[v7,0/2] gpmc wait pin additions

Message

Benedikt Niedermayr Oct. 5, 2022, 2:22 p.m. UTC

From: Benedikt Niedermayr <[e-mail]>

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.

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                    | 123 ++++++++++++++++--
 include/linux/platform_data/gpmc-omap.h       |   8 ++
 3 files changed, 125 insertions(+), 13 deletions(-)

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2.25.1