rtc: gemini: Add device tree probing

This adds bindings and simple probing for the Cortina Systems Gemini
SoC RTC.

Cc: Janos Laube <janos.dev@gmail.com>
Cc: Paulius Zaleckas <paulius.zaleckas@gmail.com>
Cc: Hans Ulli Kroll <ulli.kroll@googlemail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: devicetree@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

Documentation/devicetree/bindings/rtc/cortina,gemini.txt

+* Cortina Systems Gemini RTC
+
+Gemini SoC real-time clock.
+
+Required properties:
+- compatible : Should be "cortina,gemini-rtc"
+
+Examples:
+
+rtc@45000000 {
+	compatible = "cortina,gemini-rtc";
+	reg = <0x45000000 0x100>;
+	interrupts = <17 IRQ_TYPE_LEVEL_HIGH>;
+};

drivers/rtc/rtc-gemini.c

@@ -159,9 +159,16 @@ static int gemini_rtc_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct of_device_id gemini_rtc_dt_match[] = {
+	{ .compatible = "cortina,gemini-rtc" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, gemini_rtc_dt_match);
+
 static struct platform_driver gemini_rtc_driver = {
 	.driver		= {
 		.name	= DRV_NAME,
+		.of_match_table = gemini_rtc_dt_match,
 	},
 	.probe		= gemini_rtc_probe,
 	.remove		= gemini_rtc_remove,