[嵌入式][OpenHarmony RK3568]（四）WIFI芯片适配

一、概述

??本文讲述RK3568上移植OpenHarmony 3.2适配WIFI以及相关内容。
??硬件芯片:海华AW-NM372S
??芯片模组:43438A1

注：芯片的具体模组可以在芯片手册上查看，一般分为Boardcom(博通)/Cypress，realtek，海思等

其中海华AW-NM372S芯片基于博通43438A1模组，常见的还有正基AP6xxx芯片，都是基于博通模组；博通已经被cypress收购

1.1 WLAN固件

??WLAN固件是相当于WLAN芯片里面的一个小系统，你可以把WLAN芯片看成一个单片机，里面需要跑代码才可以和我们的SoC进行PY交易，这份固件由原厂提供，为.bin后缀。一般名字中会包含43438A1之类的芯片模组。

注：使用另外的文件作为固件的有博通和海思，而realtek则是把固件写到了驱动中去

1.2 nvram.txt

??这个文件用给固件读取并修正一些参数，来使得wlan芯片工作在最好状态下，同样由原厂提供。
?

二、内核部分

2.1 修改设备树

??其中：
??(1)sdio_pwrseq节点用于自动上点，其中reset-gpios是用于复位，对应wlan芯片上的wreg_on引脚，这里特别需要主要电平属性，高电平复位就选择GPIO_ACTIVE_HIGH，低电平复位就GPIO_ACTIVE_LOW，根据你的板子设计来调整引脚号和引脚的电平属性；如果你的芯片还有一个引脚控制wlan芯片供电的话，需要添加power-gpios子节点**（这里笔者记得不是很清楚了，可以调试一下）**
??(2)wireless_wlan节点是wifi的适配节点，wifi_chip_type 这个属性可以被忽略，填ap-6255即可，host_wake_irq引脚根据你核心板来定义
??(3)sdmmc2对应sdio的接口的属性，这里面的节点不做过多追溯，自己看下

/ {	

	sdio_pwrseq: sdio-pwrseq {
		compatible = "mmc-pwrseq-simple";
		pinctrl-names = "default";
		pinctrl-0 = <&wifi_enable_h>;
		reset-gpios = <&gpio4 RK_PA1 GPIO_ACTIVE_LOW>;
		status = "okay";
	};

	wireless_wlan: wireless-wlan {
		compatible = "wlan-platdata";
		rockchip,grf = <&grf>;
		wifi_chip_type = "ap-6255";
		clocks = <&rk809 1>;
		clock-names = "ext_clock";

		pinctrl-names = "default";
		pinctrl-0 = <&wifi_wake_host>;

		WIFI,host_wake_irq = <&gpio4 RK_P2 GPIO_ACTIVE_HIGH>;
		status = "okay";
	};
};

&sdmmc2 {
	max-frequency = <150000000>;
	supports-sdio;
	bus-width = <4>;
	disable-wp;
	cap-sd-highspeed;
	cap-sdio-irq;
	keep-power-in-suspend;
	mmc-pwrseq = <&sdio_pwrseq>;
	non-removable;
	pinctrl-names = "default";
	pinctrl-0 = <&sdmmc2m0_bus4 &sdmmc2m0_cmd &sdmmc2m0_clk>;
	sd-uhs-sdr104;
	status = "okay";
};


&pinctrl {
	wireless-wlan {
		wifi_wake_host: wifi-wake-host {
			rockchip,pins = <4 RK_PA2 RK_FUNC_GPIO &pcfg_pull_down>;
		};
    };

	sdio-pwrseq {
		wifi_enable_h: wifi-enable-h {
			rockchip,pins = <4 RK_PA1 RK_FUNC_GPIO &pcfg_pull_up>;
		};
	};
};

2.2 内核配置部分

??这里可以去看rockchip_linux_defconfig或者rk3568_defconfig这个文件(rockchip_linux_defconfig只是rk3568_defconfig在编译内核时候的拷贝)，那么你可以看到android和openharmony的区别了，android中，wlan芯片的驱动是编译成.ko，然后再复制到系统中，在启动的时候根据SDIO中读取的PID和VID值去比对，再加载对应驱动；在openharmony中，wlan驱动模块是一开始就加载到内核中去，随着内核启动一起启动。
??android的这种做法可以同时兼容多个wlan芯片，这个我觉得openharmony可以考虑一下去改进。
??这里的CONFIG_BCMDHD_FW_PATH和CONFIG_BCMDHD_NVRAM_PATH指定了frimware的固件和nvram.txt的路径

CONFIG_WL_ROCKCHIP=y
# CONFIG_WIFI_BUILD_MODULE is not set
CONFIG_WIFI_LOAD_DRIVER_WHEN_KERNEL_BOOTUP=y
# CONFIG_WIFI_GENERATE_RANDOM_MAC_ADDR is not set
CONFIG_BCMDHD=y
CONFIG_AP6XXX_WIFI6=y
CONFIG_BCMDHD_FW_PATH="/vendor/etc/firmware/fw_bcm43438a1.bin"
CONFIG_BCMDHD_NVRAM_PATH="/vendor/etc/firmware/nvram.txt"
# CONFIG_BCMDHD_STATIC_IF is not set
# CONFIG_MAC80211_HWSIM is not set
CONFIG_USB_NET_RNDIS_WLAN=y
# CONFIG_VIRT_WIFI is not set

三、系统适配部分

??那么接下来就是搬运固件和nvram.txt即可；
??首先在device/soc/rockchip/rk3568/hardware/wifi目录下面创建属于我们芯片的目录比如nm372,
??然后把我们从原厂那里拿到的固件放进去，再修改以下内容，其中 NM372_ETC_DIR 就是我们刚才创建的目录，group(“nm372”) 中deps ohos_prebuilt_etc(“fw_bcm43438a1.bin”) 和ohos_prebuilt_etc(“nvram.txt”)，意思是nm372这个组依赖于fw_bcm43438a1.bin和nvram.txt两个编译动作。
??并且可以看到resolv.conf被我单独抽出来作为一个组，因为所有芯片都会用到这个文件，所以剥离出来。

device/soc/rockchip/rk3568/hardware/wifi/BUILD.gn

# Copyright (C) 2021 HiHope Open Source Organization .
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import("//build/ohos.gni")

AP6XXX_ETC_DIR = "//device/soc/rockchip/rk3568/hardware/wifi/ap6xxx"
NM372_ETC_DIR = "//device/soc/rockchip/rk3568/hardware/wifi/nm372"
DNS_CONFIG_DIR = "//device/soc/rockchip/rk3568/hardware/wifi"

ohos_prebuilt_etc("clm_bcm43752a2_ag.blob") {
  source = "$AP6XXX_ETC_DIR/clm_bcm43752a2_ag.blob"
  install_images = [ vendor_base_dir ]
  relative_install_dir = "firmware"
  part_name = "rockchip_products"
  install_enable = true
}

ohos_prebuilt_etc("fw_bcm43752a2_ag_apsta.bin") {
  source = "$AP6XXX_ETC_DIR/fw_bcm43752a2_ag_apsta.bin"
  install_images = [ vendor_base_dir ]
  relative_install_dir = "firmware"
  part_name = "rockchip_products"
  install_enable = true
}

ohos_prebuilt_etc("fw_bcm43752a2_ag.bin") {
  source = "$AP6XXX_ETC_DIR/fw_bcm43752a2_ag.bin"
  install_images = [ vendor_base_dir ]
  relative_install_dir = "firmware"
  part_name = "rockchip_products"
  install_enable = true
}

ohos_prebuilt_etc("nvram_ap6275s.txt") {
  source = "$AP6XXX_ETC_DIR/nvram_ap6275s.txt"
  install_images = [ vendor_base_dir ]
  relative_install_dir = "firmware"
  part_name = "rockchip_products"
  install_enable = true
}


ohos_prebuilt_etc("fw_bcm43438a1.bin") {
  source = "$NM372_ETC_DIR/fw_bcm43438a1.bin"
  install_images = [ vendor_base_dir ]
  relative_install_dir = "firmware"
  part_name = "rockchip_products"
  install_enable = true
}

ohos_prebuilt_etc("nvram.txt") {
  source = "$NM372_ETC_DIR/nvram.txt"
  install_images = [ vendor_base_dir ]
  relative_install_dir = "firmware"
  part_name = "rockchip_products"
  install_enable = true
}


ohos_prebuilt_etc("resolv.conf") {
  source = "$DNS_CONFIG_DIR/etc/resolv.conf"
  install_images = [ "system" ]
  part_name = "rockchip_products"
  install_enable = true
}



group("ap6xxx") {
  deps = [
    ":clm_bcm43752a2_ag.blob",
    ":fw_bcm43752a2_ag.bin",
    ":fw_bcm43752a2_ag_apsta.bin",
    ":nvram_ap6275s.txt",
  ]
}

group("nm372") {
  deps = [
    ":fw_bcm43438a1.bin",
    ":nvram.txt",
  ]
}

group("resolv_conf") {
  deps = [
    ":resolv.conf",
  ]
}

我们抽出一个来进行细看

ohos_prebuilt_etc("fw_bcm43438a1.bin") {
  source = "$NM372_ETC_DIR/fw_bcm43438a1.bin"  //源文件
  install_images = [ vendor_base_dir ]  //安装路径以/vendor为基础
  relative_install_dir = "firmware" //安装到/vendor/firmware下
  part_name = "rockchip_products" //rockchip_products是总的part名，可以不理会
  install_enable = true //使能安装
}

那么我们的nm372这个group又由谁制定呢？我们来看上一层的BUILD.gn，把它改成下面的形式，记得也把wifi:resolv_conf这个使能

device/soc/rockchip/rk3568/hardware/BUILD.gn

import("//build/ohos.gni")

group("hardware_group") {
  deps = [
    "//device/soc/rockchip/rk3568/hardware/gpu:mali-bifrost-g52-g2p0-ohos",
    "//device/soc/rockchip/rk3568/hardware/isp:isp",
    "//device/soc/rockchip/rk3568/hardware/mpp:mpp",
    "//device/soc/rockchip/rk3568/hardware/wifi:nm372",
    "//device/soc/rockchip/rk3568/hardware/wifi:resolv_conf",
  ]
}

由于hardware_group已经被指定编译，那么编译的时候就会顺着这个几个编译路径一直走下去，最终把我们需要的文件复制到对应的路径去。