36 lines
1.3 KiB
Plaintext
36 lines
1.3 KiB
Plaintext
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General Purpose Input and Output
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To make MINIX more usable on embedded hardware, we need some way to access the
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GPIO features of the system on a chip. Generally System on Chips (SoC) designs
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provide some way to configure pads to perform basic Input/Output operations on
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selected ports. These ports are also usually grouped into banks. The end
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result is that you have a functional general input output block where you need
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to configure some the following functions.
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Functional Requirements
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We envision that the short term usage of the GPIO library will be both input
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and output handling. Input handling as we want to be able to listen to button
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presses and generate key events, and output handling because we want to be able
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to control LEDs.
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GPIO required functionality
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-Configure pins as input or output.
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-Configure the impedance of the pins.
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-Get or set the values of the pins (possibly in a single call).
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-Configure interrupt levels for input pins.
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-Configure debouncing of pins.
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Additional kernel requirements:
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-Manage the GPIO resources (who may access what)
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-Access the GPIO pins from within driver (for the keyboard)
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-Access the GPIO pins from within userland (for toggling LEDs)
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Usage:
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You have to manually mount the gpio fs using the following command
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# mkdir -p /gpio
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# mount -t gpio none /gpio
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