[PATCH v6 00/15] pinctrl: introduce the concept of a GPIO pin function category
Neil Armstrong
neil.armstrong at linaro.org
Mon Sep 1 01:20:25 PDT 2025
On 28/08/2025 18:00, Bartosz Golaszewski wrote:
> 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 at linaro.org>
> ---
> Changes in v6:
> - Select GENERIC_PINMUX_FUNCTIONS when using generic pinmux helpers in
> qcom pinctrl drivers to fix build on ARM 32-bit platforms
> - Assume that a pin can be requested in pin_request() if it has no
> mux_setting assigned
> - Also check if a function is a GPIO for pins within GPIO ranges
> - Fix an issue with the imx pinctrl driver where the conversion patch
> confused the function and pin group radix trees
> - Add a FIXME to the imx driver mentioning the need to switch to the
> provided helpers for accessing the group radix tree
> - Link to v5: https://lore.kernel.org/r/20250815-pinctrl-gpio-pinfuncs-v5-0-955de9fd91db@linaro.org
>
> Changes in v5:
> - Fix a potential NULL-pointer dereference in
> pinmux_can_be_used_for_gpio()
> - Use PINCTRL_PINFUNCTION() in pinctrl-airoha
> - Link to v4: https://lore.kernel.org/r/20250812-pinctrl-gpio-pinfuncs-v4-0-bb3906c55e64@linaro.org
>
> Changes in v4:
> - Update the GPIO pin function definitions to include the new qcom
> driver (milos)
> - Provide devm_kmemdup_const() instead of a non-managed kmemdup_const()
> as a way to avoid casting out the 'const' modifier when passing the
> const pointer to devm_add_action_or_reset()
> - Use devm_krealloc_array() where applicable instead of devm_krealloc()
> - Fix typos
> - Fix kerneldocs
> - Improve commit messages
> - Small tweaks as pointed out by Andy
> - Rebased on top of v6.17-rc1
> - Link to v3: https://lore.kernel.org/r/20250724-pinctrl-gpio-pinfuncs-v3-0-af4db9302de4@linaro.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):
> devres: provide devm_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/base/devres.c | 21 ++++++++
> drivers/pinctrl/freescale/pinctrl-imx.c | 43 +++++++--------
> drivers/pinctrl/mediatek/pinctrl-airoha.c | 19 +++----
> 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 | 26 +++++----
> drivers/pinctrl/pinctrl-single.c | 4 +-
> drivers/pinctrl/pinmux.c | 68 ++++++++++++++++++++----
> drivers/pinctrl/pinmux.h | 9 ++--
> drivers/pinctrl/qcom/Kconfig | 1 +
> 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-milos.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/device/devres.h | 2 +
> include/linux/pinctrl/pinctrl.h | 14 +++++
> include/linux/pinctrl/pinmux.h | 2 +
> 80 files changed, 287 insertions(+), 224 deletions(-)
> ---
> base-commit: 1b237f190eb3d36f52dffe07a40b5eb210280e00
> change-id: 20250701-pinctrl-gpio-pinfuncs-de82bd9aac43
>
> Best regards,
Tested on a bunch on qcom boards, no issues observed, regression of v5 no longers appears.
Tested-by: Neil Armstrong <neil.armstrong at linaro.org>
Probably only applies on patches 1, 9, 10, 11, 12, 13, 14, & 15
Neil
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