[PATCH 1/3] dt-bindings: iio: adc: add bindings for stm32 mdf filter
Olivier Moysan
olivier.moysan at foss.st.com
Thu Oct 1 07:56:45 PDT 2026
Add bindings that describes STM32 MDF settings to support
digital filtering for Pulse Density Modulation (PDM) microphones
and analog sigma delta modulators.
Signed-off-by: Olivier Moysan <olivier.moysan at foss.st.com>
---
.../bindings/iio/adc/st,stm32-mdf-adc.yaml | 383 ++++++++++++++++++
1 file changed, 383 insertions(+)
create mode 100644 Documentation/devicetree/bindings/iio/adc/st,stm32-mdf-adc.yaml
diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-mdf-adc.yaml b/Documentation/devicetree/bindings/iio/adc/st,stm32-mdf-adc.yaml
new file mode 100644
index 000000000000..f2fbc3e150e8
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-mdf-adc.yaml
@@ -0,0 +1,383 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/st,stm32-mdf-adc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: STMicroelectronics STM32 Multi-function Digital Filter (MDF) ADC
+
+maintainers:
+ - Olivier Moysan <olivier.moysan at foss.st.com>
+
+description: |
+ STM32 MDF ADC is a sigma delta analog-to-digital converter dedicated to
+ interface external sigma delta modulators to STM32 micro controllers.
+
+properties:
+ compatible:
+ enum:
+ - st,stm32mp25-mdf
+ - st,stm32mp23-mdf
+
+ reg:
+ minItems: 1
+ maxItems: 2
+
+ clocks:
+ maxItems: 1
+
+ clock-names:
+ description: Internal clock used for MDF digital processing.
+ items:
+ - const: ker_ck
+
+ "#clock-cells":
+ enum: [0, 1]
+
+ clock-output-names:
+ description: |
+ CCK0 and CCK1 are optional output clocks, which share the same clock frequency,
+ but can be gated independently to save power.
+ minItems: 1
+ maxItems: 2
+ oneOf:
+ - items:
+ - const: cck0
+ - items:
+ - const: cck1
+ - items:
+ - const: cck0
+ - const: cck1
+
+ clock-frequency:
+ description: |
+ Common clock frequency (Hz) for CCK0 and CCK1 output clocks.
+ The frequency must be a multiple of the "ker_ck" clock frequency.
+ maximum: 25000000
+
+ "#address-cells":
+ const: 1
+
+ "#size-cells":
+ const: 1
+
+ ranges: true
+
+ clock-ranges: true
+
+ resets:
+ maxItems: 1
+
+ reset-names:
+ items:
+ - const: mdf
+
+ access-controllers:
+ $ref: /schemas/types.yaml#/definitions/phandle-array
+ description: |
+ Phandle to the rifsc device to check access right.
+
+ power-domains:
+ maxItems: 1
+
+ st,interleave:
+ description: |
+ List of phandles of interleaved filters. The indexes of interleaved filters must be
+ consecutives starting from 0 (i.e in range [0..N]). The samples from interleaved filters
+ are muxed in a single channel and retrieved through the device associated to the filter 0.
+ The filters 1..N have to be enabled, but inherit their configuration from filter 0.
+ $ref: /schemas/types.yaml#/definitions/phandle-array
+
+required:
+ - compatible
+ - reg
+ - ranges
+ - clocks
+ - clock-names
+ - clock-ranges
+ - "#address-cells"
+ - "#size-cells"
+
+additionalProperties: false
+
+patternProperties:
+ "^sitf@[0-9]+$":
+ type: object
+ description: Serial interface child node
+
+ properties:
+ compatible:
+ enum:
+ - st,stm32mp25-sitf-mdf
+
+ reg:
+ description: Specify the SITF serial interface instance
+ maxItems: 1
+
+ clocks:
+ description: |
+ Serial interface clock (optional depending on interface mode)
+ maxItems: 1
+
+ st,sitf-mode:
+ description: |
+ Select serial interface protocol
+ - spi: SPI mode
+ - lf_spi: low frequency SPI mode for low power applications
+ $ref: /schemas/types.yaml#/definitions/string
+ enum:
+ - spi
+ - lf_spi
+
+ required:
+ - reg
+ - st,sitf-mode
+
+ additionalProperties: false
+
+ "^filter@[0-9]+$":
+ type: object
+ description: Digital filter path child node
+
+ properties:
+ compatible:
+ enum:
+ - st,stm32mp25-mdf-dmic
+ - st,stm32mp25-mdf-adc
+
+ reg:
+ description: Specify the MDF filter instance
+ maxItems: 1
+
+ interrupts:
+ maxItems: 1
+
+ clocks:
+ minItems: 1
+ description: Internal clock used for MDF digital processing and control blocks.
+
+ clock-names:
+ items:
+ - const: ker_ck
+
+ dmas:
+ maxItems: 1
+
+ dma-names:
+ items:
+ - const: rx
+
+ "#io-channel-cells":
+ const: 1
+
+ '#address-cells':
+ const: 1
+
+ '#size-cells':
+ const: 0
+
+ st,cic-mode:
+ description: |
+ Cascaded-integrator-comb (CIC) filter configuration
+ - 0: MCIC & ACIC filters in FastSinc mode
+ - [1-3]: MCIC & ACIC filters in Sinc mode order 1 to 3
+ - [4-5]: Single CIC filter in Sinc mode order 4 to 5
+ For audio purpose it is recommended to use CIC Sinc4 or Sinc5
+ This property is mandatory for filter 0 or filters not used in interleave mode.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 5
+
+ st,delay:
+ description: Filter delay in samples
+ $ref: /schemas/types.yaml#/definitions/uint32
+ maximum: 127
+
+ st,rs-filter-bypass:
+ description: Bypass RSFLT reshaping filter.
+ $ref: /schemas/types.yaml#/definitions/flag
+
+ st,hpf-filter-cutoff-bp:
+ description: |
+ High Pass Filter (HPF) cut-off frequency expressed as a fraction of the PCM sampling rate.
+ Cut-off frequency = st,hpf-filter-cutoff-bp x Fpcm / 10000.
+ If this property is not defined the HPF is disabled.
+ enum: [625, 1250, 2500, 9500]
+
+ st,sync:
+ description:
+ Synchronize to another filter.
+ Must contain the phandle of the filter providing the synchronization.
+ allOf:
+ - $ref: /schemas/types.yaml#/definitions/phandle-array
+ - maxItems: 1
+
+ st,sitf:
+ $ref: /schemas/types.yaml#/definitions/phandle-array
+ items:
+ - items:
+ - description: Phandle of the serial interface connected to the digital filter
+ - description: |
+ The phandle's argument selects the bitstream on the falling or rising edge
+ of the serial interface clock:
+ - 0: rising edge
+ - 1: falling edge
+ enum: [0, 1]
+ default: 0
+ description:
+ Should be phandle/bitstream pair.
+
+ required:
+ - compatible
+ - reg
+ - interrupts
+ - dmas
+ - dma-names
+ - "#io-channel-cells"
+ - "#address-cells"
+ - "#size-cells"
+ - st,sitf
+
+ unevaluatedProperties: false
+
+ patternProperties:
+ "^channel@([0-7])$":
+ type: object
+ $ref: adc.yaml
+ description: Represents the external channel which is connected to the MDF.
+
+ properties:
+ reg:
+ maximum: 7
+
+ io-backends:
+ description:
+ Used to pipe external sigma delta modulator or internal ADC backend to MDF
+ channel.
+ maxItems: 1
+
+ required:
+ - reg
+
+ unevaluatedProperties: false
+
+ allOf:
+ - if:
+ properties:
+ compatible:
+ contains:
+ const: st,stm32mp25-mdf-adc
+
+ then:
+ patternProperties:
+ "^channel@[0-7]$":
+ required:
+ - io-backends
+
+ - if:
+ properties:
+ compatible:
+ contains:
+ const: st,stm32mp25-mdf-dmic
+
+ then:
+ patternProperties:
+ "^mdf-dai+$":
+ type: object
+ description: child node
+
+ properties:
+ compatible:
+ enum:
+ - st,stm32mp25-mdf-dai
+
+ "#sound-dai-cells":
+ const: 0
+
+ io-channels:
+ description:
+ From common IIO binding. Used to pipe external sigma delta
+ modulator or internal ADC output to MDF channel.
+
+ power-domains:
+ maxItems: 1
+
+ port:
+ $ref: /schemas/sound/audio-graph-port.yaml#
+ unevaluatedProperties: false
+
+ required:
+ - compatible
+ - "#sound-dai-cells"
+ - io-channels
+
+ additionalProperties: false
+
+examples:
+ - |
+ #include <dt-bindings/clock/st,stm32mp25-rcc.h>
+ #include <dt-bindings/interrupt-controller/arm-gic.h>
+ mdf1: mdf at 504d0000 {
+ compatible = "st,stm32mp25-mdf";
+ ranges = <0 0x504d0000 0x1000>;
+ reg = <0x504d0000 0x8>, <0x504d0ff0 0x10>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ clocks = <&rcc CK_KER_MDF1>;
+ clock-names = "ker_ck";
+ clock-ranges;
+ #clock-cells = <1>;
+ clock-output-names = "cck0", "cck1";
+ clock-frequency = <2048000>;
+
+ sitf5: sitf at 300 {
+ compatible = "st,stm32mp25-sitf-mdf";
+ reg = <0x300 0x4>;
+ st,sitf-mode = "spi";
+ clocks = <&mdf1 0>;
+ };
+
+ filter0: filter at 84 {
+ compatible = "st,stm32mp25-mdf-dmic";
+ reg = <0x84 0x70>;
+ #io-channel-cells = <1>;
+ interrupts = <GIC_SPI 184 IRQ_TYPE_LEVEL_HIGH>;
+ dmas = <&hpdma 63 0x63 0x12 0>;
+ dma-names = "rx";
+ st,cic-mode = <5>;
+ st,sitf = <&sitf5 0>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ channel at 0 {
+ reg = <0>;
+ };
+
+ asoc_pdm0: mdf-dai {
+ compatible = "st,stm32mp25-mdf-dai";
+ #sound-dai-cells = <0>;
+ io-channels = <&filter0 0>;
+ };
+ };
+
+ filter1: filter at 104 {
+ compatible = "st,stm32mp25-mdf-adc";
+ reg = <0x104 0x70>;
+ #io-channel-cells = <1>;
+ interrupts = <GIC_SPI 185 IRQ_TYPE_LEVEL_HIGH>;
+ dmas = <&hpdma 64 0x63 0x12 0>;
+ dma-names = "rx";
+ st,cic-mode = <2>;
+ st,sitf = <&sitf5 1>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ channel at 1 {
+ reg = <1>;
+ settling-time-us = <1000>;
+ io-backends = <&sd_adc1>;
+ };
+ };
+ };
+
+...
--
2.43.0
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