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lib: utils/fdt: Add helpers for generic driver initialization

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Currently, each driver subsystem contains its own code for matching
drivers against the platform's devicetree blob. This bloats firmware
size because the several FDT scanning loops are almost exact copies of
each other, and is confusing because the loops do have some subtle
differences. Furthermore, the existing match algorithm is inefficient:
it scans the FDT structure separately for each driver in the list. A
faster algorithm scans the FDT blob only once, matching all drivers in
the list for each `compatible` property seen.

Add new helpers implementing this faster algorithm. Since they must
iterate through the list of drivers, the driver structure cannot be
opaque. However, since the driver list is an array of pointers, the
`struct fdt_driver` can be embedded in a subsystem-specific driver
structure if needed. These three helpers cover all existing use cases
for driver initialization within OpenSBI.

An additional benefit of centralized driver initialization is the
consistent use of fdt_node_is_enabled().

Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Samuel Holland
2024-11-11 14:02:46 -08:00
committed by Anup Patel
parent df1c100001
commit 1ccc52c427
3 changed files with 140 additions and 0 deletions
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1
lib/utils/fdt/objects.mk
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@@ -7,4 +7,5 @@
libsbiutils-objs-$(CONFIG_FDT_DOMAIN) += fdt/fdt_domain.o
libsbiutils-objs-$(CONFIG_FDT_PMU) += fdt/fdt_pmu.o
libsbiutils-objs-$(CONFIG_FDT) += fdt/fdt_helper.o
libsbiutils-objs-$(CONFIG_FDT) += fdt/fdt_driver.o
libsbiutils-objs-$(CONFIG_FDT) += fdt/fdt_fixup.o