Driver for USB3 Vision(TM) class devices
This driver is the kernel piece of a larger driver intended to acquire images from USB3 Vision class devices. USB3 Vision utilizes GenICam, a usermode generic programming interface that translates high-level actions into register read/write operations. Therefore, significant application logic outside of this kernel module is needed to incorporate GenICam and be fully compatible with the USB3Vision specification.
Devices are enumerated at /sys/class/usbmisc/u3vX, where X is a number associated with the camera. From there you can check ./device/device_guid and ensure that you've found the device you are looking for. Then you can open /dev/devX to get a file handle to the device that you can use for interacting with the ioctl interface.
The ioctl interface is provided in u3v_shared.h:
- U3V_IOCTL_READ
- U3V_IOCTL_WRITE
- U3V_IOCTL_GET_STREAM_ALIGNMENT
- U3V_IOCTL_GET_OS_MAX_TRANSFER
- U3V_IOCTL_CONFIGURE_STREAM
- U3V_IOCTL_UNCONFIGURE_STREAM
- U3V_IOCTL_CONFIGURE_BUFFER
- U3V_IOCTL_UNCONFIGURE_BUFFER
- U3V_IOCTL_QUEUE_BUFFER
- U3V_IOCTL_WAIT_FOR_BUFFER
- U3V_IOCTL_CANCEL_ALL_BUFFERS
- U3V_IOCTL_CTRL_MSG
- U3V_IOCTL_START_EVENTS
- U3V_IOCTL_WAIT_FOR_EVENT
- U3V_IOCTL_STOP_EVENTS
- U3V_IOCTL_CONFIGURE_STREAM2
These functions take a struct as a parameter with any necessary information.
For example, let's look at configuring a buffer. The struct associated with that call looks like this:
struct u3v_configure_buffer {
void __user *u_image_buffer;
void __user *u_chunk_data_buffer;
__u64 __user *u_buffer_handle;
};
Usermode code would create that struct and fill it in, then call the ioctl with the file descriptor you got from opening the device, the macro from u3v_shared, and the struct.
Here's an example:
// Do this just once, at the beginning
char* devicePath = "/dev/u3vX";
int fd = open(devicePath, O_RDWR);
if (fd == -1) {
// error handling
}
----------------------------------------------------------
// Then ioctl calls would be something like this
struct u3v_configure_buffer configureBuffer;
configureBuffer.u_image_buffer = imageBuffer; // pointer to user image data buffer
configureBuffer.u_chunk_data_buffer = chunkDataBuffer; // pointer to user chunk data buffer
configureBuffer.u_buffer_handle = bufferHandle; // pointer to uint64_t handle that will be populated by the kernel driver
int ret = ioctl(fd, U3V_IOCTL_CONFIGURE_BUFFER, &configureBuffer);
if (ret != 0) {
// error handling
}
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