openwrt/target/linux/bcm27xx/patches-5.4/950-0931-overlays-Add-maxtherm-overlay-for-MAX6675-31855.patch

From 56e726d1631c9551530b8db4127352c64c3cb94d Mon Sep 17 00:00:00 2001
From: Dougie Lawson <dl1ims@gmail.com>
Date: Mon, 27 Jul 2020 23:52:40 +0100
Subject: [PATCH] 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: https://github.com/raspberrypi/linux/pull/3763

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
 arch/arm/boot/dts/overlays/Makefile           |   1 +
 arch/arm/boot/dts/overlays/README             |  30 ++++
 .../boot/dts/overlays/maxtherm-overlay.dts    | 166 ++++++++++++++++++
 3 files changed, 197 insertions(+)
 create mode 100644 arch/arm/boot/dts/overlays/maxtherm-overlay.dts

--- a/arch/arm/boot/dts/overlays/Makefile
+++ b/arch/arm/boot/dts/overlays/Makefile
@@ -98,6 +98,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
 	justboom-digi.dtbo \
 	ltc294x.dtbo \
 	max98357a.dtbo \
+	maxtherm.dtbo \
 	mbed-dac.dtbo \
 	mcp23017.dtbo \
 	mcp23s17.dtbo \
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -1622,6 +1622,36 @@ Params: no-sdmode               Driver d
                                 of the DAC (default GPIO4 if parameter omitted).
 
 
+Name:   maxtherm
+Info:   Configure a MAX6675 or MAX31855 thermocouple as an IIO device.
+
+        For devices on spi1 or spi2, the interfaces should be enabled
+        with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
+        The overlay expects to disable the relevant spidev node, so also using
+        e.g. cs0_spidev=off is unnecessary.
+
+        Note:   with the 5.7 kernel (and later) there will also be
+                overlays for MAX31855E, MAX31855J, MAX31855K,
+                MAX31885N, MAX31855R, MAX31855S and MAX31855T.
+
+        Example:
+        MAX31855 on /dev/spidev0.0
+            dtoverlay=maxtherm,spi0-0,max31855
+
+Load:   dtoverlay=maxtherm,<param>=<val>
+Params: spi<n>-<m>              Configure device at spi<n>, cs<m>
+                                (boolean, required)
+        max6675                 Enable support for the MAX6675 (default)
+        max31855                Enable support for the MAX31855
+        max31855e               Enable support for the MAX31855E
+        max31855j               Enable support for the MAX31855J
+        max31855k               Enable support for the MAX31855K
+        max31855n               Enable support for the MAX31855N
+        max31855r               Enable support for the MAX31855R
+        max31855s               Enable support for the MAX31855S
+        max31855t               Enable support for the MAX31855T
+
+
 Name:   mbed-dac
 Info:   Configures the mbed AudioCODEC (TLV320AIC23B)
 Load:   dtoverlay=mbed-dac
--- /dev/null
+++ b/arch/arm/boot/dts/overlays/maxtherm-overlay.dts
@@ -0,0 +1,166 @@
+/*
+ * Universal device tree overlay for SPI devices
+ */
+
+/dts-v1/;
+/plugin/;
+
+/ {
+	compatible = "brcm,bcm2835";
+
+	fragment@0 {
+		target = <&spidev0>;
+		__dormant__ {
+			status = "disabled";
+		};
+	};
+
+	fragment@1 {
+		target = <&spidev1>;
+		__dormant__ {
+			status = "disabled";
+		};
+	};
+
+	fragment@2 {
+		target-path = "spi1/spidev@0";
+		__dormant__ {
+			status = "disabled";
+		};
+	};
+
+	fragment@3 {
+		target-path = "spi1/spidev@1";
+		__dormant__ {
+			status = "disabled";
+		};
+	};
+
+	fragment@4 {
+		target-path = "spi1/spidev@2";
+		__dormant__ {
+			status = "disabled";
+		};
+	};
+
+	fragment@5 {
+		target-path = "spi2/spidev@0";
+		__dormant__ {
+			status = "disabled";
+		};
+	};
+
+	fragment@6 {
+		target-path = "spi2/spidev@1";
+		__dormant__ {
+			status = "disabled";
+		};
+	};
+
+	fragment@7 {
+		target-path = "spi2/spidev@2";
+		__dormant__ {
+			status = "disabled";
+		};
+	};
+
+	maxfrag: fragment@8 {
+		target = <&spi0>;
+		__overlay__ {
+			status = "okay";
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			max: maxtherm@0 {
+				compatible = "maxim,max6675";
+				reg = <0>;
+				spi-max-frequency = <500000>;
+			};
+		};
+	};
+
+	fragment@9 {
+		target = <&max>;
+		__dormant__ {
+			compatible = "maxim,max31855e", "maxim,max31855";
+		};
+	};
+
+	fragment@10 {
+		target = <&max>;
+		__dormant__ {
+			compatible = "maxim,max31855j", "maxim,max31855";
+		};
+	};
+
+	fragment@11 {
+		target = <&max>;
+		__dormant__ {
+			compatible = "maxim,max31855k", "maxim,max31855";
+		};
+	};
+
+	fragment@12 {
+		target = <&max>;
+		__dormant__ {
+			compatible = "maxim,max31855n", "maxim,max31855";
+		};
+	};
+
+	fragment@13 {
+		target = <&max>;
+		__dormant__ {
+			compatible = "maxim,max31855r", "maxim,max31855";
+		};
+	};
+
+	fragment@14 {
+		target = <&max>;
+		__dormant__ {
+			compatible = "maxim,max31855s", "maxim,max31855";
+		};
+	};
+
+	fragment@15 {
+		target = <&max>;
+		__dormant__ {
+			compatible = "maxim,max31855t", "maxim,max31855";
+		};
+	};
+
+	__overrides__ {
+		spi0-0 = <0>, "+0",
+			 <&maxfrag>,"target:0=",<&spi0>,
+			 <&max>,"reg:0=0";
+		spi0-1 = <0>, "+1",
+			 <&maxfrag>,"target:0=",<&spi0>,
+			 <&max>,"reg:0=1";
+		spi1-0 = <0>, "+2",
+			 <&maxfrag>,"target:0=",<&spi1>,
+			 <&max>,"reg:0=0";
+		spi1-1 = <0>, "+3",
+			 <&maxfrag>,"target:0=",<&spi1>,
+			 <&max>,"reg:0=1";
+		spi1-2 = <0>, "+4",
+			 <&maxfrag>,"target:0=",<&spi1>,
+			 <&max>,"reg:0=2";
+		spi2-0 = <0>, "+5",
+			 <&maxfrag>,"target:0=",<&spi2>,
+			 <&max>,"reg:0=0";
+		spi2-1 = <0>, "+6",
+			 <&maxfrag>,"target:0=",<&spi2>,
+			 <&max>,"reg:0=1";
+		spi2-2 = <0>, "+7",
+			 <&maxfrag>,"target:0=",<&spi2>,
+			 <&max>,"reg:0=2";
+		max6675 = <&max>,"compatible=maxim,max6675";
+		max31855 = <&max>,"compatible=maxim,max31855";
+		max31855e = <0>,"+9";
+		max31855j = <0>,"+10";
+		max31855k = <0>,"+11";
+		max31855n = <0>,"+12";
+		max31855r = <0>,"+13";
+		max31855s = <0>,"+14";
+		max31855t = <0>,"+15";
+	};
+};