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DougieLawsonpopcornmix
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overlays: Add maxtherm overlay for MAX6675/31855
Add an overlay - maxtherm - to support the MAX6675 and MAX31855 family of thermocouples. Developed from an original set of overlays by Dougie Lawson. See: #3763 Signed-off-by: Phil Elwell <[email protected]>
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‎arch/arm/boot/dts/overlays/Makefile

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@@ -98,6 +98,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
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justboom-digi.dtbo \
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ltc294x.dtbo \
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max98357a.dtbo \
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maxtherm.dtbo \
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mbed-dac.dtbo \
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mcp23017.dtbo \
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mcp23s17.dtbo \

‎arch/arm/boot/dts/overlays/README

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@@ -1622,6 +1622,36 @@ Params: no-sdmode Driver does not manage the state of the DAC's
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of the DAC (default GPIO4 if parameter omitted).
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Name: maxtherm
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Info: Configure a MAX6675 or MAX31855 thermocouple as an IIO device.
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For devices on spi1 or spi2, the interfaces should be enabled
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with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
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The overlay expects to disable the relevant spidev node, so also using
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e.g. cs0_spidev=off is unnecessary.
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Note: with the 5.7 kernel (and later) there will also be
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overlays for MAX31855E, MAX31855J, MAX31855K,
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MAX31885N, MAX31855R, MAX31855S and MAX31855T.
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Example:
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MAX31855 on /dev/spidev0.0
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dtoverlay=maxtherm,spi0-0,max31855
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Load: dtoverlay=maxtherm,<param>=<val>
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Params: spi<n>-<m> Configure device at spi<n>, cs<m>
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(boolean, required)
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max6675 Enable support for the MAX6675 (default)
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max31855 Enable support for the MAX31855
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max31855e Enable support for the MAX31855E
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max31855j Enable support for the MAX31855J
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max31855k Enable support for the MAX31855K
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max31855n Enable support for the MAX31855N
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max31855r Enable support for the MAX31855R
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max31855s Enable support for the MAX31855S
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max31855t Enable support for the MAX31855T
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Name: mbed-dac
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Info: Configures the mbed AudioCODEC (TLV320AIC23B)
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Load: dtoverlay=mbed-dac

‎arch/arm/boot/dts/overlays/maxtherm-overlay.dts

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/*
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* Universal device tree overlay for SPI devices
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*/
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/dts-v1/;
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/plugin/;
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/ {
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compatible = "brcm,bcm2835";
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fragment@0 {
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target = <&spidev0>;
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__dormant__ {
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status = "disabled";
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};
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};
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fragment@1 {
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target = <&spidev1>;
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__dormant__ {
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status = "disabled";
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};
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};
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fragment@2 {
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target-path = "spi1/spidev@0";
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__dormant__ {
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status = "disabled";
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};
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};
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fragment@3 {
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target-path = "spi1/spidev@1";
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__dormant__ {
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status = "disabled";
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};
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};
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fragment@4 {
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target-path = "spi1/spidev@2";
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__dormant__ {
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status = "disabled";
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};
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};
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fragment@5 {
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target-path = "spi2/spidev@0";
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__dormant__ {
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status = "disabled";
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};
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};
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fragment@6 {
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target-path = "spi2/spidev@1";
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__dormant__ {
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status = "disabled";
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};
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};
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fragment@7 {
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target-path = "spi2/spidev@2";
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__dormant__ {
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status = "disabled";
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};
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};
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maxfrag: fragment@8 {
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target = <&spi0>;
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__overlay__ {
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status = "okay";
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#address-cells = <1>;
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#size-cells = <0>;
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max: maxtherm@0 {
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compatible = "maxim,max6675";
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reg = <0>;
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spi-max-frequency = <500000>;
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};
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};
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};
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fragment@9 {
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target = <&max>;
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__dormant__ {
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compatible = "maxim,max31855e", "maxim,max31855";
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};
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};
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fragment@10 {
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target = <&max>;
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__dormant__ {
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compatible = "maxim,max31855j", "maxim,max31855";
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};
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};
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fragment@11 {
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target = <&max>;
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__dormant__ {
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compatible = "maxim,max31855k", "maxim,max31855";
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};
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};
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fragment@12 {
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target = <&max>;
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__dormant__ {
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compatible = "maxim,max31855n", "maxim,max31855";
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};
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};
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fragment@13 {
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target = <&max>;
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__dormant__ {
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compatible = "maxim,max31855r", "maxim,max31855";
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};
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};
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fragment@14 {
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target = <&max>;
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__dormant__ {
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compatible = "maxim,max31855s", "maxim,max31855";
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};
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};
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fragment@15 {
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target = <&max>;
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__dormant__ {
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compatible = "maxim,max31855t", "maxim,max31855";
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};
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};
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__overrides__ {
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spi0-0 = <0>, "+0",
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<&maxfrag>,"target:0=",<&spi0>,
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<&max>,"reg:0=0";
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spi0-1 = <0>, "+1",
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<&maxfrag>,"target:0=",<&spi0>,
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<&max>,"reg:0=1";
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spi1-0 = <0>, "+2",
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<&maxfrag>,"target:0=",<&spi1>,
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<&max>,"reg:0=0";
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spi1-1 = <0>, "+3",
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<&maxfrag>,"target:0=",<&spi1>,
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<&max>,"reg:0=1";
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spi1-2 = <0>, "+4",
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<&maxfrag>,"target:0=",<&spi1>,
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<&max>,"reg:0=2";
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spi2-0 = <0>, "+5",
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<&maxfrag>,"target:0=",<&spi2>,
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<&max>,"reg:0=0";
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spi2-1 = <0>, "+6",
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<&maxfrag>,"target:0=",<&spi2>,
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<&max>,"reg:0=1";
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spi2-2 = <0>, "+7",
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<&maxfrag>,"target:0=",<&spi2>,
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<&max>,"reg:0=2";
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max6675 = <&max>,"compatible=maxim,max6675";
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max31855 = <&max>,"compatible=maxim,max31855";
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max31855e = <0>,"+9";
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max31855j = <0>,"+10";
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max31855k = <0>,"+11";
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max31855n = <0>,"+12";
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max31855r = <0>,"+13";
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max31855s = <0>,"+14";
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max31855t = <0>,"+15";
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};
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};

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