[PATCH v5 0/5] lx2160a: change the pad muxes through the RCW override

[Vincent Jardin via B4 Relay]

The LX2160A muxes its IIC, XSPI, SDHC, UART, IRQ and EVT pads from
fields of the RCW. They are read-only in RCWSR12..14 of DCFG, and are
changed at runtime through the override registers in the DCSR view of
DCFG, which read 0 until written.

Since commit 8a1365c7bbc1 ("arm64: dts: lx2160a: add pinmux and i2c
gpio to support bus recovery"), fsl-lx216x.dtsi drives the override
registers with pinctrl-single for the I2C bus recovery. Its first pin
state clears every other field of the word: a board whose RCW programs
a non-zero pad mux loses those pads at the first I2C probe.

This series reads the fields in effect from RCWSR and writes RCWCR, as
fsl_guts_rcw_rmw() already does for the SerDes protocols:

- patches 1 and 2 describe the pad mux as a child of the DCFG node,
  which gains its DCSR view
- patch 3 exports the RCW override of fsl-guts for the pad-mux fields
  only
- patch 4 adds the pinctrl driver: one group per RCW field, one
  function per encoding
- patch 5 moves the pad muxes of fsl-lx216x.dtsi under DCFG. Labels
  and pin node names stay, so no board file changes, and the
  pinctrl-single node goes

Patch 4 uses the exports of patch 3, so it cannot be applied alone:
patches 1 to 4 could be for the the pinctrl tree with an Ack of
the soc/fsl maintainer on patch 3,
and patch 5 through the i.MX tree once the driver is in,
since the I2C pin states of fsl-lx216x.dtsi then belong to it.

DTBs built before patch 5 keep their pinctrl-single node and behave as
before. There is no Fixes: tag, since patch 5 depends on a new driver.
I did not believe it should be backported then.

Tested on a Nodebox v3 (LX2160A) whose RCW muxes XSPI1_A_DATA[7:4],
SDHC1 and IIC5 are not set with the defaults, so I could confirm:
 - with pinctrl-single the first I2C probe cleared those fields
 - with this series RCWSR12..14 read after boot exactly what the RCW and
   the board's pin states select
 - all I2C controllers come up with their recovery states and a
   forced bus recovery on IIC1 (multi-master enabled for the test)
   changes only that field

Thanks to Vladimir Oltean for pointing at fsl_guts_rcw_rmw() when I
tried to prime the override registers from the RCW instead:
https://github.com/nxp-qoriq/rcw/pull/8

Signed-off-by: Vincent Jardin <vjardin@xxxxxxx>
---
Changes in v5:
- soc: fsl: guts: the exports become fsl_guts_pmux_read(),
  fsl_guts_pmux_override() and fsl_guts_pmux_override_supported(). guts
  lists the pad-mux fields of the LX2160A and refuses any other field
  or register, so the serdes fields cannot be changed (Vladimir Oltean)
- dt-bindings, pinctrl, dts: add the EC1, EC2, USB_EXT, GTX_CLK and
  SDHC1_DS pad muxes of RCWSR27, the second reg of the node (Vladimir Oltean)
- Patch 3 is reworked: drop the review tags, new round of review is
  needed (TBC, from Christophe Leroy and Frank Li)
- Patch 1 gets a reg, 5 groups and 4 functions:
  same drop the the Reviewed-by of Rob Herring and Frank Li
- Patch 2: its description names RCWSR27 too, I assume the
  Reviewed-by of Rob Herring can remain
- Link to v4: https://lore.kernel.org/r/20261114-for-upstream-lx2160a-rcw-pinmux-v1-v4-0-eefcea066a55@xxxxxxx

Changes in v4:
- pinctrl: MAINTAINERS with imx@xxxxxxxxxxxxxxx
  FUNC and GROUP macros with LX2160A_PMUX_ prefix (Frank Li)
- Add the Reviewed and Ack tags of Rob Herring and Frank Li
- Patches 1, 2, 3 and 5 are not changed
- Link to v3: https://lore.kernel.org/r/20261108-for-upstream-lx2160a-rcw-pinmux-v1-v3-0-5a0063f1da9e@xxxxxxx

Changes in v3:
- dt-bindings, dts: the pad-mux child is bus-addressed like the
  clock-controller child of the LS1028A dcfg: its reg is the RCWSR12
  to RCWSR14 window, under #address-cells, #size-cells and ranges on
  the dcfg node, the override registers stay the DCSR view of the
  parent (Krzysztof Kozlowski)
- cover letter: patch 4 cannot be applied without patch 3 (Linus Walleij)
- Patches 3 and 4 are unchanged
- Link to v2: https://lore.kernel.org/r/20261103-for-upstream-lx2160a-rcw-pinmux-v1-v2-0-3aad0860b984@xxxxxxx

Changes in v2:
- dt-bindings: list, for each function, the groups, so the
  schema refuses the associations the driver refuses (Frank Li)
- Patches 2 to 5 are unchanged
- Link to v1: https://lore.kernel.org/r/20261103-for-upstream-lx2160a-rcw-pinmux-v1-v1-0-0a61a9837744@xxxxxxx

---
Vincent Jardin (5):
      dt-bindings: pinctrl: add the NXP LX2160A RCW pad mux
      dt-bindings: soc: fsl: layerscape-dcfg: add the LX2160A pad-mux child
      soc: fsl: guts: add the RCW override of the pad muxes
      pinctrl: freescale: add the LX2160A RCW pad-mux driver
      arm64: dts: lx2160a: describe the pad muxes as the DCFG RCW override

 .../bindings/pinctrl/fsl,lx2160a-rcw-pinmux.yaml   | 309 ++++++++++++++++
 .../bindings/soc/fsl/fsl,layerscape-dcfg.yaml      |  18 +
 MAINTAINERS                                        |   8 +
 arch/arm64/boot/dts/freescale/fsl-lx216x.dtsi      | 377 ++++++++++---------
 drivers/pinctrl/freescale/Kconfig                  |  15 +
 drivers/pinctrl/freescale/Makefile                 |   1 +
 drivers/pinctrl/freescale/pinctrl-lx2160a.c        | 401 +++++++++++++++++++++
 drivers/soc/fsl/guts.c                             | 122 ++++++-
 include/linux/fsl/guts.h                           |   3 +
 9 files changed, 1078 insertions(+), 176 deletions(-)
---
base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
change-id: 20261103-for-upstream-lx2160a-rcw-pinmux-v1-31f9ad97dc86

Best regards,
-- 
Vincent Jardin <vjardin@xxxxxxx>