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
* 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
Changes since v6:
* Move wait-pin allocation into gpmc_probe()
* Fix s/gpmc/GPMC/ in commit description
* use ti,wait-pin-polarity instead of gpmc,wait-pin-polarity
* Refactored if clause in gpmc_alloc_waitpin()
* Revert values for GPMC_WAITPINPOLARITY_ACTIVE_LOW and
GPMC_WAITPINPOLARITY_ACTIVE_HIGH.
Use the exact same values which are written into the register.
Changes since v7:
* Renamed GPMC_WAITPINPOLARITY_DEFAULT to GPMC_WAITPINPOLARITY_INVALID
* Call gpiochip_request_own_desc() only on first wait-pin allocation
* Fixed use of old "gpmc,wait-pin-polarity" property.
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 | 122 ++++++++++++++++--
include/linux/platform_data/gpmc-omap.h | 8 ++
3 files changed, 124 insertions(+), 13 deletions(-)
--
2.25.1
