Linux kernel space

AN4503

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DocID026411 Rev 2

Then run the command: "make modules" from <KR>.

The built hts221.ko, lps25.ko and uv.ko modules, located under <KR>/drivers/misc are then

placed in the Android filesystem with the usual procedure:

 [RAS]$ adb push [modulename].ko /system/lib/hw

They can then be installed and rendered functional:

 [RAS]$ adb shell

[Android shell]$ insmod /system/lib/hw/[modulename].ko

3.2.2

Controlling the device drivers from Linux user space

The device can be controlled from Linux user space by writing the desired settings (integer

values) to the relevant control files from the shell using the proper 'echo' command, or inside

the libs or applications.

The above mentioned files are located under

"/sys/class/input/input[x]/device/<busnum>/<i2c-address>/", where busnum is the bus

number ('4' in this test case with the PandaBoard) and the i2c-address changes according

to the device in use:

hts221 : 004f

lps25h : 005d

uvis25 : 0047

The names of these control files can be found in the corresponding .c file of the driver,

specifically in the struct “attributes”.

The most important file is the 'enable_device'. In this example, the complete path for the

lps25h in our Panda-board test environment is:

"/sys/class/input/input[x]/device/4/<4-005d/enable_device"

Configure this to '1' to set the device ON, and to '0' (zero) to set it OFF.

To set the device ON or OFF from the 'Linux user space', use the following commands:

 [Android shell]$ echo 1 > /sys/class/input/input[x]/device/<busnum>/<i2c-

address>/enable_device

 [Android shell]$ echo 0 > /sys/class/input/input[x]/device/<busnum>/<i2c-

address>/enable_device

Alternatively:

 [Android shell]$ echo 1 > /sys/bus/i2c/devices/<busnum>/<i2c-address>/enable_device

 [Android shell]$ echo 0 > /sys/bus/i2c/devices/<busnum>/<i2c-address>/enable_device

The devices can be controlled through <sysfs_interface>:

 /sys/bus/i2c/devices/<busnum>/<i2c-address>/

and other features can be set as well as ON and OFF.

For example, consider lps25h to change the FIFO setting.

Recall that the FIFO modes are: