Introduction

Atheros CSI tool is used for collect CSI from atheros wireless card. However, the Atheros csi tool only provide OpenWrt firmware for old routers and the new firmware does not be updated at all.

We wants to solve this problem by building the csi tool from OpenWrt source code for any new OpenWrt system. We use OpenWrt v19.07.7 as an example. The building process has been verified by TP-Link Archer C7 AC 1750 and TP-Link TL-WDR 4310 routers.

Preparation

First, you must confirm that the OpenWrt system can be successfully compiled from the source code. The build process of an original OpenWrt system can be found on the official website. If you are new for OpenWrt and want to know the details of the source code, the overview of the source code can be found here.

Patch the Source

The source code of the csi tool that can be installed to OpenWrt can be download from GitHub. Note that these files, which are organized from the GitHub of Atheros CSI tool, only contain the source code of the Atheros CSI tool. They do not contain the OpenWrt source code. So, you shoud copy these files into the OpenWrt source code.

Besides, two Makefiles should be revised. The directory of these two files is 'openwrt/package/kernel/mac80211/" (Assume that openwrt is the directory of the OpenWrt source code). The first file that need to be revised in the directory is 'openwrt/package/kernel/mac80211/Makefile'. You should add the following two codes:

$(CP) ./csi/ar9003_csi.c  $(PKG_BUILD_DIR)/drivers/net/wireless/ath/ath9k/
$(CP) ./csi/ar9003_csi.h  $(PKG_BUILD_DIR)/drivers/net/wireless/ath/ath9k/

After

echo 'compat-wireless-$(PKG_VERSION)-$(PKG_RELEASE)-$(REVISION)' > $(PKG_BUILD_DIR)/compat_version

The new content in the revised Makefile is

echo 'compat-wireless-$(PKG_VERSION)-$(PKG_RELEASE)-$(REVISION)' > $(PKG_BUILD_DIR)/compat_version
$(CP) ./csi/ar9003_csi.c  $(PKG_BUILD_DIR)/drivers/net/wireless/ath/ath9k/
$(CP) ./csi/ar9003_csi.h  $(PKG_BUILD_DIR)/drivers/net/wireless/ath/ath9k/

The second file is "openwrt/package/kernel/mac80211/ath.mk". The following part of the original file

define KernelPackage/ath9k-common
  $(call KernelPackage/mac80211/Default)
  TITLE:=Atheros 802.11n wireless devices (common code for ath9k and ath9k_htc)
  URL:=https://wireless.wiki.kernel.org/en/users/drivers/ath9k
  HIDDEN:=1
  DEPENDS+= @PCI_SUPPORT||USB_SUPPORT||TARGET_ar71xx||TARGET_ath79 +kmod-ath +@DRIVER_11N_SUPPORT +@DRIVER_11W_SUPPORT
  FILES:= \
    $(PKG_BUILD_DIR)/drivers/net/wireless/ath/ath9k/ath9k_common.ko \
    $(PKG_BUILD_DIR)/drivers/net/wireless/ath/ath9k/ath9k_hw.ko
endef

The revised content of ath.mk is

define KernelPackage/ath9k-common
  $(call KernelPackage/mac80211/Default)
  TITLE:=Atheros 802.11n wireless devices (common code for ath9k and ath9k_htc)
  URL:=https://wireless.wiki.kernel.org/en/users/drivers/ath9k
  HIDDEN:=1
  DEPENDS+= @PCI_SUPPORT||USB_SUPPORT||TARGET_ar71xx||TARGET_ath79 +kmod-ath +@DRIVER_11N_SUPPORT +@DRIVER_11W_SUPPORT
  FILES:= \
    $(PKG_BUILD_DIR)/drivers/net/wireless/ath/ath9k/ath9k_common.ko \
    $(PKG_BUILD_DIR)/drivers/net/wireless/ath/ath9k/ath9k_hw.ko \
    $(PKG_BUILD_DIR)/drivers/net/wireless/ath/ath9k/ar9003_csi.ko
endef

Build from Source and System Upgrade

The build process can follows the Atheros CSI tool Wiki.

In our case, the router have been installed an OpenWrt before, so we use sysupgrade command in the OpenWrt to upgrade the system. If you can find sendData and recvCSI commands in the terminal, the new system has been successfully installed.