It's often the case that a codec driver will need to control its
own pins. However, if a name_prefix has been applied to this codec it
must be included in the name passed to any of the snd_soc_dapm_x_pin()
functions.

The behaviour of the existing pin control functions is reasonable, since
you may want to search for a fully-specified name within the scope of an
entire card. This means that we can't apply the prefix in these functions
because it will break card-scope searches.

Constructing a prefixed string "manually" in codec drivers leads to a lot
of repetition of the same code.

To make this tidier in codec drivers this patch adds a new set of
equivalent functions that take a struct snd_soc_component instead of a
dapm context and automatically add the component's name_prefix to the
given name. This makes it a simple change in codec drivers to be
prefix-safe.

The new functions are not quite trivial enough to be inlines and the
compiler won't be able to compile-away any part of them.

Although it looks somewhat inefficient to have to allocate a temporary
buffer and combine strings, the current design of the widget list
doesn't lend itself to a more optimized implementation - it's a single
list of all widgets on a card and is searched linearly for a matching
string. As pin state changes are generally low-frequency events it's
unlikely to be a significant issue - at least not enough to rewrite the
widget list handling just for this.

Signed-off-by: Richard Fitzgerald <redacted>
---
 include/sound/soc.h   |  25 +++++++
 sound/soc/soc-utils.c | 199 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 224 insertions(+)

diff --git a/include/sound/soc.h b/include/sound/soc.h
index 795e6c4..a46d0774 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h

@@ -1718,4 +1718,29 @@ static inline void snd_soc_dapm_mutex_unlock(struct snd_soc_dapm_context *dapm)
 	mutex_unlock(&dapm->card->dapm_mutex);
 }
 
+extern int snd_soc_component_enable_pin(struct snd_soc_component *component,
+					const char *pin);
+extern int snd_soc_component_enable_pin_unlocked(
+					struct snd_soc_component *component,
+					const char *pin);
+extern int snd_soc_component_disable_pin(struct snd_soc_component *component,
+					 const char *pin);
+extern int snd_soc_component_disable_pin_unlocked(
+					struct snd_soc_component *component,
+					const char *pin);
+extern int snd_soc_component_nc_pin(struct snd_soc_component *component,
+				    const char *pin);
+extern int snd_soc_component_nc_pin_unlocked(
+					struct snd_soc_component *component,
+					const char *pin);
+
+extern int snd_soc_component_get_pin_status(struct snd_soc_component *component,
+					    const char *pin);
+extern int snd_soc_component_force_enable_pin(
+					struct snd_soc_component *component,
+					const char *pin);
+extern int snd_soc_component_force_enable_pin_unlocked(
+					struct snd_soc_component *component,
+					const char *pin);
+