[PATCH v2 07/11] DT: Add documentation for the Skyworks AAT1290

[Jacek Anaszewski <j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>]

This patch adds device tree binding documentation for
1.5A Step-Up Current Regulator for Flash LEDs.

Signed-off-by: Jacek Anaszewski <j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
Acked-by: Kyungmin Park <kyungmin.park-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
Cc: Bryan Wu <cooloney-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Richard Purdie <rpurdie-Fm38FmjxZ/leoWH0uzbU5w@public.gmane.org>
---
 .../devicetree/bindings/leds/leds-aat1290.txt      |   70 ++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-aat1290.txt

diff --git a/Documentation/devicetree/bindings/leds/leds-aat1290.txt b/Documentation/devicetree/bindings/leds/leds-aat1290.txt
new file mode 100644
index 0000000..c3df4e9
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/leds-aat1290.txt
@@ -0,0 +1,70 @@
+* Skyworks Solutions, Inc. AAT1290 Current Regulator for Flash LEDs
+
+The device is controlled through two pins: FL_EN and EN_SET. The pins when,
+asserted high, enable flash strobe and movie mode (max 1/2 of flash current)
+respectively. In order to add a capability of selecting the strobe signal source
+(e.g. GPIO or ISP) there is an additional switch required, independent of the
+flash chip. The switch is controlled with pin control.
+
+Required properties:
+
+- compatible : Must be "skyworks,aat1290".
+- flen-gpios : Must be device tree identifier of the flash device FL_EN pin.
+- enset-gpios : Must be device tree identifier of the flash device EN_SET pin.
+
+Optional properties:
+- pinctrl-names : Must contain entries: "default", "host", "isp". Entries
+		"default" and "host" must refer to the same pin configuration
+		node, which sets the host as a strobe signal provider. Entry
+		"isp" must refer to the pin configuration node, which sets the
+		ISP as a strobe signal provider.
+
+A discrete LED element connected to the device must be represented by a child
+node - see Documentation/devicetree/bindings/leds/common.txt.
+
+Required properties of the LED child node:
+- flash-max-microamp : Maximum intensity in microamperes of the flash LED -
+		       it can be calculated using following formula:
+		       I = 1A * 162kohm / Rset.
+- flash-timeout-us : Maximum flash timeout in microseconds -
+		     it can be calculated using following formula:
+		     T = 8.82 * 10^9 * Ct.
+
+Optional properties of the LED child node:
+- label : see Documentation/devicetree/bindings/leds/common.txt
+
+Example (by Ct = 220nF, Rset = 160kohm and exynos4412-trats2 board with
+a switch that allows for routing strobe signal either from host or from ISP):
+
+#include "exynos4412.dtsi"
+
+aat1290 {
+	compatible = "skyworks,aat1290";
+	flen-gpios = <&gpj1 1 GPIO_ACTIVE_HIGH>;
+	enset-gpios = <&gpj1 2 GPIO_ACTIVE_HIGH>;
+
+	pinctrl-names = "default", "host", "isp";
+	pinctrl-0 = <&camera_flash_host>;
+	pinctrl-1 = <&camera_flash_host>;
+	pinctrl-2 = <&camera_flash_isp>;
+
+	camera_flash: flash-led {
+		label = "aat1290-flash";
+		flash-max-microamp = <1012500>;
+		flash-timeout-us = <1940000>;
+	};
+};
+
+&pinctrl_0 {
+	camera_flash_host: camera-flash-host {
+		samsung,pins = "gpj1-0";
+		samsung,pin-function = <1>;
+		samsung,pin-val = <0>;
+	};
+
+	camera_flash_isp: camera-flash-isp {
+		samsung,pins = "gpj1-0";
+		samsung,pin-function = <1>;
+		samsung,pin-val = <1>;
+	};
+};
-- 
1.7.9.5

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