From: Benedikt Niedermayr <benedikt.niedermayr@xxxxxxxxxxx>
There is currently no possibility for the gpmc to set either the
waitp-pin polarity or use the same wait-pin for different cs-regions.
While the current implementation may fullfill most usecases, it may not
be sufficient for more complex setups (e.g. FPGA/ASIC interfaces), where
more complex interfacing options where possible.
For example interfacing an ASIC which offers multiple cs-regions but
only one waitpin the current driver and dt-bindings are not sufficient.
While using the same waitpin for different cs-regions worked for older
kernels (4.14) the omap-gpmc.c driver refused to probe (-EBUSY) with
newer kernels (>5.10).
Changes since v1:
* Rebase against recent 6.0.0-rc3 kernel, but the maintainers list
stays the same!
./scripts/get_maintainer.pl drivers/memory/omap-gpmc.c
Roger Quadros <rogerq@xxxxxxxxxx> (maintainer:OMAP GENERAL PURPOSE MEMORY CONTROLLER SUPPORT)
Tony Lindgren <tony@xxxxxxxxxxx> (maintainer:OMAP GENERAL PURPOSE MEMORY CONTROLLER SUPPORT)
Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> (maintainer:MEMORY CONTROLLER DRIVERS)
linux-omap@xxxxxxxxxxxxxxx (open list:OMAP GENERAL PURPOSE MEMORY CONTROLLER SUPPORT)
linux-kernel@xxxxxxxxxxxxxxx (open list:MEMORY CONTROLLER DRIVERS)
./scripts/get_maintainer.pl Documentation/devicetree/bindings/memory-controllers/ti,gpmc-child.yaml
Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> (maintainer:MEMORY CONTROLLER DRIVERS)
Rob Herring <robh+dt@xxxxxxxxxx> (maintainer:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS)
Tony Lindgren <tony@xxxxxxxxxxx> (in file)
Roger Quadros <rogerq@xxxxxxxxxx> (in file)
linux-kernel@xxxxxxxxxxxxxxx (open list:MEMORY CONTROLLER DRIVERS)
devicetree@xxxxxxxxxxxxxxx (open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS)
Benedikt Niedermayr (3):
memory: omap-gpmc: allow shared wait pins
memory: omap-gpmc: add support for wait pin polarity
dt-bindings: memory-controllers: gpmc-child: Add binding for
wait-pin-polarity
.../memory-controllers/ti,gpmc-child.yaml | 7 ++++
drivers/memory/omap-gpmc.c | 38 +++++++++++++++----
include/linux/platform_data/gpmc-omap.h | 1 +
3 files changed, 39 insertions(+), 7 deletions(-)
--
2.25.1
