devicetree: Prefix and Postfix helpers for enums #59786
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Added helper macros to simplify handling of enum-strings defined in the dt-bindings. With these new macros you can define C-enums and generate by parsing the devicetree the enum values. This makes the devicetree simpler to read and the implementation of device drivers more straight-forward. Signed-off-by: Matthias Gilch <[email protected]>
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@mbolivar-ampere can you take a look and update the MAINTAINER file with your new handle? |
| * @brief Get a string property's value as a token. | ||
| * | ||
| * This removes "the quotes" from a string property's value, | ||
| * converting any non-alphanumeric characters to underscores. This can | ||
| * be useful, for example, when programmatically using the value to | ||
| * form a C variable or code. |
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Please revisit the docstring. It looks like things were copy/pasted from elsewhere that don't accurately reflect the behavior of these macros.
| * and with special characters converted to underscores | ||
| */ | ||
| #define DT_STRING_TOKEN_PREFIX(node_id, prop, prefix) \ | ||
| UTIL_CAT(prefix, DT_STRING_TOKEN(node_id, prop)) |
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We use DT_CAT, not UTIL_CAT, for reasons documented at the end of the file where the DT_CAT macros are defined.
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Thanks for the review. If I were using DT_CAT I'd need to wrap these macros, because DT_STRING_TOKEN needs to expand first, which would not happen if I'd simply replaced UTIL_CAT with DT_CAT.
UTIL_CAT is already used on other occasions in this file, so I was thinking it's better to use it, instead of wrapping it.
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OK. Can you address the other comment?
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@DaGuich will you have time to look at incorporating feedback from @mbolivar-ampere ? |
MaureenHelm
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Added helper macros to simplify handling of enum-strings defined in the dt-bindings. With these new macros you can define C-enums and generate by parsing the devicetree the enum values.
This makes the devicetree simpler to read and the implementation of device drivers more straight-forward.
Enumerations with possible (device) register values are neat because the author or reviewers of a driver can easily get the meaning of different values. But this has the drawback that you're not able to directly bring these (C-enums) into the devictree. One alternative solution would be to use defines. But then you'd need to maintain (bugs?) the same value in two different locations. The solution I propose is using string-enums in the dt-bindings with a meaningful name. You could document these values in the dt-bindings.
If you implement a driver you could then parse the string as a token. But usually we are using prefixes, so we have unique enum members. Here comes the new macros of this PR into play. These macros are helping users to prefix the string tokens with the corresponding prefixes and automagically use the enum values while parsing the devicetree.
Related to: #59256
Edit: Added some background on why I've implemented the change