[RFC PATCH 3/5] ASoC: audio-graph-card: Add bindings for sysclk and pll
From: Sameer Pujar <hidden>
Date: 2021-02-25 18:09:36
Also in:
alsa-devel, lkml
Subsystem:
open firmware and flattened device tree bindings, sound - generic sound card (simple-audio-card, audio-graph-card), sound - soc layer / dynamic audio power management (asoc), the rest · Maintainers:
Rob Herring, Krzysztof Kozlowski, Conor Dooley, Mark Brown, Kuninori Morimoto, Liam Girdwood, Linus Torvalds
ASoC core provides callbacks snd_soc_dai_set_sysclk() and snd_soc_dai_set_pll() for system clock (sysclk) and pll configurations respectively. Add bindings for flexible sysclk or pll configurations which can be driven from CPU/Codec DAI or endpoint subnode from DT. This in turn helps to avoid hard codings in driver and makes it more generic. Also add system-clock related bindings, "system-clock-direction-out" and "system-clock-frequency", which are already supported. Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Cc: Rob Herring <robh@kernel.org> Signed-off-by: Sameer Pujar <redacted> --- .../bindings/sound/audio-graph-port.yaml | 71 ++++++++++++++++++++++ 1 file changed, 71 insertions(+)
diff --git a/Documentation/devicetree/bindings/sound/audio-graph-port.yaml b/Documentation/devicetree/bindings/sound/audio-graph-port.yaml
index 766e910..4f50291 100644
--- a/Documentation/devicetree/bindings/sound/audio-graph-port.yaml
+++ b/Documentation/devicetree/bindings/sound/audio-graph-port.yaml@@ -71,6 +71,77 @@ properties: description: CPU to Codec rate channels. $ref: /schemas/types.yaml#/definitions/uint32 + system-clock-frequency: + description: | + Specify system clock (sysclk) frequency for CPU or Codec + component. Or if a clock is specified in the CPU or Codec + device node and a scaling factor is given with "mclk-fs", + sysclk will be calculated as a multiple of stream sample + rate and "mclk-fs". The rate is updated when stream starts. + $ref: /schemas/types.yaml#/definitions/uint32 + + system-clock-direction-out: + description: | + Specifies clock direction as "out" on initialization. It + is useful for some CPUs with fixed clocks. + $ref: /schemas/types.yaml#/definitions/flag + + system-clock-id: + description: | + CPU or Codec component may have multiple clocks. A specific + clock may have to be configured. In such cases the clock + ID needs to be specified. + $ref: /schemas/types.yaml#/definitions/uint32 + + system-clock-source: + description: | + CPU or Codec component may have multiple sources for its + system clock (sysclk). In such cases the sysclk source + needs to be specified. + $ref: /schemas/types.yaml#/definitions/uint32 + + pll-id: + description: | + Specify PLL that needs to be configured. This is useful + when the CPU or Codec component has multiple PLLs. + $ref: /schemas/types.yaml#/definitions/uint32 + + pll-source: + description: | + When PLL has multiple reference clock sources, the exact + source needs to be specified for the required configuration. + $ref: /schemas/types.yaml#/definitions/uint32 + + pll-input-reference: + description: | + Specify how to calculate input frequency for the PLL. + Depending on the identifier, input frequency can be + calculated at runtime. For example if I2S bit clock is used + as reference, rate depends on actual PCM parameters (rate, + channels and bits) during an audio session. If a fixed rate + is used, then "pll-input-frequency" can be used instead. + $ref: /schemas/types.yaml#/definitions/uint32 + const: 2 + + pll-input-frequency: + description: Specify fixed input frequency + $ref: /schemas/types.yaml#/definitions/uint32 + + pll-output-reference: + description: | + Specify how to calculate output frequency for the PLL. + Depending on the identifier, output frequency can be + calculated at runtime. If output clock is used for MCLK purpose, + then it may depend on "mclk-fs" scale factor. In such cases it + needs to be calculated at runtime. If a fixed output frequency + is needed, then "pll-output-frequency" can be used instead. + $ref: /schemas/types.yaml#/definitions/uint32 + const: 1 + + pll-output-frequency: + description: Specify fixed output frequency + $ref: /schemas/types.yaml#/definitions/uint32 + ports: description: multi OF-Graph subnode type: object
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2.7.4