Re: [PATCH 02/11] mux: core: Add support for getting a mux controller on a non DT platform

[Hans de Goede]

Hi,

On 04-09-17 13:19, Peter Rosin wrote:

Hi!

Some comments inline...

On 2017-09-01 23:48, Hans de Goede wrote:

On non DT platforms we cannot get the mux_chip by pnode. Other subsystems
(regulator, clock, pwm) have the same problem and solve this by allowing
platform / board-setup code to add entries to a lookup table and then use
this table to look things up.

This commit adds support for getting a mux controller on a non DT platform
following this pattern. It is based on a simplified version of the pwm
subsys lookup code, the dev_id and mux_name parts of a lookup table entry
are mandatory in the mux-core implementation.

Signed-off-by: Hans de Goede 
---
  drivers/mux/core.c   | 96 +++-
  include/linux/mux/consumer.h | 11 +
  2 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index 6142493c327b..8864cc745506 100644
--- a/drivers/mux/core.c
+++ b/drivers/mux/core.c
@@ -24,6 +24,9 @@
  #include 
  #include 
  
+static DEFINE_MUTEX(mux_lookup_lock);

+static LIST_HEAD(mux_lookup_list);
+
  /*
   * The idle-as-is "state" is not an actual state that may be selected, it
   * only implies that the state should not be changed. So, use that state
@@ -408,6 +411,23 @@ int mux_control_deselect(struct mux_control *mux)
  }
  EXPORT_SYMBOL_GPL(mux_control_deselect);
  
+static int parent_name_match(struct device *dev, const void *data)

+{
+   const char *parent_name = dev_name(dev->parent);
+   const char *name = data;
+
+   return strcmp(parent_name, name) == 0;
+}
+
+static struct mux_chip *mux_chip_get_by_name(const char *name)
+{
+   struct device *dev;
+
+   dev = class_find_device(_class, NULL, name, parent_name_match);
+
+   return dev ? to_mux_chip(dev) : NULL;
+}
+
  static int of_dev_node_match(struct device *dev, const void *data)
  {
return dev->of_node == data;
@@ -479,6 +499,42 @@ static struct mux_control *of_mux_control_get(struct 
device *dev,
  }
  
  /**

+ * mux_add_table() - register PWM device consumers


register mux controllers (because you are not registering consumers, right?
someone is registering controllers so that they can be found by consumers?)



Actually what is being registered is a "consumer to mux-controller mapping",
I will update the kernel-doc comments to use that everywhere.




+ * @table: array of consumers to register
+ * @num: number of consumers in table


controllers?


mappings :)


+ */
+void mux_add_table(struct mux_lookup *table, size_t num)
+{
+   mutex_lock(_lookup_lock);
+
+   while (num--) {
+   list_add_tail(>list, _lookup_list);
+   table++;
+   }


I prefer

for (; num--; table++)
list_add_tail(>list, _lookup_list);


Sure, works for me.


+
+   mutex_unlock(_lookup_lock);
+}
+EXPORT_SYMBOL_GPL(mux_add_table);
+
+/**
+ * mux_remove_table() - unregister PWM device consumers


unregister mux controllers(?)


+ * @table: array of consumers to unregister
+ * @num: number of consumers in table


controllers?


+ */
+void mux_remove_table(struct mux_lookup *table, size_t num)
+{
+   mutex_lock(_lookup_lock);
+
+   while (num--) {
+   list_del(>list);
+   table++;
+   }


for() loop here as well.


Ack.


+
+   mutex_unlock(_lookup_lock);
+}
+EXPORT_SYMBOL_GPL(mux_remove_table);
+
+/**
   * mux_control_get() - Get the mux-control for a device.
   * @dev: The device that needs a mux-control.
   * @mux_name: The name identifying the mux-control.
@@ -487,11 +543,49 @@ static struct mux_control *of_mux_control_get(struct 
device *dev,
   */
  struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
  {
+   struct mux_lookup *m, *chosen = NULL;
+   const char *dev_id = dev_name(dev);
+   struct mux_chip *mux_chip;
+
/* look up via DT first */
if (IS_ENABLED(CONFIG_OF) && dev->of_node)
return of_mux_control_get(dev, mux_name);
  
-	return ERR_PTR(-ENODEV);

+   /*
+* For non DT we look up the provider in the static table typically
+* provided by board setup code.
+*
+* If a match is found, the provider mux chip is looked up by name
+* and a mux-control is requested using the table provided index.
+*/
+   mutex_lock(_lookup_lock);
+   list_for_each_entry(m, _lookup_list, list) {
+   if (WARN_ON(!m->dev_id || !m->mux_name || !m->provider))
+   continue;
+
+   if (strcmp(m->dev_id, dev_id) == 0 &&
+   strcmp(m->mux_name, mux_name) == 0) {


I want the below format (with ! instead of == 0 and the brace on the next line
when the condition has a line break):


Ok, I think checkpatch is going to not like that "{" there, but
I'm fine with putting it there.


if (!strcmp(m->dev_id, dev_id) &&

Re: [PATCH 02/11] mux: core: Add support for getting a mux controller on a non DT platform

[Hans de Goede]

Hi,

On 02-09-17 21:13, sathya wrote:

Hi,


On 09/01/2017 02:48 PM, Hans de Goede wrote:

On non DT platforms we cannot get the mux_chip by pnode. Other subsystems
(regulator, clock, pwm) have the same problem and solve this by allowing
platform / board-setup code to add entries to a lookup table and then use
this table to look things up.

This commit adds support for getting a mux controller on a non DT platform
following this pattern. It is based on a simplified version of the pwm
subsys lookup code, the dev_id and mux_name parts of a lookup table entry
are mandatory in the mux-core implementation.

Signed-off-by: Hans de Goede 
---
  drivers/mux/core.c   | 96 +++-
  include/linux/mux/consumer.h | 11 +
  2 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index 6142493c327b..8864cc745506 100644
--- a/drivers/mux/core.c
+++ b/drivers/mux/core.c
@@ -24,6 +24,9 @@
  #include 
  #include 
+static DEFINE_MUTEX(mux_lookup_lock);
+static LIST_HEAD(mux_lookup_list);
+
  /*
   * The idle-as-is "state" is not an actual state that may be selected, it
   * only implies that the state should not be changed. So, use that state
@@ -408,6 +411,23 @@ int mux_control_deselect(struct mux_control *mux)
  }
  EXPORT_SYMBOL_GPL(mux_control_deselect);
+static int parent_name_match(struct device *dev, const void *data)
+{
+const char *parent_name = dev_name(dev->parent);

Device name usually contains id section (devname.id). Did you take this into 
consideration ?

+const char *name = data;
+
+return strcmp(parent_name, name) == 0;
+}
+
+static struct mux_chip *mux_chip_get_by_name(const char *name)
+{
+struct device *dev;
+
+dev = class_find_device(_class, NULL, name, parent_name_match);
+
+return dev ? to_mux_chip(dev) : NULL;
+}
+
  static int of_dev_node_match(struct device *dev, const void *data)
  {
  return dev->of_node == data;
@@ -479,6 +499,42 @@ static struct mux_control *of_mux_control_get(struct 
device *dev,
  }
  /**
+ * mux_add_table() - register PWM device consumers

PWM -> MUX


Thank you, good catch, fixed for v2.

Regards,

Hans



+ * @table: array of consumers to register
+ * @num: number of consumers in table
+ */
+void mux_add_table(struct mux_lookup *table, size_t num)
+{
+mutex_lock(_lookup_lock);
+
+while (num--) {
+list_add_tail(>list, _lookup_list);
+table++;
+}
+
+mutex_unlock(_lookup_lock);
+}
+EXPORT_SYMBOL_GPL(mux_add_table);
+
+/**
+ * mux_remove_table() - unregister PWM device consumers
+ * @table: array of consumers to unregister
+ * @num: number of consumers in table
+ */
+void mux_remove_table(struct mux_lookup *table, size_t num)
+{
+mutex_lock(_lookup_lock);
+
+while (num--) {
+list_del(>list);
+table++;
+}
+
+mutex_unlock(_lookup_lock);
+}
+EXPORT_SYMBOL_GPL(mux_remove_table);
+
+/**
   * mux_control_get() - Get the mux-control for a device.
   * @dev: The device that needs a mux-control.
   * @mux_name: The name identifying the mux-control.
@@ -487,11 +543,49 @@ static struct mux_control *of_mux_control_get(struct 
device *dev,
   */
  struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
  {
+struct mux_lookup *m, *chosen = NULL;
+const char *dev_id = dev_name(dev);
+struct mux_chip *mux_chip;
+
  /* look up via DT first */
  if (IS_ENABLED(CONFIG_OF) && dev->of_node)
  return of_mux_control_get(dev, mux_name);
-return ERR_PTR(-ENODEV);
+/*
+ * For non DT we look up the provider in the static table typically
+ * provided by board setup code.
+ *
+ * If a match is found, the provider mux chip is looked up by name
+ * and a mux-control is requested using the table provided index.
+ */
+mutex_lock(_lookup_lock);
+list_for_each_entry(m, _lookup_list, list) {
+if (WARN_ON(!m->dev_id || !m->mux_name || !m->provider))
+continue;
+
+if (strcmp(m->dev_id, dev_id) == 0 &&
+strcmp(m->mux_name, mux_name) == 0) {
+chosen = m;
+break;
+}
+}
+mutex_unlock(_lookup_lock);
+
+if (!chosen)
+return ERR_PTR(-ENODEV);
+
+mux_chip = mux_chip_get_by_name(chosen->provider);
+if (!mux_chip)
+return ERR_PTR(-EPROBE_DEFER);
+
+if (chosen->index >= mux_chip->controllers) {
+dev_err(dev, "Mux lookup table index out of bounds %u >= %u\n",
+chosen->index, mux_chip->controllers);
+put_device(_chip->dev);
+return ERR_PTR(-EINVAL);
+}
+
+return _chip->mux[chosen->index];
  }
  EXPORT_SYMBOL_GPL(mux_control_get);
diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h
index ea96d4c82be7..912dd48a3a5d 100644
--- a/include/linux/mux/consumer.h
+++ b/include/linux/mux/consumer.h
@@ -18,6 +18,17 @@
  struct device;
  struct mux_control;
+struct 

Re: [PATCH 02/11] mux: core: Add support for getting a mux controller on a non DT platform

[Peter Rosin]

Hi!

Some comments inline...

On 2017-09-01 23:48, Hans de Goede wrote:
> On non DT platforms we cannot get the mux_chip by pnode. Other subsystems
> (regulator, clock, pwm) have the same problem and solve this by allowing
> platform / board-setup code to add entries to a lookup table and then use
> this table to look things up.
> 
> This commit adds support for getting a mux controller on a non DT platform
> following this pattern. It is based on a simplified version of the pwm
> subsys lookup code, the dev_id and mux_name parts of a lookup table entry
> are mandatory in the mux-core implementation.
> 
> Signed-off-by: Hans de Goede 
> ---
>  drivers/mux/core.c   | 96 
> +++-
>  include/linux/mux/consumer.h | 11 +
>  2 files changed, 106 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mux/core.c b/drivers/mux/core.c
> index 6142493c327b..8864cc745506 100644
> --- a/drivers/mux/core.c
> +++ b/drivers/mux/core.c
> @@ -24,6 +24,9 @@
>  #include 
>  #include 
>  
> +static DEFINE_MUTEX(mux_lookup_lock);
> +static LIST_HEAD(mux_lookup_list);
> +
>  /*
>   * The idle-as-is "state" is not an actual state that may be selected, it
>   * only implies that the state should not be changed. So, use that state
> @@ -408,6 +411,23 @@ int mux_control_deselect(struct mux_control *mux)
>  }
>  EXPORT_SYMBOL_GPL(mux_control_deselect);
>  
> +static int parent_name_match(struct device *dev, const void *data)
> +{
> + const char *parent_name = dev_name(dev->parent);
> + const char *name = data;
> +
> + return strcmp(parent_name, name) == 0;
> +}
> +
> +static struct mux_chip *mux_chip_get_by_name(const char *name)
> +{
> + struct device *dev;
> +
> + dev = class_find_device(_class, NULL, name, parent_name_match);
> +
> + return dev ? to_mux_chip(dev) : NULL;
> +}
> +
>  static int of_dev_node_match(struct device *dev, const void *data)
>  {
>   return dev->of_node == data;
> @@ -479,6 +499,42 @@ static struct mux_control *of_mux_control_get(struct 
> device *dev,
>  }
>  
>  /**
> + * mux_add_table() - register PWM device consumers

register mux controllers (because you are not registering consumers, right?
someone is registering controllers so that they can be found by consumers?)

> + * @table: array of consumers to register
> + * @num: number of consumers in table

controllers?

> + */
> +void mux_add_table(struct mux_lookup *table, size_t num)
> +{
> + mutex_lock(_lookup_lock);
> +
> + while (num--) {
> + list_add_tail(>list, _lookup_list);
> + table++;
> + }

I prefer

for (; num--; table++)
list_add_tail(>list, _lookup_list);

> +
> + mutex_unlock(_lookup_lock);
> +}
> +EXPORT_SYMBOL_GPL(mux_add_table);
> +
> +/**
> + * mux_remove_table() - unregister PWM device consumers

unregister mux controllers(?)

> + * @table: array of consumers to unregister
> + * @num: number of consumers in table

controllers?

> + */
> +void mux_remove_table(struct mux_lookup *table, size_t num)
> +{
> + mutex_lock(_lookup_lock);
> +
> + while (num--) {
> + list_del(>list);
> + table++;
> + }

for() loop here as well.

> +
> + mutex_unlock(_lookup_lock);
> +}
> +EXPORT_SYMBOL_GPL(mux_remove_table);
> +
> +/**
>   * mux_control_get() - Get the mux-control for a device.
>   * @dev: The device that needs a mux-control.
>   * @mux_name: The name identifying the mux-control.
> @@ -487,11 +543,49 @@ static struct mux_control *of_mux_control_get(struct 
> device *dev,
>   */
>  struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
>  {
> + struct mux_lookup *m, *chosen = NULL;
> + const char *dev_id = dev_name(dev);
> + struct mux_chip *mux_chip;
> +
>   /* look up via DT first */
>   if (IS_ENABLED(CONFIG_OF) && dev->of_node)
>   return of_mux_control_get(dev, mux_name);
>  
> - return ERR_PTR(-ENODEV);
> + /*
> +  * For non DT we look up the provider in the static table typically
> +  * provided by board setup code.
> +  *
> +  * If a match is found, the provider mux chip is looked up by name
> +  * and a mux-control is requested using the table provided index.
> +  */
> + mutex_lock(_lookup_lock);
> + list_for_each_entry(m, _lookup_list, list) {
> + if (WARN_ON(!m->dev_id || !m->mux_name || !m->provider))
> + continue;
> +
> + if (strcmp(m->dev_id, dev_id) == 0 &&
> + strcmp(m->mux_name, mux_name) == 0) {

I want the below format (with ! instead of == 0 and the brace on the next line
when the condition has a line break):

if (!strcmp(m->dev_id, dev_id) &&
!strcmp(m->mux_name, mux_name))
{

> + chosen = m;
> + break;
> + }
> + }
> + mutex_unlock(_lookup_lock);
> +
> + if 

Re: [PATCH 02/11] mux: core: Add support for getting a mux controller on a non DT platform

[sathya]

Hi,


On 09/01/2017 02:48 PM, Hans de Goede wrote:

On non DT platforms we cannot get the mux_chip by pnode. Other subsystems
(regulator, clock, pwm) have the same problem and solve this by allowing
platform / board-setup code to add entries to a lookup table and then use
this table to look things up.

This commit adds support for getting a mux controller on a non DT platform
following this pattern. It is based on a simplified version of the pwm
subsys lookup code, the dev_id and mux_name parts of a lookup table entry
are mandatory in the mux-core implementation.

Signed-off-by: Hans de Goede 
---
  drivers/mux/core.c   | 96 +++-
  include/linux/mux/consumer.h | 11 +
  2 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index 6142493c327b..8864cc745506 100644
--- a/drivers/mux/core.c
+++ b/drivers/mux/core.c
@@ -24,6 +24,9 @@
  #include 
  #include 
  
+static DEFINE_MUTEX(mux_lookup_lock);

+static LIST_HEAD(mux_lookup_list);
+
  /*
   * The idle-as-is "state" is not an actual state that may be selected, it
   * only implies that the state should not be changed. So, use that state
@@ -408,6 +411,23 @@ int mux_control_deselect(struct mux_control *mux)
  }
  EXPORT_SYMBOL_GPL(mux_control_deselect);
  
+static int parent_name_match(struct device *dev, const void *data)

+{
+   const char *parent_name = dev_name(dev->parent);
Device name usually contains id section (devname.id). Did you take this 
into consideration ?

+   const char *name = data;
+
+   return strcmp(parent_name, name) == 0;
+}
+
+static struct mux_chip *mux_chip_get_by_name(const char *name)
+{
+   struct device *dev;
+
+   dev = class_find_device(_class, NULL, name, parent_name_match);
+
+   return dev ? to_mux_chip(dev) : NULL;
+}
+
  static int of_dev_node_match(struct device *dev, const void *data)
  {
return dev->of_node == data;
@@ -479,6 +499,42 @@ static struct mux_control *of_mux_control_get(struct 
device *dev,
  }
  
  /**

+ * mux_add_table() - register PWM device consumers

PWM -> MUX

+ * @table: array of consumers to register
+ * @num: number of consumers in table
+ */
+void mux_add_table(struct mux_lookup *table, size_t num)
+{
+   mutex_lock(_lookup_lock);
+
+   while (num--) {
+   list_add_tail(>list, _lookup_list);
+   table++;
+   }
+
+   mutex_unlock(_lookup_lock);
+}
+EXPORT_SYMBOL_GPL(mux_add_table);
+
+/**
+ * mux_remove_table() - unregister PWM device consumers
+ * @table: array of consumers to unregister
+ * @num: number of consumers in table
+ */
+void mux_remove_table(struct mux_lookup *table, size_t num)
+{
+   mutex_lock(_lookup_lock);
+
+   while (num--) {
+   list_del(>list);
+   table++;
+   }
+
+   mutex_unlock(_lookup_lock);
+}
+EXPORT_SYMBOL_GPL(mux_remove_table);
+
+/**
   * mux_control_get() - Get the mux-control for a device.
   * @dev: The device that needs a mux-control.
   * @mux_name: The name identifying the mux-control.
@@ -487,11 +543,49 @@ static struct mux_control *of_mux_control_get(struct 
device *dev,
   */
  struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
  {
+   struct mux_lookup *m, *chosen = NULL;
+   const char *dev_id = dev_name(dev);
+   struct mux_chip *mux_chip;
+
/* look up via DT first */
if (IS_ENABLED(CONFIG_OF) && dev->of_node)
return of_mux_control_get(dev, mux_name);
  
-	return ERR_PTR(-ENODEV);

+   /*
+* For non DT we look up the provider in the static table typically
+* provided by board setup code.
+*
+* If a match is found, the provider mux chip is looked up by name
+* and a mux-control is requested using the table provided index.
+*/
+   mutex_lock(_lookup_lock);
+   list_for_each_entry(m, _lookup_list, list) {
+   if (WARN_ON(!m->dev_id || !m->mux_name || !m->provider))
+   continue;
+
+   if (strcmp(m->dev_id, dev_id) == 0 &&
+   strcmp(m->mux_name, mux_name) == 0) {
+   chosen = m;
+   break;
+   }
+   }
+   mutex_unlock(_lookup_lock);
+
+   if (!chosen)
+   return ERR_PTR(-ENODEV);
+
+   mux_chip = mux_chip_get_by_name(chosen->provider);
+   if (!mux_chip)
+   return ERR_PTR(-EPROBE_DEFER);
+
+   if (chosen->index >= mux_chip->controllers) {
+   dev_err(dev, "Mux lookup table index out of bounds %u >= %u\n",
+   chosen->index, mux_chip->controllers);
+   put_device(_chip->dev);
+   return ERR_PTR(-EINVAL);
+   }
+
+   return _chip->mux[chosen->index];
  }
  EXPORT_SYMBOL_GPL(mux_control_get);
  
diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h

index 

[PATCH 02/11] mux: core: Add support for getting a mux controller on a non DT platform

[Hans de Goede]

On non DT platforms we cannot get the mux_chip by pnode. Other subsystems
(regulator, clock, pwm) have the same problem and solve this by allowing
platform / board-setup code to add entries to a lookup table and then use
this table to look things up.

This commit adds support for getting a mux controller on a non DT platform
following this pattern. It is based on a simplified version of the pwm
subsys lookup code, the dev_id and mux_name parts of a lookup table entry
are mandatory in the mux-core implementation.

Signed-off-by: Hans de Goede 
---
 drivers/mux/core.c   | 96 +++-
 include/linux/mux/consumer.h | 11 +
 2 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/drivers/mux/core.c b/drivers/mux/core.c
index 6142493c327b..8864cc745506 100644
--- a/drivers/mux/core.c
+++ b/drivers/mux/core.c
@@ -24,6 +24,9 @@
 #include 
 #include 
 
+static DEFINE_MUTEX(mux_lookup_lock);
+static LIST_HEAD(mux_lookup_list);
+
 /*
  * The idle-as-is "state" is not an actual state that may be selected, it
  * only implies that the state should not be changed. So, use that state
@@ -408,6 +411,23 @@ int mux_control_deselect(struct mux_control *mux)
 }
 EXPORT_SYMBOL_GPL(mux_control_deselect);
 
+static int parent_name_match(struct device *dev, const void *data)
+{
+   const char *parent_name = dev_name(dev->parent);
+   const char *name = data;
+
+   return strcmp(parent_name, name) == 0;
+}
+
+static struct mux_chip *mux_chip_get_by_name(const char *name)
+{
+   struct device *dev;
+
+   dev = class_find_device(_class, NULL, name, parent_name_match);
+
+   return dev ? to_mux_chip(dev) : NULL;
+}
+
 static int of_dev_node_match(struct device *dev, const void *data)
 {
return dev->of_node == data;
@@ -479,6 +499,42 @@ static struct mux_control *of_mux_control_get(struct 
device *dev,
 }
 
 /**
+ * mux_add_table() - register PWM device consumers
+ * @table: array of consumers to register
+ * @num: number of consumers in table
+ */
+void mux_add_table(struct mux_lookup *table, size_t num)
+{
+   mutex_lock(_lookup_lock);
+
+   while (num--) {
+   list_add_tail(>list, _lookup_list);
+   table++;
+   }
+
+   mutex_unlock(_lookup_lock);
+}
+EXPORT_SYMBOL_GPL(mux_add_table);
+
+/**
+ * mux_remove_table() - unregister PWM device consumers
+ * @table: array of consumers to unregister
+ * @num: number of consumers in table
+ */
+void mux_remove_table(struct mux_lookup *table, size_t num)
+{
+   mutex_lock(_lookup_lock);
+
+   while (num--) {
+   list_del(>list);
+   table++;
+   }
+
+   mutex_unlock(_lookup_lock);
+}
+EXPORT_SYMBOL_GPL(mux_remove_table);
+
+/**
  * mux_control_get() - Get the mux-control for a device.
  * @dev: The device that needs a mux-control.
  * @mux_name: The name identifying the mux-control.
@@ -487,11 +543,49 @@ static struct mux_control *of_mux_control_get(struct 
device *dev,
  */
 struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
 {
+   struct mux_lookup *m, *chosen = NULL;
+   const char *dev_id = dev_name(dev);
+   struct mux_chip *mux_chip;
+
/* look up via DT first */
if (IS_ENABLED(CONFIG_OF) && dev->of_node)
return of_mux_control_get(dev, mux_name);
 
-   return ERR_PTR(-ENODEV);
+   /*
+* For non DT we look up the provider in the static table typically
+* provided by board setup code.
+*
+* If a match is found, the provider mux chip is looked up by name
+* and a mux-control is requested using the table provided index.
+*/
+   mutex_lock(_lookup_lock);
+   list_for_each_entry(m, _lookup_list, list) {
+   if (WARN_ON(!m->dev_id || !m->mux_name || !m->provider))
+   continue;
+
+   if (strcmp(m->dev_id, dev_id) == 0 &&
+   strcmp(m->mux_name, mux_name) == 0) {
+   chosen = m;
+   break;
+   }
+   }
+   mutex_unlock(_lookup_lock);
+
+   if (!chosen)
+   return ERR_PTR(-ENODEV);
+
+   mux_chip = mux_chip_get_by_name(chosen->provider);
+   if (!mux_chip)
+   return ERR_PTR(-EPROBE_DEFER);
+
+   if (chosen->index >= mux_chip->controllers) {
+   dev_err(dev, "Mux lookup table index out of bounds %u >= %u\n",
+   chosen->index, mux_chip->controllers);
+   put_device(_chip->dev);
+   return ERR_PTR(-EINVAL);
+   }
+
+   return _chip->mux[chosen->index];
 }
 EXPORT_SYMBOL_GPL(mux_control_get);
 
diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h
index ea96d4c82be7..912dd48a3a5d 100644
--- a/include/linux/mux/consumer.h
+++ b/include/linux/mux/consumer.h
@@ -18,6 +18,17 @@
 struct device;
 struct mux_control;
 
+struct mux_lookup {
+