On 25-11-2013 11:37, Mark Rutland wrote: > On Tue, Nov 12, 2013 at 07:46:04PM +0000, Eduardo Valentin wrote: >> This patch introduces a device tree bindings for >> describing the hardware thermal behavior and limits. >> Also a parser to read and interpret the data and feed >> it in the thermal framework is presented. >> >> This patch introduces a thermal data parser for device >> tree. The parsed data is used to build thermal zones >> and thermal binding parameters. The output data >> can then be used to deploy thermal policies. >> >> This patch adds also documentation regarding this >> API and how to define tree nodes to use >> this infrastructure. >> >> Note that, in order to be able to have control >> on the sensor registration on the DT thermal zone, >> it was required to allow changing the thermal zone >> .get_temp callback. For this reason, this patch >> also removes the 'const' modifier from the .ops >> field of thermal zone devices. >> >> Cc: Zhang Rui <rui.zhang@xxxxxxxxx> >> Cc: linux-pm@xxxxxxxxxxxxxxx >> Cc: linux-kernel@xxxxxxxxxxxxxxx >> Cc: Mark Rutland <mark.rutland@xxxxxxx> >> Signed-off-by: Eduardo Valentin <eduardo.valentin@xxxxxx> >> --- >> >> Hello all, >> >> Very minor changes from v8 to v9. >> >> Changelog: >> >> - Rephrase a couple of sentences in the binding document >> - Fixed a couple of property types in the binding document >> - Removed the constant macro definitions for trip type. This >> change also affected the bindings posted on patches 09/14/15. >> >> .../devicetree/bindings/thermal/thermal.txt | 586 ++++++++++++++ >> drivers/thermal/Kconfig | 13 + >> drivers/thermal/Makefile | 1 + >> drivers/thermal/of-thermal.c | 849 +++++++++++++++++++++ >> drivers/thermal/thermal_core.c | 9 +- >> drivers/thermal/thermal_core.h | 9 + >> include/dt-bindings/thermal/thermal.h | 17 + >> include/linux/thermal.h | 28 +- >> 8 files changed, 1509 insertions(+), 3 deletions(-) >> create mode 100644 Documentation/devicetree/bindings/thermal/thermal.txt >> create mode 100644 drivers/thermal/of-thermal.c >> create mode 100644 include/dt-bindings/thermal/thermal.h >> >> diff --git a/Documentation/devicetree/bindings/thermal/thermal.txt b/Documentation/devicetree/bindings/thermal/thermal.txt >> new file mode 100644 >> index 0000000..59f5bd2 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/thermal/thermal.txt >> @@ -0,0 +1,586 @@ >> +* Thermal Framework Device Tree descriptor >> + >> +This file describes a generic binding to provide a way of >> +defining hardware thermal structure using device tree. >> +A thermal structure includes thermal zones and their components, >> +such as trip points, polling intervals, sensors and cooling devices >> +binding descriptors. >> + >> +The target of device tree thermal descriptors is to describe only >> +the hardware thermal aspects. The thermal device tree bindings are >> +not about how the system must control or which algorithm or policy >> +must be taken in place. >> + >> +There are five types of nodes involved to describe thermal bindings: >> +- thermal sensors: devices which may be used to take temperature >> + measurements. >> +- cooling devices: devices which may be used to dissipate heat. >> +- trip points: describe key temperatures at which cooling is recommended. The >> + set of points should be chosen based on hardware limits. >> +- cooling maps: used to describe links between trip points and cooling devices; >> +- thermal zones: used to describe thermal data within the hardware; >> + >> +The following is a description of each of these node types. >> + >> +* Thermal sensor devices >> + >> +Thermal sensor devices are nodes providing temperature sensing capabilities on >> +thermal zones. Typical devices are I2C ADC converters and bandgaps. These are >> +nodes providing temperature data to thermal zones. Thermal sensor devices may >> +control one or more internal sensors. >> + >> +Required property: >> +- #thermal-sensor-cells: Used to provide sensor device specific information >> + Type: unsigned while referring to it. Typically 0 on thermal sensor >> + Size: one cell nodes with only one sensor, and at least 1 on nodes >> + with several internal sensors, in order >> + to identify uniquely the sensor instances within >> + the IC. See thermal zone binding for more details >> + on how consumers refer to sensor devices. >> + >> +* Cooling device nodes >> + >> +Cooling devices are nodes providing control on power dissipation. There >> +are essentially two ways to provide control on power dissipation. First >> +is by means of regulating device performance, which is known as passive >> +cooling. A typical passive cooling is a CPU that has dynamic voltage and >> +frequency scaling (DVFS), and uses lower frequencies as cooling states. >> +Second is by means of activating devices in order to remove >> +the dissipated heat, which is known as active cooling, e.g. regulating >> +fan speeds. In both cases, cooling devices shall have a way to determine >> +the state of cooling in which the device is. >> + >> +Required properties: >> +- cooling-min-state: An integer indicating the smallest >> + Type: unsigned cooling state accepted. Typically 0. >> + Size: one cell >> + >> +- cooling-max-state: An integer indicating the largest >> + Type: unsigned cooling state accepted. >> + Size: one cell >> + >> +- #cooling-cells: Used to provide cooling device specific information >> + Type: unsigned while referring to it. Must be at least 2, in order >> + Size: one cell to specify minimum and maximum cooling state used >> + in the reference. The first cell is the minimum >> + cooling state requested and the second cell is >> + the maximum cooling state requested in the reference. >> + See Cooling device maps section below for more details >> + on how consumers refer to cooling devices. > > This is the point I'm still most concerned with, as it provides a > definite meaning to an otherwise abstract property. However, if you > believe this is sane and unlikely to be problematic, then I am happy to > leave the decision to you. > >> + >> +* Trip points >> + >> +The trip node is a node to describe a point in the temperature domain >> +in which the system takes an action. This node describes just the point, >> +not the action. >> + >> +Required properties: >> +- temperature: An integer indicating the trip temperature level, >> + Type: signed in millicelsius. >> + Size: one cell >> + >> +- hysteresis: A low hysteresis value on temperature property (above). >> + Type: unsigned This is a relative value, in millicelsius. >> + Size: one cell >> + >> +- type: a string containing the trip type. Supported values are: > > Get rid of the "Supported", that's a Linux detail. > > s/Supported/expected/ ? OK. > > Given the discussion has otherwise boiled down to bits that I think can > change later, I'm happy to give my ack: > > Acked-by: Mark Rutland <mark.rutland@xxxxxxx> > Thanks for your valuable contributions to this work. For sure it would not be at the state it is without your punctual and objective review. > I'll leave it to the others to fight against this if they still have > concerns. > > Thanks, > Mark. > > -- You have got to be excited about what you are doing. (L. Lamport) Eduardo Valentin
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