bulk transfer. The direction of the transfer is inferred from
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* the direction bits of the endpoint address.
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*
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* For bulk reads, the <tt>length</tt> field indicates the maximum length of
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* data you are expecting to receive. If less data arrives than expected,
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* this function will return that data, so be sure to check the
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* <tt>transferred</tt> output parameter.
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*
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* You should also check the <tt>transferred</tt> parameter for bulk writes.
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* Not all of the data may have been written.
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*
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* Also check <tt>transferred</tt> when dealing with a timeout error code.
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* libusb may have to split your transfer into a number of chunks to satisfy
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* underlying O/S requirements, meaning that the timeout may expire after
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* the first few chunks have completed. libusb is careful not to lose any data
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* that may have been transferred; do not assume that timeout conditions
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* indicate a complete lack of I/O. See \ref asynctimeout for more details.
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*
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* \param dev_handle a handle for the device to communicate with
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* \param endpoint the address of a valid endpoint to communicate with
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* \param data a suitably-sized data buffer for either input or output
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* (depending on endpoint)
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* \param length for bulk writes, the number of bytes from data to be sent. for
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* bulk reads, the maximum number of bytes to receive into the data buffer.
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* \param transferred output location for the number of bytes actually
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* transferred. Since version 1.0.21 (\ref LIBUSB_API_VERSION >= 0x01000105),
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* it is legal to pass a NULL pointer if you do not wish to receive this
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* information.
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* \param timeout timeout (in milliseconds) that this function should wait
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* before giving up due to no response being received. For an unlimited
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* timeout, use value 0.
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*
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* \returns 0 on success (and populates <tt>transferred</tt>)
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* \returns LIBUSB_ERROR_TIMEOUT if the transfer timed out (and populates
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* <tt>transferred</tt>)
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* \returns LIBUSB_ERROR_PIPE if the endpoint halted
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* \returns LIBUSB_ERROR_OVERFLOW if the device offered more data, see
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* \ref libusb_packetoverflow
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* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
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* \returns LIBUSB_ERROR_BUSY if called from event handling context
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* \returns LIBUSB_ERROR_INVALID_PARAM if the transfer size is larger than
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* the operating system and/or hardware can support (see \ref asynclimits)
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* \returns another LIBUSB_ERROR code on other failures
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*/
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int API_EXPORTED libusb_bulk_transfer(libusb_device_handle *dev_handle,
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unsigned char endpoint, unsigned char *data, int length,
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int *transferred, unsigned int timeout);
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```
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#### 2.8.3 中断传输
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```c
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/** \ingroup libusb_syncio
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* Perform a USB interrupt transfer. The direction of the transfer is inferred
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* from the direction bits of the endpoint address.
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*
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* For interrupt reads, the <tt>length</tt> field indicates the maximum length
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* of data you are expecting to receive. If less data arrives than expected,
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* this function will return that data, so be sure to check the
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* <tt>transferred</tt> output parameter.
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*
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* You should also check the <tt>transferred</tt> parameter for interrupt
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* writes. Not all of the data may have been written.
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*
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* Also check <tt>transferred</tt> when dealing with a timeout error code.
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* libusb may have to split your transfer into a number of chunks to satisfy
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* underlying O/S requirements, meaning that the timeout may expire after
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* the first few chunks have completed. libusb is careful not to lose any data
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* that may have been transferred; do not assume that timeout conditions
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* indicate a complete lack of I/O. See \ref asynctimeout for more details.
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*
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* The default endpoint bInterval value is used as the polling interval.
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*
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* \param dev_handle a handle for the device to communicate with
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* \param endpoint the address of a valid endpoint to communicate with
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* \param data a suitably-sized data buffer for either input or output
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* (depending on endpoint)
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* \param length for bulk writes, the number of bytes from data to be sent. for
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* bulk reads, the maximum number of bytes to receive into the data buffer.
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* \param transferred output location for the number of bytes actually
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* transferred. Since version 1.0.21 (\ref LIBUSB_API_VERSION >= 0x01000105),
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* it is legal to pass a NULL pointer if you do not wish to receive this
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* information.
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* \param timeout timeout (in milliseconds) that this function should wait
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* before giving up due to no response being received. For an unlimited
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* timeout, use value 0.
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*
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* \returns 0 on success (and populates <tt>transferred</tt>)
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* \returns LIBUSB_ERROR_TIMEOUT if the transfer timed out
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* \returns LIBUSB_ERROR_PIPE if the endpoint halted
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* \returns LIBUSB_ERROR_OVERFLOW if the device offered more data, see
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* \ref libusb_packetoverflow
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* \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
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* \returns LIBUSB_ERROR_BUSY if called from event handling context
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* \returns LIBUSB_ERROR_INVALID_PARAM if the transfer size is larger than
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* the operating system and/or hardware can support (see \ref asynclimits)
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* \returns another LIBUSB_ERROR code on other error
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*/
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int API_EXPORTED libusb_interrupt_transfer(libusb_device_handle *dev_handle,
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unsigned char endpoint, unsigned char *data, int length,
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int *transferred, unsigned int timeout);
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```
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### 2.9 异步传输函数
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#### 2.9.1 使用步骤
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