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device: simplify structure of handles array

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Force the inclusion of a `DEVICE_HANDLE_SEP` at the end of the
devicetree dependency section of the array. This lets us simplify the
implementation of `device_required_handles_get`, as there is only one
symbol the section ends with.

This does not use any extra ROM as the array is padded out to the
original size with `DEVICE_HANDLE_ENDS` anyway.

Also adds a description of the array format where the array is
instantiated.

Signed-off-by: Jordan Yates <jordan.yates@data61.csiro.au>
This commit is contained in:
Jordan Yates 2021-08-20 18:43:38 +10:00 • committed by Anas Nashif
commit ec331c6fe2
2 changed files with 19 additions and 3 deletions
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19
include/device.h
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@ -478,8 +478,7 @@ device_required_handles_get(const struct device *dev,
if (rv != NULL) {
size_t i = 0;
while ((rv[i] != DEVICE_HANDLE_ENDS)
&& (rv[i] != DEVICE_HANDLE_SEP)) {
while (rv[i] != DEVICE_HANDLE_SEP) {
++i;
}
*count = i;
@ -674,6 +673,22 @@ static inline bool device_is_ready(const struct device *dev)
* in a distinct pass1 section (which will be replaced by
* postprocessing).
*
* Before processing in gen_handles.py, the array format is:
* {
* DEVICE_ORDINAL (or DEVICE_HANDLE_NULL if not a devicetree node),
* List of devicetree dependency ordinals (if any),
* DEVICE_HANDLE_SEP,
* List of injected dependency ordinals (if any),
* }
*
* After processing in gen_handles.py, the format is updated to:
* {
* List of existing devicetree dependency handles (if any),
* DEVICE_HANDLE_SEP,
* List of injected dependency ordinals (if any),
* DEVICE_HANDLE_NULL padding to original length (at least one)
* }
*
* It is also (experimentally) necessary to provide explicit alignment
* on each object. Otherwise x86-64 builds will introduce padding
* between objects in the same input section in individual object

3
scripts/gen_handles.py
View file

@ -294,10 +294,11 @@ def main():
dep_paths.append(dn.path)
else:
dep_paths.append('(%s)' % dn.path)
# Force separator to signal start of injected dependencies
hdls.append(DEVICE_HANDLE_SEP)
if len(hs.ext_deps) > 0:
# TODO: map these to something smaller?
ext_paths.extend(map(str, hs.ext_deps))
hdls.append(DEVICE_HANDLE_SEP)
hdls.extend(hs.ext_deps)
# When CONFIG_USERSPACE is enabled the pre-built elf is