From: Benedikt Niedermayr <benedikt.niedermayr@xxxxxxxxxxx>
Currently it is not possible to configure the WAIT0PINPOLARITY and
WAIT1PINPOLARITY bits of the GPMC_CONFIG register directly via
device tree properties.
It is also not possible to 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!
* Updated eMail recipients list
Changes since v2:
* Remove the gpmc register configuration out of the gpiochip
callbacks. In this case the memory interface configuration
is not done via gpio bindings.
* Some minor code fixes
* Changed git commit descriptions
Change since v3:
* Use a uint32 dt-property instean a boolean one
* If the dt-property is not set, then don't touch the
GPMC_CONFIG register
* Changed git commit descriptions
Changes since v4:
* Use checkpatch with "--strict" option
* Moved wait-pin sanity checks to gpmc_read_settings_dt()
* Always assign WAITPINPOLARITY_DEFAULT on error cases
* Track waitpin allocation within gpmc for determine
allocation origin
Changes since v5:
* Tracking of wait-pin allocations with polarity change detection
* Introduced a new struct gpmc_waitpin
* Add GPMC_* to global header definitions
* Don't allow GPMC_WAITPINPOLARITY_DEFAULT when parsing dt-properties
* Squashed wait-pin-polarity and shared-wait-pin patches, since they
should not be separated
Benedikt Niedermayr (2):
memory: omap-gpmc: wait pin additions
dt-bindings: memory-controllers: gpmc-child: add wait-pin polarity
.../memory-controllers/ti,gpmc-child.yaml | 7 ++
drivers/memory/omap-gpmc.c | 115 ++++++++++++++++--
include/linux/platform_data/gpmc-omap.h | 8 ++
3 files changed, 118 insertions(+), 12 deletions(-)
--
2.25.1
