Some Renesas SoC based boards mux SD and eMMC on a single sdio
controller, exposing user control by dip switch and software control by
gpio.

Purpose is to simplify development and provisioning by selecting boot
media at power-on, and again before starting linux.

Add binding and driver support for linking a (gpio) mux to renesas sdio
controller.

Introduce generic helper functions for getting managed and selected
mux-state objects, and switch i2c-omap and phy-can-transceiver drivers.

Cc: Yazan Shhady <yazan.shhady@solid-run.com>
Cc: Jon Nettleton <jon@solid-run.com>
Cc: Mikhail Anikin <mikhail.anikin@solid-run.com>
To: Marc Kleine-Budde <mkl@pengutronix.de>
To: Vincent Mailhol <mailhol@kernel.org>
To: Vinod Koul <vkoul@kernel.org>
To: Neil Armstrong <neil.armstrong@linaro.org>
To: Peter Rosin <peda@axentia.se>
To: Aaro Koskinen <aaro.koskinen@iki.fi>
To: Andreas Kemnade <andreas@kemnade.info>
To: Kevin Hilman <khilman@baylibre.com>
To: Roger Quadros <rogerq@kernel.org>
To: Tony Lindgren <tony@atomide.com>
To: Janusz Krzysztofik <jmkrzyszt@gmail.com>
To: Vignesh R <vigneshr@ti.com>
To: Andi Shyti <andi.shyti@kernel.org>
To: Ulf Hansson <ulf.hansson@linaro.org>
To: Rob Herring <robh@kernel.org>
To: Krzysztof Kozlowski <krzk+dt@kernel.org>
To: Conor Dooley <conor+dt@kernel.org>
To: Geert Uytterhoeven <geert+renesas@glider.be>
To: Magnus Damm <magnus.damm@gmail.com>
To: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: linux-can@vger.kernel.org
Cc: linux-phy@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-omap@vger.kernel.org
Cc: linux-i2c@vger.kernel.org
Cc: linux-mmc@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org
Signed-off-by: Josua Mayer <josua@solid-run.com>

Changes in v5:
- implemented automatic mux deselect for devm_*_selected.
  (Reported-by: Wolfram Sang <wsa+renesas@sang-engineering.com>)
- because of semantic changes I dropped reviewed and acks from omap-i2c
  patch (Andreas Kemnade / Wolfram Sang).
- fix invalid return value in void function for mux helper stubs
  (Reported-by: kernel test robot <lkp@intel.com>)
- Link to v4: https://lore.kernel.org/r/20251229-rz-sdio-mux-v4-0-a023e55758fe@solid-run.com

Changes in v4:
- added MULTIPLEXER Kconfig help text.
- removed "select MULTIPLEXER" from renesas sdhi Kconfig, as it is
  not required for all devices using this driver.
- added stubs for all symbols exported by mux core.
  (Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>)
- refactored mux core logic to silence ENOENT errors only on optional
  code paths, keeping error printing unchanged otherwise.
  (Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>)
- picked up various reviewed- and acked-by tags
- Link to v3: https://lore.kernel.org/r/20251210-rz-sdio-mux-v3-0-ca628db56d60@solid-run.com

Changes in v3:
- updated omap-i2c and phy-can-transceiver to use new helpers.
- created generic helper functions for getting managed optional mux-state.
  (Reported-by: Rob Herring <robh@kernel.org>)
- picked up binding ack by Rob Herring.
- replaced use of "SDIO" with "SD/SDIO/eMMC" in binding document and
  commit descriptions.
  (Reported-by: Ulf Hansson <ulf.hansson@linaro.org>)
- Link to v2: https://lore.kernel.org/r/20251201-rz-sdio-mux-v2-0-bcb581b88dd7@solid-run.com

Changes in v2:
- dropped mux-controller node from dt binding example
  (Reported-by: Conor Dooley <conor@kernel.org>
- Link to v1: https://lore.kernel.org/r/20251128-rz-sdio-mux-v1-0-1ede318d160f@solid-run.com

Reported-by: 
---
Josua Mayer (7):
      phy: can-transceiver: rename temporary helper function to avoid conflict
      mux: Add helper functions for getting optional and selected mux-state
      mux: add help text for MULTIPLEXER config option
      phy: can-transceiver: drop temporary helper getting optional mux-state
      i2c: omap: switch to new generic helper for getting selected mux-state
      dt-bindings: mmc: renesas,sdhi: Add mux-states property
      mmc: host: renesas_sdhi_core: support selecting an optional mux

 .../devicetree/bindings/mmc/renesas,sdhi.yaml      |   6 +
 drivers/i2c/busses/i2c-omap.c                      |  24 +--
 drivers/mmc/host/renesas_sdhi_core.c               |   6 +
 drivers/mux/Kconfig                                |   8 +
 drivers/mux/core.c                                 | 175 +++++++++++++++++----
 drivers/phy/phy-can-transceiver.c                  |  10 --
 include/linux/mux/consumer.h                       | 111 ++++++++++++-
 7 files changed, 278 insertions(+), 62 deletions(-)
---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251128-rz-sdio-mux-acc5137f1618

Best regards,
-- 
Josua Mayer <josua@solid-run.com>