| 1 | Parallel Port Devices
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| 2 | =====================
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| 3 |
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| 4 | .. kernel-doc:: include/linux/parport.h
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| 5 | :internal:
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| 6 |
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| 7 | .. kernel-doc:: drivers/parport/ieee1284.c
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| 8 | :export:
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| 9 |
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| 10 | .. kernel-doc:: drivers/parport/share.c
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| 11 | :export:
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| 12 |
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| 13 | .. kernel-doc:: drivers/parport/daisy.c
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| 14 | :internal:
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| 15 |
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| 16 | 16x50 UART Driver
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| 17 | =================
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| 18 |
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| 19 | .. kernel-doc:: drivers/tty/serial/8250/8250_core.c
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| 20 | :export:
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| 21 |
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| 22 | See serial/driver.rst for related APIs.
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| 23 |
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| 24 | Pulse-Width Modulation (PWM)
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| 25 | ============================
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| 26 |
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| 27 | Pulse-width modulation is a modulation technique primarily used to
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| 28 | control power supplied to electrical devices.
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| 29 |
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| 30 | The PWM framework provides an abstraction for providers and consumers of
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| 31 | PWM signals. A controller that provides one or more PWM signals is
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| 32 | registered as :c:type:`struct pwm_chip <pwm_chip>`. Providers
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| 33 | are expected to embed this structure in a driver-specific structure.
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| 34 | This structure contains fields that describe a particular chip.
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| 35 |
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| 36 | A chip exposes one or more PWM signal sources, each of which exposed as
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| 37 | a :c:type:`struct pwm_device <pwm_device>`. Operations can be
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| 38 | performed on PWM devices to control the period, duty cycle, polarity and
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| 39 | active state of the signal.
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| 40 |
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| 41 | Note that PWM devices are exclusive resources: they can always only be
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| 42 | used by one consumer at a time.
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| 43 |
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| 44 | .. kernel-doc:: include/linux/pwm.h
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| 45 | :internal:
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| 46 |
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| 47 | .. kernel-doc:: drivers/pwm/core.c
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| 48 | :export:
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