Message-Id: <20250724-pinctrl-gpio-pinfuncs-v3-0-af4db9302de4@linaro.org>
Date: Thu, 24 Jul 2025 11:24:28 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Linus Walleij <linus.walleij@...aro.org>, 
 Bjorn Andersson <andersson@...nel.org>, 
 Konrad Dybcio <konradybcio@...nel.org>, 
 Alexey Klimov <alexey.klimov@...aro.org>, 
 Lorenzo Bianconi <lorenzo@...nel.org>, Sean Wang <sean.wang@...nel.org>, 
 Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 Paul Cercueil <paul@...pouillou.net>, Kees Cook <kees@...nel.org>, 
 Andy Shevchenko <andy@...nel.org>, 
 Andrew Morton <akpm@...ux-foundation.org>, 
 David Hildenbrand <david@...hat.com>, 
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, 
 Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>, 
 Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>, 
 Dong Aisheng <aisheng.dong@....com>, Fabio Estevam <festevam@...il.com>, 
 Shawn Guo <shawnguo@...nel.org>, Jacky Bai <ping.bai@....com>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 NXP S32 Linux Team <s32@....com>, Sascha Hauer <s.hauer@...gutronix.de>, 
 Tony Lindgren <tony@...mide.com>, 
 Haojian Zhuang <haojian.zhuang@...aro.org>, 
 Geert Uytterhoeven <geert+renesas@...der.be>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-msm@...r.kernel.org, linux-mediatek@...ts.infradead.org, 
 linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org, 
 linux-hardening@...r.kernel.org, linux-mm@...ck.org, imx@...ts.linux.dev, 
 linux-omap@...r.kernel.org, linux-renesas-soc@...r.kernel.org, 
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, 
 Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Subject: [PATCH v3 00/15] pinctrl: introduce the concept of a GPIO pin
 function category

NOTE: This is obviously targetting v6.18.

NOTER: This series is a bit all over the place and looks like it should
be split into at least two separate ones but I figured sending it in its
entirety better shows the whole picture - namely the fact that the
pinfunction handling rework is there to allow using the generic pinux
functions in qualcomm drivers without ballooning up runtime memory
usage.

NOTEST: I tested several Qualcomm platforms but I have no means of
testing Mediatek and others. Tested-by tags are appreciated.

Problem: when pinctrl core binds pins to a consumer device and the
pinmux ops of the underlying driver are marked as strict, the pin in
question can no longer be requested as a GPIO using the GPIO descriptor
API. It will result in the following error:

[    5.095688] sc8280xp-tlmm f100000.pinctrl: pin GPIO_25 already requested by regulator-edp-3p3; cannot claim for f100000.pinctrl:570
[    5.107822] sc8280xp-tlmm f100000.pinctrl: error -EINVAL: pin-25 (f100000.pinctrl:570)

This typically makes sense except when the pins are muxed to a function
that actually says "GPIO". Of course, the function name is just a string
so it has no meaning to the pinctrl subsystem.

We have many Qualcomm SoCs (and I can imagine it's a common pattern in
other platforms as well) where we mux a pin to "gpio" function using the
`pinctrl-X` property in order to configure bias or drive-strength and
then access it using the gpiod API. This makes it impossible to mark the
pin controller module as "strict".

This series proposes to introduce a concept of a sub-category of
pinfunctions: GPIO functions where the above is not true and the pin
muxed as a GPIO can still be accessed via the GPIO consumer API even for
strict pinmuxers.

To that end: we first clean up the drivers that use struct function_desc
and make them use the smaller struct pinfunction instead - which is the
correct structure for drivers to describe their pin functions with. We
also rework pinmux core to not duplicate memory used to store the
pinfunctions unless they're allocated dynamically.

First: provide the kmemdup_const() helper which only duplicates memory
if it's not in the .rodata section. Then rework all pinctrl drivers that
instantiate objects of type struct function_desc as they should only be
created by pinmux core. Next constify the return value of the accessor
used to expose these structures to users and finally convert the
pinfunction object within struct function_desc to a pointer and use
kmemdup_const() to assign it. With this done proceed to add
infrastructure for the GPIO pin function category and use it in Qualcomm
drivers. At the very end: make the Qualcomm pinmuxer strict.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
Changes in v3:
- Add more patches in front: convert pinctrl drivers to stop defining
  their own struct function_desc objects and make pinmux core not
  duplicate .rodata memory in which struct pinfunction objects are
  stored.
- Add a patch constifying pinmux_generic_get_function().
- Drop patches that were applied upstream.
- Link to v2: https://lore.kernel.org/r/20250709-pinctrl-gpio-pinfuncs-v2-0-b6135149c0d9@linaro.org

Changes in v2:
- Extend the series with providing pinmux_generic_add_pinfunction(),
  using it in several drivers and converting pinctrl-msm to using
  generic pinmux helpers
- Add a generic function_is_gpio() callback for pinmux_ops
- Convert all qualcomm drivers to using the new GPIO pin category so
  that we can actually enable the strict flag
- Link to v1: https://lore.kernel.org/r/20250702-pinctrl-gpio-pinfuncs-v1-0-ed2bd0f9468d@linaro.org

---
Bartosz Golaszewski (15):
      lib: provide kmemdup_const()
      pinctrl: ingenic: use struct pinfunction instead of struct function_desc
      pinctrl: airoha: replace struct function_desc with struct pinfunction
      pinctrl: mediatek: mt7988: use PINCTRL_PIN_FUNCTION()
      pinctrl: mediatek: moore: replace struct function_desc with struct pinfunction
      pinctrl: imx: don't access the pin function radix tree directly
      pinctrl: keembay: release allocated memory in detach path
      pinctrl: keembay: use a dedicated structure for the pinfunction description
      pinctrl: constify pinmux_generic_get_function()
      pinctrl: make struct pinfunction a pointer in struct function_desc
      pinctrl: qcom: use generic pin function helpers
      pinctrl: allow to mark pin functions as requestable GPIOs
      pinctrl: qcom: add infrastructure for marking pin functions as GPIOs
      pinctrl: qcom: mark the `gpio` and `egpio` pins function as non-strict functions
      pinctrl: qcom: make the pinmuxing strict

 drivers/pinctrl/freescale/pinctrl-imx.c          | 42 ++++++----------
 drivers/pinctrl/mediatek/pinctrl-airoha.c        | 18 +++----
 drivers/pinctrl/mediatek/pinctrl-moore.c         | 10 ++--
 drivers/pinctrl/mediatek/pinctrl-moore.h         |  7 +--
 drivers/pinctrl/mediatek/pinctrl-mt7622.c        |  2 +-
 drivers/pinctrl/mediatek/pinctrl-mt7623.c        |  2 +-
 drivers/pinctrl/mediatek/pinctrl-mt7629.c        |  2 +-
 drivers/pinctrl/mediatek/pinctrl-mt7981.c        |  2 +-
 drivers/pinctrl/mediatek/pinctrl-mt7986.c        |  2 +-
 drivers/pinctrl/mediatek/pinctrl-mt7988.c        | 44 +++++++----------
 drivers/pinctrl/mediatek/pinctrl-mtk-common-v2.h |  2 +-
 drivers/pinctrl/pinctrl-equilibrium.c            |  2 +-
 drivers/pinctrl/pinctrl-ingenic.c                | 49 +++++++++---------
 drivers/pinctrl/pinctrl-keembay.c                | 25 ++++++----
 drivers/pinctrl/pinctrl-single.c                 |  4 +-
 drivers/pinctrl/pinmux.c                         | 63 +++++++++++++++++++++---
 drivers/pinctrl/pinmux.h                         |  9 ++--
 drivers/pinctrl/qcom/pinctrl-ipq5018.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-ipq5332.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-ipq5424.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-ipq6018.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-ipq8074.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-ipq9574.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-mdm9607.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-mdm9615.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-msm.c               | 45 ++++++-----------
 drivers/pinctrl/qcom/pinctrl-msm.h               |  5 ++
 drivers/pinctrl/qcom/pinctrl-msm8226.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-msm8660.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-msm8909.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-msm8916.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-msm8917.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-msm8953.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-msm8960.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-msm8976.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-msm8994.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-msm8996.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-msm8998.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-msm8x74.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-qcm2290.c           |  4 +-
 drivers/pinctrl/qcom/pinctrl-qcs404.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-qcs615.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-qcs8300.c           |  4 +-
 drivers/pinctrl/qcom/pinctrl-qdu1000.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-sa8775p.c           |  4 +-
 drivers/pinctrl/qcom/pinctrl-sar2130p.c          |  2 +-
 drivers/pinctrl/qcom/pinctrl-sc7180.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sc7280.c            |  4 +-
 drivers/pinctrl/qcom/pinctrl-sc8180x.c           |  2 +-
 drivers/pinctrl/qcom/pinctrl-sc8280xp.c          |  4 +-
 drivers/pinctrl/qcom/pinctrl-sdm660.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sdm670.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sdm845.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sdx55.c             |  2 +-
 drivers/pinctrl/qcom/pinctrl-sdx65.c             |  2 +-
 drivers/pinctrl/qcom/pinctrl-sdx75.c             |  2 +-
 drivers/pinctrl/qcom/pinctrl-sm4450.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sm6115.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sm6125.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sm6350.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sm6375.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sm7150.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sm8150.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sm8250.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sm8350.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sm8450.c            |  4 +-
 drivers/pinctrl/qcom/pinctrl-sm8550.c            |  2 +-
 drivers/pinctrl/qcom/pinctrl-sm8650.c            |  4 +-
 drivers/pinctrl/qcom/pinctrl-sm8750.c            |  4 +-
 drivers/pinctrl/qcom/pinctrl-x1e80100.c          |  2 +-
 drivers/pinctrl/renesas/pinctrl-rza1.c           |  2 +-
 drivers/pinctrl/renesas/pinctrl-rza2.c           |  2 +-
 drivers/pinctrl/renesas/pinctrl-rzg2l.c          |  2 +-
 drivers/pinctrl/renesas/pinctrl-rzv2m.c          |  2 +-
 include/linux/pinctrl/pinctrl.h                  | 14 ++++++
 include/linux/pinctrl/pinmux.h                   |  2 +
 include/linux/string.h                           |  1 +
 mm/util.c                                        | 21 ++++++++
 78 files changed, 275 insertions(+), 224 deletions(-)
---
base-commit: 05adbee3ad528100ab0285c15c91100e19e10138
change-id: 20250701-pinctrl-gpio-pinfuncs-de82bd9aac43

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

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