From 500c619219968b72a9b8bd1f6bd78ff16a7d3ab9 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Tue, 1 May 2018 09:35:56 +0100
Subject: [PATCH 319/321] overlays: Add ltc294x (battery gauge)

Support the LTC294x range of I2C-connected battery monitors.

See: https://github.com/raspberrypi/linux/issues/2537

Signed-off-by: Phil Elwell <phil@raspberrypi.org>
---
 arch/arm/boot/dts/overlays/Makefile            |  1 +
 arch/arm/boot/dts/overlays/README              | 25 ++++++++
 arch/arm/boot/dts/overlays/ltc294x-overlay.dts | 86 ++++++++++++++++++++++++++
 3 files changed, 112 insertions(+)
 create mode 100644 arch/arm/boot/dts/overlays/ltc294x-overlay.dts

diff --git a/arch/arm/boot/dts/overlays/Makefile b/arch/arm/boot/dts/overlays/Makefile
index 18cb057ce127..22f7aa2952aa 100644
--- a/arch/arm/boot/dts/overlays/Makefile
+++ b/arch/arm/boot/dts/overlays/Makefile
@@ -60,6 +60,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
 	justboom-dac.dtbo \
 	justboom-digi.dtbo \
 	lirc-rpi.dtbo \
+	ltc294x.dtbo \
 	mbed-dac.dtbo \
 	mcp23017.dtbo \
 	mcp23s17.dtbo \
diff --git a/arch/arm/boot/dts/overlays/README b/arch/arm/boot/dts/overlays/README
index e00c7e10c2bc..37484904c2d5 100644
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -1020,6 +1020,31 @@ Params: gpio_out_pin            GPIO for output (default "17")
                                 (default "off")
 
 
+Name:   ltc294x
+Info:   Adds support for the ltc294x family of battery gauges
+Load:   dtoverlay=ltc294x,<param>=<val>
+Params: ltc2941                 Select the ltc2941 device
+
+        ltc2942                 Select the ltc2942 device
+
+        ltc2943                 Select the ltc2943 device
+
+        ltc2944                 Select the ltc2944 device
+
+        resistor-sense          The sense resistor value in milli-ohms.
+                                Can be a 32-bit negative value when the battery
+                                has been connected to the wrong end of the
+                                resistor.
+
+        prescaler-exponent      Range and accuracy of the gauge. The value is
+                                programmed into the chip only if it differs
+                                from the current setting.
+                                For LTC2941 only:
+                                - Default value is 128
+                                - the exponent is in the range 0-7 (default 7)
+                                See the datasheet for more information.
+
+
 Name:   mbed-dac
 Info:   Configures the mbed AudioCODEC (TLV320AIC23B)
 Load:   dtoverlay=mbed-dac
diff --git a/arch/arm/boot/dts/overlays/ltc294x-overlay.dts b/arch/arm/boot/dts/overlays/ltc294x-overlay.dts
new file mode 100644
index 000000000000..6d971f3649ca
--- /dev/null
+++ b/arch/arm/boot/dts/overlays/ltc294x-overlay.dts
@@ -0,0 +1,86 @@
+/dts-v1/;
+/plugin/;
+
+
+/ {
+	compatible = "brcm,bcm2835";
+
+	fragment@0 {
+		target = <&i2c_arm>;
+		__dormant__ {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "okay";
+
+			ltc2941: ltc2941@64 {
+				compatible = "lltc,ltc2941";
+				reg = <0x64>;
+				lltc,resistor-sense = <50>;
+				lltc,prescaler-exponent = <7>; 
+			};
+		};
+	};
+
+	fragment@1 {
+		target = <&i2c_arm>;
+		__dormant__ {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "okay";
+
+			ltc2942: ltc2942@64 {
+				compatible = "lltc,ltc2942";
+				reg = <0x64>;
+				lltc,resistor-sense = <50>;
+				lltc,prescaler-exponent = <7>; 
+			};
+		};
+	};
+
+	fragment@2 {
+		target = <&i2c_arm>;
+		__dormant__ {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "okay";
+
+			ltc2943: ltc2943@64 {
+				compatible = "lltc,ltc2943";
+				reg = <0x64>;
+				lltc,resistor-sense = <50>;
+				lltc,prescaler-exponent = <7>; 
+			};
+		};
+	};
+
+	fragment@3 {
+		target = <&i2c_arm>;
+		__dormant__ {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "okay";
+
+			ltc2944: ltc2944@64 {
+				compatible = "lltc,ltc2944";
+				reg = <0x64>;
+				lltc,resistor-sense = <50>;
+				lltc,prescaler-exponent = <7>; 
+			};
+		};
+	};
+
+	__overrides__ {
+		ltc2941 = <0>,"+0";
+		ltc2942 = <0>,"+1";
+		ltc2943 = <0>,"+2";
+		ltc2944 = <0>,"+3";
+		resistor-sense = <&ltc2941>, "lltc,resistor-sense:0",
+			         <&ltc2942>, "lltc,resistor-sense:0",
+				 <&ltc2943>, "lltc,resistor-sense:0",
+				 <&ltc2944>, "lltc,resistor-sense:0";
+		prescaler-exponent = <&ltc2941>, "lltc,prescaler-exponent:0",
+			         <&ltc2942>, "lltc,prescaler-exponent:0",
+				 <&ltc2943>, "lltc,prescaler-exponent:0",
+				 <&ltc2944>, "lltc,prescaler-exponent:0";
+	};
+};
-- 
2.16.1