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@linaro.org --- Changes in v7: - Add a patch checking the return value of the get_function_name() callback in pinmux_func_name_to_selector(). This fixes a NULL-pointer dereference on IMX platforms - Don't assign the number of functions in pinctrl device in the IMX driver as it's done automatically when adding the pinfunctions using the provided API. This fixes a warning from pinctrl core on IMX platforms triggered by the conversion from accessing the radix tree directly - Link to v6: https://lore.kernel.org/r/20250828-pinctrl-gpio-pinfuncs-v6-0-c9abb6bdb689@l...
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@l...
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@l...
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@l...
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@l...
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@l...
--- Bartosz Golaszewski (16): pinctrl: check the return value of pinmux_ops::get_function_name() 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 | 45 +++++++-------- 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 | 70 ++++++++++++++++++++---- 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, 288 insertions(+), 227 deletions(-) --- base-commit: b320789d6883cc00ac78ce83bccbfe7ed58afcf0 change-id: 20250701-pinctrl-gpio-pinfuncs-de82bd9aac43
Best regards,