ramips: mt7621: create DTSI for Xiaomi NAND devices

This creates a DTSI for Xiaomi devices with 128M NAND.

This allows to consolidate the partitions and a few other nodes for
AC2100 family and Mi Router 3G.

Note that the Mi Router 3 Pro has 256M NAND and differently sized
partitions.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

1 files changed, 109 insertions, 0 deletions

diff --git a/target/linux/ramips/dts/mt7621_xiaomi_nand_128m.dtsi b/target/linux/ramips/dts/mt7621_xiaomi_nand_128m.dtsi
new file mode 100644
index 0000000000..12e6bccc2e
--- /dev/null
+++ b/target/linux/ramips/dts/mt7621_xiaomi_nand_128m.dtsi
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+
+#include "mt7621.dtsi"
+
+#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/input/input.h>
+
+/ {
+	chosen {
+		bootargs = "console=ttyS0,115200n8";
+	};
+
+	keys: keys {
+		compatible = "gpio-keys";
+
+		reset {
+			label = "reset";
+			gpios = <&gpio 18 GPIO_ACTIVE_LOW>;
+			linux,code = <KEY_RESTART>;
+		};
+	};
+};
+
+&nand {
+	status = "okay";
+
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		partition@0 {
+			label = "Bootloader";
+			reg = <0x0 0x80000>;
+			read-only;
+		};
+
+		partition@80000 {
+			label = "Config";
+			reg = <0x80000 0x40000>;
+		};
+
+		partition@c0000 {
+			label = "Bdata";
+			reg = <0xc0000 0x40000>;
+			read-only;
+		};
+
+		factory: partition@100000 {
+			label = "factory";
+			reg = <0x100000 0x40000>;
+			read-only;
+		};
+
+		partition@140000 {
+			label = "crash";
+			reg = <0x140000 0x40000>;
+		};
+
+		partition@180000 {
+			label = "crash_syslog";
+			reg = <0x180000 0x40000>;
+		};
+
+		partition@1c0000 {
+			label = "reserved0";
+			reg = <0x1c0000 0x40000>;
+			read-only;
+		};
+
+		/* uboot expects to find kernels at 0x200000 & 0x600000
+		 * referred to as system 1 & system 2 respectively.
+		 * a kernel is considered suitable for handing control over
+		 * if its linux magic number exists & uImage CRC are correct.
+		 * If either of those conditions fail, a matching sys'n'_fail flag
+		 * is set in uboot env & a restart performed in the hope that the
+		 * alternate kernel is okay.
+		 * if neither kernel checksums ok and both are marked failed, system 2
+		 * is booted anyway.
+		 *
+		 * Note uboot's tftp flash install writes the transferred
+		 * image to both kernel partitions.
+		 */
+
+		/* We keep stock xiaomi firmware (kernel0) here */
+		partition@200000 {
+			label = "kernel_stock";
+			reg = <0x200000 0x400000>;
+		};
+
+		partition@600000 {
+			label = "kernel";
+			reg = <0x600000 0x400000>;
+		};
+
+		/* ubi partition is the result of squashing
+		 * next consecutive stock partitions:
+		 * - rootfs0 (rootfs partition for stock kernel0),
+		 * - rootfs1 (rootfs partition for stock failsafe kernel1),
+		 * - overlay (used as ubi overlay in stock fw)
+		 * resulting 117,5MiB space for packages.
+		 */
+
+		partition@a00000 {
+			label = "ubi";
+			reg = <0xa00000 0x7580000>;
+		};
+	};
+};