Driver structures: libfprint Reference Manual

## Driver structures Driver structures — Driver structures |

## Types and Values

struct | usb_id
enum | fp_driver_type

## Includes

    #include <fpi-core.h>

## Description

Driver structures need to be defined inside each driver in order for the core library to know what function to call, and the capabilities of the driver and the devices it supports.

## Functions

## Types and Values

### struct usb_id

    struct usb_id {
    	uint16_t vendor;
    	uint16_t product;
    	unsigned long driver_data;
    };

The struct usb_id is used to declare devices supported by a particular driver. The `driver_data` information is used to differentiate different models of devices which only need small changes compared to the default driver behaviour to function.

For example, a device might have a different initialisation from the stock device, so the driver could do:

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    if (driver_data == MY_DIFFERENT_DEVICE_QUIRK) {
        ...
    } else {
        ...
    }

The default value is zero, so the `driver_data` needs to be a non-zero to be useful.

#### Members

uint16_t `vendor`; | the USB vendor ID |
uint16_t `product`; | the USB product ID |
unsigned long `driver_data`; | data to differentiate devices of different vendor and product IDs. |

### enum fp_driver_type

The type of device the driver supports.

#### Members

DRIVER_PRIMITIVE | primitive, non-imaging, driver |
DRIVER_IMAGING | imaging driver |