[PATCH 0/9] thermal: introduce DT thermal zone build

[Eduardo Valentin]

Hello all,

As you noticed, I am working in a way to represent thermal data
using device tree [1]. Essentially, this should be a way to say
what to do with a sensor and how to associate (cooling) actions
with it.

The motivation to create such infrastructure is:
(i) - to reuse the existing temperature sensor code base;
(ii) - have a way to easily describe thermal data across different
boards for the same sensor. Say you have an i2c temp sensor,
which is placed close to your battery on board A but on
board B, another instance of this same senor is placed
close to your display, for instance.

This series introduces then a DT parser. The data expected in
DT must contain the needed properties to build a thermal zone
out of the desired sensor. All properties are documented and
they are derived from the existing requirements of current
thermal API.

In order to perform a binding with cooling devices,
the new thermal zone built using DT nodes will use
the existing thermal API that uses binding parameters. This is
the current proposed way to register thermal zones with platform
information, written by Durga.

There are some virtual concepts that are pushed to device tree,
I know. But I believe using device tree to do this makes sense
because we are still describing the HW and how they are related
to each other. Things like cooling devices are not represented
in device tree though, as I believe that will cause a lot of
confusion with real devices (as already does).

So the series is short but I think it makes sense to describe
how it is organized, as it touches several places. First four
patches are a preparation for this parser. There is a change
on cpufreq-cpu0, so that it knows now how to load its
corresponding cooling device. There is a change on thermal_core
to split its hwmon code, because I think we may need to improve
this code base when we start to integrate better with hwmon
temperature sensors. Then, another needed preparation is to
improve the bind_params, so that we are able to bind with
upper and lower limits. The remaining patches are the changes
with the proposed DT parser. A part from the DT thermal zone
builder itself (patch 05), I also changed the ti-soc-thermal
driver to use this new API and the omap4430 bandgap DT node,
as an example (this has been tested on panda omap4430); and also changed
the hwmon drivers lm75 and tmp102 to have the option to build
a thermal zone using DT. I haven't touched any dts file using
lm75 or tmp102 because this should come on a need basis.

I believe this code is pretty usable the way it is, but might
need to be revisited, in case the enhancement proposed by Durga
get in. This is because representing virtual thermal zones
built out of several sensors may need a different representation
in DT.

[1] - RFC of this work:
http://comments.gmane.org/gmane.linux.power-management.general/35874

Changes from RFC:
- Added a way to load cpufreq cooling device out of DT
- Added a way to bind with upper and lower limits using bind_params
- Added a way to specify upper and lower binding limits on DT
- Added DT thermal builder support to lm75 and tmp102 hwmon drivers
- Changed ERANGE to EDOM
- Added thermal constants for zone type and bind limit, so that
  dts file could be more readable

Tested on panda omap4430 (3.11-rc1 with minor changes for getting cpufreq working)

BR,

Eduardo Valentin (9):
  cpufreq: cpufreq-cpu0: add dt node parsing for 'needs-cooling'
  thermal: hwmon: move hwmon support to single file
  thermal: thermal_core: allow binding with limits on bind_params
  arm: dts: flag omap4430 with needs-cooling for cpu node
  thermal: introduce device tree parser
  thermal: ti-soc-thermal: use thermal DT infrastructure
  arm: dts: add omap4430 thermal data
  hwmon: lm75: expose to thermal fw via DT nodes
  hwmon: tmp102: expose to thermal fw via DT nodes

 .../devicetree/bindings/cpufreq/cpufreq-cpu0.txt   |   3 +
 .../devicetree/bindings/thermal/thermal.txt        | 133 ++++++
 Documentation/thermal/sysfs-api.txt                |   7 +
 arch/arm/boot/dts/omap443x.dtsi                    |  32 +-
 drivers/cpufreq/cpufreq-cpu0.c                     |   8 +
 drivers/hwmon/lm75.c                               |  29 ++
 drivers/hwmon/tmp102.c                             |  25 ++
 drivers/thermal/Kconfig                            |  22 +
 drivers/thermal/Makefile                           |   4 +
 drivers/thermal/thermal_core.c                     | 274 +-----------
 drivers/thermal/thermal_dt.c                       | 458 +++++++++++++++++++++
 drivers/thermal/thermal_hwmon.c                    | 269 ++++++++++++
 drivers/thermal/thermal_hwmon.h                    |  49 +++
 drivers/thermal/ti-soc-thermal/ti-thermal-common.c |  46 ++-
 include/dt-bindings/thermal/thermal.h              |  27 ++
 include/linux/thermal.h                            |  13 +
 16 files changed, 1129 insertions(+), 270 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/thermal/thermal.txt
 create mode 100644 drivers/thermal/thermal_dt.c
 create mode 100644 drivers/thermal/thermal_hwmon.c
 create mode 100644 drivers/thermal/thermal_hwmon.h
 create mode 100644 include/dt-bindings/thermal/thermal.h

-- 
1.8.2.1.342.gfa7285d

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