From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001
From: root <root@artemis.panaceas.org>
Date: Fri, 25 Dec 2015 04:40:36 +0000
Subject: initial_commit

---
 .../devicetree/bindings/i2c/ce4100-i2c.txt         | 93 ++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/ce4100-i2c.txt

(limited to 'Documentation/devicetree/bindings/i2c/ce4100-i2c.txt')

diff --git a/Documentation/devicetree/bindings/i2c/ce4100-i2c.txt b/Documentation/devicetree/bindings/i2c/ce4100-i2c.txt
new file mode 100644
index 00000000..569b1624
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+++ b/Documentation/devicetree/bindings/i2c/ce4100-i2c.txt
@@ -0,0 +1,93 @@
+CE4100 I2C
+----------
+
+CE4100 has one PCI device which is described as the I2C-Controller. This
+PCI device has three PCI-bars, each bar contains a complete I2C
+controller. So we have a total of three independent I2C-Controllers
+which share only an interrupt line.
+The driver is probed via the PCI-ID and is gathering the information of
+attached devices from the devices tree.
+Grant Likely recommended to use the ranges property to map the PCI-Bar
+number to its physical address and to use this to find the child nodes
+of the specific I2C controller. This were his exact words:
+
+       Here's where the magic happens.  Each entry in
+       ranges describes how the parent pci address space
+       (middle group of 3) is translated to the local
+       address space (first group of 2) and the size of
+       each range (last cell).  In this particular case,
+       the first cell of the local address is chosen to be
+       1:1 mapped to the BARs, and the second is the
+       offset from be base of the BAR (which would be
+       non-zero if you had 2 or more devices mapped off
+       the same BAR)
+
+       ranges allows the address mapping to be described
+       in a way that the OS can interpret without
+       requiring custom device driver code.
+
+This is an example which is used on FalconFalls:
+------------------------------------------------
+	i2c-controller@b,2 {
+		#address-cells = <2>;
+		#size-cells = <1>;
+		compatible = "pci8086,2e68.2",
+				"pci8086,2e68",
+				"pciclass,ff0000",
+				"pciclass,ff00";
+
+		reg = <0x15a00 0x0 0x0 0x0 0x0>;
+		interrupts = <16 1>;
+
+		/* as described by Grant, the first number in the group of
+		* three is the bar number followed by the 64bit bar address
+		* followed by size of the mapping. The bar address
+		* requires also a valid translation in parents ranges
+		* property.
+		*/
+		ranges = <0 0   0x02000000 0 0xdffe0500 0x100
+			  1 0   0x02000000 0 0xdffe0600 0x100
+			  2 0   0x02000000 0 0xdffe0700 0x100>;
+
+		i2c@0 {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			compatible = "intel,ce4100-i2c-controller";
+
+			/* The first number in the reg property is the
+			* number of the bar
+			*/
+			reg = <0 0 0x100>;
+
+			/* This I2C controller has no devices */
+		};
+
+		i2c@1 {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			compatible = "intel,ce4100-i2c-controller";
+			reg = <1 0 0x100>;
+
+			/* This I2C controller has one gpio controller */
+			gpio@26 {
+				#gpio-cells = <2>;
+				compatible = "ti,pcf8575";
+				reg = <0x26>;
+				gpio-controller;
+			};
+		};
+
+		i2c@2 {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			compatible = "intel,ce4100-i2c-controller";
+			reg = <2 0 0x100>;
+
+			gpio@26 {
+				#gpio-cells = <2>;
+				compatible = "ti,pcf8575";
+				reg = <0x26>;
+				gpio-controller;
+			};
+		};
+	};
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