ASoC: wm8904: Add DMIC and DRC support

Merge series from Francesco Dolcini <francesco@dolcini.it>:

This patch series adds DMIC and DRC support to the WM8904 driver, a new
of_ helper is added to simplify the driver code.

DRC functionality is added in the same patch series to provide the
necessary dynamic range control to make DMIC support useful.

The WM8904 supports digital microphones on two of its inputs:
IN1L/DMICDAT1 and IN1R/DMICDAT2. These two inputs can either be
connected to an ADC or to the DMIC system. There is an ADC for each
line, and only one DMIC block. This DMIC block is either connected to
DMICDAT1 or to DMICDAT2. One DMIC data line supports two digital
microphones via time multiplexing.

The pin's functionality is decided during hardware design (IN1L vs
DMICDAT1 and IN1R vs DMICDAT2). This is reflected in the Device Tree.

If one line is analog and one is DMIC, we need to be able to switch
between ADC and DMIC at runtime. The DMIC source is known from the
Device Tree. If both are DMIC inputs, we need to be able to switch the
DMIC source. There is no need to switch between ADC and DMIC at runtime.

Therefore, kcontrols are dynamically added by the driver depending on
its Device Tree configuration.

This is a heavy rework of a previous patch series provided by Alifer
Moraes and Pierluigi Passaro,
https://lore.kernel.org/lkml/20220307141041.27538-1-alifer.m@variscite.com.

1 files changed, 10 insertions, 13 deletions

diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
index 7fd1ea8265a5..e25d047f3c82 100644
--- a/rust/kernel/init.rs
+++ b/rust/kernel/init.rs
@@ -259,7 +259,7 @@ pub mod macros;
 ///     },
 /// }));
 /// let foo: Pin<&mut Foo> = foo;
-/// pr_info!("a: {}", &*foo.a.lock());
+/// pr_info!("a: {}\n", &*foo.a.lock());
 /// ```
 ///
 /// # Syntax
@@ -319,7 +319,7 @@ macro_rules! stack_pin_init {
 ///     }, GFP_KERNEL)?,
 /// }));
 /// let foo = foo.unwrap();
-/// pr_info!("a: {}", &*foo.a.lock());
+/// pr_info!("a: {}\n", &*foo.a.lock());
 /// ```
 ///
 /// ```rust,ignore
@@ -352,7 +352,7 @@ macro_rules! stack_pin_init {
 ///         x: 64,
 ///     }, GFP_KERNEL)?,
 /// }));
-/// pr_info!("a: {}", &*foo.a.lock());
+/// pr_info!("a: {}\n", &*foo.a.lock());
 /// # Ok::<_, AllocError>(())
 /// ```
 ///
@@ -882,7 +882,7 @@ pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
     ///
     /// impl Foo {
     ///     fn setup(self: Pin<&mut Self>) {
-    ///         pr_info!("Setting up foo");
+    ///         pr_info!("Setting up foo\n");
     ///     }
     /// }
     ///
@@ -986,7 +986,7 @@ pub unsafe trait Init<T: ?Sized, E = Infallible>: PinInit<T, E> {
     ///
     /// impl Foo {
     ///     fn setup(&mut self) {
-    ///         pr_info!("Setting up foo");
+    ///         pr_info!("Setting up foo\n");
     ///     }
     /// }
     ///
@@ -1336,7 +1336,7 @@ impl<T> InPlaceWrite<T> for UniqueArc<MaybeUninit<T>> {
 /// #[pinned_drop]
 /// impl PinnedDrop for Foo {
 ///     fn drop(self: Pin<&mut Self>) {
-///         pr_info!("Foo is being dropped!");
+///         pr_info!("Foo is being dropped!\n");
 ///     }
 /// }
 /// ```
@@ -1418,17 +1418,14 @@ impl_zeroable! {
     // SAFETY: `T: Zeroable` and `UnsafeCell` is `repr(transparent)`.
     {<T: ?Sized + Zeroable>} UnsafeCell<T>,
 
-    // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee).
+    // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee:
+    // https://doc.rust-lang.org/stable/std/option/index.html#representation).
     Option<NonZeroU8>, Option<NonZeroU16>, Option<NonZeroU32>, Option<NonZeroU64>,
     Option<NonZeroU128>, Option<NonZeroUsize>,
     Option<NonZeroI8>, Option<NonZeroI16>, Option<NonZeroI32>, Option<NonZeroI64>,
     Option<NonZeroI128>, Option<NonZeroIsize>,
-
-    // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee).
-    //
-    // In this case we are allowed to use `T: ?Sized`, since all zeros is the `None` variant.
-    {<T: ?Sized>} Option<NonNull<T>>,
-    {<T: ?Sized>} Option<KBox<T>>,
+    {<T>} Option<NonNull<T>>,
+    {<T>} Option<KBox<T>>,
 
     // SAFETY: `null` pointer is valid.
     //