overlays: Fix sc16is752-spi1 emulation

[1] Removed the sc16is752-spi1 overlay, replacing it with an entry in
overlay_map.dts that invokes sc16is75x-spi with specific parameters.
This does not work because it fails to configure the SPI1 interface.
Most such overlays would require the respective SPI interface to have
already been configured using one of the spi<n>-<m> overlays, but it is
not possible to do that using overlay_map, and it is unreasonable to
suddenly impose that requirement on users.

Work around that specific problem by adding an extra parameter to
sc16is75x to configure SPI1. It's not ideal, but better than a complete
dedicated overlay.

Link: #6962
Fixes: ce20a8f ("overlays: sc16is75x: Add generic SPI overlay")
Signed-off-by: Phil Elwell <phil@raspberrypi.com>

[1] commit ce20a8f ("overlays: sc16is75x: Add generic SPI overlay")

Author: pelwell

arch/arm/boot/dts/overlays/README

@@ -4543,7 +4543,7 @@ Load:   <Deprecated>
 
 Name:   sc16is752-spi1
 Info:   This overlay is now deprecated. Use
-        "dtoverlay=sc16is75x-spi,sc16is752,spi1-0,..." instead.
+        "dtoverlay=sc16is75x-spi,sc16is752,spi1-1cs,spi1-0,..." instead.
 Load:   <Deprecated>
 
 
@@ -4558,6 +4558,8 @@ Params: sc16is750               Device is a SC16IS750 UART (default on)
                                 (boolean, required)
         int_pin                 GPIO used for IRQ (default 24)
         xtal                    On-board crystal frequency (default 14745600)
+        spi1-1cs                A special case to support sc16is752-spi1. Not
+                                intended for general use.
 
 
 Name:   sdhost

arch/arm/boot/dts/overlays/overlay_map.dts

@@ -292,16 +292,12 @@
 		renamed = "sc16is75x-spi,sc16is750,spi0-0";
 	};
 
-	sc16is750-spi1 {
-		renamed = "sc16is75x-spi,sc16is750,spi1-0";
-	};
-
 	sc16is752-spi0 {
 		renamed = "sc16is75x-spi,sc16is752,spi0-0";
 	};
 
 	sc16is752-spi1 {
-		renamed = "sc16is75x-spi,sc16is752,spi1-0";
+		renamed = "sc16is75x-spi,sc16is752,spi1-1cs,spi1-0";
 	};
 
 	sdhost {

arch/arm/boot/dts/overlays/sc16is75x-spi-overlay.dts

@@ -53,14 +53,48 @@
 	fragment@3 {
 		target = <&gpio>;
 		__overlay__ {
-			sc16is75x_pins: sc16is75x_pins@24 {
+			sc16is75x_pins: sc16is75x_pins@18 {
 				brcm,pins = <24>;
 				brcm,function = <BCM2835_FSEL_GPIO_IN>;
 				brcm,pull = <BCM2835_PUD_OFF>;
 			};
 		};
 	};
 
+	fragment@4 {
+		target = <&gpio>;
+		__dormant__ {
+			spi1_pins: spi1_pins {
+				brcm,pins = <19 20 21>;
+				brcm,function = <3>; /* alt4 */
+			};
+
+			spi1_cs_pins: spi1_cs_pins {
+				brcm,pins = <18>;
+				brcm,function = <1>; /* output */
+			};
+		};
+	};
+
+	fragment@5 {
+		target = <&spi1>;
+		__dormant__ {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			pinctrl-names = "default";
+			pinctrl-0 = <&spi1_pins &spi1_cs_pins>;
+			cs-gpios = <&gpio 18 1>;
+			status = "okay";
+		};
+	};
+
+	fragment@6 {
+		target = <&aux>;
+		__dormant__ {
+			status = "okay";
+		};
+	};
+
 	__overrides__ {
 		sc16is750 = <&sc16is75x>,"compatible=nxp,sc16is750",
 			<&sc16is75x>, "name=sc16is750@0";
@@ -80,6 +114,7 @@
 		spi1-0 = <0>, "-0",
 			<&sc16is75x_frag>, "target:0=", <&spi1>,
 			<&sc16is75x_pins>, "name=sc16is75x_spi1_0_pins";
+		spi1-1cs = <0>,"+4+5+6";
 		spi1-1 = <0>, "-0",
 			<&sc16is75x_frag>, "target:0=", <&spi1>,
 			<&sc16is75x>, "reg:0=1",