ARM: dts: bcm2711: Add reserved memory template to hold firmware configuration

raspberrypi inclusion
category: feature
bugzilla: 50432

--------------------------------

RPi4's co-processor will copy the board's bootloader[1] configuration
into memory for the OS to consume. Specifically, for the bootloader
configuration and upgrade user-space routines to query it through
nvmem's sysfs interface.

Introduce a reserved-memory area template for the co-processor to edit
before booting the system so as for Linux not to overwrite that memory
and to expose it as an nvmem device.
Signed-off-by: NNicolas Saenz Julienne <nsaenzjulienne@suse.de>

[1] https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2711_bootloader_config.mdSigned-off-by: NFang Yafen <yafen@iscas.ac.cn>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

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

@@ -24,6 +24,7 @@
 		emmc2bus = &emmc2bus;
 		ethernet0 = &genet;
 		pcie0 = &pcie0;
+		blconfig = &blconfig;
 	};
 
 	leds {
@@ -215,6 +216,22 @@
 	status = "okay";
 };
 
+&rmem {
+	/*
+	 * RPi4's co-processor will copy the board's bootloader configuration
+	 * into memory for the OS to consume. It'll also update this node with
+	 * its placement information.
+	 */
+	blconfig: nvram@0 {
+		compatible = "raspberrypi,bootloader-config", "nvmem-rmem";
+		#address-cells = <1>;
+		#size-cells = <1>;
+		reg = <0x0 0x0 0x0>;
+		no-map;
+		status = "disabled";
+	};
+};
+
 /* SDHCI is used to control the SDIO for wireless */
 &sdhci {
 	#address-cells = <1>;