Re: [PATCHv8 03/18] thermal: introduce device tree parser

From: Eduardo Valentin
Date: Tue Nov 05 2013 - 13:10:21 EST

Hello device tree maintainers,

On 07-10-2013 16:51, Mark Rutland wrote:
> Hi all,
>
> Given that this is a complex new class of binding, I'd appreciate if at least
> one other device tree maintainer could also take a look over this and voice any
> concerns or suggestions. I've left the entire patch context for this.

Here is just a gentle reminder. Looks like no one else has had the time
to provide us a third opinion on this work. Shall we continue
progressing here? Its been about four weeks the series is waiting on
extra feedback.

I was on paternity leave :-) So, getting back to get this one rolling.

>
> Apologies for the munged whitespace -- my mail server appears to have helpfully
> and irreparably replaced all tabs with spaces.
>
> On Tue, Oct 01, 2013 at 03:39:26AM +0100, 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
>> Signed-off-by: Eduardo Valentin <eduardo.valentin@xxxxxx>
>> ---
>> Hello Mark, folks,
>>
>> So, here is v8. Pretty small changes. Most are better
>> English phrasing in the binding document. It follows changelog:
>> - Several rephrasing in the binding document, including
>> spelling, grammar and better phrasing.
>> - Removed WiP warning from binding document.
>> - Several spacing and formatting changes in the binding document
>> - Used the '-specifier' nomenclature properly in the binding doc
>> - Removed the optional property 'thermal-sensors-names', because
>> it does not provide useful runtime information
>> - Fixed description of 'polling-delay-passive'
>> - Improved examples by adding comments and better explanation
>> - s/fw/framework/g
>> - Added a WARN when sensors specifiers are greater and 1.
>>
>> All best,
>>
>> Eduardo
>>
>> ---
>> .../devicetree/bindings/thermal/thermal.txt | 587 ++++++++++++++
>> 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 | 27 +
>> include/linux/thermal.h | 28 +-
>> 8 files changed, 1520 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..ad06a8d
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/thermal/thermal.txt
>> @@ -0,0 +1,587 @@
>> +* Thermal Framework Device Tree descriptor
>> +
>> +This file describes a generic binding to provide a way of
>> +defining hardware thermal structure using device tree.
>
> s/defining/describing/
>
>> +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.
>
> I'm not quite sure what this is saying -- it seems to contradict the
> design of the binding where trip points get linked to cooling device
> configuration, and thus we're defining a policy along the lines of "when
> sensor $W hits temperature $X, configure cooling device $Y with value
> $Z". I don't see how that can't be considered policy.
>
> At best, we can say that policy is being defined because describing the
> physical properties of a device and dealing with this at runtime is not
> feasible.
>
>> +
>> +There are five types of nodes involved to describe thermal bindings:
>> +- sensors: used to describe the device source of temperature sensing;
>
> - thermal sensors: devices which may be used to take temperature
> measurements.
>
>> +- cooling devices: used to describe devices source of power dissipation control;
>
> - cooling devices: devices which may be used to dissipate heat.
>
>> +- trip points: used to describe points in temperature domain defined to
>> +make the system aware of hardware limits;
>
> - 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;
>> +
>> +It follows a description of each type of these device tree nodes.
>
> How about:
>
> 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.
>
> I'd probably say "heat dissipation" rather than "power dissipation", unless
> this is a technical term I am not aware of?
>
> Why is the determination of the state of the cooling device important?
>
>> +
>> +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.
>
> Is it assumed that all the values between min and max are valid, or might this
> be a sparse set of cooling values?
>
>> +
>> +* 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'. This is a
>> + Type: unsigned relative value, in millicelsius.
>> + Size: one cell
>
> What is it relative to?
>
> Why is 'temperature' in quotes?
>
>> +
>> +- type: a string containing the trip type. Supported values are:
>> + "active": A trip point to enable active cooling
>> + "passive": A trip point to enable passive cooling
>> + "hot": A trip point to notify emergency
>> + "critical": Hardware not reliable.
>> + Type: string
>> +
>> +There are also string constants defined at
>> +include/dt-bindings/thermal/thermal.h.
>
> Why?
>
>> +
>> +* Cooling device maps
>> +
>> +The cooling device maps node is a node to describe how cooling devices
>> +get assigned to trip points of the zone. The cooling devices are expected
>> +to be loaded in the target system.
>> +
>> +Required properties:
>> +- cooling-device: A phandle of a cooling device with its specifier,
>> + Type: phandle of referring to which cooling device is used in this
>> + cooling device binding. In the cooling specifier, the first cell
>> + is the minimum cooling state and the second cell
>> + is the maximum cooling state used in this map.
>
> The type is wrong here -- it's a phandle + cooling-cells, not just a phandle.
>
>> +- trip: A phandle of a trip point node within the same thermal
>> + Type: phandle of zone.
>> + trip point node
>> +
>> +Optional property:
>> +- contribution: The cooling contribution to the thermal zone of the
>> + Type: unsigned referred cooling device at the referred trip point.
>> + Size: one cell The contribution is a ratio of the sum
>> + of all cooling contributions within a thermal zone.
>> +
>> +Note: Using the THERMAL_NO_LIMIT (-1UL) constant in the cooling-device phandle
>> +limit specifier means:
>> +(i) - minimum state allowed for minimum cooling state used in the reference.
>> +(ii) - maximum state allowed for maximum cooling state used in the reference.
>> +Refer to include/dt-bindings/thermal/thermal.h for definition of this constant.
>> +
>> +* Thermal zone nodes
>> +
>> +The thermal zone node is the node containing all the required info
>> +for describing a thermal zone, including its cooling device bindings. The
>> +thermal zone node must contain, apart from its own properties, one sub-node
>> +containing trip nodes and one sub-node containing all the zone cooling maps.
>> +
>> +Required properties:
>> +- polling-delay: The maximum number of milliseconds to wait between polls
>> + Type: unsigned when checking this thermal zone.
>> + Size: one cell
>> +
>> +- polling-delay-passive: The maximum number of milliseconds to wait
>> + Type: unsigned between polls when performing passive cooling.
>> + Size: one cell
>> +
>> +- thermal-sensors: A list of thermal sensor phandles and sensor specifier
>> + Type: list of used while monitoring the thermal zone.
>> + sensor phandles
>
> The type is wrong here. A list of phandle + sensor specifiers.
>
>> +
>> +- trips: A sub-node which is a container of only trip point nodes
>> + Type: sub-node required to describe the thermal zone.
>> +
>> +- cooling-maps: A sub-node which is a container of only cooling device
>> + Type: sub-node map nodes, used to describe the relation between trips
>> + and cooling devices.
>> +
>> +Optional property:
>> +- coefficients: An array of integers (one signed cell) containing
>> + Type: array coefficients to compose a linear relation between
>> + Elem size: one cell the sensors listed in the thermal-sensors property.
>> + Elem type: signed Coefficients defaults to 1, in case this property
>> + is not specified. A simple linear polynomial is used:
>> + Z = c0 * x0 + c1 + x1 + ... + c(n-1) * x(n-1) + cn.
>> +
>> + The coefficients are ordered and they match with sensors
>> + by means of sensor ID. Additional coefficients are
>> + interpreted as constant offset.
>> +
>> +Note: The delay properties are bound to the maximum dT/dt (temperature
>> +derivative over time) in two situations for a thermal zone:
>> +(i) - when passive cooling is activated (polling-delay-passive); and
>> +(ii) - when the zone just needs to be monitored (polling-delay) or
>> +when active cooling is activated.
>> +
>> +The maximum dT/dt is highly bound to hardware power consumption and dissipation
>> +capability. The delays should be chosen to account for said max dT/dt,
>> +such that a device does not cross several trip boundaries unexpectedly
>> +between polls. Choosing the right polling delays shall avoid having the
>> +device in temperature ranges that may damage the silicon structures and
>> +reduce silicon lifetime.
>> +
>> +* The thermal-zones node
>> +
>> +The "thermal-zones" node is a container for all thermal zone nodes. It shall
>> +contain only sub-nodes describing thermal zones as in the section
>> +"Thermal zone nodes". The "thermal-zones" node appears under "/".
>> +
>> +* Examples
>> +
>> +Below are several examples on how to use thermal data descriptors
>> +using device tree bindings:
>> +
>> +(a) - CPU thermal zone
>> +
>> +The CPU thermal zone example below describes how to setup one thermal zone
>> +using one single sensor as temperature source and many cooling devices and
>> +power dissipation control sources.
>> +
>> +#include <dt-bindings/thermal/thermal.h>
>> +
>> +cpus {
>> + /*
>> + * Here is an example of describing a cooling device for a DVFS
>> + * capable CPU. The CPU node describes its four OPPs.
>> + * The cooling states possible are 0..3, and they are
>> + * used as OPP indexes. The minimum cooling state is 0, which means
>> + * all four OPPs can be available to the system. The maximum
>> + * cooling state is 3, which means only the lowest OPPs (198MHz@xxxxx)
>> + * can be available in the system.
>> + */
>> + cpu0: cpu@0 {
>> + ...
>> + operating-points = <
>> + /* kHz uV */
>> + 970000 1200000
>> + 792000 1100000
>> + 396000 950000
>> + 198000 850000
>> + >;
>> + cooling-min-state = <0>;
>> + cooling-max-state = <3>;
>> + #cooling-cells = <2>; /* min followed by max */
>> + };
>> + ...
>> +};
>> +
>> +&i2c1 {
>> + ...
>> + /*
>> + * A simple fan controller which supports 10 speeds of operation
>> + * (represented as 0-9).
>> + */
>> + fan0: fan@0x48 {
>> + ...
>> + cooling-min-state = <0>;
>> + cooling-max-state = <9>;
>> + #cooling-cells = <2>; /* min followed by max */
>> + };
>> +};
>> +
>> +ocp {
>> + ...
>> + /*
>> + * A simple IC with a single bandgap temperature sensor.
>> + */
>> + bandgap0: bandgap@0x0000ED00 {
>> + ...
>> + #thermal-sensor-cells = <0>;
>> + };
>> +};
>> +
>> +thermal-zones {
>> + cpu-thermal: cpu-thermal {
>> + polling-delay-passive = <250>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + thermal-sensors = <&bandgap0>;
>> +
>> + trips {
>> + cpu-alert0: cpu-alert {
>> + temperature = <90000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "active";
>> + };
>> + cpu-alert1: cpu-alert {
>> + temperature = <100000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + };
>> + cpu-crit: cpu-crit {
>> + temperature = <125000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "critical";
>> + };
>> + };
>> +
>> + cooling-maps {
>> + map0 {
>> + trip = <&cpu-alert0>;
>> + cooling-device = <&fan0 THERMAL_NO_LIMITS 4>;
>> + };
>> + map1 {
>> + trip = <&cpu-alert1>;
>> + cooling-device = <&fan0 5 THERMAL_NO_LIMITS>;
>> + };
>> + map2 {
>> + trip = <&cpu-alert1>;
>> + cooling-device =
>> + <&cpu0 THERMAL_NO_LIMITS THERMAL_NO_LIMITS>;
>> + };
>> + };
>> + };
>> +};
>> +
>> +In the example above, the ADC sensor (bandgap0) at address 0x0000ED00 is
>> +used to monitor the zone 'cpu-thermal' using its sole sensor. A fan
>> +device (fan0) is controlled via I2C bus 1, at address 0x48, and has ten
>> +different cooling states 0-9. It is used to remove the heat out of
>> +the thermal zone 'cpu-thermal' using its cooling states
>> +from its minimum to 4, when it reaches trip point 'cpu-alert0'
>> +at 90C, as an example of active cooling. The same cooling device is used at
>> +'cpu-alert1', but from 5 to its maximum state. The cpu@0 device is also
>> +linked to the same thermal zone, 'cpu-thermal', as a passive cooling device,
>> +using all its cooling states at trip point 'cpu-alert1',
>> +which is a trip point at 100C. On the thermal zone 'cpu-thermal', at the
>> +temperature of 125C, represented by the trip point 'cpu-crit', the silicon
>> +is not reliable anymore.
>> +
>> +(b) - IC with several internal sensors
>> +
>> +The example below describes how to deploy several thermal zones based off a
>> +single sensor IC, assuming it has several internal sensors. This is a common
>> +case on SoC designs with several internal IPs that may need different thermal
>> +requirements, and thus may have their own sensor to monitor or detect internal
>> +hotspots in their silicon.
>> +
>> +#include <dt-bindings/thermal/thermal.h>
>> +
>> +ocp {
>> + ...
>> + /*
>> + * A simple IC with several bandgap temperature sensors.
>> + */
>> + bandgap0: bandgap@0x0000ED00 {
>> + ...
>> + #thermal-sensor-cells = <1>;
>> + };
>> +};
>> +
>> +thermal-zones {
>> + cpu-thermal: cpu-thermal {
>> + polling-delay-passive = <250>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&bandgap0 0>;
>> +
>> + trips {
>> + /* each zone within the SoC may have its own trips */
>> + cpu-alert: cpu-alert {
>> + temperature = <100000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + };
>> + cpu-crit: cpu-crit {
>> + temperature = <125000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "critical";
>> + };
>> + };
>> +
>> + cooling-maps {
>> + /* each zone within the SoC may have its own cooling */
>> + ...
>> + };
>> + };
>> +
>> + gpu-thermal: gpu-thermal {
>> + polling-delay-passive = <120>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&bandgap0 1>;
>> +
>> + trips {
>> + /* each zone within the SoC may have its own trips */
>> + gpu-alert: gpu-alert {
>> + temperature = <90000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + };
>> + gpu-crit: gpu-crit {
>> + temperature = <105000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "critical";
>> + };
>> + };
>> +
>> + cooling-maps {
>> + /* each zone within the SoC may have its own cooling */
>> + ...
>> + };
>> + };
>> +
>> + dsp-thermal: dsp-thermal {
>> + polling-delay-passive = <50>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&bandgap0 2>;
>> +
>> + trips {
>> + /* each zone within the SoC may have its own trips */
>> + dsp-alert: gpu-alert {
>> + temperature = <90000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + };
>> + dsp-crit: gpu-crit {
>> + temperature = <135000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "critical";
>> + };
>> + };
>> +
>> + cooling-maps {
>> + /* each zone within the SoC may have its own cooling */
>> + ...
>> + };
>> + };
>> +};
>> +
>> +In the example above, there is one bandgap IC which has the capability to
>> +monitor three sensors. The hardware has been designed so that sensors are
>> +placed on different places in the DIE to monitor different temperature
>> +hotspots: one for CPU thermal zone, one for GPU thermal zone and the
>> +other to monitor a DSP thermal zone.
>> +
>> +Thus, there is a need to assign each sensor provided by the bandgap IC
>> +to different thermal zones. This is achieved by means of using the
>> +#thermal-sensor-cells property and using the first cell of the sensor
>> +specifier as sensor ID. In the example, then, <bandgap 0> is used to
>> +monitor CPU thermal zone, <bandgap 1> is used to monitor GPU thermal
>> +zone and <bandgap 2> is used to monitor DSP thermal zone. Each zone
>> +may be uncorrelated, having its own dT/dt requirements, trips
>> +and cooling maps.
>> +
>> +
>> +(c) - Several sensors within one single thermal zone
>> +
>> +The example below illustrates how to use more than one sensor within
>> +one thermal zone.
>> +
>> +#include <dt-bindings/thermal/thermal.h>
>> +
>> +&i2c1 {
>> + ...
>> + /*
>> + * A simple IC with a single temperature sensor.
>> + */
>> + adc: sensor@0x49 {
>> + ...
>> + #thermal-sensor-cells = <0>;
>> + };
>> +};
>> +
>> +ocp {
>> + ...
>> + /*
>> + * A simple IC with a single bandgap temperature sensor.
>> + */
>> + bandgap0: bandgap@0x0000ED00 {
>> + ...
>> + #thermal-sensor-cells = <0>;
>> + };
>> +};
>> +
>> +thermal-zones {
>> + cpu-thermal: cpu-thermal {
>> + polling-delay-passive = <250>; /* milliseconds */
>> + polling-delay = <1000>; /* milliseconds */
>> +
>> + thermal-sensors = <&bandgap0>, /* cpu */
>> + <&adc>; /* pcb north */
>> +
>> + /* hotspot = 100 * bandgap - 120 * adc + 484 */
>> + coefficients = <100 -120 484>;
>> +
>> + trips {
>> + ...
>> + };
>> +
>> + cooling-maps {
>> + ...
>> + };
>> + };
>> +};
>> +
>> +In some cases, there is a need to use more than one sensor to extrapolate
>> +a thermal hotspot in the silicon. The above example illustrates this situation.
>> +For instance, it may be the case that a sensor external to CPU IP may be placed
>> +close to CPU hotspot and together with internal CPU sensor, it is used
>> +to determine the hotspot. Assuming this is the case for the above example,
>> +the hypothetical extrapolation rule would be:
>> + hotspot = 100 * bandgap - 120 * adc + 484
>> +
>> +In other context, the same idea can be used to add fixed offset. For instance,
>> +consider the hotspot extrapolation rule below:
>> + hotspot = 1 * adc + 6000
>> +
>> +In the above equation, the hotspot is always 6C higher than what is read
>> +from the ADC sensor. The binding would be then:
>> + thermal-sensors = <&adc>;
>> +
>> + /* hotspot = 1 * adc + 6000 */
>> + coefficients = <1 6000>;
>> +
>> +(d) - Board thermal
>> +
>> +The board thermal example below illustrates how to setup one thermal zone
>> +with many sensors and many cooling devices.
>> +
>> +#include <dt-bindings/thermal/thermal.h>
>> +
>> +&i2c1 {
>> + ...
>> + /*
>> + * An IC with several temperature sensor.
>> + */
>> + adc-dummy: sensor@0x50 {
>> + ...
>> + #thermal-sensor-cells = <1>; /* sensor internal ID */
>> + };
>> +};
>> +
>> +thermal-zones {
>> + batt-thermal {
>> + polling-delay-passive = <500>; /* milliseconds */
>> + polling-delay = <2500>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&adc-dummy 4>;
>> +
>> + trips {
>> + ...
>> + };
>> +
>> + cooling-maps {
>> + ...
>> + };
>> + };
>> +
>> + board-thermal: board-thermal {
>> + polling-delay-passive = <1000>; /* milliseconds */
>> + polling-delay = <2500>; /* milliseconds */
>> +
>> + /* sensor ID */
>> + thermal-sensors = <&adc-dummy 0>, /* pcb top edge */
>> + <&adc-dummy 1>, /* lcd */
>> + <&adc-dymmy 2>; /* back cover */
>> + /*
>> + * An array of coefficients describing the sensor
>> + * linear relation. E.g.:
>> + * z = c1*x1 + c2*x2 + c3*x3
>> + */
>> + coefficients = <1200 -345 890>;
>> +
>> + trips {
>> + /* Trips are based on resulting linear equation */
>> + cpu-trip: cpu-trip {
>> + temperature = <60000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + };
>> + gpu-trip: gpu-trip {
>> + temperature = <55000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + }
>> + lcd-trip: lcp-trip {
>> + temperature = <53000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "passive";
>> + };
>> + crit-trip: crit-trip {
>> + temperature = <68000>; /* millicelsius */
>> + hysteresis = <2000>; /* millicelsius */
>> + type = "critical";
>> + };
>> + };
>> +
>> + cooling-maps {
>> + map0 {
>> + trip = <&cpu-trip>;
>> + cooling-device = <&cpu0 0 2>;
>> + contribution = <55>;
>> + };
>> + map1 {
>> + trip = <&gpu-trip>;
>> + cooling-device = <&gpu0 0 2>;
>> + contribution = <20>;
>> + };
>> + map2 {
>> + trip = <&lcd-trip>;
>> + cooling-device = <&lcd0 5 10>;
>> + contribution = <15>;
>> + };
>> + };
>> + };
>> +};
>> +
>> +The above example is a mix of previous examples, a sensor IP with several internal
>> +sensors used to monitor different zones, one of them is composed by several sensors and
>> +with different cooling devices.
>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>> index dbfc390..dd81eb8 100644
>> --- a/drivers/thermal/Kconfig
>> +++ b/drivers/thermal/Kconfig
>> @@ -29,6 +29,19 @@ config THERMAL_HWMON
>> Say 'Y' here if you want all thermal sensors to
>> have hwmon sysfs interface too.
>>
>> +config THERMAL_OF
>> + bool
>> + prompt "APIs to parse thermal data out of device tree"
>> + depends on OF
>> + default y
>> + help
>> + This options provides helpers to add the support to
>> + read and parse thermal data definitions out of the
>> + device tree blob.
>> +
>> + Say 'Y' here if you need to build thermal infrastructure
>> + based on device tree.
>> +
>> choice
>> prompt "Default Thermal governor"
>> default THERMAL_DEFAULT_GOV_STEP_WISE
>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>> index 584b363..4b03956 100644
>> --- a/drivers/thermal/Makefile
>> +++ b/drivers/thermal/Makefile
>> @@ -7,6 +7,7 @@ thermal_sys-y += thermal_core.o
>>
>> # interface to/from other layers providing sensors
>> thermal_sys-$(CONFIG_THERMAL_HWMON) += thermal_hwmon.o
>> +thermal_sys-$(CONFIG_THERMAL_OF) += of-thermal.o
>>
>> # governors
>> thermal_sys-$(CONFIG_THERMAL_GOV_FAIR_SHARE) += fair_share.o
>> diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
>> new file mode 100644
>> index 0000000..66f9eb2
>> --- /dev/null
>> +++ b/drivers/thermal/of-thermal.c
>> @@ -0,0 +1,849 @@
>> +/*
>> + * of-thermal.c - Generic Thermal Management device tree support.
>> + *
>> + * Copyright (C) 2013 Texas Instruments
>> + * Copyright (C) 2013 Eduardo Valentin <eduardo.valentin@xxxxxx>
>> + *
>> + *
>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; version 2 of the License.
>> + *
>> + * This program is distributed in the hope that it will be useful, but
>> + * WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
>> + * General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along
>> + * with this program; if not, write to the Free Software Foundation, Inc.,
>> + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
>> + *
>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + */
>> +#include <linux/thermal.h>
>> +#include <linux/slab.h>
>> +#include <linux/types.h>
>> +#include <linux/of_device.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/err.h>
>> +#include <linux/export.h>
>> +#include <linux/string.h>
>> +
>> +#include "thermal_core.h"
>> +
>> +/*** Private data structures to represent thermal device tree data ***/
>> +
>> +/**
>> + * struct __thermal_trip - representation of a point in temperature domain
>> + * @np: pointer to struct device_node that this trip point was created from
>> + * @temperature: temperature value in miliCelsius
>> + * @hysteresis: relative hysteresis in miliCelsius
>> + * @type: trip point type
>> + */
>> +
>> +struct __thermal_trip {
>> + struct device_node *np;
>> + unsigned long int temperature;
>> + unsigned long int hysteresis;
>> + enum thermal_trip_type type;
>> +};
>> +
>> +/**
>> + * struct __thermal_bind_param - a match between trip and cooling device
>> + * @cooling_device: a pointer to identify the referred cooling device
>> + * @trip_id: the trip point index
>> + * @usage: the percentage (from 0 to 100) of cooling contribution
>> + * @min: minimum cooling state used at this trip point
>> + * @max: maximum cooling state used at this trip point
>> + */
>> +
>> +struct __thermal_bind_params {
>> + struct device_node *cooling_device;
>> + unsigned int trip_id;
>> + unsigned int usage;
>> + unsigned long min;
>> + unsigned long max;
>> +};
>> +
>> +/**
>> + * struct __thermal_zone - internal representation of a thermal zone
>> + * @mode: current thermal zone device mode (enabled/disabled)
>> + * @passive_delay: polling interval while passive cooling is activated
>> + * @polling_delay: zone polling interval
>> + * @ntrips: number of trip points
>> + * @trips: an array of trip points (0..ntrips - 1)
>> + * @num_tbps: number of thermal bind params
>> + * @tbps: an array of thermal bind params (0..num_tbps - 1)
>> + * @sensor_data: sensor private data used while reading temperature and trend
>> + * @get_temp: sensor callback to read temperature
>> + * @get_trend: sensor callback to read temperature trend
>> + */
>> +
>> +struct __thermal_zone {
>> + enum thermal_device_mode mode;
>> + int passive_delay;
>> + int polling_delay;
>> +
>> + /* trip data */
>> + int ntrips;
>> + struct __thermal_trip *trips;
>> +
>> + /* cooling binding data */
>> + int num_tbps;
>> + struct __thermal_bind_params *tbps;
>> +
>> + /* sensor interface */
>> + void *sensor_data;
>> + int (*get_temp)(void *, long *);
>> + int (*get_trend)(void *, long *);
>> +};
>> +
>> +/*** DT thermal zone device callbacks ***/
>> +
>> +static int of_thermal_get_temp(struct thermal_zone_device *tz,
>> + unsigned long *temp)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (!data->get_temp)
>> + return -EINVAL;
>> +
>> + return data->get_temp(data->sensor_data, temp);
>> +}
>> +
>> +static int of_thermal_get_trend(struct thermal_zone_device *tz, int trip,
>> + enum thermal_trend *trend)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> + long dev_trend;
>> + int r;
>> +
>> + if (!data->get_trend)
>> + return -EINVAL;
>> +
>> + r = data->get_trend(data->sensor_data, &dev_trend);
>> + if (r)
>> + return r;
>> +
>> + /* TODO: These intervals might have some thresholds, but in core code */
>> + if (dev_trend > 0)
>> + *trend = THERMAL_TREND_RAISING;
>> + else if (dev_trend < 0)
>> + *trend = THERMAL_TREND_DROPPING;
>> + else
>> + *trend = THERMAL_TREND_STABLE;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_bind(struct thermal_zone_device *thermal,
>> + struct thermal_cooling_device *cdev)
>> +{
>> + struct __thermal_zone *data = thermal->devdata;
>> + int i;
>> +
>> + if (!data || IS_ERR(data))
>> + return -ENODEV;
>> +
>> + /* find where to bind */
>> + for (i = 0; i < data->num_tbps; i++) {
>> + struct __thermal_bind_params *tbp = data->tbps + i;
>> +
>> + if (tbp->cooling_device == cdev->np) {
>> + int ret;
>> +
>> + ret = thermal_zone_bind_cooling_device(thermal,
>> + tbp->trip_id, cdev,
>> + tbp->min,
>> + tbp->max);
>> + if (ret)
>> + return ret;
>> + }
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_unbind(struct thermal_zone_device *thermal,
>> + struct thermal_cooling_device *cdev)
>> +{
>> + struct __thermal_zone *data = thermal->devdata;
>> + int i;
>> +
>> + if (!data || IS_ERR(data))
>> + return -ENODEV;
>> +
>> + /* find where to unbind */
>> + for (i = 0; i < data->num_tbps; i++) {
>> + struct __thermal_bind_params *tbp = data->tbps + i;
>> +
>> + if (tbp->cooling_device == cdev->np) {
>> + int ret;
>> +
>> + ret = thermal_zone_unbind_cooling_device(thermal,
>> + tbp->trip_id, cdev);
>> + if (ret)
>> + return ret;
>> + }
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_get_mode(struct thermal_zone_device *tz,
>> + enum thermal_device_mode *mode)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + *mode = data->mode;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_set_mode(struct thermal_zone_device *tz,
>> + enum thermal_device_mode mode)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + mutex_lock(&tz->lock);
>> +
>> + if (mode == THERMAL_DEVICE_ENABLED)
>> + tz->polling_delay = data->polling_delay;
>> + else
>> + tz->polling_delay = 0;
>> +
>> + mutex_unlock(&tz->lock);
>> +
>> + data->mode = mode;
>> + thermal_zone_device_update(tz);
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_get_trip_type(struct thermal_zone_device *tz, int trip,
>> + enum thermal_trip_type *type)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (trip >= data->ntrips || trip < 0)
>> + return -EDOM;
>> +
>> + *type = data->trips[trip].type;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_get_trip_temp(struct thermal_zone_device *tz, int trip,
>> + unsigned long *temp)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (trip >= data->ntrips || trip < 0)
>> + return -EDOM;
>> +
>> + *temp = data->trips[trip].temperature;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_set_trip_temp(struct thermal_zone_device *tz, int trip,
>> + unsigned long temp)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (trip >= data->ntrips || trip < 0)
>> + return -EDOM;
>> +
>> + /* thermal framework should take care of data->mask & (1 << trip) */
>> + data->trips[trip].temperature = temp;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_get_trip_hyst(struct thermal_zone_device *tz, int trip,
>> + unsigned long *hyst)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (trip >= data->ntrips || trip < 0)
>> + return -EDOM;
>> +
>> + *hyst = data->trips[trip].hysteresis;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_set_trip_hyst(struct thermal_zone_device *tz, int trip,
>> + unsigned long hyst)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> +
>> + if (trip >= data->ntrips || trip < 0)
>> + return -EDOM;
>> +
>> + /* thermal framework should take care of data->mask & (1 << trip) */
>> + data->trips[trip].hysteresis = hyst;
>> +
>> + return 0;
>> +}
>> +
>> +static int of_thermal_get_crit_temp(struct thermal_zone_device *tz,
>> + unsigned long *temp)
>> +{
>> + struct __thermal_zone *data = tz->devdata;
>> + int i;
>> +
>> + for (i = 0; i < data->ntrips; i++)
>> + if (data->trips[i].type == THERMAL_TRIP_CRITICAL) {
>> + *temp = data->trips[i].temperature;
>> + return 0;
>> + }
>> +
>> + return -EINVAL;
>> +}
>> +
>> +static struct thermal_zone_device_ops of_thermal_ops = {
>> + .get_mode = of_thermal_get_mode,
>> + .set_mode = of_thermal_set_mode,
>> +
>> + .get_trip_type = of_thermal_get_trip_type,
>> + .get_trip_temp = of_thermal_get_trip_temp,
>> + .set_trip_temp = of_thermal_set_trip_temp,
>> + .get_trip_hyst = of_thermal_get_trip_hyst,
>> + .set_trip_hyst = of_thermal_set_trip_hyst,
>> + .get_crit_temp = of_thermal_get_crit_temp,
>> +
>> + .bind = of_thermal_bind,
>> + .unbind = of_thermal_unbind,
>> +};
>> +
>> +/*** sensor API ***/
>> +
>> +static struct thermal_zone_device *
>> +thermal_zone_of_add_sensor(struct device_node *zone,
>> + struct device_node *sensor, void *data,
>> + int (*get_temp)(void *, long *),
>> + int (*get_trend)(void *, long *))
>> +{
>> + struct thermal_zone_device *tzd;
>> + struct __thermal_zone *tz;
>> +
>> + tzd = thermal_zone_get_zone_by_name(zone->name);
>> + if (IS_ERR(tzd))
>> + return ERR_PTR(-EPROBE_DEFER);
>> +
>> + tz = tzd->devdata;
>> +
>> + mutex_lock(&tzd->lock);
>> + tz->get_temp = get_temp;
>> + tz->get_trend = get_trend;
>> + tz->sensor_data = data;
>> +
>> + tzd->ops->get_temp = of_thermal_get_temp;
>> + tzd->ops->get_trend = of_thermal_get_trend;
>> + mutex_unlock(&tzd->lock);
>> +
>> + return tzd;
>> +}
>> +
>> +/**
>> + * thermal_zone_of_sensor_register - registers a sensor to a DT thermal zone
>> + * @dev: a valid struct device pointer of a sensor device. Must contain
>> + * a valid .of_node, for the sensor node.
>> + * @sensor_id: a sensor identifier, in case the sensor IP has more
>> + * than one sensors
>> + * @data: a private pointer (owned by the caller) that will be passed
>> + * back, when a temperature reading is needed.
>> + * @get_temp: a pointer to a function that reads the sensor temperature.
>> + * @get_trend: a pointer to a function that reads the sensor temperature trend.
>> + *
>> + * This function will search the list of thermal zones described in device
>> + * tree and look for the zone that refer to the sensor device pointed by
>> + * @dev->of_node as temperature providers. For the zone pointing to the
>> + * sensor node, the sensor will be added to the DT thermal zone device.
>> + *
>> + * The thermal zone temperature is provided by the @get_temp function
>> + * pointer. When called, it will have the private pointer @data back.
>> + *
>> + * The thermal zone temperature trend is provided by the @get_trend function
>> + * pointer. When called, it will have the private pointer @data back.
>> + *
>> + * TODO:
>> + * 01 - This function must enqueue the new sensor instead of using
>> + * it as the only source of temperature values.
>> + *
>> + * 02 - There must be a way to match the sensor with all thermal zones
>> + * that refer to it.
>> + *
>> + * Return: On success returns a valid struct thermal_zone_device,
>> + * otherwise, it returns a corresponding ERR_PTR(). Caller must
>> + * check the return value with help of IS_ERR() helper.
>> + */
>> +struct thermal_zone_device *
>> +thermal_zone_of_sensor_register(struct device *dev, int sensor_id,
>> + void *data, int (*get_temp)(void *, long *),
>> + int (*get_trend)(void *, long *))
>> +{
>> + struct device_node *np, *child, *sensor_np;
>> +
>> + np = of_find_node_by_name(NULL, "thermal-zones");
>> + if (!np)
>> + return ERR_PTR(-ENODEV);
>> +
>> + if (!dev || !dev->of_node)
>> + return ERR_PTR(-EINVAL);
>> +
>> + sensor_np = dev->of_node;
>> +
>> + for_each_child_of_node(np, child) {
>> + struct of_phandle_args sensor_specs;
>> + int ret, id;
>> +
>> + /* For now, thermal framework supports only 1 sensor per zone */
>> + ret = of_parse_phandle_with_args(child, "thermal-sensors",
>> + "#thermal-sensor-cells",
>> + 0, &sensor_specs);
>> + if (ret)
>> + continue;
>> +
>> + if (sensor_specs.args_count >= 1) {
>> + id = sensor_specs.args[0];
>> + WARN(sensor_specs.args_count > 1,
>> + "%s: too many cells in sensor specifier %d\n",
>> + sensor_specs.np->name, sensor_specs.args_count);
>> + } else {
>> + id = 0;
>> + }
>> +
>> + if (sensor_specs.np == sensor_np && id == sensor_id) {
>> + of_node_put(np);
>> + return thermal_zone_of_add_sensor(child, sensor_np,
>> + data,
>> + get_temp,
>> + get_trend);
>> + }
>> + }
>> + of_node_put(np);
>> +
>> + return ERR_PTR(-ENODEV);
>> +}
>> +EXPORT_SYMBOL_GPL(thermal_zone_of_sensor_register);
>> +
>> +/**
>> + * thermal_zone_of_sensor_unregister - unregisters a sensor from a DT thermal zone
>> + * @dev: a valid struct device pointer of a sensor device. Must contain
>> + * a valid .of_node, for the sensor node.
>> + * @tzd: a pointer to struct thermal_zone_device where the sensor is registered.
>> + *
>> + * This function removes the sensor callbacks and private data from the
>> + * thermal zone device registered with thermal_zone_of_sensor_register()
>> + * API. It will also silent the zone by remove the .get_temp() and .get_trend()
>> + * thermal zone device callbacks.
>> + *
>> + * TODO: When the support to several sensors per zone is added, this
>> + * function must search the sensor list based on @dev parameter.
>> + *
>> + */
>> +void thermal_zone_of_sensor_unregister(struct device *dev,
>> + struct thermal_zone_device *tzd)
>> +{
>> + struct __thermal_zone *tz;
>> +
>> + if (!dev || !tzd || !tzd->devdata)
>> + return;
>> +
>> + tz = tzd->devdata;
>> +
>> + /* no __thermal_zone, nothing to be done */
>> + if (!tz)
>> + return;
>> +
>> + mutex_lock(&tzd->lock);
>> + tzd->ops->get_temp = NULL;
>> + tzd->ops->get_trend = NULL;
>> +
>> + tz->get_temp = NULL;
>> + tz->get_trend = NULL;
>> + tz->sensor_data = NULL;
>> + mutex_unlock(&tzd->lock);
>> +}
>> +EXPORT_SYMBOL_GPL(thermal_zone_of_sensor_unregister);
>> +
>> +/*** functions parsing device tree nodes ***/
>> +
>> +/**
>> + * thermal_of_populate_bind_params - parse and fill cooling map data
>> + * @np: DT node containing a cooling-map node
>> + * @__tbp: data structure to be filled with cooling map info
>> + * @trips: array of thermal zone trip points
>> + * @ntrips: number of trip points inside trips.
>> + *
>> + * This function parses a cooling-map type of node represented by
>> + * @np parameter and fills the read data into @__tbp data structure.
>> + * It needs the already parsed array of trip points of the thermal zone
>> + * in consideration.
>> + *
>> + * Return: 0 on success, proper error code otherwise
>> + */
>> +static int thermal_of_populate_bind_params(struct device_node *np,
>> + struct __thermal_bind_params *__tbp,
>> + struct __thermal_trip *trips,
>> + int ntrips)
>> +{
>> + struct of_phandle_args cooling_spec;
>> + struct device_node *trip;
>> + int ret, i;
>> + u32 prop;
>> +
>> + /* Default weight. Usage is optional */
>> + __tbp->usage = 0;
>> + ret = of_property_read_u32(np, "contribution", &prop);
>> + if (ret == 0)
>> + __tbp->usage = prop;
>> +
>> + trip = of_parse_phandle(np, "trip", 0);
>> + if (!trip) {
>> + pr_err("missing trip property\n");
>> + return -ENODEV;
>> + }
>> +
>> + /* match using device_node */
>> + for (i = 0; i < ntrips; i++)
>> + if (trip == trips[i].np) {
>> + __tbp->trip_id = i;
>> + break;
>> + }
>> +
>> + if (i == ntrips) {
>> + ret = -ENODEV;
>> + goto end;
>> + }
>> +
>> + ret = of_parse_phandle_with_args(np, "cooling-device", "#cooling-cells",
>> + 0, &cooling_spec);
>> + if (ret < 0) {
>> + pr_err("missing cooling_device property\n");
>> + goto end;
>> + }
>> + __tbp->cooling_device = cooling_spec.np;
>> + if (cooling_spec.args_count >= 2) { /* at least min and max */
>> + __tbp->min = cooling_spec.args[0];
>> + __tbp->max = cooling_spec.args[1];
>> + } else {
>> + pr_err("wrong reference to cooling device, missing limits\n");
>> + }
>> +
>> +end:
>> + of_node_put(trip);
>> +
>> + return ret;
>> +}
>> +
>> +/**
>> + * It maps 'enum thermal_trip_type' found in include/linux/thermal.h
>> + * into the device tree binding of 'trip', property type.
>> + */
>> +static const char * const trip_types[] = {
>> + [THERMAL_TRIP_ACTIVE] = "active",
>> + [THERMAL_TRIP_PASSIVE] = "passive",
>> + [THERMAL_TRIP_HOT] = "hot",
>> + [THERMAL_TRIP_CRITICAL] = "critical",
>> +};
>> +
>> +/**
>> + * thermal_of_get_trip_type - Get phy mode for given device_node
>> + * @np: Pointer to the given device_node
>> + * @type: Pointer to resulting trip type
>> + *
>> + * The function gets trip type string from property 'type',
>> + * and store its index in trip_types table in @type,
>> + *
>> + * Return: 0 on success, or errno in error case.
>> + */
>> +static int thermal_of_get_trip_type(struct device_node *np,
>> + enum thermal_trip_type *type)
>> +{
>> + const char *t;
>> + int err, i;
>> +
>> + err = of_property_read_string(np, "type", &t);
>> + if (err < 0)
>> + return err;
>> +
>> + for (i = 0; i < ARRAY_SIZE(trip_types); i++)
>> + if (!strcasecmp(t, trip_types[i])) {
>> + *type = i;
>> + return 0;
>> + }
>> +
>> + return -ENODEV;
>> +}
>> +
>> +/**
>> + * thermal_of_populate_trip - parse and fill one trip point data
>> + * @np: DT node containing a trip point node
>> + * @trip: trip point data structure to be filled up
>> + *
>> + * This function parses a trip point type of node represented by
>> + * @np parameter and fills the read data into @trip data structure.
>> + *
>> + * Return: 0 on success, proper error code otherwise
>> + */
>> +static int thermal_of_populate_trip(struct device_node *np,
>> + struct __thermal_trip *trip)
>> +{
>> + int prop;
>> + int ret;
>> +
>> + ret = of_property_read_u32(np, "temperature", &prop);
>> + if (ret < 0) {
>> + pr_err("missing temperature property\n");
>> + return ret;
>> + }
>> + trip->temperature = prop;
>> +
>> + ret = of_property_read_u32(np, "hysteresis", &prop);
>> + if (ret < 0) {
>> + pr_err("missing hysteresis property\n");
>> + return ret;
>> + }
>> + trip->hysteresis = prop;
>> +
>> + ret = thermal_of_get_trip_type(np, &trip->type);
>> + if (ret < 0) {
>> + pr_err("wrong trip type property\n");
>> + return ret;
>> + }
>> +
>> + /* Required for cooling map matching */
>> + trip->np = np;
>> +
>> + return 0;
>> +}
>> +
>> +/**
>> + * thermal_of_build_thermal_zone - parse and fill one thermal zone data
>> + * @np: DT node containing a thermal zone node
>> + *
>> + * This function parses a thermal zone type of node represented by
>> + * @np parameter and fills the read data into a __thermal_zone data structure
>> + * and return this pointer.
>> + *
>> + * TODO: Missing properties to parse: thermal-sensor-names and coefficients
>> + *
>> + * Return: On success returns a valid struct __thermal_zone,
>> + * otherwise, it returns a corresponding ERR_PTR(). Caller must
>> + * check the return value with help of IS_ERR() helper.
>> + */
>> +static struct __thermal_zone *
>> +thermal_of_build_thermal_zone(struct device_node *np)
>> +{
>> + struct device_node *child = NULL, *gchild;
>> + struct __thermal_zone *tz;
>> + int ret, i;
>> + u32 prop;
>> +
>> + if (!np) {
>> + pr_err("no thermal zone np\n");
>> + return ERR_PTR(-EINVAL);
>> + }
>> +
>> + tz = kzalloc(sizeof(*tz), GFP_KERNEL);
>> + if (!tz)
>> + return ERR_PTR(-ENOMEM);
>> +
>> + ret = of_property_read_u32(np, "polling-delay-passive", &prop);
>> + if (ret < 0) {
>> + pr_err("missing polling-delay-passive property\n");
>> + goto free_tz;
>> + }
>> + tz->passive_delay = prop;
>> +
>> + ret = of_property_read_u32(np, "polling-delay", &prop);
>> + if (ret < 0) {
>> + pr_err("missing polling-delay property\n");
>> + goto free_tz;
>> + }
>> + tz->polling_delay = prop;
>> +
>> + /* trips */
>> + child = of_get_child_by_name(np, "trips");
>> +
>> + /* No trips provided */
>> + if (!child)
>> + goto finish;
>> +
>> + tz->ntrips = of_get_child_count(child);
>> + if (tz->ntrips == 0) /* must have at least one child */
>> + goto finish;
>> +
>> + tz->trips = kzalloc(tz->ntrips * sizeof(*tz->trips), GFP_KERNEL);
>> + if (!tz->trips) {
>> + ret = -ENOMEM;
>> + goto free_tz;
>> + }
>> +
>> + i = 0;
>> + for_each_child_of_node(child, gchild) {
>> + ret = thermal_of_populate_trip(gchild, &tz->trips[i++]);
>> + if (ret)
>> + goto free_trips;
>> + }
>> +
>> + of_node_put(child);
>> +
>> + /* cooling-maps */
>> + child = of_get_child_by_name(np, "cooling-maps");
>> +
>> + /* cooling-maps not provided */
>> + if (!child)
>> + goto finish;
>> +
>> + tz->num_tbps = of_get_child_count(child);
>> + if (tz->num_tbps == 0)
>> + goto finish;
>> +
>> + tz->tbps = kzalloc(tz->num_tbps * sizeof(*tz->tbps), GFP_KERNEL);
>> + if (!tz->tbps) {
>> + ret = -ENOMEM;
>> + goto free_trips;
>> + }
>> +
>> + i = 0;
>> + for_each_child_of_node(child, gchild)
>> + ret = thermal_of_populate_bind_params(gchild, &tz->tbps[i++],
>> + tz->trips, tz->ntrips);
>> + if (ret)
>> + goto free_tbps;
>> +
>> +finish:
>> + of_node_put(child);
>> + tz->mode = THERMAL_DEVICE_DISABLED;
>> +
>> + return tz;
>> +
>> +free_tbps:
>> + kfree(tz->tbps);
>> +free_trips:
>> + kfree(tz->trips);
>> +free_tz:
>> + kfree(tz);
>> + of_node_put(child);
>> +
>> + return ERR_PTR(ret);
>> +}
>> +
>> +static inline void of_thermal_free_zone(struct __thermal_zone *tz)
>> +{
>> + kfree(tz->tbps);
>> + kfree(tz->trips);
>> + kfree(tz);
>> +}
>> +
>> +/**
>> + * of_parse_thermal_zones - parse device tree thermal data
>> + *
>> + * Initialization function that can be called by machine initialization
>> + * code to parse thermal data and populate the thermal framework
>> + * with hardware thermal zones info. This function only parses thermal zones.
>> + * Cooling devices and sensor devices nodes are supposed to be parsed
>> + * by their respective drivers.
>> + *
>> + * Return: 0 on success, proper error code otherwise
>> + *
>> + */
>> +int __init of_parse_thermal_zones(void)
>> +{
>> + struct device_node *np, *child;
>> + struct __thermal_zone *tz;
>> + struct thermal_zone_device_ops *ops;
>> +
>> + np = of_find_node_by_name(NULL, "thermal-zones");
>> + if (!np) {
>> + pr_debug("unable to find thermal zones\n");
>> + return 0; /* Run successfully on systems without thermal DT */
>> + }
>> +
>> + for_each_child_of_node(np, child) {
>> + struct thermal_zone_device *zone;
>> + struct thermal_zone_params *tzp;
>> +
>> + tz = thermal_of_build_thermal_zone(child);
>> + if (IS_ERR(tz)) {
>> + pr_err("failed to build thermal zone %s: %ld\n",
>> + child->name,
>> + PTR_ERR(tz));
>> + continue;
>> + }
>> +
>> + ops = kmemdup(&of_thermal_ops, sizeof(*ops), GFP_KERNEL);
>> + if (!ops)
>> + goto exit_free;
>> +
>> + tzp = kzalloc(sizeof(*tzp), GFP_KERNEL);
>> + if (!tzp) {
>> + kfree(ops);
>> + goto exit_free;
>> + }
>> +
>> + /* No hwmon because there might be hwmon drivers registering */
>> + tzp->no_hwmon = true;
>> +
>> + zone = thermal_zone_device_register(child->name, tz->ntrips,
>> + 0, tz,
>> + ops, tzp,
>> + tz->passive_delay,
>> + tz->polling_delay);
>> + if (IS_ERR(zone)) {
>> + pr_err("Failed to build %s zone %ld\n", child->name,
>> + PTR_ERR(zone));
>> + kfree(tzp);
>> + kfree(ops);
>> + of_thermal_free_zone(tz);
>> + /* attempting to build remaining zones still */
>> + }
>> + }
>> +
>> + return 0;
>> +
>> +exit_free:
>> + of_thermal_free_zone(tz);
>> +
>> + /* no memory available, so free what we have built */
>> + of_thermal_destroy_zones();
>> +
>> + return -ENOMEM;
>> +}
>> +
>> +/**
>> + * of_thermal_destroy_zones - remove all zones parsed and allocated resources
>> + *
>> + * Finds all zones parsed and added to the thermal framework and remove them
>> + * from the system, together with their resources.
>> + *
>> + */
>> +void __exit of_thermal_destroy_zones(void)
>> +{
>> + struct device_node *np, *child;
>> +
>> + np = of_find_node_by_name(NULL, "thermal-zones");
>> + if (!np) {
>> + pr_err("unable to find thermal zones\n");
>> + return;
>> + }
>> +
>> + for_each_child_of_node(np, child) {
>> + struct thermal_zone_device *zone;
>> +
>> + zone = thermal_zone_get_zone_by_name(child->name);
>> + if (IS_ERR(zone))
>> + continue;
>> +
>> + thermal_zone_device_unregister(zone);
>> + kfree(zone->tzp);
>> + kfree(zone->ops);
>> + of_thermal_free_zone(zone->devdata);
>> + }
>> +}
>> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
>> index f7a9f4f..fec3351 100644
>> --- a/drivers/thermal/thermal_core.c
>> +++ b/drivers/thermal/thermal_core.c
>> @@ -1371,7 +1371,7 @@ static void remove_trip_attrs(struct thermal_zone_device *tz)
>> */
>> struct thermal_zone_device *thermal_zone_device_register(const char *type,
>> int trips, int mask, void *devdata,
>> - const struct thermal_zone_device_ops *ops,
>> + struct thermal_zone_device_ops *ops,
>> const struct thermal_zone_params *tzp,
>> int passive_delay, int polling_delay)
>> {
>> @@ -1751,8 +1751,14 @@ static int __init thermal_init(void)
>> if (result)
>> goto unregister_class;
>>
>> + result = of_parse_thermal_zones();
>> + if (result)
>> + goto exit_netlink;
>> +
>> return 0;
>>
>> +exit_netlink:
>> + genetlink_exit();
>> unregister_governors:
>> thermal_unregister_governors();
>> unregister_class:
>> @@ -1768,6 +1774,7 @@ error:
>>
>> static void __exit thermal_exit(void)
>> {
>> + of_thermal_destroy_zones();
>> genetlink_exit();
>> class_unregister(&thermal_class);
>> thermal_unregister_governors();
>> diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
>> index 7cf2f66..3db339f 100644
>> --- a/drivers/thermal/thermal_core.h
>> +++ b/drivers/thermal/thermal_core.h
>> @@ -77,4 +77,13 @@ static inline int thermal_gov_user_space_register(void) { return 0; }
>> static inline void thermal_gov_user_space_unregister(void) {}
>> #endif /* CONFIG_THERMAL_GOV_USER_SPACE */
>>
>> +/* device tree support */
>> +#ifdef CONFIG_THERMAL_OF
>> +int of_parse_thermal_zones(void);
>> +void of_thermal_destroy_zones(void);
>> +#else
>> +static inline int of_parse_thermal_zones(void) { return 0; }
>> +static inline void of_thermal_destroy_zones(void) { }
>> +#endif
>> +
>> #endif /* __THERMAL_CORE_H__ */
>> diff --git a/include/dt-bindings/thermal/thermal.h b/include/dt-bindings/thermal/thermal.h
>> new file mode 100644
>> index 0000000..59c4581
>> --- /dev/null
>> +++ b/include/dt-bindings/thermal/thermal.h
>> @@ -0,0 +1,27 @@
>> +/*
>> + * This header provides constants for most thermal bindings.
>> + *
>> + * Copyright (C) 2013 Texas Instruments
>> + * Eduardo Valentin <eduardo.valentin@xxxxxx>
>> + *
>> + * GPLv2 only
>> + */
>> +
>> +#ifndef _DT_BINDINGS_THERMAL_THERMAL_H
>> +#define _DT_BINDINGS_THERMAL_THERMAL_H
>> +
>> +/*
>> + * Here are the thermal trip types. This must
>> + * match with enum thermal_trip_type at
>> + * include/linux/thermal.h
>> + */
>> +#define THERMAL_TRIP_ACTIVE "active"
>> +#define THERMAL_TRIP_PASSIVE "passive"
>> +#define THERMAL_TRIP_HOT "hot"
>> +#define THERMAL_TRIP_CRITICAL "critical"
>
> I don't like this. If someone wants to include this in a C file they can't do so
> at the same time as include/linux/thermal.h. The defined names are longer than
> the actual string values, and the comment makes it sound like these could be
> modified rather than being a fixed ABI.
>
> I do not see the point of these constants.
>
> Thanks,
> Mark.
>
>> +
>> +/* On cooling devices upper and lower limits */
>> +#define THERMAL_NO_LIMIT (-1UL)
>> +
>> +#endif
>> +
>> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
>> index b268d3c..b780c5b 100644
>> --- a/include/linux/thermal.h
>> +++ b/include/linux/thermal.h
>> @@ -143,6 +143,7 @@ struct thermal_cooling_device {
>> int id;
>> char type[THERMAL_NAME_LENGTH];
>> struct device device;
>> + struct device_node *np;
>> void *devdata;
>> const struct thermal_cooling_device_ops *ops;
>> bool updated; /* true if the cooling device does not need update */
>> @@ -172,7 +173,7 @@ struct thermal_zone_device {
>> int emul_temperature;
>> int passive;
>> unsigned int forced_passive;
>> - const struct thermal_zone_device_ops *ops;
>> + struct thermal_zone_device_ops *ops;
>> const struct thermal_zone_params *tzp;
>> struct thermal_governor *governor;
>> struct list_head thermal_instances;
>> @@ -242,8 +243,31 @@ struct thermal_genl_event {
>> };
>>
>> /* Function declarations */
>> +#ifdef CONFIG_THERMAL_OF
>> +struct thermal_zone_device *
>> +thermal_zone_of_sensor_register(struct device *dev, int id,
>> + void *data, int (*get_temp)(void *, long *),
>> + int (*get_trend)(void *, long *));
>> +void thermal_zone_of_sensor_unregister(struct device *dev,
>> + struct thermal_zone_device *tz);
>> +#else
>> +static inline struct thermal_zone_device *
>> +thermal_zone_of_sensor_register(struct device *dev, int id,
>> + void *data, int (*get_temp)(void *, long *),
>> + int (*get_trend)(void *, long *))
>> +{
>> + return NULL;
>> +}
>> +
>> +static inline
>> +void thermal_zone_of_sensor_unregister(struct device *dev,
>> + struct thermal_zone_device *tz)
>> +{
>> +}
>> +
>> +#endif
>> struct thermal_zone_device *thermal_zone_device_register(const char *, int, int,
>> - void *, const struct thermal_zone_device_ops *,
>> + void *, struct thermal_zone_device_ops *,
>> const struct thermal_zone_params *, int, int);
>> void thermal_zone_device_unregister(struct thermal_zone_device *);
>>
>> --
>> 1.8.2.1.342.gfa7285d
>>
>>
>
>


--
You have got to be excited about what you are doing. (L. Lamport)

Eduardo Valentin

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