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[v5,0/3] gpmc wait-pin additions

Message ID 20220916120749.2517727-1-benedikt.niedermayr@siemens.com (mailing list archive)
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Series gpmc wait-pin additions | expand

Message

Benedikt Niedermayr Sept. 16, 2022, 12:07 p.m. UTC 
From: Benedikt Niedermayr <benedikt.niedermayr@siemens.com>

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


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 wait-pin polarity

 .../memory-controllers/ti,gpmc-child.yaml     |  7 ++++
 drivers/memory/omap-gpmc.c                    | 39 ++++++++++++++++++-
 include/linux/platform_data/gpmc-omap.h       |  6 +++
 3 files changed, 50 insertions(+), 2 deletions(-)

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2.34.1