ramips: add support for Sercomm CPJ routers

This commit adds support for following wireless routers:
 - Rostelecom RT-FL-1 (Serсomm RT-FL-1)
 - Rostelecom S1010 (Serсomm S1010.RT)

The devices are almost identical and the only difference is one bit in the
factory image PID (thanks to Maximilian Weinmann <x1@disroot.org>
(@MaxS0niX) for the info and idea to make one PR for two devices at once).

Devices specification
---------------------
   SoC:          MediaTek MT7620A, MIPS
   RAM:          64 MB
   Flash:        16 MB SPI NOR
   Wireless 2.4: MT7620 (b/g/n, 2x2)
   Wireless 5:   MT7612EN (a/n/ac, 2x2)
   Ethernet:     5xFE (WAN, LAN1-4)
   BootLoader:   U-Boot
   Buttons:      2 (wps, reset)
   LEDs:         1 amber and 1 green status GPIO leds
                 5 green ethernet GPIO leds
                 1 green GPIO 2.4 GHz WLAN led
                 1 green PHY 5 GHz WLAN led
                 1 green unmanaged power led
   USB ports:    No
   Power:        12 VDC, 1 A
   Connector:    Barrel

OEM easy installation
---------------------
1. Remove all dots from the factory image filename (except the dot
   before file extension)
2. Upload and update the firmware via the original web interface
3. Wait until green status led stops blinking (can take several minutes)
4. Login to OpenWrt initramsfs. It's recommended to make a backup of the
   mtd partitions at this point.
4. Perform sysupgrade using the following command (or use Luci):
   sysupgrade -n sysupgrade.bin
5. Wait until green status les stops blinking (can take several minutes)
6. Mission acomplished

Return to Stock
---------------
Option 1. Restore firmware Slot1 from a backup (firmware2.bin):
   cd /tmp
   mtd -e Firmware2 write firmware2.bin Firmware2
   printf 1 | dd bs=1 seek=$((0x18007)) count=1 of=/dev/mtdblock2
   reboot

Option 2. Decrypt, ungzip and split stock firmware image into the parts,
take Slot1 parts (kernel2.bin, rootfs2.bin) and write them:
   cd /tmp
   mtd -e Kernel2 write kernel2.bin Kernel2
   mtd -e RootFS2 write rootfs2.bin RootFS2
   printf 1 | dd bs=1 seek=$((0x18007)) count=1 of=/dev/mtdblock2
   reboot
More about stock firmware decryption:
Link: https://github.com/Psychotropos/sercomm_fwutils/

Debricking
----------
Use sercomm-recovery tool. You can use "ALL" mtd partition backup as a
recovery image.
Link: https://github.com/danitool/sercomm-recovery

MAC addresses
-------------
+---------+-------------------+-----------+
|         | MAC               | Algorithm |
+---------+-------------------+-----------+
| label   | 48:3e:xx:xx:xx:1e | label     |
| LAN     | 48:3e:xx:xx:xx:1e | label     |
| WAN     | 48:3e:xx:xx:xx:28 | label+10  |
| WLAN 2g | 48:3e:xx:xx:xx:20 | label+2   |
| WLAN 5g | 48:3e:xx:xx:xx:24 | label+6   |
+---------+-------------------+-----------+

Co-authored-by: Vadzim Vabishchevich <bestmc2009@gmail.com>
Signed-off-by: Mikhail Zhilkin <csharper2005@gmail.com>

2 files changed, 85 insertions, 0 deletions

diff --git a/target/linux/ramips/image/common-sercomm.mk b/target/linux/ramips/image/common-sercomm.mk
index 182f2251ba7..09870109112 100644
--- a/target/linux/ramips/image/common-sercomm.mk
+++ b/target/linux/ramips/image/common-sercomm.mk
@@ -23,6 +23,35 @@ define Build/sercomm-crypto
 	rm -f $@.enc $@.key
 endef
 
+define Build/sercomm-factory-cpj
+	dd bs=$$((0x1fff00)) count=1 if=$@ of=$@.kernel conv=notrunc \
+		2>/dev/null
+	dd bs=$$((0x1fff00)) skip=1 if=$@ of=$@.rootfs1 conv=notrunc \
+		2>/dev/null
+	cp $@.rootfs1 $@.rootfs2
+	$(TOPDIR)/scripts/sercomm-kernel-header.py \
+		--kernel-image $@.kernel \
+		--kernel-offset $(SERCOMM_KERNEL_OFFSET) \
+		--rootfs-image $@.rootfs1 \
+		--rootfs-offset $(SERCOMM_ROOTFS_OFFSET) \
+		--output-header $@.header1
+	$(TOPDIR)/scripts/sercomm-kernel-header.py \
+		--kernel-image $@.kernel \
+		--kernel-offset $(SERCOMM_KERNEL2_OFFSET) \
+		--rootfs-image $@.rootfs2 \
+		--rootfs-offset $(SERCOMM_ROOTFS2_OFFSET) \
+		--output-header $@.header2
+	cat $@.header1 $@.kernel > $@.kernel1
+	cat $@.header2 $@.kernel > $@.kernel2
+	rm $@.header1 $@.header2 $@.kernel
+	$(call Build/sercomm-part-tag-common,kernel $@.kernel1)
+	$(call Build/sercomm-part-tag-common,kernel2 $@.kernel2)
+	$(call Build/sercomm-part-tag-common,rootfs $@.rootfs1)
+	$(call Build/sercomm-part-tag-common,rootfs2 $@.rootfs2)
+	cat $@.kernel2 $@.rootfs2 $@.kernel1 $@.rootfs1 > $@
+	rm $@.kernel1 $@.rootfs1 $@.kernel2 $@.rootfs2
+endef
+
 define Build/sercomm-factory-cqr
 	$(TOPDIR)/scripts/sercomm-pid.py \
 		--hw-version $(SERCOMM_HWVER) \
@@ -117,12 +146,46 @@ define Build/sercomm-reset-slot1-chksum
 		dd of=$@ seek=$$((0x118)) bs=1 conv=notrunc 2>/dev/null
 endef
 
+define Build/sercomm-sysupgrade-cpj
+	dd bs=$$((0x1fff00)) count=1 if=$@ of=$@.kernel conv=notrunc \
+		2>/dev/null
+	dd bs=$$((0x1fff00)) skip=1 if=$@ of=$@.rootfs conv=notrunc \
+		2>/dev/null
+	$(TOPDIR)/scripts/sercomm-kernel-header.py \
+		--kernel-image $@.kernel \
+		--kernel-offset $(SERCOMM_KERNEL_OFFSET) \
+		--rootfs-image $@.rootfs \
+		--rootfs-offset $(SERCOMM_ROOTFS_OFFSET) \
+		--output-header $@.header
+	cat $@.header $@.kernel $@.rootfs > $@
+	rm $@.header $@.kernel $@.rootfs
+endef
+
 define Device/sercomm
   $(Device/nand)
   LOADER_TYPE := bin
   IMAGES += factory.img
 endef
 
+define Device/sercomm_cpj
+  SOC := mt7620a
+  DEVICE_VENDOR := Rostelecom
+  DEVICE_ALT0_VENDOR := Sercomm
+  IMAGE_SIZE := 7743k
+  SERCOMM_HWID := CPJ
+  SERCOMM_HWVER := 10000
+  SERCOMM_SWVER := 1001
+  SERCOMM_KERNEL_OFFSET := 0x70100
+  SERCOMM_ROOTFS_OFFSET := 0x270000
+  SERCOMM_KERNEL2_OFFSET := 0x800100
+  SERCOMM_ROOTFS2_OFFSET := 0xa00000
+  IMAGE/sysupgrade.bin := append-kernel | append-rootfs | \
+	sercomm-sysupgrade-cpj | pad-rootfs | check-size | \
+	append-metadata
+  ARTIFACTS := initramfs-factory.img
+  DEVICE_PACKAGES := kmod-mt76x2
+endef
+
 define Device/sercomm_cxx_dxx
   $(Device/sercomm)
   KERNEL_SIZE := 6144k
diff --git a/target/linux/ramips/image/mt7620.mk b/target/linux/ramips/image/mt7620.mk
index f85f3c8521e..883aacabe06 100644
--- a/target/linux/ramips/image/mt7620.mk
+++ b/target/linux/ramips/image/mt7620.mk
@@ -2,6 +2,7 @@
 # MT7620A Profiles
 #
 
+include ./common-sercomm.mk
 include ./common-tp-link.mk
 
 DEVICE_VARS += DLINK_ROM_ID DLINK_FAMILY_MEMBER DLINK_FIRMWARE_SIZE DLINK_IMAGE_OFFSET
@@ -1102,6 +1103,27 @@ define Device/ravpower_rp-wd03
 endef
 TARGET_DEVICES += ravpower_rp-wd03
 
+define Device/rostelecom_rt-fl-1
+  $(Device/sercomm_cpj)
+  DEVICE_MODEL := RT-FL-1
+  DEVICE_ALT0_MODEL := RT-FL-1
+  ARTIFACT/initramfs-factory.img := \
+	append-image-stage initramfs-kernel.bin | check-size | \
+	sercomm-factory-cpj | gzip | sercomm-payload | \
+	sercomm-pid-setbit 0x11 | sercomm-crypto
+endef
+TARGET_DEVICES += rostelecom_rt-fl-1
+
+define Device/rostelecom_s1010
+  $(Device/sercomm_cpj)
+  DEVICE_MODEL := S1010
+  DEVICE_ALT0_MODEL := S1010.RT
+  ARTIFACT/initramfs-factory.img := \
+	append-image-stage initramfs-kernel.bin | check-size | \
+	sercomm-factory-cpj | gzip | sercomm-payload | sercomm-crypto
+endef
+TARGET_DEVICES += rostelecom_s1010
+
 define Device/sanlinking_d240
   SOC := mt7620a
   IMAGE_SIZE := 16064k