[Android-Frameworks] Improvement of USB Mass Storage_android 6 usb mass storage-优快云博客

本文介绍了一个针对UMS机制的改进方案，通过动态调整LUN数量来实现不同模式下的USB存储功能，包括双盘符和单盘符模式。

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PURPOSE: 改造ums lun机制，实现动态增加

FILE : android.c

FUNCTION: mass_storage_function_init

CONTEXT:

LINE: 68

// add by leon _zhang 20130117 start

static int ums_lun_counter = 0;

// add by leon _zhang 20130117 end

LINE: 578

-----------------------------------start-------------------------------------------------

// add by leon_zhang 20120117 start

if (ums_lun_counter <= 1) {

ums_lun_counter = 0;

config-> fsg. nluns = 2;

config-> fsg. luns[0].removable = 1;

config-> fsg. luns[1].removable = 1;

config-> fsg. luns[0].cdrom = 0;

config-> fsg. luns[1].cdrom = 0;

common = fsg_common_init(NULL, cdev, &config-> fsg);

if (IS_ERR(common)) {

kfree(config);

return PTR_ERR(common);

}

err = sysfs_create_link(&f-> dev-> kobj,

&common-> luns[0].dev.kobj,

"lun0");

err = sysfs_create_link(&f-> dev-> kobj,

&common-> luns[1].dev.kobj,

"lun1");

} else if (ums_lun_counter == 2) {

ums_lun_counter = 0;

config-> fsg. nluns = 1;

config-> fsg. luns[0].removable = 1;

config-> fsg. luns[0].cdrom = 0;

common = fsg_common_init(NULL, cdev, &config-> fsg);

if (IS_ERR(common)) {

kfree(config);

return PTR_ERR(common);

}

err = sysfs_create_link(&f-> dev-> kobj,

&common-> luns[0].dev.kobj,

"lun0");

}

// add by leon_zhang 20130117 end

-----------------------------------------end-------------------------------------------------------

LINE: 891

// add by leon _zhang 20130117 start

if(++ums_lun_counter > 2) {

ums_lun_counter = 0;

pr_err( "android_usb: ums_lun_counter out of ground '%d'" , ums_lun_counter);

}

// add by leon _zhang 20130117 end

LINE: 958

// add by leon _zhang 20120117 start

ums_lun_counter = 0;

// add by leon _zhang 20120117 end

PURPOSE: /vendor/intel/medfield/init.mfld.usb.rc

FILE : /vendor/intel/medfield/init.mfld.usb.rc

LINE : 88 & 115

CONTEXT:

--------------------------------start--------------------------------

# UMS improvement

on property:sys.usb.config=mass_storage, adb,single

write / sys/class/android_usb/android0/enable 0

# Intel PID/VID for UMS + ADB mode

write / sys/class/android_usb/android0/idVendor 0x8087

write / sys/class/android_usb/android0/idProduct 0x09f2

write / sys/class/android_usb/android0/iProduct "Android-Phone"

write /sys/class/android_usb/android0/functions $sys.usb.config

write /sys/class/android_usb/android0/enable 1

start adbd

setprop sys.usb.state $sys.usb.config

# UMS improvement

on property:sys.usb.config=mass_storage,single

write / sys/class/android_usb/android0/enable 0

# Intel PID/VID for UMS + ADB mode

write / sys/class/android_usb/android0/idVendor 0x8087

write / sys/class/android_usb/android0/idProduct 0x09f2

write / sys/class/android_usb/android0/iProduct "Android-Phone"

write / sys/class/android_usb/android0/functions $sys.usb.config

write / sys/class/android_usb/android0/enable 1

start adbd

setprop sys.usb.state $sys.usb.config

---------------------------------end---------------------------------

Verify:

getprop sys.usb.config

- result:

setprop sys.usb.config mass_storage,adb

- PC端出现两个盘符
- result: fail

setprop sys.usb.config mass_storage,adb,single

- PC端出现一个盘符
- result: fail

Analysis:

加入print，观察计数器变化
熟悉android.c运行流程