ASoC: ti: davinci-mcasp: Add asynchronous mode

Merge series from Sen Wang <sen@ti.com>:

This series adds asynchronous mode support to the McASP driver, which
enables independent configuration of bitclocks, frame sync, and audio
configurations between tx(playback) and rx(record). And achieves
simultaneous playback & record using different audio configurations.

It also adds two clean up patches to the McASP driver that disambiguate
and simplifies the logic which avoids the async enhancement from being
too convoluted to review and analyze.

The implementation is based on vendor documentation and patches tested in
both SK-AM62P-LP (sync mode, McASP slave) and AM62D-EVM
(async mode, McASP master, rx & tx has different TDM configs).
Testing verifies async mode functionality while maintaining backward
compatibility with the default sync mode.

Bootlog and Async mode tests on AM62D-EVM: [0]

[0]: https://gist.github.com/SenWang125/f31f9172b186d414695e37c8b9ef127d

1 files changed, 66 insertions, 5 deletions

diff --git a/Documentation/devicetree/bindings/sound/davinci-mcasp-audio.yaml b/Documentation/devicetree/bindings/sound/davinci-mcasp-audio.yaml
index beef193aaaeb..87559d0d079a 100644
--- a/Documentation/devicetree/bindings/sound/davinci-mcasp-audio.yaml
+++ b/Documentation/devicetree/bindings/sound/davinci-mcasp-audio.yaml
@@ -40,11 +40,33 @@ properties:
   tdm-slots:
     $ref: /schemas/types.yaml#/definitions/uint32
     description:
-      number of channels over one serializer
-      the property is ignored in DIT mode
+      Number of channels over one serializer. This property
+      specifies the TX playback TDM slot count, along with default RX slot count
+      if tdm-slots-rx is not specified.
+      The property is ignored in DIT mode.
     minimum: 2
     maximum: 32
 
+  tdm-slots-rx:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Number of RX capture channels over one serializer. If specified,
+      allows independent RX TDM slot count separate from TX. Requires
+      ti,async-mode to be enabled for independent TX/RX clock rates.
+      The property is ignored in DIT mode.
+    minimum: 2
+    maximum: 32
+
+  ti,async-mode:
+    description:
+      Specify to allow independent TX & RX clocking,
+      to enable audio playback & record with different sampling rate,
+      and different number of bits per frame.
+      if property is omitted, TX and RX will share same bit clock and frame clock signals,
+      thus RX need to use same bits per frame and sampling rate as TX in synchronous mode.
+      the property is ignored in DIT mode (as DIT is TX-only)
+    type: boolean
+
   serial-dir:
     description:
       A list of serializer configuration
@@ -125,7 +147,21 @@ properties:
 
   auxclk-fs-ratio:
     $ref: /schemas/types.yaml#/definitions/uint32
-    description: ratio of AUCLK and FS rate if applicable
+    description:
+      Ratio of AUCLK and FS rate if applicable. This property specifies
+      the TX ratio, along with default RX ratio if auxclk-fs-ratio-rx
+      is not specified.
+      When not specified, the inputted system clock frequency via set_sysclk
+      callback by the machine driver is used for divider calculation.
+
+  auxclk-fs-ratio-rx:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Ratio of AUCLK and FS rate for RX. If specified, allows
+      for a different RX ratio. Requires ti,async-mode to be
+      enabled when the ratio differs from auxclk-fs-ratio.
+      When not specified, it defaults to the value of auxclk-fs-ratio.
+      The property is ignored in DIT mode.
 
   gpio-controller: true
 
@@ -170,14 +206,38 @@ allOf:
   - $ref: dai-common.yaml#
   - if:
       properties:
-        opmode:
+        op-mode:
           enum:
             - 0
-
     then:
       required:
         - tdm-slots
 
+  - if:
+      properties:
+        op-mode:
+          const: 1
+    then:
+      properties:
+        tdm-slots: false
+        tdm-slots-rx: false
+        ti,async-mode: false
+        auxclk-fs-ratio-rx: false
+
+  - if:
+      required:
+        - tdm-slots-rx
+    then:
+      required:
+        - ti,async-mode
+
+  - if:
+      required:
+        - auxclk-fs-ratio-rx
+    then:
+      required:
+        - ti,async-mode
+
 unevaluatedProperties: false
 
 examples:
@@ -190,6 +250,7 @@ examples:
       interrupt-names = "tx", "rx";
       op-mode = <0>;		/* MCASP_IIS_MODE */
       tdm-slots = <2>;
+      ti,async-mode;
       dmas = <&main_udmap 0xc400>, <&main_udmap 0x4400>;
       dma-names = "tx", "rx";
       serial-dir = <