38 lines
1.2 KiB
Plaintext
38 lines
1.2 KiB
Plaintext
GPIO-based Sysinfo device
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This binding describes several GPIOs which specify a board revision. Each GPIO
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forms a digit in a ternary revision number. This revision is then mapped to a
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name using the revisions and names properties.
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Each GPIO may be floating, pulled-up, or pulled-down, mapping to digits 2, 1,
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and 0, respectively. The first GPIO forms the least-significant digit of the
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revision. For example, consider the property
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gpios = <&gpio 0>, <&gpio 1>, <&gpio 2>;
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If GPIO 0 is pulled-up, GPIO 1 is pulled-down, and GPIO 2 is floating, then the
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revision would be
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0t201 = 2*9 + 0*3 + 1*3 = 19
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If instead GPIO 0 is floating, GPIO 1 is pulled-up, and GPIO 2 is pulled-down,
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then the revision would be
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0t012 = 0*9 + 1*3 + 2*1 = 5
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Required properties:
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- compatible: should be "gpio-sysinfo".
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- gpios: should be a list of gpios forming the revision number,
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least-significant-digit first
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- revisions: a list of known revisions; any revisions not present will have the
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name "unknown"
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- names: the name of each revision in revisions
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Example:
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sysinfo {
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compatible = "gpio-sysinfo";
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gpios = <&gpio_a 15>, <&gpio_a 16>, <&gpio_a 17>;
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revisions = <19>, <5>;
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names = "rev_a", "foo";
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};
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