Re: [PATCH v10 3/9] mux: Add helper functions for getting optional and selected mux-state

Re: [PATCH v10 3/9] mux: Add helper functions for getting optional and selected mux-state

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
In-Reply-To: <20260225-rz-sdio-mux-v10-3-1ee44f2ea112@solid-run.com>
References: <20260225-rz-sdio-mux-v10-3-1ee44f2ea112@solid-run.com>
TO: Josua Mayer <josua@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@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-dev@sang-engineering.com>
TO: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
CC: Yazan Shhady <yazan.shhady@solid-run.com>
CC: Jon Nettleton <jon@solid-run.com>
CC: Vladimir Oltean <olteanv@gmail.com>
CC: Mikhail Anikin <mikhail.anikin@solid-run.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

Hi Josua,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f]

url:    https://github.com/intel-lab-lkp/linux/commits/Josua-Mayer/phy-can-transceiver-rename-temporary-helper-function-to-avoid-conflict/20260225-194325
base:   6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
patch link:    https://lore.kernel.org/r/20260225-rz-sdio-mux-v10-3-1ee44f2ea112%40solid-run.com
patch subject: [PATCH v10 3/9] mux: Add helper functions for getting optional and selected mux-state
:::::: branch date: 4 hours ago
:::::: commit date: 4 hours ago
config: sparc-randconfig-r053-20260225 (https://download.01.org/0day-ci/archive/20260225/202602252310.2cVbnvYP-lkp@intel.com/config)
compiler: sparc-linux-gcc (GCC) 13.4.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Julia Lawall <julia.lawall@inria.fr>
| Closes: https://lore.kernel.org/r/202602252310.2cVbnvYP-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> drivers/mux/core.c:733:18-24: ERROR: reference preceded by free on line 732

vim +733 drivers/mux/core.c

a3b02a9c6591ce drivers/mux/mux-core.c Peter Rosin    2017-05-14  712  
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25  713  /**
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  714   * mux_state_get() - Get the mux-state for a device.
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  715   * @dev: The device that needs a mux-state.
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  716   * @mux_name: The name identifying the mux-state.
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25  717   * @optional: Whether to return NULL and silence errors when mux doesn't exist.
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  718   *
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25  719   * Return: Pointer to the mux-state on success, an ERR_PTR with a negative errno on error,
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25  720   * or NULL if optional is true and mux doesn't exist.
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  721   */
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25  722  static struct mux_state *mux_state_get(struct device *dev, const char *mux_name, bool optional)
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  723  {
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  724  	struct mux_state *mstate;
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  725  
bf4afc53b77aea drivers/mux/core.c     Linus Torvalds 2026-02-21  726  	mstate = kzalloc_obj(*mstate);
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  727  	if (!mstate)
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  728  		return ERR_PTR(-ENOMEM);
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  729  
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25  730  	mstate->mux = mux_get(dev, mux_name, &mstate->state, optional);
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  731  	if (IS_ERR(mstate->mux)) {
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07 @732  		kfree(mstate);
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25 @733  		return ERR_CAST(mstate->mux);
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25  734  	} else if (optional && !mstate->mux) {
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25  735  		kfree(mstate);
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25  736  		return NULL;
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25  737  	} else if (!mstate->mux) {
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25  738  		kfree(mstate);
a67ef2fe0fda72 drivers/mux/core.c     Josua Mayer    2026-02-25  739  		return ERR_PTR(-ENOENT);
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  740  	}
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  741  
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  742  	return mstate;
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  743  }
6632866df852bd drivers/mux/core.c     Peter Rosin    2022-01-07  744  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

[PATCH v10 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 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 prompt and help text to CONFIG_MULTIPLEXER making it visible
      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/Kconfig                           |   1 +
 drivers/mmc/host/renesas_sdhi_core.c               |   6 +
 drivers/mux/Kconfig                                |   9 +-
 drivers/mux/core.c                                 | 206 +++++++++++++++++----
 drivers/phy/phy-can-transceiver.c                  |  10 -
 drivers/phy/renesas/phy-rcar-gen3-usb2.c           |  30 +--
 include/linux/mux/consumer.h                       | 108 ++++++++++-
 9 files changed, 307 insertions(+), 93 deletions(-)
---
base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
change-id: 20251128-rz-sdio-mux-acc5137f1618

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

[PATCH v10 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           | 206 ++++++++++++++++++++++++++++++++++++-------
 include/linux/mux/consumer.h | 108 ++++++++++++++++++++++-
 2 files changed, 279 insertions(+), 35 deletions(-)

diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index f09ee8782e3d..6033da0a9e17 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-state 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.
@@ -657,10 +694,13 @@ struct mux_control *devm_mux_control_get(struct device *dev,
 	if (!ptr)
 		return ERR_PTR(-ENOMEM);
 
-	mux = mux_control_get(dev, mux_name);
+	mux = mux_get(dev, mux_name, NULL, false);
 	if (IS_ERR(mux)) {
 		devres_free(ptr);
 		return mux;
+	} else if (!mux) {
+		devres_free(ptr);
+		return ERR_PTR(-ENOENT);
 	}
 
 	*ptr = mux;
@@ -670,14 +710,16 @@ 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 +727,16 @@ 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);
+		return ERR_CAST(mstate->mux);
+	} else if (optional && !mstate->mux) {
+		kfree(mstate);
+		return NULL;
+	} else if (!mstate->mux) {
+		kfree(mstate);
+		return ERR_PTR(-ENOENT);
 	}
 
 	return mstate;
@@ -710,9 +756,66 @@ 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 +825,69 @@ 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 v10 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           | 206 ++++++++++++++++++++++++++++++++++++-------
 include/linux/mux/consumer.h | 108 ++++++++++++++++++++++-
 2 files changed, 279 insertions(+), 35 deletions(-)

diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index f09ee8782e3d..6033da0a9e17 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-state 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.
@@ -657,10 +694,13 @@ struct mux_control *devm_mux_control_get(struct device *dev,
 	if (!ptr)
 		return ERR_PTR(-ENOMEM);
 
-	mux = mux_control_get(dev, mux_name);
+	mux = mux_get(dev, mux_name, NULL, false);
 	if (IS_ERR(mux)) {
 		devres_free(ptr);
 		return mux;
+	} else if (!mux) {
+		devres_free(ptr);
+		return ERR_PTR(-ENOENT);
 	}
 
 	*ptr = mux;
@@ -670,14 +710,16 @@ 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 +727,16 @@ 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);
+		return ERR_CAST(mstate->mux);
+	} else if (optional && !mstate->mux) {
+		kfree(mstate);
+		return NULL;
+	} else if (!mstate->mux) {
+		kfree(mstate);
+		return ERR_PTR(-ENOENT);
 	}
 
 	return mstate;
@@ -710,9 +756,66 @@ 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 +825,69 @@ 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


-- 
linux-phy mailing list
linux-phy@lists.infradead.org
https://lists.infradead.org/mailman/listinfo/linux-phy

Re: [PATCH v10 3/9] mux: Add helper functions for getting optional and selected mux-state

[Josua Mayer]

Am 25.02.26 um 12:34 schrieb 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           | 206 ++++++++++++++++++++++++++++++++++++-------
>  include/linux/mux/consumer.h | 108 ++++++++++++++++++++++-
>  2 files changed, 279 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/mux/core.c b/drivers/mux/core.c
> index f09ee8782e3d..6033da0a9e17 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-state 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.
> @@ -657,10 +694,13 @@ struct mux_control *devm_mux_control_get(struct device *dev,
>  	if (!ptr)
>  		return ERR_PTR(-ENOMEM);
>  
> -	mux = mux_control_get(dev, mux_name);
> +	mux = mux_get(dev, mux_name, NULL, false);
>  	if (IS_ERR(mux)) {
>  		devres_free(ptr);
>  		return mux;
> +	} else if (!mux) {
> +		devres_free(ptr);
> +		return ERR_PTR(-ENOENT);
>  	}
>  
>  	*ptr = mux;
> @@ -670,14 +710,16 @@ 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 +727,16 @@ 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);
> +		return ERR_CAST(mstate->mux);
kernel robot found a use-after-free here which I will resolve for v11.
> +	} else if (optional && !mstate->mux) {
> +		kfree(mstate);
> +		return NULL;
> +	} else if (!mstate->mux) {
> +		kfree(mstate);
> +		return ERR_PTR(-ENOENT);
>  	}
>  
>  	return mstate;
> @@ -710,9 +756,66 @@ 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 +825,69 @@ 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 */
>

Re: [PATCH v10 3/9] mux: Add helper functions for getting optional and selected mux-state

[Josua Mayer]

Am 25.02.26 um 12:34 schrieb 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           | 206 ++++++++++++++++++++++++++++++++++++-------
>  include/linux/mux/consumer.h | 108 ++++++++++++++++++++++-
>  2 files changed, 279 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/mux/core.c b/drivers/mux/core.c
> index f09ee8782e3d..6033da0a9e17 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-state 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.
> @@ -657,10 +694,13 @@ struct mux_control *devm_mux_control_get(struct device *dev,
>  	if (!ptr)
>  		return ERR_PTR(-ENOMEM);
>  
> -	mux = mux_control_get(dev, mux_name);
> +	mux = mux_get(dev, mux_name, NULL, false);
>  	if (IS_ERR(mux)) {
>  		devres_free(ptr);
>  		return mux;
> +	} else if (!mux) {
> +		devres_free(ptr);
> +		return ERR_PTR(-ENOENT);
>  	}
>  
>  	*ptr = mux;
> @@ -670,14 +710,16 @@ 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 +727,16 @@ 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);
> +		return ERR_CAST(mstate->mux);
kernel robot found a use-after-free here which I will resolve for v11.
> +	} else if (optional && !mstate->mux) {
> +		kfree(mstate);
> +		return NULL;
> +	} else if (!mstate->mux) {
> +		kfree(mstate);
> +		return ERR_PTR(-ENOENT);
>  	}
>  
>  	return mstate;
> @@ -710,9 +756,66 @@ 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 +825,69 @@ 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 */
>
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