ipq40xx: add support for Cisco Meraki MR20

This commit adds support for the Cisco Meraki MR20/Go GR10.

The Meraki MR20 is a Cisco 802.11ac/WiFi 5 AP with 1 Ethernet port.
It can be powered by a 12V DC barrel jack (5.5x2.5mm, center positive)
or via 802.3af POE.

The Meraki Go GR10 (codename: Maggot) is identical to the MR20
(codename: Grub), so this document will refer to both devices as the MR20.

MR20 hardware info:
* CPU: Qualcomm IPQ4029
* RAM: 256MB DDR3
* Storage: 128 MB (MX30LF1G18AC)
* Networking: 1 Gigabit Ethernet
* WiFi: QCA4019 802.11b/g/n/ac
* Serial: Internal header (J10, 2.54mm, unpopulated)

This device ships with secure boot, and cannot be flashed without
external programmers (TSOP48 NAND and I2C EEEPROM)!

Disassembly:

Remove the four rubber feet on the rear of the AP and the four
Torx T8 screws under the feet.

Using a guitar pick or similar plastic tool, insert it on the side
along the seam around the edge. Push in gently while gently lifting
the front of the housing to release the plastic retention clips.

There are 15 clips in total.

Once you have removed the plastic front (shown above already removed
so you know where the clips are), remove the 4 Philips screws holding
down the two metal WiFi antennas.

Lift the PCB gently while pushing the Ethernet port into the housing
to release it. The PCB should come free from the metal heat spreader.

The TSOP48 NAND flash (U9, Macronix/MXIC MX30LF1G18AC) is located on
the opposite side of the PCB.

To flash, you need to desolder the TSOP48 or use a 360 clip.

You also need to reprogram the I2C EEPROM (U20, Atmel 24c64).

Installation:

The dumps to flash can be found in this repository:
https://github.com/halmartin/meraki-openwrt-docs/tree/main/mr20_gr10

The device has the following flash layout (offsets with OOB data):
```
0x000000000000-0x000000100000 : "sbl1"
0x000000100000-0x000000200000 : "mibib"
0x000000200000-0x000000300000 : "bootconfig"
0x000000300000-0x000000400000 : "qsee"
0x000000400000-0x000000500000 : "qsee_alt"
0x000000500000-0x000000580000 : "cdt"
0x000000580000-0x000000600000 : "cdt_alt"
0x000000600000-0x000000680000 : "ddrparams"
0x000000700000-0x000000900000 : "u-boot"
0x000000900000-0x000000b00000 : "u-boot-backup"
0x000000b00000-0x000000b80000 : "ART"
0x000000c00000-0x000007c00000 : "ubi"
```

* Dump your original NAND (if using nanddump, include OOB data).

* Decompress `u-boot.bin.gz` dump from the GitHub repository above (dump
contains OOB data) and overwrite the `u-boot` portion of NAND from
`0x738000`-`0x948000` (length `0x210000`). Offsets here include OOB data.

* Decompress `ubi.bin.gz` dump from the GitHub repository above (dump
contains OOB data) and overwrite the `ubi` portion of NAND from
`0xc60000`-`0x8400000` (length `0x77a0000`). Offsets here include OOB data.

* Dump your original EEPROM. Change the byte at offset `0x49` to `0x1e`
(originally `0x2c` or `0x25`). Remember to re-write the EEPROM with the
modified data.
    * This can be done on Linux via the following command:
    `printf "\x1e" | dd of=/tmp/eeprom.bin bs=1 seek=$((0x49)) conv=notrunc`

**Note**: the device will not boot if you modify the board major number and
have not yet overwritten the `ubi` and `u-boot` regions of NAND.

* Resolder the NAND after overwriting the `u-boot` and `ubi` regions.

OpenWrt Installation:

* After flashing NAND and EEPROM with external programmers. Plug in an
Ethernet cable and power up the device.

* The new U-Boot build uses the space character `" "` (without quotes) to
interrupt boot.

* Interrupt U-Boot and `tftpboot` the OpenWrt initramfs image from your
tftp server
```
dhcp
setenv serverip <your_tftp>
tftpboot openwrt-ipq40xx-generic-meraki_mr20-initramfs-uImage.itb
```

* Once booted into the OpenWrt initramfs, created the `ART` ubivol with
the WiFi radio calibration from the mtd partition:
```
cat /dev/mtd10 > /tmp/ART.bin
ubiupdatevol /dev/ubi0_1 /tmp/ART.bin
```

* `scp` the `sysupgrade` image to
the device and run the normal `sysupgrade` procedure:
```
scp -O openwrt-ipq40xx-generic-meraki_mr20-squashfs-sysupgrade.bin [email protected]:/tmp/
ssh [email protected] "sysupgrade -n /tmp/openwrt-ipq40xx-generic-meraki_mr20-squashfs-sysupgrade.bin"
```

* OpenWrt should now be installed on the device.

Signed-off-by: Hal Martin <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20646
Signed-off-by: Robert Marko <[email protected]>

package/firmware/ipq-wifi/Makefile

@@ -60,6 +60,7 @@ ALLWIFIBOARDS:= \
 	linksys_spnmx56 \
 	linksys_whw03 \
 	meraki_mr30h \
+	meraki_underdog \
 	meraki_z3 \
 	netgear_lbr20 \
 	netgear_rax120v2 \
@@ -241,6 +242,7 @@ $(eval $(call generate-ipq-wifi-package,linksys_mx8500,Linksys MX8500))
 $(eval $(call generate-ipq-wifi-package,linksys_spnmx56,Linksys SPNMX56))
 $(eval $(call generate-ipq-wifi-package,linksys_whw03,Linksys WHW03))
 $(eval $(call generate-ipq-wifi-package,meraki_mr30h,Meraki MR30H))
+$(eval $(call generate-ipq-wifi-package,meraki_underdog,Meraki underdog))
 $(eval $(call generate-ipq-wifi-package,meraki_z3,Meraki Z3))
 $(eval $(call generate-ipq-wifi-package,netgear_lbr20,Netgear LBR20))
 $(eval $(call generate-ipq-wifi-package,netgear_rax120v2,Netgear RAX120v2))

target/linux/ipq40xx/base-files/etc/board.d/02_network

@@ -57,6 +57,7 @@ ipq40xx_setup_interfaces()
 	dlink,dap-2610|\
 	engenius,eap1300|\
 	extreme-networks,ws-ap3915i|\
+	meraki,mr20|\
 	meraki,mr33|\
 	meraki,mr74|\
 	mikrotik,lhgg-60ad|\

target/linux/ipq40xx/base-files/lib/upgrade/platform.sh

@@ -178,6 +178,7 @@ platform_do_upgrade() {
 	linksys,whw03)
 		platform_do_upgrade_linksys_emmc "$1"
 		;;
+	meraki,mr20|\
 	meraki,gx20|\
 	meraki,z3)
 		# DO NOT set CI_KERNPART to part.safe,

target/linux/ipq40xx/files-6.12/arch/arm/boot/dts/qcom/qcom-ipq4029-meraki-underdog.dtsi

@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Device Tree Source for Meraki devices
+ *
+ * Copyright (C) 2017 Chris Blake <[email protected]>
+ * Copyright (C) 2017 Christian Lamparter <[email protected]>
+ * Copyright (C) 2025 Hal Martin <[email protected]>
+ *
+ * Based on Cisco Meraki DTS from GPL release r25-linux-3.14-20170427
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without
+ * any warranty of any kind, whether express or implied.
+ */
+
+#include "qcom-ipq4029-meraki-common.dtsi"
+
+/ {
+	aliases {
+		led-boot = &status_green;
+		led-failsafe = &status_red;
+		led-running = &status_green;
+		led-upgrade = &power_orange;
+	};
+
+	leds {
+		compatible = "gpio-leds";
+
+		power_orange: power {
+			function = LED_FUNCTION_POWER;
+			color = <LED_COLOR_ID_ORANGE>;
+			gpios = <&tlmm 49 GPIO_ACTIVE_HIGH>;
+			panic-indicator;
+		};
+	};
+};
+
+&blsp1_i2c3 {
+	eeprom@56 {
+		compatible = "atmel,24c64";
+		pagesize = <32>;
+		reg = <0x56>;
+		read-only; /* This holds our MAC & Meraki board-data */
+
+		nvmem-layout {
+			compatible = "fixed-layout";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			mac_address: mac-address@66 {
+				compatible = "mac-base";
+				reg = <0x66 0x6>;
+				#nvmem-cell-cells = <1>;
+			};
+		};
+	};
+};
+
+&tlmm {
+	i2c_0_pins: i2c_0_pinmux {
+		function = "blsp_i2c0";
+		pins = "gpio10", "gpio11";
+		drive-strength = <16>;
+		bias-disable;
+	};
+};
+
+&mdio {
+	ethernet-phy-package@0 {
+		status = "disabled";
+	};
+};
+
+&switch {
+	/delete-property/ psgmii-ethphy;
+};
+
+&ethphy0 {
+	status = "disabled";
+};
+
+&ethphy1 {
+	status = "disabled";
+};
+
+&ethphy2 {
+	status = "disabled";
+};
+
+&ethphy3 {
+	status = "disabled";
+};
+
+&ethphy4 {
+	status = "disabled";
+};
+
+&psgmiiphy {
+	status = "disabled";
+};
+

target/linux/ipq40xx/files-6.12/arch/arm/boot/dts/qcom/qcom-ipq4029-mr20.dts

@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Device Tree Source for Meraki MR20 (Grub) / Go GR10 (Maggot)
+
+#include "qcom-ipq4029-meraki-underdog.dtsi"
+
+/ {
+	model = "Meraki MR20";
+	compatible = "meraki,mr20";
+
+	leds {
+		compatible = "gpio-leds";
+
+		status_green: led_green {
+			color = <LED_COLOR_ID_GREEN>;
+			gpios = <&tlmm 34 GPIO_ACTIVE_HIGH>;
+		};
+
+		status_blue: led_blue {
+			color = <LED_COLOR_ID_BLUE>;
+			gpios = <&tlmm 35 GPIO_ACTIVE_HIGH>;
+		};
+
+		status_red: led_red {
+			color = <LED_COLOR_ID_RED>;
+			gpios = <&tlmm 8 GPIO_ACTIVE_HIGH>;
+		};
+
+	};
+
+	soc {
+		ess_tcsr@1953000 {
+			qcom,ess-interface-select = <TCSR_ESS_PSGMII_RGMII5>;
+		};
+	};
+};
+
+&mdio {
+	ar8035: ethernet-phy@0 {
+		compatible = "ethernet-phy-ieee802.3-c22";
+		reg = <0>;
+	};
+};
+
+&swport5 {
+	status = "okay";
+	label = "lan";
+	phy-handle = <&ar8035>;
+	phy-mode = "rgmii-id";
+};
+
+&wifi0 {
+	status = "okay";
+	qcom,ath10k-calibration-variant = "Meraki-underdog";
+};
+
+&wifi1 {
+	status = "okay";
+	qcom,ath10k-calibration-variant = "Meraki-underdog";
+};

target/linux/ipq40xx/image/generic.mk

@@ -822,6 +822,14 @@ define Device/meraki_common
 	DEVICE_PACKAGES := ath10k-firmware-qca9887-ct
 endef
 
+define Device/meraki_mr20
+	$(call Device/meraki_common)
+	DEVICE_MODEL := MR20
+	DEVICE_DTS_CONFIG := config@4
+	DEVICE_PACKAGES := ipq-wifi-meraki_underdog
+endef
+TARGET_DEVICES += meraki_mr20
+
 define Device/meraki_mr30h
 	$(call Device/meraki_common)
 	DEVICE_MODEL := MR30H