clearfog: Enable MAX14830 quad UART
I had to be very careful when it came to clock naming; simply using
"oscillator" actually mangled the "refclk" on the SoC, which had a nice
side effect of confusing the watchdog timer. Sweet times.
Another funny point were the interrupts. The Mikrobus INT line is
actually pulled *down* by the SoC. The only accessible GPIOs with a
pull-up are J18 (unpopulated) and the UART's TX. Let's just reconfigure
MPP25 (formerly UART TX) for interrupts; this involves the pinctrl
dance, too.
Change-Id: I8a0adb3d15586797ffe6d95fda2365df87ba9e36
diff --git a/board/czechlight/clearfog/czechlight-clearfog.dts b/board/czechlight/clearfog/czechlight-clearfog.dts
index 9a4c0e5..83fb83b 100644
--- a/board/czechlight/clearfog/czechlight-clearfog.dts
+++ b/board/czechlight/clearfog/czechlight-clearfog.dts
@@ -3,3 +3,54 @@
&w25q32 {
status = "okay";
};
+
+/ {
+ clocks {
+ spi_uart_clk: osc_max14830 {
+ compatible = "fixed-clock";
+ #clock-cells = <0>;
+ clock-frequency = <3686400>;
+ };
+ };
+};
+
+&uart1_pins {
+ status = "disabled";
+};
+
+&uart1 {
+ status = "disabled";
+};
+
+&pinctrl {
+ hack_pins: hack_pins {
+ marvell,pins = "mpp25";
+ marvell,function = "gpio";
+ };
+};
+
+&gpio0 {
+ mikrobus_uart_tx {
+ gpio-hog;
+ /* Mark this as "active high", i.e. "1 is 1", so that the interrupts act on the falling edge */
+ gpios = <25 GPIO_ACTIVE_HIGH>;
+ input;
+ line-name = "SPI-int";
+ };
+};
+
+&spi1 {
+ max14830: max14830@2 {
+ compatible = "maxim,max14830";
+ reg = <2>;
+ clocks = <&spi_uart_clk>;
+ clock-names = "xtal";
+ interrupt-parent = <&gpio0>;
+ interrupts = <25 IRQ_TYPE_EDGE_FALLING>;
+ pinctrl-0 = <&hack_pins>;
+ pinctrl-names = "default";
+ gpio-controller;
+ #gpio-cells = <2>;
+ spi-max-frequency = <26000000>;
+ };
+};
diff --git a/board/czechlight/clearfog/linux.fragment b/board/czechlight/clearfog/linux.fragment
index 2ccbf53..b2db091 100644
--- a/board/czechlight/clearfog/linux.fragment
+++ b/board/czechlight/clearfog/linux.fragment
@@ -11,3 +11,6 @@
# PMBus for the PSUs
CONFIG_PMBUS=y
CONFIG_SENSORS_PMBUS=y
+
+# SPI-to-Quad-UART
+CONFIG_SERIAL_MAX310X=y