Allocating and registering an input device

Before the events that are supported by an input device can be seen by the system, memory needs to be allocated for this device first using the devm_input_allocate_device() API. Then, the device needs to be registered with the system using input_device_register(). The former API will take care of freeing up the memory and unregistering the device when it leaves the system. However, non-managed allocation is still available but not recommended, input_allocate_device(). By using non-managed allocation, the driver becomes responsible for making sure that input_unregister_device() and input_free_device() are called to unregister the device and free its memory when they're on the unloading path of the driver, respectively. The following are the respective prototypes of these APIs:

struct input_dev *input_allocate_device(void)
struct input_dev *devm_input_allocate_device(
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