[PATCH v6 0/5] pinctrl: mediatek: Enable module build support

[Justin Yeh]

This series lets the MediaTek pinctrl drivers be built as loadable
kernel modules. This is required for Android GKI + vendor_dlkm
deployments, where vendor-specific drivers must be kept separate from
the GKI vmlinux and loaded as modules from the vendor partition.

Enabling the individual SoC drivers as modules is a single logical step,
but it has a few prerequisites, so the series is:

  1. Fix a pre-existing GPIO chip lifecycle bug. The gpio_chip lives in
     device-managed memory but is registered with the non-managed
     gpiochip_add_data(). While the drivers were built-in only this was
     harmless, but once they can be unbound/rmmod'd, devm frees the
     backing memory while the chip is still registered (use-after-free).
     Switch to devm_gpiochip_add_data() in the shared probe/init paths.

  2. Fix a pre-existing EINT resource leak on unbind. mtk_eint_do_init()
     creates an IRQ domain, an interrupt mapping per EINT line and a
     chained handler on the parent interrupt, none of which were ever
     released. Once the drivers can be unbound/rmmod'd this leaves a
     dangling IRQ domain, mappings whose chip data points at freed
     memory, and a chained handler still firing into that freed data.
     Tear them down with a device-managed action, matching the devm
     lifecycle used for the gpio_chip.

  3. Make the shared common code modular. The SoC drivers link against
     pinctrl-mtk-common.c (v1), pinctrl-moore.c and pinctrl-mtmips.c,
     whose Kconfig symbols were bool and which exported nothing. Without
     this, selecting a SoC driver as =m forces the common symbol to =y
     and the module fails to link against the unexported entry points.
     Convert PINCTRL_MTK, PINCTRL_MTK_MOORE and PINCTRL_MTK_MTMIPS to
     tristate, export the entry points, and add MODULE_LICENSE()/
     MODULE_DESCRIPTION(). The already-modular v2 common code
     additionally needs mtk_rmw() exported, since it is called directly
     by SoC drivers such as mt7623. The shared symbols are exported in
     the "MTK_PINCTRL" symbol namespace (EXPORT_SYMBOL_NS_GPL()), and
     each SoC driver that uses them declares MODULE_IMPORT_NS().

  4. Convert the MT7986 driver to a single initcall. It registers two
     platform drivers (mt7986a/mt7986b) and used to call arch_initcall()
     twice. A module has only one module_init(), so two arch_initcall()s
     break the module build with a redefinition of
     init_module()/__inittest(). Fold both drivers into one
     platform_register_drivers() call from a single initcall. No
     functional change when built-in.

  5. Flip every SoC driver's Kconfig from bool to tristate and add the
     module metadata.

The series builds cleanly under allmodconfig on arm64 (all SoC drivers
as =m).

Changes in v6:
 - Export the shared common symbols in the "MTK_PINCTRL" namespace using
   EXPORT_SYMBOL_NS_GPL() instead of the global EXPORT_SYMBOL_GPL(), and
   add MODULE_IMPORT_NS("MTK_PINCTRL") to every SoC driver that consumes
   them, as suggested by Chen-Yu Tsai while reviewing the common-driver
   patch (patch 3/5).
 - Added a new patch, "pinctrl: mediatek: free EINT resources on unbind"
   (patch 2/5). Chen-Yu Tsai pointed out that the manual cleanup removed
   in patch 1/5 also used to cover mtk_eint_init(), and that converting
   to devm without an EINT counterpart would leave a dangling IRQ domain
   and an active-but-stale chained handler on rmmod/unbind. As suggested,
   this is a separate patch rather than folded into patch 1/5.
 - Added Reviewed-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx> to patch 1/5
   (devm_gpiochip_add_data) and patch 4/5 (mt7986 single initcall).

Review status: patches 1/5 and 4/5 carry Chen-Yu Tsai's Reviewed-by;
patch 5/5 carries AngeloGioacchino Del Regno's Reviewed-by (from the
per-driver patches reviewed in v4, preserved across the squash). Patches
2/5 and 3/5 have not been reviewed yet.

Justin Yeh (5):
  pinctrl: mediatek: use devm_gpiochip_add_data() for GPIO chip
  pinctrl: mediatek: free EINT resources on unbind
  pinctrl: mediatek: allow common drivers to be built as modules
  pinctrl: mediatek: mt7986: register both platform drivers from a
    single initcall
  pinctrl: mediatek: enable module build support for all SoC drivers

 drivers/pinctrl/mediatek/Kconfig              | 70 +++++++++----------
 drivers/pinctrl/mediatek/mtk-eint.c           | 21 +++++-
 drivers/pinctrl/mediatek/pinctrl-moore.c      | 11 +--
 drivers/pinctrl/mediatek/pinctrl-mt2701.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt2712.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt6397.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt6795.c     |  3 +
 drivers/pinctrl/mediatek/pinctrl-mt6797.c     |  3 +
 drivers/pinctrl/mediatek/pinctrl-mt6878.c     |  1 +
 drivers/pinctrl/mediatek/pinctrl-mt6893.c     |  1 +
 drivers/pinctrl/mediatek/pinctrl-mt7620.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt7621.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt7622.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt7623.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt7629.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt76x8.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt7981.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt7986.c     | 19 ++---
 drivers/pinctrl/mediatek/pinctrl-mt7988.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt8127.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt8135.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt8167.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt8173.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-mt8183.c     |  3 +
 drivers/pinctrl/mediatek/pinctrl-mt8186.c     |  3 +
 drivers/pinctrl/mediatek/pinctrl-mt8188.c     |  1 +
 drivers/pinctrl/mediatek/pinctrl-mt8189.c     |  1 +
 drivers/pinctrl/mediatek/pinctrl-mt8192.c     |  1 +
 drivers/pinctrl/mediatek/pinctrl-mt8195.c     |  3 +
 drivers/pinctrl/mediatek/pinctrl-mt8196.c     |  1 +
 drivers/pinctrl/mediatek/pinctrl-mt8365.c     |  2 +
 drivers/pinctrl/mediatek/pinctrl-mt8516.c     |  4 ++
 .../pinctrl/mediatek/pinctrl-mtk-common-v2.c  |  1 +
 drivers/pinctrl/mediatek/pinctrl-mtk-common.c | 22 +++---
 drivers/pinctrl/mediatek/pinctrl-mtmips.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-paris.c      |  2 +-
 drivers/pinctrl/mediatek/pinctrl-rt2880.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-rt305x.c     |  4 ++
 drivers/pinctrl/mediatek/pinctrl-rt3883.c     |  4 ++
 39 files changed, 190 insertions(+), 59 deletions(-)


base-commit: bee763d5f341b99cf472afeb508d4988f62a6ca1
-- 
2.45.2