Skip to content

0176_USB_gadget_serial_configfs.md

Latest commit

 

History

History
113 lines (89 loc) · 3.05 KB

0176_USB_gadget_serial_configfs.md

File metadata and controls

113 lines (89 loc) · 3.05 KB

USB gadget serial configfs

分析Android USB gadget串口配置

参考文档

configfs相关配置

configfs

  • mount | grep configfs 
    none on /config type configfs (rw,nosuid,nodev,noexec,relatime)

usb配置

  • device/mediatek/<soc chip>/init.<soc chip>.usb.rc 
    # ...省略

on boot
    # ...省略
    setprop vendor.usb.acm_port0 0
    setprop vendor.usb.acm_port1 ""
    # ...省略

# ...省略

on property:sys.usb.ffs.ready=1 && property:sys.usb.config=adb && \
property:vendor.usb.acm_enable=1 && property:sys.usb.configfs=1
    write /config/usb_gadget/g1/configs/b.1/strings/0x409/configuration "adb_acm"
    write /config/usb_gadget/g1/idProduct ${vendor.usb.pid}
    write /sys/devices/platform/mt_usb/saving 1
    symlink /config/usb_gadget/g1/functions/ffs.adb /config/usb_gadget/g1/configs/b.1/f1
    symlink /config/usb_gadget/g1/functions/acm.gs${vendor.usb.acm_port0} /config/usb_gadget/g1/configs/b.1/f2
    symlink /config/usb_gadget/g1/functions/acm.gs${vendor.usb.acm_port1} /config/usb_gadget/g1/configs/b.1/f3
    write /config/usb_gadget/g1/UDC ${vendor.usb.controller}
    setprop sys.usb.state ${sys.usb.config}

# ...省略
  • getprop | grep usb

UDC

  • getprop vendor.usb.controller 
    musb-hdrc
  • ls -al /sys/class/udc/musb-hdrc 
    lrwxrwxrwx 1 root root 0 2000-01-07 09:06 /sys/class/udc/musb-hdrc -> ../../devices/platform/mt_usb/musb-hdrc/udc/musb-hdrc

functions

  • ls -1 /config/usb_gadget/g1/functions 
    accessory.gs2
acm.gs0
acm.gs1
acm.gs2
acm.gs3
audio_source.gs3
ffs.adb
hid.gs0
mass_storage.usb0
midi.gs5
mtp.gs0
ptp.gs1
via_atc.gs0
via_ets.gs0
via_modem.gs0

configs

  • ls -1 /config/usb_gadget/g1/configs/b.1 
    -rw-r--r-- 1 root root 4096 2000-01-07 07:21 MaxPower
-rw-r--r-- 1 root root 4096 2000-01-07 08:42 bmAttributes
lrwxrwxrwx 1 root root    0 2000-01-07 07:27 f1 -> ../../../../usb_gadget/g1/functions/ffs.adb
lrwxrwxrwx 1 root root    0 2000-01-07 07:27 f2 -> ../../../../usb_gadget/g1/functions/acm.gs2
drwxr-xr-x 3 root root    0 2000-01-07 07:21 strings

functions与configs关系

  • functions定义设备；
  • configs通过软链接来绑定设备使设备生效；
symlink /config/usb_gadget/g1/functions/ffs.adb /config/usb_gadget/g1/configs/b.1/f1
symlink /config/usb_gadget/g1/functions/acm.gs${vendor.usb.acm_port0} /config/usb_gadget/g1/configs/b.1/f2

Android相关配置

  • 参考文档
  • source
    • kernel-4.9/drivers/usb/gadget/android.c
  • init.rc
    • system/core/rootdir/init.usb.rc
  • sys节点
    • /sys/class/android_usb/android0