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48 lines
1.8 KiB
Text
48 lines
1.8 KiB
Text
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The U-Boot Driver Model Project
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===============================
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Keyboard input analysis
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=======================
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Marek Vasut <marek.vasut@gmail.com>
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2012-02-20
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I) Overview
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-----------
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The keyboard drivers are most often registered with STDIO subsystem. There are
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components of the keyboard drivers though, which operate in severe ad-hoc
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manner, often being related to interrupt-driven keypress reception. This
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components will require the most sanitization of all parts of keyboard input
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subsystem.
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Otherwise, the keyboard is no different from other standard input but with the
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necessity to decode scancodes. These are decoded using tables provided by
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keyboard drivers. These tables are often driver specific.
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II) Approach
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------------
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The most problematic part is the interrupt driven keypress reception. For this,
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the buffers that are currently shared throughout the whole U-Boot would need to
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be converted into driver's private data.
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III) Analysis of in-tree drivers
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--------------------------------
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1) board/mpl/common/kbd.c
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-------------------------
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This driver is a classic STDIO driver, no problem with conversion is expected.
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Only necessary change will be to move this driver to a proper location.
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2) board/rbc823/kbd.c
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---------------------
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This driver is a classic STDIO driver, no problem with conversion is expected.
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Only necessary change will be to move this driver to a proper location.
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3) drivers/input/keyboard.c
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---------------------------
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This driver is special in many ways. Firstly because this is a universal stub
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driver for converting scancodes from i8042 and the likes. Secondly because the
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buffer is filled by various other ad-hoc implementations of keyboard input by
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using this buffer as an extern. This will need to be fixed by allowing drivers
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to pass certain routines to this driver via platform data.
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