Parallel Port Devices===================== .. kernel-doc:: include/linux/parport.h   :internal: .. kernel-doc:: drivers/parport/ieee1284.c   :export: .. kernel-doc:: drivers/parport/share.c   :export: .. kernel-doc:: drivers/parport/daisy.c   :internal: 16x50 UART Driver================= .. kernel-doc:: drivers/tty/serial/8250/8250_core.c   :export: See serial/driver.rst for related APIs. Pulse-Width Modulation (PWM)============================ Pulse-width modulation is a modulation technique primarily used tocontrol power supplied to electrical devices. The PWM framework provides an abstraction for providers and consumers ofPWM signals. A controller that provides one or more PWM signals isregistered as :c:type:`struct pwm_chip <pwm_chip>`. Providersare expected to embed this structure in a driver-specific structure.This structure contains fields that describe a particular chip. A chip exposes one or more PWM signal sources, each of which exposed asa :c:type:`struct pwm_device <pwm_device>`. Operations can beperformed on PWM devices to control the period, duty cycle, polarity andactive state of the signal. Note that PWM devices are exclusive resources: they can always only beused by one consumer at a time. .. kernel-doc:: include/linux/pwm.h   :internal: .. kernel-doc:: drivers/pwm/core.c   :export: