Generic PWM API implementation

This series implements a Generic PWM Device API, including reference implementations for the Atmel PWMC device, an LED device, and an LED trigger. It is based on linux-2.6.27.

This API is motivated by the author's need to support pluggable devices; a secondary objective is to consolidate the existing PWM implementations behind an agreeable, consistent, redundancy-reducing interface.

The code included in this patch series draws heavily from the existing PWM infrastructure and driver for the AT91SAM9263 PWMC. The author is grateful to Russell King, Eric Miao, David Brownell and many others for providing such tall "shoulders" to stand upon. Modifications to their code as described in this changeset should not be interpreted as attempts to address shortcomings, but rather to extend functionality in ways that were not originally required.

The implementation of the Generic PWM Device API is structurally similar to the generic GPIO API, except that the PWM code uses platform bus_id strings instead of integers to identify target deviices. A configuration structure is also provided, both to facilitate atomic hardware state changes and so that the API can be extended in a source-code-compatible way to accomodate devices with features not anticipated by the current code.

Pulse width modulated signals are used in an astounding number and range of applications, and there is no "one true way" of either realizing them or employing them to accomplish real work. The review process revealed many use cases to the author, but countless others undoubtedly remain. The current API attempts to provide a useful feature set for the most basic users, packaged in such a way as to allow the API to be extended in a backwards-compatible way as new needs are identified.

The proposed code has been run-tested on a Cogent CSB737 (AT91SAM9263), mated to a custom circuit that drives multiple DC motors and sensors.

Feedback is welcome!

b.g.
--
Bill Gatliff
<[email protected]>

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Bill Gatliff (6):
[PWM] Generic PWM API implementation
[PWM] Changes to existing include/linux/pwm.h to adapt to generic PWM
API
[PWM] Documentation
[PWM] Driver for Atmel PWMC peripheral
[PWM] Install new Atmel PWMC driver in Kconfig, expunge old one [PWM] New LED driver and trigger that use PWM API

 Documentation/pwm.txt      |  258 +++++++++++++++++
 arch/arm/Kconfig           |    2 +
 drivers/Makefile           |    2 +
 drivers/leds/Kconfig       |   24 ++-
 drivers/leds/Makefile      |    2 +
 drivers/leds/leds-pwm.c    |  167 +++++++++++
 drivers/leds/ledtrig-dim.c |   95 ++++++
 drivers/misc/Kconfig       |    9 -
 drivers/misc/Makefile      |    1 -
 drivers/misc/atmel_pwm.c   |  409 --------------------------
 drivers/pwm/Kconfig        |   24 ++
 drivers/pwm/Makefile       |    6 +
 drivers/pwm/atmel-pwm.c    |  633 ++++++++++++++++++++++++++++++++++++++++
 drivers/pwm/pwm.c          |  681 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/pwm-led.h    |   34 +++
 include/linux/pwm.h        |  172 ++++++++++--
 16 files changed, 2074 insertions(+), 445 deletions(-)
 create mode 100644 Documentation/pwm.txt
 create mode 100644 drivers/leds/leds-pwm.c
 create mode 100644 drivers/leds/ledtrig-dim.c
 delete mode 100644 drivers/misc/atmel_pwm.c
 create mode 100644 drivers/pwm/Kconfig
 create mode 100644 drivers/pwm/Makefile
 create mode 100644 drivers/pwm/atmel-pwm.c
 create mode 100644 drivers/pwm/pwm.c
 create mode 100644 include/linux/pwm-led.h