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devicetree: re-work DT_INST_FOREACH()

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Due to the use of UTIL_EVAL*() macros, the UTIL_LISTIFY() macro used
by DT_INST_FOREACH(foo) can cause long build errors when there is a
build error in the expansion for "foo". More than a thousand lines of
build error output have been observed for an error in a single line of
faulty C.

To improve the situation, re-work the implementation details so the
errors are a bit shorter and easier to read. The use of COND_CODE_1
still makes the error messages quite long, due to GCC generating notes
for various intermediate expansions (__DEBRACKET,
__GET_ARG_2_DEBRACKET, __COND_CODE, Z_COND_CODE_1, COND_CODE1), but
it's better than the long list of UTIL_EVAL notes.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>
This commit is contained in:
Martí Bolívar 2020-04-06 15:13:53 -07:00 • committed by Kumar Gala
commit 63d5529a0d
4 changed files with 43 additions and 5 deletions
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4
doc/guides/dts/macros.bnf
View file

@ -125,6 +125,10 @@ prop-suf = 1*( "_" gen-name ["_" dt-name] )
other-macro = %s"DT_N_" alternate-id
; Total count of enabled instances of a compatible.
other-macro =/ %s"DT_N_INST_" dt-name %s"_NUM"
; These are used internally by DT_INST_FOREACH, which iterates over
; each enabled instance of a compatible.
other-macro =/ %s"DT_FOREACH_INST_" dt-name
other-macro =/ %s"DT_FOREACH_IMPL_" DIGIT
; E.g.: #define DT_CHOSEN_zephyr_flash
other-macro =/ %s"DT_CHOSEN_" dt-name
; Declares that a compatible has at least one node on a bus.

5
include/devicetree.h
View file

@ -1389,7 +1389,8 @@
* Has to accept instance_number as only parameter.
*/
#define DT_INST_FOREACH(inst_expr) \
UTIL_LISTIFY(DT_NUM_INST(DT_DRV_COMPAT), DT_CALL_WITH_ARG, inst_expr)
COND_CODE_1(DT_HAS_COMPAT(DT_DRV_COMPAT), \
(UTIL_CAT(DT_FOREACH_INST_, DT_DRV_COMPAT)(inst_expr)), ())
/**
* @brief Does a DT_DRV_COMPAT instance have a property?
@ -1489,7 +1490,5 @@
#define DT_DASH(...) MACRO_MAP_CAT(DT_DASH_PREFIX, __VA_ARGS__)
/** @internal helper for DT_DASH(): prepends _ to a name */
#define DT_DASH_PREFIX(name) _##name
/** @internal DT_INST_FOREACH helper */
#define DT_CALL_WITH_ARG(arg, expr) expr(arg);
#endif /* DEVICETREE_H */

19
scripts/dts/gen_defines.py
View file

@ -525,9 +525,24 @@ def write_global_compat_info(edt):
if bus is not None and bus not in compat2buses[compat]:
compat2buses[compat].append(bus)
out_comment("Number of enabled instances of each compatible\n")
out_comment("Helpers for calling a macro/function a fixed number of times"
"\n")
for numinsts in range(1, max(compat2numinst.values(), default=0) + 1):
out_define(f"DT_FOREACH_IMPL_{numinsts}(fn)",
" ".join([f"fn({i});" for i in range(numinsts)]))
out_comment("Macros for enabled instances of each compatible\n")
n_inst_macros = {}
for_each_macros = {}
for compat, numinst in compat2numinst.items():
out_define(f"DT_N_INST_{str2ident(compat)}_NUM", numinst)
ident = str2ident(compat)
n_inst_macros[f"DT_N_INST_{ident}_NUM"] = numinst
for_each_macros[f"DT_FOREACH_INST_{ident}(fn)"] = \
f"DT_FOREACH_IMPL_{numinst}(fn)"
for macro, value in n_inst_macros.items():
out_define(macro, value)
for macro, value in for_each_macros.items():
out_define(macro, value)
out_comment("Bus information for enabled nodes of each compatible\n")
for compat, buses in compat2buses.items():

20
tests/lib/devicetree/src/main.c
View file

@ -1022,6 +1022,7 @@ static void test_devices(void)
struct device *dev0;
struct device *dev1;
struct device *dev_abcd;
unsigned int val;
zassert_true(DT_HAS_NODE(INST(0)), "inst 0 device");
zassert_true(DT_HAS_NODE(INST(1)), "inst 1 device");
@ -1044,6 +1045,25 @@ static void test_devices(void)
zassert_not_null(dev_abcd, "abcd");
zassert_equal(to_info(dev_abcd)->reg_addr, 0xabcd1234, "abcd addr");
zassert_equal(to_info(dev_abcd)->reg_len, 0x500, "abcd len");
/*
* Make sure DT_INST_FOREACH can be called from functions
* using macros with side effects in the current scope.
*/
#undef SET_BIT
#define SET_BIT(i) do { unsigned int bit = BIT(i); val |= bit; } while (0)
val = 0;
DT_INST_FOREACH(SET_BIT);
zassert_equal(val, 0x3, "foreach vnd_gpio");
/*
* Make sure DT_INST_FOREACH works with 0 instances, and does
* not expand its argument at all.
*/
#undef DT_DRV_COMPAT
#define DT_DRV_COMPAT xxxx
#define BUILD_BUG_ON_EXPANSION (there is a bug in devicetree.h)
DT_INST_FOREACH(BUILD_BUG_ON_EXPANSION);
}
static void test_cs_gpios(void)