Specifications

CHAPTER 2. DRIVERS AND INTERFACES 9

USB HC USB HCI USB HID

Input Core

USB HID Input

USB Device

USB Device Driver

Figure 2.2: Linux USB Input

USB HID and USB HID input but use the input core driver, too. They are indicated as “USB

Device Driver” in Figure 2.2.

USB support for the Linux kernel is enabled by setting the conﬁguration option CONFIG USB

to either y (compile static into kernel) or m (compile as module). In addition, it is mandatory

to choose a driver for the USB host controller. Linux supports the host controllers EHCI

(USB 2.0), OHCI and UHCI. Their corresponding conﬁguration options are CONFIG EHCI,

CONFIG OHCI and CONFIG UHCI. To enable USB HID support the conﬁguration options USB HID

and USB HIDINPUT have either to be set to y or n.

2.4 Bluetooth Input Device Drivers

The Bluetooth speciﬁcation [Sig04] deﬁnes several proﬁles. Each proﬁle represents a class of

similar Bluetooth devices. Bluetooth input devices are referred to the HID proﬁle, which is

speciﬁed in [RG03]. Both the USB HID speciﬁcation and the Bluetooth HID speciﬁcation are

very similar and list the same type of devices which are considered as HID. Again, this fact is

important to support future devices without developing a new driver for every new device.

Due to the fact that Bluetooth host controllers can be attached in several ways, Figure 2.3

shows the diﬀerent connection methods. It is possible to use USB, PCMCIA or UART (serial

connection) to connect a Bluetooth host controller. There are also Bluetooth host controllers

which use a serial connection via PCMCIA. This method is not shown in Figure 2.3.

BT HIDP

Input Core

UART

TTY

BT HC

USB HC

PCMCIA

USB HCI

BT HCI

BT Devices

Figure 2.3: Linux Bluetooth Input