ARM: dts: Add Bluetooth nodes for Raspberry Pi

Add device tree nodes for Bluetooth on supported Raspberry Pi boards.
It's disabled by default and can be enabled by `krnbt=on` dtparam. It's
an alternative way of configuring Bluetooth, as compared to hciattach or
btattach. When the dtparam is enabled, the Bluetooth driver is probed
automatically and doesn't require any additional bring-up scripts.

Note that Raspberry Pi 3 B rev 1.2 doesn't have the required hardware
flow control pins of UART0 connected to the Bluetooth module, so the
user should decrease the baudrate by passing `krnbt_baudrate=921600`
dtparam to make it more stable. It resembles the behavior of the btuart
script from Raspbian.

The miniuart-bt overlay was modified to support Bluetooth probing with
device tree, too. It's disabled by default and can be enabled by
`krnbt=on` parameter of the miniuart-bt overlay.

Signed-off-by: Maxim Mikityanskiy <[email protected]>

Author: gentoo-root

arch/arm/boot/dts/bcm2708-rpi-bt.dtsi

@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+
+&uart0 {
+	bt: bluetooth {
+		compatible = "brcm,bcm43438-bt";
+		max-speed = <3000000>;
+		shutdown-gpios = <&gpio 45 GPIO_ACTIVE_HIGH>;
+		status = "disabled";
+	};
+};
+
+&uart1 {
+	minibt: bluetooth {
+		compatible = "brcm,bcm43438-bt";
+		max-speed = <460800>;
+		shutdown-gpios = <&gpio 45 GPIO_ACTIVE_HIGH>;
+		status = "disabled";
+	};
+};
+
+/ {
+	__overrides__ {
+		krnbt = <&bt>,"status";
+		krnbt_baudrate = <&bt>,"max-speed:0";
+	};
+};

arch/arm/boot/dts/bcm2708-rpi-zero-w.dts

@@ -4,6 +4,7 @@
 #include "bcm2708-rpi.dtsi"
 #include "bcm283x-rpi-csi1-2lane.dtsi"
 #include "bcm283x-rpi-i2c0mux_0_28.dtsi"
+#include "bcm2708-rpi-bt.dtsi"
 
 / {
 	compatible = "raspberrypi,model-zero-w", "brcm,bcm2835";

arch/arm/boot/dts/bcm2710-rpi-3-b-plus.dts

@@ -5,6 +5,7 @@
 #include "bcm283x-rpi-lan7515.dtsi"
 #include "bcm283x-rpi-csi1-2lane.dtsi"
 #include "bcm283x-rpi-i2c0mux_0_44.dtsi"
+#include "bcm271x-rpi-bt.dtsi"
 
 / {
 	compatible = "raspberrypi,3-model-b-plus", "brcm,bcm2837";

arch/arm/boot/dts/bcm2710-rpi-3-b.dts

@@ -5,6 +5,7 @@
 #include "bcm283x-rpi-smsc9514.dtsi"
 #include "bcm283x-rpi-csi1-2lane.dtsi"
 #include "bcm283x-rpi-i2c0mux_0_44.dtsi"
+#include "bcm271x-rpi-bt.dtsi"
 
 / {
 	compatible = "raspberrypi,3-model-b", "brcm,bcm2837";

arch/arm/boot/dts/bcm2711-rpi-4-b.dts

@@ -219,6 +219,7 @@
 // Downstream rpi- changes
 
 #include "bcm270x.dtsi"
+#include "bcm271x-rpi-bt.dtsi"
 
 / {
 	soc {
@@ -287,8 +288,6 @@
 &uart0 {
 	pinctrl-0 = <&uart0_pins &bt_pins>;
 	status = "okay";
-
-	/delete-node/ bluetooth;
 };
 
 &uart1 {

arch/arm/boot/dts/bcm271x-rpi-bt.dtsi

@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+
+&uart0 {
+	bt: bluetooth {
+		compatible = "brcm,bcm43438-bt";
+		max-speed = <3000000>;
+		shutdown-gpios = <&expgpio 0 GPIO_ACTIVE_HIGH>;
+		status = "disabled";
+	};
+};
+
+&uart1 {
+	minibt: bluetooth {
+		compatible = "brcm,bcm43438-bt";
+		max-speed = <460800>;
+		shutdown-gpios = <&expgpio 0 GPIO_ACTIVE_HIGH>;
+		status = "disabled";
+	};
+};
+
+/ {
+	__overrides__ {
+		krnbt = <&bt>,"status";
+		krnbt_baudrate = <&bt>,"max-speed:0";
+	};
+};

arch/arm/boot/dts/overlays/README

@@ -162,6 +162,13 @@ Params:
         i2s                     Set to "on" to enable the i2s interface
                                 (default "off")
 
+        krnbt                   Set to "on" to enable autoprobing of Bluetooth
+                                driver without need of hciattach/btattach
+                                (default "off")
+
+        krnbt_baudrate          Set the baudrate of the PL011 UART when used
+                                with krnbt=on
+
         spi                     Set to "on" to enable the spi interfaces
                                 (default "off")
 
@@ -1748,8 +1755,9 @@ Info:   Switch the onboard Bluetooth function on Pi 3B, 3B+, 3A+, 4B and Zero W
         in which case use /dev/serial1 instead because it will always be
         correct. Furthermore, you must also set core_freq and core_freq_min to
         the same value in config.txt or the miniuart will not work.
-Load:   dtoverlay=miniuart-bt
-Params: <None>
+Load:   dtoverlay=miniuart-bt,<param>=<val>
+Params: krnbt                   Set to "on" to enable autoprobing of Bluetooth
+                                driver without need of hciattach/btattach
 
 
 Name:   mmc

arch/arm/boot/dts/overlays/disable-bt-overlay.dts

@@ -8,6 +8,8 @@
        sudo systemctl disable hciuart
 */
 
+#include <dt-bindings/gpio/gpio.h>
+
 /{
 	compatible = "brcm,bcm2835";
 
@@ -28,6 +30,13 @@
 	};
 
 	fragment@2 {
+		target = <&bt>;
+		__overlay__ {
+			status = "disabled";
+		};
+	};
+
+	fragment@3 {
 		target = <&uart0_pins>;
 		__overlay__ {
 			brcm,pins;
@@ -36,7 +45,7 @@
 		};
 	};
 
-	fragment@3 {
+	fragment@4 {
 		target = <&bt_pins>;
 		__overlay__ {
 			brcm,pins;
@@ -45,7 +54,7 @@
 		};
 	};
 
-	fragment@4 {
+	fragment@5 {
 		target-path = "/aliases";
 		__overlay__ {
 			serial0 = "/soc/serial@7e201000";

arch/arm/boot/dts/overlays/miniuart-bt-overlay.dts

@@ -15,6 +15,8 @@
    this overlay is used.
 */
 
+#include <dt-bindings/gpio/gpio.h>
+
 /{
 	compatible = "brcm,bcm2835";
 
@@ -28,6 +30,13 @@
 	};
 
 	fragment@1 {
+		target = <&bt>;
+		__overlay__ {
+			status = "disabled";
+		};
+	};
+
+	fragment@2 {
 		target = <&uart1>;
 		__overlay__ {
 			pinctrl-names = "default";
@@ -36,7 +45,7 @@
 		};
 	};
 
-	fragment@2 {
+	fragment@3 {
 		target = <&uart0_pins>;
 		__overlay__ {
 			brcm,pins;
@@ -45,7 +54,7 @@
 		};
 	};
 
-	fragment@3 {
+	fragment@4 {
 		target = <&uart1_pins>;
 		__overlay__ {
 			brcm,pins = <32 33>;
@@ -54,7 +63,7 @@
 		};
 	};
 
-	fragment@4 {
+	fragment@5 {
 		target = <&gpio>;
 		__overlay__ {
 			fake_bt_cts: fake_bt_cts {
@@ -64,11 +73,15 @@
 		};
 	};
 
-	fragment@5 {
+	fragment@6 {
 		target-path = "/aliases";
 		__overlay__ {
 			serial0 = "/soc/serial@7e201000";
 			serial1 = "/soc/serial@7e215040";
 		};
 	};
+
+	__overrides__ {
+		krnbt = <&minibt>,"status";
+	};
 };