最終更新:2022-08-24 (水) 18:17:20 (611d)  

g_zero
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概要

  • Gadget Zero is a two-configuration device. It either sinks and sources bulk data; or it loops back a configurable number of transfers. It also implements control requests, for "chapter 9" conformance. The driver needs only two bulk-capable endpoints, so it can work on top of most device-side usb controllers. It's useful for testing, and is also a working example showing how USB "gadget drivers" can be written.
  • Make this be the first driver you try using on top of any new USB peripheral controller driver. Then you can use host-side test software, like the "usbtest" driver, to put your hardware and its driver through a basic set of functional tests.
  • Gadget Zero also works with the host-side "usb-skeleton" driver, and with many kinds of host-side test software. You may need to tweak product and vendor IDs before host software knows about this device, and arrange to select an appropriate configuration.
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.config

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実装の歴史

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Linux 3.17

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Linux 3.14

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Linux 3.9

  • ファンクションの読み込みを新しいインターフェイスに変更
  • includeをやめ、usb_get_function_instanceでファンクション(SourceSink?,Loopback)を呼び出し 
    usb_get_function_instance("SourceSink");
usb_get_function_instance("Loopback");
  • CONFIG_USB_F_SS_LB?の場合はMakefileのほうでリンク 
    f_ss_lb-y			:= f_loopback.o f_sourcesink.o
obj-$(CONFIG_USB_F_SS_LB)	+= f_ss_lb.o
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Linux 3.7

  • libcompositeが導入された
    • composite.oなどへのリンクを各モジュールでのincludeからlibcompositeへの依存に変更、下記のincludeを削除 
      #include "composite.c"
#include "usbstring.c"
#include "config.c"
#include "epautoconf.c"
  • この時点ではまだf_をincludeしている 
    • #include "f_sourcesink.c"
#include "f_loopback.c"
    obj-$(CONFIG_USB_LIBCOMPOSITE)	+= libcomposite.o
libcomposite-y			:= usbstring.o config.o epautoconf.o
libcomposite-y			+= composite.o

g_zero-y			:= zero.o
obj-$(CONFIG_USB_ZERO)		+= g_zero.o
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Linux 2.6.28

  • モジュールのリンクをMakefileではなくソースコード側のincludeで行うように修正 
    #include "composite.c"
#include "usbstring.c"
#include "config.c"
#include "epautoconf.c"

#include "f_sourcesink.c"
#include "f_loopback.c"
    g_zero-objs			:= zero.o
obj-$(CONFIG_USB_ZERO)		+= g_zero.o
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Linux 2.6.27

  • コンポジットフレームワーク追加
    • composite.oを追加、下記のファンクションを分割、Makefileでファンクションをリンク
      • f_sourcesink?
      • f_loopback?
    C_UTILS =			composite.o usbstring.o config.o epautoconf.o
g_zero-objs			:= zero.o f_sourcesink.o f_loopback.o $(C_UTILS)
obj-$(CONFIG_USB_ZERO)		+= g_zero.o
  • https://github.com/torvalds/linux/commit/097db1d034b0927056f3d9e844dc80b3ba881765
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Linux 2.5.70

  • Makefileでリンク 
    g_zero-objs			:= zero.o usbstring.o config.o epautoconf.o
obj-$(CONFIG_USB_ZERO)		+= g_zero.o
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ソースコード




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