RFC add at91sam9 LCDC DRM driver

New DRM based driver for at91sam9 SOC's that uses the Atmel LCDC IP core.

This is first version of a patch set that adds
drivers for the Atmel LCDC IP core.
Posted for review as the basics works now.

The LCDC IP core contains two devices:
- a PWM often used for backlight
- a LCD display controller

Both devices are supported today by the atmel_lcdfb driver. For this new set of drivers the compatible strings was selected to avoid clash with the existing compatible strings used for the atmel_lcdfb driver to allow them to co-exist.

This patchset implements three drivers.
- A MFD driver that include the generic parts.
- A PWM driver.
- A DRM display controller driver.
This is the same split as used for the Atmel hlcdc IP.

The hlcdc and lcdc has only a few things in common and trying to share the code for them was not a viable solution.

The DRM implementation has a few shortcomings compared to the existing fbdev based driver:
- STN displays are not supported
Binding support is missing but most of the STN specific functionality is otherwise ported from the fbdev driver.
I assume the info should come from the panel but as I lack HW I have not looked too much into what is required.
- gamma support is missing
The driver utilises drm_simple_kms_helper and this helper lacks support for setting up gamma. If this is useful please let me know and I will extend drm_simple_kms_helper to support this and update the driver.
- modesetting is not checked (see TODO in file)
Is this required for such a simple setup?
- support for extra modes as applicable (and lcd-wiring-mode)
- support for AVR32 (is it relevant?)

The first patch renames .../drm/atmel-hlcdc to .../drm/atmel to have a nice home for both drivers.

The drivers _works_ on a proprietary at91sam9263 based board and I will eventually migrate the at91sam9263ek over to use it as well.

Works is maybe a stretch - the following was tested:
modetest shows reasonable output
modetest -s shows some nice colored squares
vbltest shows 45.70 Hz (after terminating modetest -s with SIGINT) drmdevice shows reasonable output
brightness can be controlled

Anything else that can be recommended for some basic tests? How to test suspend/resume?

REVIEW
Please give feedback on general structure/architecture Please check if the drm framework is used in the optimal way And then the usual review from spelling errors, names, style etc.

All feedback (from spelling errors to general structure) appreciated!

Sam

Sam Ravnborg (7):
atmel-hlcdc: renamed directory to drm/atmel/
dt-binding: add bindings for Atmel LCDC mfd
mfd: add atmel-lcdc driver
dt-bindings: add bindings for Atmel LCDC pwm
pwm: add pwm-atmel-lcdc driver
dt-bindings: add bindings for Atmel lcdc-display-controller
drm: add Atmel LCDC display controller support

 .../display/atmel/lcdc-display-controller.txt      |   40 +
 .../devicetree/bindings/mfd/atmel-lcdc.txt         |   75 ++
 .../devicetree/bindings/pwm/atmel-lcdc-pwm.txt     |   30 +
 MAINTAINERS                                        |    9 +-
 drivers/gpu/drm/Kconfig                            |    2 +-
 drivers/gpu/drm/Makefile                           |    2 +-
 drivers/gpu/drm/atmel-hlcdc/Kconfig                |   10 -
 drivers/gpu/drm/atmel/Kconfig                      |   28 +
 drivers/gpu/drm/{atmel-hlcdc => atmel}/Makefile    |    2 +
 .../drm/{atmel-hlcdc => atmel}/atmel_hlcdc_crtc.c  |    0
 .../drm/{atmel-hlcdc => atmel}/atmel_hlcdc_dc.c    |    0
 .../drm/{atmel-hlcdc => atmel}/atmel_hlcdc_dc.h    |    0
 .../{atmel-hlcdc => atmel}/atmel_hlcdc_output.c    |    0
 .../drm/{atmel-hlcdc => atmel}/atmel_hlcdc_plane.c |    0
 drivers/gpu/drm/atmel/atmel_lcdc-dc.c              | 1094 ++++++++++++++++++++
 drivers/mfd/Kconfig                                |   10 +
 drivers/mfd/Makefile                               |    1 +
 drivers/mfd/atmel-lcdc.c                           |  158 +++
 drivers/pwm/Kconfig                                |   13 +
 drivers/pwm/Makefile                               |    1 +
 drivers/pwm/pwm-atmel-lcdc.c                       |  178 ++++
 include/linux/mfd/atmel-lcdc.h                     |  184 ++++
 22 files changed, 1824 insertions(+), 13 deletions(-)