Low-Level Keypad Driver
i.MX51 EVK Linux Reference Manual
20-4
Freescale Semiconductor
20.6
Menu Configuration Options
The following Linux kernel configuration options are provided for this module. To get to these options,
use the
./ltib -c
command when located in the
<ltib dir>
. On the screen displayed, select Configure
the Kernel
and exit. When the next screen appears, select the following options to enable this module:
•
CONFIG_MXC_KEYBOARD—MXC Keypad driver used for the MXC KPP. In menuconfig this
option is available under
Device Drivers
>
Input device support
>
Keyboards
>
MXC Keypad Driver.
•
CONFIG_INPUT_EVDEV—Enabling this option creates the device node
/dev/input/event0
. In
menuconfig
,
this option is available under
Device Drivers
>
Input device support
>
Event interface.
The following source code configuration options are available for this module:
•
Matrix config—The keypad matrix can be configured for up to eight rows and eight columns. The
keypad matrix configuration can be done by changing the
rowmax
and
colmax
members in the
keypad_plat_data
structure in the platform specific file (see
).
•
Debounce delay—The user can configure the debounce delay by changing the variable
KScanRate
defined in
mxc_keyb.c.
20.7
Programming Interface
User space applications can get information about the keypad driver through the standard proc and sysfs
files such as
/proc/bus/input/devices
and the files under
/sys/class/input/event0/
.
20.8
Interrupt Requirements
lists the keypad interrupt timer requirements.
.
20.9
Device-Specific Information
shows key connections, key scan codes, and key map codes of the keys on the keypad for a
specific platform.
Table 20-2. Keypad Interrupt Timer Requirements
Parameter
Equation
Typical
Worst-Case
Key scanning interrupt
(X number of instruction/MHz)
×
64
(X/MHz)
×
64
(X/MHz)
×
64
Alarm for key polling
None
10 ms
10 ms
Table 20-3. Key Connections for Keypad
Key
Row
Column
Scancode
Linux Key Code
Platform
1
0
0
0
KEY_1
i.MX51
2
0
1
1
KEY_2
i.MX51
3
0
2
2
KEY_3
i.MX51
Summary of Contents for i.MX51 EVK
Page 1: ...Part Number 924 76374 Rev 10 11 01 11 2010 i MX51 EVK Linux Reference Manual...
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Page 118: ...Low Level Keypad Driver i MX51 EVK Linux Reference Manual 20 6 Freescale Semiconductor...
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