[PATCH v11 0/9] mmc: host: renesas_sdhi_core: support configuring an optional sdio mux

[PATCH v11 0/9] mmc: host: renesas_sdhi_core: support configuring an optional sdio mux

[Josua Mayer]

This series has evolved over time from adding generic mux support for
renesas sdhi driver, to partial rewrite of the mux framework.

Several drivers have started implementing driver-local managed and
unmanaged helper functions for getting and selecting a mux-state object.

mmc maintainers have requested that new code shall intreoduce and use
generic helper functions that can be shared by all drivers, avoiding
code duplication.

This series is structured in 5 parts, each of which is self-sufficient
depending only on the previous patches. This shall allow the first N
patches to be applied even if the last ones need further discussion.

1. Rename driver-local helper functions to avoid name collision with
   global version to be introduced later.

2. Implement generic device-managed helper functions in mux core.

3. Convert driver local code from similar patterns to use the newly
   added global helpers.

4. Change mux-core Kconfig so that it can be enabled through menuconfig,
   without an explicit "select" dependency from other drivers.

5. add dt bindings and driver support for mux in renesas sdhi driver.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
Changes in v11:
- changed approach to Kconfig making MULTIPLEXER a bool, and adding a
  user-visible wrapper for menuconfig.
  (Reported-by: Ulf Hansson <ulf.hansson@linaro.org>)
- dropped the "default m if COMPILE_TEST".
  (Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>)
- improved kerneldoc line wrapping.
- removed unnecessary changes to original devm_mux_control-get.
- fix "reference preceded by free" in mux_state_get function
- Link to v10: https://lore.kernel.org/r/20260225-rz-sdio-mux-v10-0-1ee44f2ea112@solid-run.com

Changes in v10:
- added renesas-sdhi Kconfig dependency for MULTIPLEXER, avoiding build
  errors in case setting SDHI=y and MULTIPLEXER=m is attempted.
  Trailers were dropped on this patch to encourage fresh review.
- renamed phy-can-transceiver driver-local helper function to be
  consistent with other driver-local functions, and dropped all trailers
  for this particular patch.
- reconsidered the Kconfig changes due to inputs from mux core author
- handle newly-added mux usage in rcar-gen3-usb2 introduced with
  v7.0-rc1
- streamline patch sequence
- rebase on v7.0-rc1
- Link to v9: https://lore.kernel.org/r/20260208-rz-sdio-mux-v9-0-9a3be13c1280@solid-run.com

Changes in v9:
- compile-tested on x86 with MULTIPLEXER=m/y/unset.
- fixed Kconfig changes so that CONFIG_MULTIPLEXER can be selected.
  through menuconfig / .config as intended.
- updated trailers
- document null return value for mux_control_get_optional.
- fix build error for CONFIG_MULTIPLEXER=m, found with x86_64
  allmodconfig: replaced ifdef ... with if IS_ENABLED(...).
  (Reported-by: Mark Brown <broonie@kernel.org>)
- Link to v8: https://lore.kernel.org/r/20260203-rz-sdio-mux-v8-0-024ea405863e@solid-run.com

Changes in v8:
- Add defensive null checks for all non-optional calls to internal
  mux_get function.
- Document NULL return value on applicable functions.
- Avoid IS_ERR_OR_NULL and ERR_PTR(0) to disarm smatch errors.
- Link to v7: https://lore.kernel.org/r/20260128-rz-sdio-mux-v7-0-92ebb6da0df8@solid-run.com

Changes in v7:
- picked up reviewed-tags
- fix Kconfig change to add the missing prompt for CONFIG_MULTIPLEXER,
  and enable it by default when COMPILE_TEST is set.
  (Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>)
- fix another kernel build robot warning: undocumented C struct member
- Link to v6: https://lore.kernel.org/r/20260121-rz-sdio-mux-v6-0-38aa39527928@solid-run.com

Changes in v6:
- replaced /* with /** for devm_mux_state_state function description.
- collected review tags.
- fixed checkpatch warnings (space-before-tab, void-return).
  (Reported-by: Geert Uytterhoeven)
- fixed use-after-free in mux core mux_get function.
  (Reported-by: Geert Uytterhoeven)
- fix mux helper error path uninitialised return code variable.
  (Reported-by: kernel test robot <lkp@intel.com>)
- Link to v5: https://lore.kernel.org/r/20260118-rz-sdio-mux-v5-0-3c37e8872683@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>
   Reported-by: Krzysztof Kozlowski <krzk@kernel.org>)
- Link to v1: https://lore.kernel.org/r/20251128-rz-sdio-mux-v1-0-1ede318d160f@solid-run.com

---
Josua Mayer (9):
      phy: can-transceiver: rename temporary helper function to avoid conflict
      phy: renesas: rcar-gen3-usb2: rename local mux helper to avoid conflict
      mux: Add helper functions for getting optional and selected mux-state
      phy: can-transceiver: drop temporary helper getting optional mux-state
      phy: renesas: rcar-gen3-usb2: drop 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
      mux: add visible config symbol to enable multiplexer subsystem
      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                                |  17 +-
 drivers/mux/core.c                                 | 194 ++++++++++++++++++---
 drivers/phy/phy-can-transceiver.c                  |  10 --
 drivers/phy/renesas/phy-rcar-gen3-usb2.c           |  30 +---
 include/linux/mux/consumer.h                       | 108 +++++++++++-
 8 files changed, 305 insertions(+), 90 deletions(-)
---
base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
change-id: 20251128-rz-sdio-mux-acc5137f1618

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

[PATCH v11 1/9] phy: can-transceiver: rename temporary helper function to avoid conflict

[Josua Mayer]

Rename the temporary devm_mux_state_get_optional function to avoid
conflict with upcoming implementation in multiplexer subsystem.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/phy/phy-can-transceiver.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/phy-can-transceiver.c b/drivers/phy/phy-can-transceiver.c
index 330356706ad7..fcbca9d2bded 100644
--- a/drivers/phy/phy-can-transceiver.c
+++ b/drivers/phy/phy-can-transceiver.c
@@ -128,7 +128,7 @@ MODULE_DEVICE_TABLE(of, can_transceiver_phy_ids);
 
 /* Temporary wrapper until the multiplexer subsystem supports optional muxes */
 static inline struct mux_state *
-devm_mux_state_get_optional(struct device *dev, const char *mux_name)
+can_transceiver_phy_mux_state_get_optional(struct device *dev, const char *mux_name)
 {
 	if (!of_property_present(dev->of_node, "mux-states"))
 		return NULL;
@@ -183,7 +183,7 @@ static int can_transceiver_phy_probe(struct platform_device *pdev)
 	priv->num_ch = num_ch;
 	platform_set_drvdata(pdev, priv);
 
-	mux_state = devm_mux_state_get_optional(dev, NULL);
+	mux_state = can_transceiver_phy_mux_state_get_optional(dev, NULL);
 	if (IS_ERR(mux_state))
 		return PTR_ERR(mux_state);
 

-- 
2.43.0

[PATCH v11 2/9] phy: renesas: rcar-gen3-usb2: rename local mux helper to avoid conflict

[Josua Mayer]

Rename the temporary devm_mux_state_get_optional function to avoid
conflict with upcoming implementation in multiplexer subsystem.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/phy/renesas/phy-rcar-gen3-usb2.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/renesas/phy-rcar-gen3-usb2.c b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
index cfc2a8d9028d..1155b111420a 100644
--- a/drivers/phy/renesas/phy-rcar-gen3-usb2.c
+++ b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
@@ -941,7 +941,7 @@ static int rcar_gen3_phy_usb2_vbus_regulator_register(struct rcar_gen3_chan *cha
 
 /* Temporary wrapper until the multiplexer subsystem supports optional muxes */
 static inline struct mux_state *
-devm_mux_state_get_optional(struct device *dev, const char *mux_name)
+rcar_gen3_phy_mux_state_get_optional(struct device *dev, const char *mux_name)
 {
 	if (!of_property_present(dev->of_node, "mux-states"))
 		return NULL;
@@ -1036,7 +1036,7 @@ static int rcar_gen3_phy_usb2_probe(struct platform_device *pdev)
 		phy_set_drvdata(channel->rphys[i].phy, &channel->rphys[i]);
 	}
 
-	mux_state = devm_mux_state_get_optional(dev, NULL);
+	mux_state = rcar_gen3_phy_mux_state_get_optional(dev, NULL);
 	if (IS_ERR(mux_state))
 		return PTR_ERR(mux_state);
 	if (mux_state) {

-- 
2.43.0

[PATCH v11 3/9] mux: Add helper functions for getting optional and selected mux-state

[Josua Mayer]

In-tree phy-can-transceiver and phy_rcar_gen3_usb2 have already
implemented local versions of devm_mux_state_get_optional.

The omap-i2c driver gets and selects an optional mux in its probe
function without using any helper.

Add new helper functions covering both aforementioned use-cases:

- mux_control_get_optional:
  Get a mux-control if specified in dt, return NULL otherwise.
- devm_mux_state_get_optional:
  Get a mux-state if specified in dt, return NULL otherwise.
- devm_mux_state_get_selected:
  Get and select a mux-state specified in dt, return error otherwise.
- devm_mux_state_get_optional_selected:
  Get and select a mux-state if specified in dt, return error or NULL.

Existing mux_get helper function is changed to take an extra argument
indicating whether the mux is optional.
In this case no error is printed, and NULL returned in case of ENOENT.

Calling code is adapted to handle NULL return case, and to pass optional
argument as required.

To support automatic deselect for _selected helper, a new structure is
created storing an exit pointer similar to clock core which is called on
release.

To facilitate code sharing between optional/mandatory/selected helpers,
a new internal helper function is added to handle quiet (optional) and
verbose (mandatory) errors, as well as storing the correct callback for
devm release: __devm_mux_state_get

Due to this structure devm_mux_state_get_*_selected can no longer print
a useful error message when select fails. Instead callers should print
errors where needed.

Commit e153fdea9db04 ("phy: can-transceiver: Re-instate "mux-states"
property presence check") noted that "mux_get() always prints an error
message in case of an error, including when the property is not present,
confusing the user."

The first error message covers the case that a mux name is not matched
in dt. The second error message is based on of_parse_phandle_with_args
return value.

In optional case no error is printed and NULL is returned.
This ensures that the new helper functions will not confuse the user
either.

With the addition of optional helper functions it became clear that
drivers should compile and link even if CONFIG_MULTIPLEXER was not enabled.
Add stubs for all symbols exported by mux core.

Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/mux/core.c           | 194 +++++++++++++++++++++++++++++++++++++------
 include/linux/mux/consumer.h | 108 +++++++++++++++++++++++-
 2 files changed, 271 insertions(+), 31 deletions(-)

diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index f09ee8782e3d..23538de2c91b 100644
--- a/drivers/mux/core.c
+++ b/drivers/mux/core.c
@@ -46,6 +46,16 @@ static const struct class mux_class = {
 	.name = "mux",
 };
 
+/**
+ * struct devm_mux_state_state -	Tracks managed resources for mux-state objects.
+ * @mstate:				Pointer to a mux state.
+ * @exit:				An optional callback to execute before free.
+ */
+struct devm_mux_state_state {
+	struct mux_state *mstate;
+	int (*exit)(struct mux_state *mstate);
+};
+
 static DEFINE_IDA(mux_ida);
 
 static int __init mux_init(void)
@@ -516,17 +526,19 @@ static struct mux_chip *of_find_mux_chip_by_node(struct device_node *np)
 	return dev ? to_mux_chip(dev) : NULL;
 }
 
-/*
+/**
  * mux_get() - Get the mux-control for a device.
  * @dev: The device that needs a mux-control.
  * @mux_name: The name identifying the mux-control.
  * @state: Pointer to where the requested state is returned, or NULL when
  *         the required multiplexer states are handled by other means.
+ * @optional: Whether to return NULL and silence errors when mux doesn't exist.
  *
- * Return: A pointer to the mux-control, or an ERR_PTR with a negative errno.
+ * Return: Pointer to the mux-control on success, an ERR_PTR with a negative
+ * errno on error, or NULL if optional is true and mux doesn't exist.
  */
 static struct mux_control *mux_get(struct device *dev, const char *mux_name,
-				   unsigned int *state)
+				   unsigned int *state, bool optional)
 {
 	struct device_node *np = dev->of_node;
 	struct of_phandle_args args;
@@ -542,7 +554,9 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
 		else
 			index = of_property_match_string(np, "mux-control-names",
 							 mux_name);
-		if (index < 0) {
+		if (index < 0 && optional) {
+			return NULL;
+		} else if (index < 0) {
 			dev_err(dev, "mux controller '%s' not found\n",
 				mux_name);
 			return ERR_PTR(index);
@@ -558,8 +572,12 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
 						 "mux-controls", "#mux-control-cells",
 						 index, &args);
 	if (ret) {
+		if (optional && ret == -ENOENT)
+			return NULL;
+
 		dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
-			np, state ? "state" : "control", mux_name ?: "", index);
+			np, state ? "state" : "control",
+			mux_name ?: "", index);
 		return ERR_PTR(ret);
 	}
 
@@ -617,10 +635,29 @@ static struct mux_control *mux_get(struct device *dev, const char *mux_name,
  */
 struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
 {
-	return mux_get(dev, mux_name, NULL);
+	struct mux_control *mux = mux_get(dev, mux_name, NULL, false);
+
+	if (!mux)
+		return ERR_PTR(-ENOENT);
+
+	return mux;
 }
 EXPORT_SYMBOL_GPL(mux_control_get);
 
+/**
+ * mux_control_get_optional() - Get the optional mux-control for a device.
+ * @dev: The device that needs a mux-control.
+ * @mux_name: The name identifying the mux-control.
+ *
+ * Return: Pointer to the mux-control on success, an ERR_PTR with a negative
+ * errno on error, or NULL if mux doesn't exist.
+ */
+struct mux_control *mux_control_get_optional(struct device *dev, const char *mux_name)
+{
+	return mux_get(dev, mux_name, NULL, true);
+}
+EXPORT_SYMBOL_GPL(mux_control_get_optional);
+
 /**
  * mux_control_put() - Put away the mux-control for good.
  * @mux: The mux-control to put away.
@@ -670,14 +707,16 @@ struct mux_control *devm_mux_control_get(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(devm_mux_control_get);
 
-/*
+/**
  * mux_state_get() - Get the mux-state for a device.
  * @dev: The device that needs a mux-state.
  * @mux_name: The name identifying the mux-state.
+ * @optional: Whether to return NULL and silence errors when mux doesn't exist.
  *
- * Return: A pointer to the mux-state, or an ERR_PTR with a negative errno.
+ * Return: Pointer to the mux-state on success, an ERR_PTR with a negative
+ * errno on error, or NULL if optional is true and mux doesn't exist.
  */
-static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
+static struct mux_state *mux_state_get(struct device *dev, const char *mux_name, bool optional)
 {
 	struct mux_state *mstate;
 
@@ -685,12 +724,15 @@ static struct mux_state *mux_state_get(struct device *dev, const char *mux_name)
 	if (!mstate)
 		return ERR_PTR(-ENOMEM);
 
-	mstate->mux = mux_get(dev, mux_name, &mstate->state);
+	mstate->mux = mux_get(dev, mux_name, &mstate->state, optional);
 	if (IS_ERR(mstate->mux)) {
 		int err = PTR_ERR(mstate->mux);
 
 		kfree(mstate);
 		return ERR_PTR(err);
+	} else if (!mstate->mux) {
+		kfree(mstate);
+		return optional ? NULL : ERR_PTR(-ENOENT);
 	}
 
 	return mstate;
@@ -710,9 +752,66 @@ static void mux_state_put(struct mux_state *mstate)
 
 static void devm_mux_state_release(struct device *dev, void *res)
 {
-	struct mux_state *mstate = *(struct mux_state **)res;
+	struct devm_mux_state_state *devm_state = res;
+
+	if (devm_state->exit)
+		devm_state->exit(devm_state->mstate);
+
+	mux_state_put(devm_state->mstate);
+}
+
+/**
+ * __devm_mux_state_get() - Get the optional mux-state for a device,
+ *			    with resource management.
+ * @dev: The device that needs a mux-state.
+ * @mux_name: The name identifying the mux-state.
+ * @optional: Whether to return NULL and silence errors when mux doesn't exist.
+ * @init: Optional function pointer for mux-state object initialisation.
+ * @exit: Optional function pointer for mux-state object cleanup on release.
+ *
+ * Return: Pointer to the mux-state on success, an ERR_PTR with a negative
+ * errno on error, or NULL if optional is true and mux doesn't exist.
+ */
+static struct mux_state *__devm_mux_state_get(struct device *dev, const char *mux_name,
+					      bool optional,
+					      int (*init)(struct mux_state *mstate),
+					      int (*exit)(struct mux_state *mstate))
+{
+	struct devm_mux_state_state *devm_state;
+	struct mux_state *mstate;
+	int ret;
+
+	mstate = mux_state_get(dev, mux_name, optional);
+	if (IS_ERR(mstate))
+		return ERR_CAST(mstate);
+	else if (optional && !mstate)
+		return NULL;
+	else if (!mstate)
+		return ERR_PTR(-ENOENT);
+
+	devm_state = devres_alloc(devm_mux_state_release, sizeof(*devm_state), GFP_KERNEL);
+	if (!devm_state) {
+		ret = -ENOMEM;
+		goto err_devres_alloc;
+	}
+
+	if (init) {
+		ret = init(mstate);
+		if (ret)
+			goto err_mux_state_init;
+	}
+
+	devm_state->mstate = mstate;
+	devm_state->exit = exit;
+	devres_add(dev, devm_state);
 
+	return mstate;
+
+err_mux_state_init:
+	devres_free(devm_state);
+err_devres_alloc:
 	mux_state_put(mstate);
+	return ERR_PTR(ret);
 }
 
 /**
@@ -722,28 +821,69 @@ static void devm_mux_state_release(struct device *dev, void *res)
  * @mux_name: The name identifying the mux-control.
  *
  * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
+ *
+ * The mux-state will automatically be freed on release.
  */
-struct mux_state *devm_mux_state_get(struct device *dev,
-				     const char *mux_name)
+struct mux_state *devm_mux_state_get(struct device *dev, const char *mux_name)
 {
-	struct mux_state **ptr, *mstate;
-
-	ptr = devres_alloc(devm_mux_state_release, sizeof(*ptr), GFP_KERNEL);
-	if (!ptr)
-		return ERR_PTR(-ENOMEM);
+	return __devm_mux_state_get(dev, mux_name, false, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(devm_mux_state_get);
 
-	mstate = mux_state_get(dev, mux_name);
-	if (IS_ERR(mstate)) {
-		devres_free(ptr);
-		return mstate;
-	}
+/**
+ * devm_mux_state_get_optional() - Get the optional mux-state for a device,
+ *				   with resource management.
+ * @dev: The device that needs a mux-state.
+ * @mux_name: The name identifying the mux-state.
+ *
+ * Return: Pointer to the mux-state on success, an ERR_PTR with a negative
+ * errno on error, or NULL if mux doesn't exist.
+ *
+ * The mux-state will automatically be freed on release.
+ */
+struct mux_state *devm_mux_state_get_optional(struct device *dev, const char *mux_name)
+{
+	return __devm_mux_state_get(dev, mux_name, true, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(devm_mux_state_get_optional);
 
-	*ptr = mstate;
-	devres_add(dev, ptr);
+/**
+ * devm_mux_state_get_selected() - Get the mux-state for a device, with
+ *				   resource management.
+ * @dev: The device that needs a mux-state.
+ * @mux_name: The name identifying the mux-state.
+ *
+ * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
+ *
+ * The returned mux-state (if valid) is already selected.
+ *
+ * The mux-state will automatically be deselected and freed on release.
+ */
+struct mux_state *devm_mux_state_get_selected(struct device *dev, const char *mux_name)
+{
+	return __devm_mux_state_get(dev, mux_name, false, mux_state_select, mux_state_deselect);
+}
+EXPORT_SYMBOL_GPL(devm_mux_state_get_selected);
 
-	return mstate;
+/**
+ * devm_mux_state_get_optional_selected() - Get the optional mux-state for
+ *					    a device, with resource management.
+ * @dev: The device that needs a mux-state.
+ * @mux_name: The name identifying the mux-state.
+ *
+ * Return: Pointer to the mux-state on success, an ERR_PTR with a negative
+ * errno on error, or NULL if mux doesn't exist.
+ *
+ * The returned mux-state (if valid) is already selected.
+ *
+ * The mux-state will automatically be deselected and freed on release.
+ */
+struct mux_state *devm_mux_state_get_optional_selected(struct device *dev,
+						       const char *mux_name)
+{
+	return __devm_mux_state_get(dev, mux_name, true, mux_state_select, mux_state_deselect);
 }
-EXPORT_SYMBOL_GPL(devm_mux_state_get);
+EXPORT_SYMBOL_GPL(devm_mux_state_get_optional_selected);
 
 /*
  * Using subsys_initcall instead of module_init here to try to ensure - for
diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h
index 2e25c838f831..a961861a503b 100644
--- a/include/linux/mux/consumer.h
+++ b/include/linux/mux/consumer.h
@@ -16,6 +16,8 @@ struct device;
 struct mux_control;
 struct mux_state;
 
+#if IS_ENABLED(CONFIG_MULTIPLEXER)
+
 unsigned int mux_control_states(struct mux_control *mux);
 int __must_check mux_control_select_delay(struct mux_control *mux,
 					  unsigned int state,
@@ -54,11 +56,109 @@ int mux_control_deselect(struct mux_control *mux);
 int mux_state_deselect(struct mux_state *mstate);
 
 struct mux_control *mux_control_get(struct device *dev, const char *mux_name);
+struct mux_control *mux_control_get_optional(struct device *dev, const char *mux_name);
 void mux_control_put(struct mux_control *mux);
 
-struct mux_control *devm_mux_control_get(struct device *dev,
-					 const char *mux_name);
-struct mux_state *devm_mux_state_get(struct device *dev,
-				     const char *mux_name);
+struct mux_control *devm_mux_control_get(struct device *dev, const char *mux_name);
+struct mux_state *devm_mux_state_get(struct device *dev, const char *mux_name);
+struct mux_state *devm_mux_state_get_optional(struct device *dev, const char *mux_name);
+struct mux_state *devm_mux_state_get_selected(struct device *dev, const char *mux_name);
+struct mux_state *devm_mux_state_get_optional_selected(struct device *dev, const char *mux_name);
+
+#else
+
+static inline unsigned int mux_control_states(struct mux_control *mux)
+{
+	return 0;
+}
+static inline int __must_check mux_control_select_delay(struct mux_control *mux,
+							unsigned int state, unsigned int delay_us)
+{
+	return -EOPNOTSUPP;
+}
+static inline int __must_check mux_state_select_delay(struct mux_state *mstate,
+						      unsigned int delay_us)
+{
+	return -EOPNOTSUPP;
+}
+static inline int __must_check mux_control_try_select_delay(struct mux_control *mux,
+							    unsigned int state,
+							    unsigned int delay_us)
+{
+	return -EOPNOTSUPP;
+}
+static inline int __must_check mux_state_try_select_delay(struct mux_state *mstate,
+							  unsigned int delay_us)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __must_check mux_control_select(struct mux_control *mux,
+						  unsigned int state)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __must_check mux_state_select(struct mux_state *mstate)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __must_check mux_control_try_select(struct mux_control *mux,
+						      unsigned int state)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __must_check mux_state_try_select(struct mux_state *mstate)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int mux_control_deselect(struct mux_control *mux)
+{
+	return -EOPNOTSUPP;
+}
+static inline int mux_state_deselect(struct mux_state *mstate)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct mux_control *mux_control_get_optional(struct device *dev,
+							   const char *mux_name)
+{
+	return NULL;
+}
+static inline void mux_control_put(struct mux_control *mux) {}
+
+static inline struct mux_control *devm_mux_control_get(struct device *dev, const char *mux_name)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct mux_state *devm_mux_state_get(struct device *dev, const char *mux_name)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct mux_state *devm_mux_state_get_optional(struct device *dev,
+							    const char *mux_name)
+{
+	return NULL;
+}
+static inline struct mux_state *devm_mux_state_get_selected(struct device *dev,
+							    const char *mux_name)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct mux_state *devm_mux_state_get_optional_selected(struct device *dev,
+								     const char *mux_name)
+{
+	return NULL;
+}
+
+#endif /* CONFIG_MULTIPLEXER */
 
 #endif /* _LINUX_MUX_CONSUMER_H */

-- 
2.43.0

[PATCH v11 4/9] phy: can-transceiver: drop temporary helper getting optional mux-state

[Josua Mayer]

Multiplexer subsystem has now added helpers for getting managed optional
mux-state.

Switch to the new devm_mux_state_get_optional helper.

This change is only compile-tested.

Acked-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/phy/phy-can-transceiver.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/drivers/phy/phy-can-transceiver.c b/drivers/phy/phy-can-transceiver.c
index fcbca9d2bded..2b52e47f247a 100644
--- a/drivers/phy/phy-can-transceiver.c
+++ b/drivers/phy/phy-can-transceiver.c
@@ -126,16 +126,6 @@ static const struct of_device_id can_transceiver_phy_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, can_transceiver_phy_ids);
 
-/* Temporary wrapper until the multiplexer subsystem supports optional muxes */
-static inline struct mux_state *
-can_transceiver_phy_mux_state_get_optional(struct device *dev, const char *mux_name)
-{
-	if (!of_property_present(dev->of_node, "mux-states"))
-		return NULL;
-
-	return devm_mux_state_get(dev, mux_name);
-}
-
 static struct phy *can_transceiver_phy_xlate(struct device *dev,
 					     const struct of_phandle_args *args)
 {
@@ -183,7 +173,7 @@ static int can_transceiver_phy_probe(struct platform_device *pdev)
 	priv->num_ch = num_ch;
 	platform_set_drvdata(pdev, priv);
 
-	mux_state = can_transceiver_phy_mux_state_get_optional(dev, NULL);
+	mux_state = devm_mux_state_get_optional(dev, NULL);
 	if (IS_ERR(mux_state))
 		return PTR_ERR(mux_state);
 

-- 
2.43.0

[PATCH v11 5/9] phy: renesas: rcar-gen3-usb2: drop helper getting optional mux-state

[Josua Mayer]

Multiplexer subsystem has now added helpers for getting managed optional
mux-state.

Switch to the new devm_mux_state_get_optional_selected helper.

This change is only compile-tested.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/phy/renesas/phy-rcar-gen3-usb2.c | 30 ++----------------------------
 1 file changed, 2 insertions(+), 28 deletions(-)

diff --git a/drivers/phy/renesas/phy-rcar-gen3-usb2.c b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
index 1155b111420a..79e820e2fe55 100644
--- a/drivers/phy/renesas/phy-rcar-gen3-usb2.c
+++ b/drivers/phy/renesas/phy-rcar-gen3-usb2.c
@@ -939,21 +939,6 @@ static int rcar_gen3_phy_usb2_vbus_regulator_register(struct rcar_gen3_chan *cha
 	return rcar_gen3_phy_usb2_vbus_regulator_get_exclusive_enable(channel, enable);
 }
 
-/* Temporary wrapper until the multiplexer subsystem supports optional muxes */
-static inline struct mux_state *
-rcar_gen3_phy_mux_state_get_optional(struct device *dev, const char *mux_name)
-{
-	if (!of_property_present(dev->of_node, "mux-states"))
-		return NULL;
-
-	return devm_mux_state_get(dev, mux_name);
-}
-
-static void rcar_gen3_phy_mux_state_deselect(void *data)
-{
-	mux_state_deselect(data);
-}
-
 static int rcar_gen3_phy_usb2_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -1036,20 +1021,9 @@ static int rcar_gen3_phy_usb2_probe(struct platform_device *pdev)
 		phy_set_drvdata(channel->rphys[i].phy, &channel->rphys[i]);
 	}
 
-	mux_state = rcar_gen3_phy_mux_state_get_optional(dev, NULL);
+	mux_state = devm_mux_state_get_optional_selected(dev, NULL);
 	if (IS_ERR(mux_state))
-		return PTR_ERR(mux_state);
-	if (mux_state) {
-		ret = mux_state_select(mux_state);
-		if (ret)
-			return dev_err_probe(dev, ret, "Failed to select USB mux\n");
-
-		ret = devm_add_action_or_reset(dev, rcar_gen3_phy_mux_state_deselect,
-					       mux_state);
-		if (ret)
-			return dev_err_probe(dev, ret,
-					     "Failed to register USB mux state deselect\n");
-	}
+		return dev_err_probe(dev, PTR_ERR(mux_state), "Failed to get USB mux\n");
 
 	if (channel->phy_data->no_adp_ctrl && channel->is_otg_channel) {
 		ret = rcar_gen3_phy_usb2_vbus_regulator_register(channel);

-- 
2.43.0

[PATCH v11 6/9] i2c: omap: switch to new generic helper for getting selected mux-state

[Josua Mayer]

Multiplexer subsystem has added generic helper functions for getting an
already selected mux-state object.

Replace existing logic in probe with the equivalent helper function.

There is a functional difference in that the mux is now automatically
deselected on release, replacing the explicit mux_state_deselect call.

This change is only compile-tested.

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Andreas Kemnade <andreas@kemnade.info>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/i2c/busses/i2c-omap.c | 24 +++++-------------------
 1 file changed, 5 insertions(+), 19 deletions(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index d9f590f0c384..f02d294db42a 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -1453,27 +1453,16 @@ omap_i2c_probe(struct platform_device *pdev)
 				       (1000 * omap->speed / 8);
 	}
 
-	if (of_property_present(node, "mux-states")) {
-		struct mux_state *mux_state;
-
-		mux_state = devm_mux_state_get(&pdev->dev, NULL);
-		if (IS_ERR(mux_state)) {
-			r = PTR_ERR(mux_state);
-			dev_dbg(&pdev->dev, "failed to get I2C mux: %d\n", r);
-			goto err_put_pm;
-		}
-		omap->mux_state = mux_state;
-		r = mux_state_select(omap->mux_state);
-		if (r) {
-			dev_err(&pdev->dev, "failed to select I2C mux: %d\n", r);
-			goto err_put_pm;
-		}
+	omap->mux_state = devm_mux_state_get_optional_selected(&pdev->dev, NULL);
+	if (IS_ERR(omap->mux_state)) {
+		r = PTR_ERR(omap->mux_state);
+		goto err_put_pm;
 	}
 
 	/* reset ASAP, clearing any IRQs */
 	r = omap_i2c_init(omap);
 	if (r)
-		goto err_mux_state_deselect;
+		goto err_put_pm;
 
 	if (omap->rev < OMAP_I2C_OMAP1_REV_2)
 		r = devm_request_irq(&pdev->dev, omap->irq, omap_i2c_omap1_isr,
@@ -1515,9 +1504,6 @@ omap_i2c_probe(struct platform_device *pdev)
 
 err_unuse_clocks:
 	omap_i2c_write_reg(omap, OMAP_I2C_CON_REG, 0);
-err_mux_state_deselect:
-	if (omap->mux_state)
-		mux_state_deselect(omap->mux_state);
 err_put_pm:
 	pm_runtime_put_sync(omap->dev);
 err_disable_pm:

-- 
2.43.0

[PATCH v11 7/9] dt-bindings: mmc: renesas,sdhi: Add mux-states property

[Josua Mayer]

Add mux controller support for data or control lines that are muxed
between a host and multiple cards.

There are several devices supporting a choice of eMMC or SD on a single
board by both dip switch and gpio, e.g. Renesas RZ/G2L SMARC SoM and
SolidRun RZ/G2L SoM.

In-tree dts for the Renesas boards currently rely on preprocessor macros
and gpio hogs to describe the respective cards.

By adding mux-states property to sdhi controller description, boards can
correctly describe the mux that already exists in hardware - and drivers
can coordinate between mux selection and probing for cards.

Acked-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml b/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
index c754ea71f51f..64fac0d11329 100644
--- a/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
+++ b/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
@@ -106,6 +106,11 @@ properties:
   iommus:
     maxItems: 1
 
+  mux-states:
+    description:
+      mux controller node to route the SD/SDIO/eMMC signals from SoC to cards.
+    maxItems: 1
+
   power-domains:
     maxItems: 1
 
@@ -275,6 +280,7 @@ examples:
         max-frequency = <195000000>;
         power-domains = <&sysc R8A7790_PD_ALWAYS_ON>;
         resets = <&cpg 314>;
+        mux-states = <&mux 0>;
     };
 
     sdhi1: mmc@ee120000 {

-- 
2.43.0

[PATCH v11 8/9] mux: add visible config symbol to enable multiplexer subsystem

[Josua Mayer]

The multiplexer subsystem was initially designed to be completely
hidden, relying on consumers to "select MULTIPLEXER" explicitly.

Drivers implementing multiplexers depend on this hidden symbol.

This prevents users from manually enabling both the mux core and any of
the multiplexer drivers.

All multiplexer drivers in drivers/mux/ can operate standalone without a
consumer. This is particularly useful in a device-tree, where a default
state can be set through the idle-state property.

Over time, several drivers have added "select MULTIPLEXER" dependencies,
some of which require a mux and some consider it optional. v7.0-rc1
shows 15 such occurrences in Kconfig files, in a variety of subsystems.

The natural step forward to allow enabling mux core and drivers would be
adding a prompt and help text to the existing symbol.

This violates the general Kbuild advice to avoid selecting visible
symbols for all existing consumers of the mux core.

Add the new config symbol MUX_CORE with a prompt and help text as a
wrapper for users to enable manually. This avoids existing consumers
automatically selecting a visible symbol.

Change the MULTIPLEXER symbol from tristate to bool. This avoids complex
dependencies if users were to attempt a configuration where the mux is a
module but one of its consumers is built-in, as well as difficulties
keeping the state of visible and invisible symbols in sync.

Further convert the "menu ... depends on ..." structure to "if ... menu
... endmenu endif". These are functionally equivalent, but the new
structure is more efficient and can support future source statements
within the conditional block.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/mux/Kconfig | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
index c68132e38138..6d17dfa25dad 100644
--- a/drivers/mux/Kconfig
+++ b/drivers/mux/Kconfig
@@ -4,10 +4,21 @@
 #
 
 config MULTIPLEXER
-	tristate
+	bool
+
+config MUX_CORE
+	bool "Generic Multiplexer Support"
+	select MULTIPLEXER
+	help
+	  This framework is designed to abstract multiplexer handling for
+	  devices via various GPIO-, MMIO/Regmap or specific multiplexer
+	  controller chips.
+
+	  If unsure, say no.
+
+if MULTIPLEXER
 
 menu "Multiplexer drivers"
-	depends on MULTIPLEXER
 
 config MUX_ADG792A
 	tristate "Analog Devices ADG792A/ADG792G Multiplexers"
@@ -60,3 +71,5 @@ config MUX_MMIO
 	  be called mux-mmio.
 
 endmenu
+
+endif # MULTIPLEXER

-- 
2.43.0

[PATCH v11 9/9] mmc: host: renesas_sdhi_core: support selecting an optional mux

[Josua Mayer]

Some hardware designs route data or control signals through a mux to
support multiple devices on a single sdhi controller.

In particular SolidRun RZ/G2L/G2LC/V2L System on Module use a mux for
switching between soldered eMMC and an optional microSD on a carrier
board, e.g. for development or provisioning.

SD/SDIO/eMMC are not well suited for runtime switching between different
cards, however boot-time selection is possible and useful - in
particular considering dt overlays.

Add support for an optional SD/SDIO/eMMC mux defined in dt, and select
it during probe.

Similar functionality already exists in other places, e.g. i2c-omap.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
 drivers/mmc/host/renesas_sdhi_core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
index 2a310a145785..f9ec78d699f4 100644
--- a/drivers/mmc/host/renesas_sdhi_core.c
+++ b/drivers/mmc/host/renesas_sdhi_core.c
@@ -26,6 +26,7 @@
 #include <linux/mmc/mmc.h>
 #include <linux/mmc/slot-gpio.h>
 #include <linux/module.h>
+#include <linux/mux/consumer.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/pinctrl/pinctrl-state.h>
 #include <linux/platform_data/tmio.h>
@@ -1062,6 +1063,7 @@ int renesas_sdhi_probe(struct platform_device *pdev,
 	struct regulator_dev *rdev;
 	struct renesas_sdhi_dma *dma_priv;
 	struct device *dev = &pdev->dev;
+	struct mux_state *mux_state;
 	struct tmio_mmc_host *host;
 	struct renesas_sdhi *priv;
 	int num_irqs, irq, ret, i;
@@ -1116,6 +1118,10 @@ int renesas_sdhi_probe(struct platform_device *pdev,
 						"state_uhs");
 	}
 
+	mux_state = devm_mux_state_get_optional_selected(&pdev->dev, NULL);
+	if (IS_ERR(mux_state))
+		return PTR_ERR(mux_state);
+
 	host = tmio_mmc_host_alloc(pdev, mmc_data);
 	if (IS_ERR(host))
 		return PTR_ERR(host);

-- 
2.43.0

Re: [PATCH v11 1/9] phy: can-transceiver: rename temporary helper function to avoid conflict

[Vinod Koul]

On 26-02-26, 15:21, Josua Mayer wrote:
> Rename the temporary devm_mux_state_get_optional function to avoid
> conflict with upcoming implementation in multiplexer subsystem.

Acked-by: Vinod Koul <vkoul@kernel.org>

-- 
~Vinod

Re: [PATCH v11 2/9] phy: renesas: rcar-gen3-usb2: rename local mux helper to avoid conflict

[Vinod Koul]

On 26-02-26, 15:21, Josua Mayer wrote:
> Rename the temporary devm_mux_state_get_optional function to avoid
> conflict with upcoming implementation in multiplexer subsystem.

Acked-by: Vinod Koul <vkoul@kernel.org>

-- 
~Vinod

Re: [PATCH v11 5/9] phy: renesas: rcar-gen3-usb2: drop helper getting optional mux-state

[Vinod Koul]

On 26-02-26, 15:21, Josua Mayer wrote:
> Multiplexer subsystem has now added helpers for getting managed optional
> mux-state.
> 
> Switch to the new devm_mux_state_get_optional_selected helper.

Acked-by: Vinod Koul <vkoul@kernel.org>


-- 
~Vinod

Re: [PATCH v11 0/9] mmc: host: renesas_sdhi_core: support configuring an optional sdio mux

[Ulf Hansson]

On Thu, 26 Feb 2026 at 14:21, Josua Mayer <josua@solid-run.com> wrote:
>
> This series has evolved over time from adding generic mux support for
> renesas sdhi driver, to partial rewrite of the mux framework.
>
> Several drivers have started implementing driver-local managed and
> unmanaged helper functions for getting and selecting a mux-state object.
>
> mmc maintainers have requested that new code shall intreoduce and use
> generic helper functions that can be shared by all drivers, avoiding
> code duplication.
>
> This series is structured in 5 parts, each of which is self-sufficient
> depending only on the previous patches. This shall allow the first N
> patches to be applied even if the last ones need further discussion.
>
> 1. Rename driver-local helper functions to avoid name collision with
>    global version to be introduced later.
>
> 2. Implement generic device-managed helper functions in mux core.
>
> 3. Convert driver local code from similar patterns to use the newly
>    added global helpers.
>
> 4. Change mux-core Kconfig so that it can be enabled through menuconfig,
>    without an explicit "select" dependency from other drivers.
>
> 5. add dt bindings and driver support for mux in renesas sdhi driver.
>
> Signed-off-by: Josua Mayer <josua@solid-run.com>
> ---
> Changes in v11:
> - changed approach to Kconfig making MULTIPLEXER a bool, and adding a
>   user-visible wrapper for menuconfig.
>   (Reported-by: Ulf Hansson <ulf.hansson@linaro.org>)
> - dropped the "default m if COMPILE_TEST".
>   (Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>)
> - improved kerneldoc line wrapping.
> - removed unnecessary changes to original devm_mux_control-get.
> - fix "reference preceded by free" in mux_state_get function
> - Link to v10: https://lore.kernel.org/r/20260225-rz-sdio-mux-v10-0-1ee44f2ea112@solid-run.com
>

[...]

To me, this looks ready for a new try. Unless I hear some objections,
I intend to apply this as material for v7.1 via my mmc tree on Monday.

The complete series will be available on an immutable branch, for
other subsystem maintainers to pull in if that turns out to be needed.
I let you know of more details on Monday.

Kind regards
Uffe

Re: [PATCH v11 1/9] phy: can-transceiver: rename temporary helper function to avoid conflict

[Wolfram Sang]

On Thu, Feb 26, 2026 at 03:21:09PM +0200, Josua Mayer wrote:
> Rename the temporary devm_mux_state_get_optional function to avoid
> conflict with upcoming implementation in multiplexer subsystem.
> 
> Signed-off-by: Josua Mayer <josua@solid-run.com>

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Re: [PATCH v11 2/9] phy: renesas: rcar-gen3-usb2: rename local mux helper to avoid conflict

[Wolfram Sang]

On Thu, Feb 26, 2026 at 03:21:10PM +0200, Josua Mayer wrote:
> Rename the temporary devm_mux_state_get_optional function to avoid
> conflict with upcoming implementation in multiplexer subsystem.
> 
> Signed-off-by: Josua Mayer <josua@solid-run.com>

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Re: [PATCH v11 5/9] phy: renesas: rcar-gen3-usb2: drop helper getting optional mux-state

[Wolfram Sang]

On Thu, Feb 26, 2026 at 03:21:13PM +0200, Josua Mayer wrote:
> Multiplexer subsystem has now added helpers for getting managed optional
> mux-state.
> 
> Switch to the new devm_mux_state_get_optional_selected helper.
> 
> This change is only compile-tested.
> 
> Signed-off-by: Josua Mayer <josua@solid-run.com>

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Re: [PATCH v11 9/9] mmc: host: renesas_sdhi_core: support selecting an optional mux

[Wolfram Sang]

On Thu, Feb 26, 2026 at 03:21:17PM +0200, Josua Mayer wrote:
> Some hardware designs route data or control signals through a mux to
> support multiple devices on a single sdhi controller.
> 
> In particular SolidRun RZ/G2L/G2LC/V2L System on Module use a mux for
> switching between soldered eMMC and an optional microSD on a carrier
> board, e.g. for development or provisioning.
> 
> SD/SDIO/eMMC are not well suited for runtime switching between different
> cards, however boot-time selection is possible and useful - in
> particular considering dt overlays.
> 
> Add support for an optional SD/SDIO/eMMC mux defined in dt, and select
> it during probe.
> 
> Similar functionality already exists in other places, e.g. i2c-omap.
> 
> Signed-off-by: Josua Mayer <josua@solid-run.com>

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Re: [PATCH v11 0/9] mmc: host: renesas_sdhi_core: support configuring an optional sdio mux

[Ulf Hansson]

On Thu, 5 Mar 2026 at 17:19, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>
> On Thu, 26 Feb 2026 at 14:21, Josua Mayer <josua@solid-run.com> wrote:
> >
> > This series has evolved over time from adding generic mux support for
> > renesas sdhi driver, to partial rewrite of the mux framework.
> >
> > Several drivers have started implementing driver-local managed and
> > unmanaged helper functions for getting and selecting a mux-state object.
> >
> > mmc maintainers have requested that new code shall intreoduce and use
> > generic helper functions that can be shared by all drivers, avoiding
> > code duplication.
> >
> > This series is structured in 5 parts, each of which is self-sufficient
> > depending only on the previous patches. This shall allow the first N
> > patches to be applied even if the last ones need further discussion.
> >
> > 1. Rename driver-local helper functions to avoid name collision with
> >    global version to be introduced later.
> >
> > 2. Implement generic device-managed helper functions in mux core.
> >
> > 3. Convert driver local code from similar patterns to use the newly
> >    added global helpers.
> >
> > 4. Change mux-core Kconfig so that it can be enabled through menuconfig,
> >    without an explicit "select" dependency from other drivers.
> >
> > 5. add dt bindings and driver support for mux in renesas sdhi driver.
> >
> > Signed-off-by: Josua Mayer <josua@solid-run.com>
> > ---
> > Changes in v11:
> > - changed approach to Kconfig making MULTIPLEXER a bool, and adding a
> >   user-visible wrapper for menuconfig.
> >   (Reported-by: Ulf Hansson <ulf.hansson@linaro.org>)
> > - dropped the "default m if COMPILE_TEST".
> >   (Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>)
> > - improved kerneldoc line wrapping.
> > - removed unnecessary changes to original devm_mux_control-get.
> > - fix "reference preceded by free" in mux_state_get function
> > - Link to v10: https://lore.kernel.org/r/20260225-rz-sdio-mux-v10-0-1ee44f2ea112@solid-run.com
> >
>
> [...]
>
> To me, this looks ready for a new try. Unless I hear some objections,
> I intend to apply this as material for v7.1 via my mmc tree on Monday.
>
> The complete series will be available on an immutable branch, for
> other subsystem maintainers to pull in if that turns out to be needed.
> I let you know of more details on Monday.

I have now queued up this series for v7.1 via my next branch.

The series is also available at the immutable "mux" branch (based on
v7.0-rc1) via my mmc tree, which other subsystem maintainers can pull
in if needed.

Kind regards
Uffe