i2c: add sc18is600 driver

This adds an I²C master driver for SPI -> I²C bus bridge chips.
It currently supports NXP's SC18IS600 and SC18IS601, as well as
Silicon Labs' CP2120. The driver was only tested on SC18IS600.

TODO:
 - test runtime PM stuff
 - test clock stretching
 - proper platform_data for gpio subdevice

Signed-off-By: Sebastian Reichel <sre@kernel.org>

2 files changed, 46 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/i2c/i2c-cp2120.txt b/Documentation/devicetree/bindings/i2c/i2c-cp2120.txt
new file mode 100644
index 000000000000..95e06e74f288
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-cp2120.txt
@@ -0,0 +1 @@
+Please see binding for i2c-sc18is600
diff --git a/Documentation/devicetree/bindings/i2c/i2c-sc18is600.txt b/Documentation/devicetree/bindings/i2c/i2c-sc18is600.txt
new file mode 100644
index 000000000000..d6d77061ca22
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-sc18is600.txt
@@ -0,0 +1,45 @@
+NXP SC18IS600 and Silabs CP2120 - SPI to I2C bus bridge
+
+Required properties:
+  - compatible: Should contain one of
+      * "nxp,sc18is600"
+      * "nxp,sc18is601"
+      * "silabs,cp2120"
+  - reg: address of the chip on SPI bus
+  - interrupts: Interrupt specifier. Refer to interrupt bindings.
+  - #address-cells: Should be 1.
+  - #size-cells: Should be 0.
+
+Required properties for sc18is601:
+  - clkin: Clock specifier for CLKIN pin
+
+Optional properties:
+  - clock-frequency:
+    Desired I2C bus frequency in Hz, otherwise defaults to 100000
+  - wakeup-gpios (sc18is60x only):
+    GPIO specifier for SC18IS600's WAKEUP/IO4 pin, which can be used
+    to wakeup the sc18is600 from power down mode. It's active low.
+  - reset-gpios
+    GPIO specifier for reset pin, which is active low.
+  - vdd-supply
+    Regulator specifier for VDD supply.
+  - Child nodes conforming to i2c bus binding
+
+Example:
+
+&spi_controller {
+	sc18is600: i2c@0 {
+		compatible = "nxp,sc18is600";
+		clock-frequency = <100000>;
+		reg = <0>;
+
+		vdd-supply = <&regulator_v33>;
+		wakeup-gpios = <&gpio_controller 0 GPIO_ACTIVE_LOW>;
+		reset-gpios = <&gpio_controller 1 GPIO_ACTIVE_LOW>;
+
+		i2c_device@42 {
+			compatible = "some,i2c-device";
+			reg = <0x42>;
+		};
+	};
+}