How does device driver communicate with hardware?

A driver communicates with the device through the computer bus or communications subsystem to which the hardware connects. When a calling program invokes a routine in the driver, the driver issues commands to the device.

How are device drivers coded?

Device drivers are typically written in C, using the Driver Development Kit (DDK). There are functional and object-oriented ways to program drivers, depending on the language chosen to write in.

How do I know if my device is I2C?

The I2C device driver must implement the detect() method, which identifies a supported device by reading from arbitrary registers. Only buses which are likely to have a supported device and agree to be probed, will be probed. For example this avoids probing for hardware monitoring chips on a TV adapter.

Can GPIO controllers be interfaced over i2c/spi?

GPIO controllers interfaced over I2C/SPI are not supported. The controller driver is a memory mapped controller if it sets the MemoryMappedController flag in the CLIENT_CONTROLLER_BASIC_INFORMATION structure in response to the CLIENT_QueryControllerBasicInformation callback. Each pin requires both a GpioIO and a GpioInt resource.

How do GPIO I/O resources work?

If a peripheral device driver opens a GPIO I/O resource for reads, the driver uses all of the pins in the resource as data inputs. If a driver opens a GPIO I/O resource for writes, the driver uses all of the pins in the resource as data outputs.

What is the difference between the GPIO controller driver and gpioclx?

The GPIO controller driver directly accesses the hardware registers of the GPIO controller device. GpioClx handles I/O requests from the drivers for peripheral devices that physically connect to GPIO pins.

What is the I/O pin on a GPIO controller for?

Typically, an I/O pin on a GPIO controller can be configured either for input or for output, depending on the capabilities of the controller hardware and the device that is physically connected to the pin. Thus, a driver can open a logical connection to this pin for either write or read operations, but not both.