[RFC v2 00/11] iio: add iio backend device type

[RFC v2 00/11] iio: add iio backend device type

[Olivier Moysan]

This v2 is an addon to initial RFC:
https://lore.kernel.org/lkml/20230623140944.2613002-1-olivier.moysan@foss.st.com/

Despite the "IIO backend" naming has to be changed (as pointed out by
Jonathan previously), it has been kept here, for time being. The
appropriated naming still has to be discussed later on.

In the previous RFC the "IIO backend" concept was proposed through
a set of template APIs.

This v2 implements a functionnal exemple based on STM32 DFSDM,
to bring scaling support to this peripheral.

Olivier Moysan (11):
  iio: introduce iio backend device
  of: property: add device link support for io-backends
  dt-bindings: iio: stm32-dfsdm-adc: add scaling support
  dt-bindings: iio: adc: add scaling support to sd modulator
  iio: adc: stm32-dfsdm: manage dfsdm as a channel provider
  iio: adc: stm32-dfsdm: adopt generic channel bindings
  iio: adc: stm32-dfsdm: add scaling support to dfsdm
  iio: adc: sd modulator: add scale and offset support
  ARM: dts: stm32: adopt new dfsdm bindings on stm32mp151
  ARM: dts: stm32: add dfsdm pins muxing on stm32mp15
  ARM: dts: stm32: add dfsdm iio support on stm32mp157c-ev

 .../iio/adc/sigma-delta-modulator.yaml        |   9 +-
 .../bindings/iio/adc/st,stm32-dfsdm-adc.yaml  | 189 ++++++------------
 arch/arm/boot/dts/st/stm32mp15-pinctrl.dtsi   |  39 ++++
 arch/arm/boot/dts/st/stm32mp151.dtsi          |  18 +-
 arch/arm/boot/dts/st/stm32mp157c-ev1.dts      |  68 +++++++
 drivers/iio/Makefile                          |   1 +
 drivers/iio/adc/sd_adc_modulator.c            | 106 ++++++++--
 drivers/iio/adc/stm32-dfsdm-adc.c             | 187 +++++++++++------
 drivers/iio/industrialio-backend.c            | 107 ++++++++++
 drivers/of/property.c                         |   2 +
 include/linux/iio/backend.h                   |  56 ++++++
 11 files changed, 561 insertions(+), 221 deletions(-)
 create mode 100644 drivers/iio/industrialio-backend.c
 create mode 100644 include/linux/iio/backend.h

-- 
2.25.1

[RFC v2 02/11] of: property: add device link support for io-backends

[Olivier Moysan]

Add support for creating device links out of more DT properties.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 drivers/of/property.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/of/property.c b/drivers/of/property.c
index ddc75cd50825..864e29e4707c 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1244,6 +1244,7 @@ DEFINE_SIMPLE_PROP(interconnects, "interconnects", "#interconnect-cells")
 DEFINE_SIMPLE_PROP(iommus, "iommus", "#iommu-cells")
 DEFINE_SIMPLE_PROP(mboxes, "mboxes", "#mbox-cells")
 DEFINE_SIMPLE_PROP(io_channels, "io-channel", "#io-channel-cells")
+DEFINE_SIMPLE_PROP(io_backends, "io-backend", "#io-backend-cells")
 DEFINE_SIMPLE_PROP(interrupt_parent, "interrupt-parent", NULL)
 DEFINE_SIMPLE_PROP(dmas, "dmas", "#dma-cells")
 DEFINE_SIMPLE_PROP(power_domains, "power-domains", "#power-domain-cells")
@@ -1332,6 +1333,7 @@ static const struct supplier_bindings of_supplier_bindings[] = {
 	{ .parse_prop = parse_iommu_maps, .optional = true, },
 	{ .parse_prop = parse_mboxes, },
 	{ .parse_prop = parse_io_channels, },
+	{ .parse_prop = parse_io_backends, },
 	{ .parse_prop = parse_interrupt_parent, },
 	{ .parse_prop = parse_dmas, .optional = true, },
 	{ .parse_prop = parse_power_domains, },
-- 
2.25.1

[RFC v2 03/11] dt-bindings: iio: stm32-dfsdm-adc: add scaling support

[Olivier Moysan]

Add scaling support to STM32 DFSDM.

This introduces the following changes:
- Add ADC generic channel binding and remove support of deprecated
channel bindings.
- DFSDM is now implemented as a channel provider, so remove io-channels
properties.
- Add iio-backend property to connect DFSDM to an SD modulator.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 .../bindings/iio/adc/st,stm32-dfsdm-adc.yaml  | 189 ++++++------------
 1 file changed, 63 insertions(+), 126 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
index 1970503389aa..128545cedc7f 100644
--- a/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
@@ -85,22 +85,14 @@ patternProperties:
         description: Specifies the DFSDM filter instance used.
         maxItems: 1
 
-      interrupts:
-        maxItems: 1
+      '#address-cells':
+        const: 1
 
-      st,adc-channels:
-        description: |
-          List of single-ended channels muxed for this ADC.
-          On stm32h7 and stm32mp1:
-          - For st,stm32-dfsdm-adc: up to 8 channels numbered from 0 to 7.
-          - For st,stm32-dfsdm-dmic: 1 channel numbered from 0 to 7.
-        $ref: /schemas/types.yaml#/definitions/uint32-array
-        items:
-          minimum: 0
-          maximum: 7
+      '#size-cells':
+        const: 0
 
-      st,adc-channel-names:
-        description: List of single-ended channel names.
+      interrupts:
+        maxItems: 1
 
       st,filter-order:
         description: |
@@ -111,39 +103,6 @@ patternProperties:
         $ref: /schemas/types.yaml#/definitions/uint32
         maximum: 5
 
-      "#io-channel-cells":
-        const: 1
-
-      st,adc-channel-types:
-        description: |
-          Single-ended channel input type.
-          - "SPI_R": SPI with data on rising edge (default)
-          - "SPI_F": SPI with data on falling edge
-          - "MANCH_R": manchester codec, rising edge = logic 0, falling edge = logic 1
-          - "MANCH_F": manchester codec, rising edge = logic 1, falling edge = logic 0
-        items:
-          enum: [ SPI_R, SPI_F, MANCH_R, MANCH_F ]
-        $ref: /schemas/types.yaml#/definitions/non-unique-string-array
-
-      st,adc-channel-clk-src:
-        description: |
-          Conversion clock source.
-          - "CLKIN": external SPI clock (CLKIN x)
-          - "CLKOUT": internal SPI clock (CLKOUT) (default)
-          - "CLKOUT_F": internal SPI clock divided by 2 (falling edge).
-          - "CLKOUT_R": internal SPI clock divided by 2 (rising edge).
-        items:
-          enum: [ CLKIN, CLKOUT, CLKOUT_F, CLKOUT_R ]
-        $ref: /schemas/types.yaml#/definitions/non-unique-string-array
-
-      st,adc-alt-channel:
-        description:
-          Must be defined if two sigma delta modulators are
-          connected on same SPI input.
-          If not set, channel n is connected to SPI input n.
-          If set, channel n is connected to SPI input n + 1.
-        type: boolean
-
       st,filter0-sync:
         description:
           Set to 1 to synchronize with DFSDM filter instance 0.
@@ -157,14 +116,68 @@ patternProperties:
         items:
           - const: rx
 
+    patternProperties:
+      "^channel@([0-9]|1[0-9])$":
+        type: object
+        $ref: "adc.yaml"
+        description: Represents the external channels which are connected to the DFSDM.
+
+        properties:
+          reg:
+            items:
+              minimum: 0
+              maximum: 19
+
+          label:
+            description: |
+              Unique name to identify channel.
+
+          st,adc-channel-types:
+            description: |
+              Single-ended channel input type.
+              - "SPI_R": SPI with data on rising edge (default)
+              - "SPI_F": SPI with data on falling edge
+              - "MANCH_R": manchester codec, rising edge = logic 0, falling edge = logic 1
+              - "MANCH_F": manchester codec, rising edge = logic 1, falling edge = logic 0
+            items:
+              enum: [ SPI_R, SPI_F, MANCH_R, MANCH_F ]
+            $ref: /schemas/types.yaml#/definitions/non-unique-string-array
+
+          st,adc-channel-clk-src:
+            description: |
+              Conversion clock source.
+              - "CLKIN": external SPI clock (CLKIN x)
+              - "CLKOUT": internal SPI clock (CLKOUT) (default)
+              - "CLKOUT_F": internal SPI clock divided by 2 (falling edge).
+              - "CLKOUT_R": internal SPI clock divided by 2 (rising edge).
+            items:
+              enum: [ CLKIN, CLKOUT, CLKOUT_F, CLKOUT_R ]
+            $ref: /schemas/types.yaml#/definitions/non-unique-string-array
+
+          st,adc-alt-channel:
+            description:
+              Must be defined if two sigma delta modulators are
+              connected on same SPI input.
+              If not set, channel n is connected to SPI input n.
+              If set, channel n is connected to SPI input n + 1.
+            type: boolean
+
+          io-backends:
+            description: |
+              phandle to an external sigma delta modulator or internal ADC output.
+            $ref: /schemas/types.yaml#/definitions/phandle
+
+        required:
+          - reg
+          - io-backends
+
+        additionalProperties: false
+
     required:
       - compatible
       - reg
       - interrupts
-      - st,adc-channels
-      - st,adc-channel-names
       - st,filter-order
-      - "#io-channel-cells"
 
     allOf:
       - if:
@@ -175,14 +188,6 @@ patternProperties:
 
         then:
           properties:
-            st,adc-channels:
-              minItems: 1
-              maxItems: 8
-
-            st,adc-channel-names:
-              minItems: 1
-              maxItems: 8
-
             st,adc-channel-types:
               minItems: 1
               maxItems: 8
@@ -191,14 +196,6 @@ patternProperties:
               minItems: 1
               maxItems: 8
 
-            io-channels:
-              description:
-                From common IIO binding. Used to pipe external sigma delta
-                modulator or internal ADC output to DFSDM channel.
-
-          required:
-            - io-channels
-
       - if:
           properties:
             compatible:
@@ -207,12 +204,6 @@ patternProperties:
 
         then:
           properties:
-            st,adc-channels:
-              maxItems: 1
-
-            st,adc-channel-names:
-              maxItems: 1
-
             st,adc-channel-types:
               maxItems: 1
 
@@ -237,15 +228,9 @@ patternProperties:
                 "#sound-dai-cells":
                   const: 0
 
-                io-channels:
-                  description:
-                    From common IIO binding. Used to pipe external sigma delta
-                    modulator or internal ADC output to DFSDM channel.
-
               required:
                 - compatible
                 - "#sound-dai-cells"
-                - io-channels
 
 allOf:
   - if:
@@ -278,52 +263,4 @@ allOf:
                 minimum: 0
                 maximum: 5
 
-examples:
-  - |
-    #include <dt-bindings/interrupt-controller/arm-gic.h>
-    #include <dt-bindings/clock/stm32mp1-clks.h>
-    dfsdm: dfsdm@4400d000 {
-      compatible = "st,stm32mp1-dfsdm";
-      reg = <0x4400d000 0x800>;
-      clocks = <&rcc DFSDM_K>, <&rcc ADFSDM_K>;
-      clock-names = "dfsdm", "audio";
-      #address-cells = <1>;
-      #size-cells = <0>;
-
-      dfsdm0: filter@0 {
-        compatible = "st,stm32-dfsdm-dmic";
-        reg = <0>;
-        interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
-        dmas = <&dmamux1 101 0x400 0x01>;
-        dma-names = "rx";
-        #io-channel-cells = <1>;
-        st,adc-channels = <1>;
-        st,adc-channel-names = "dmic0";
-        st,adc-channel-types = "SPI_R";
-        st,adc-channel-clk-src = "CLKOUT";
-        st,filter-order = <5>;
-
-        asoc_pdm0: dfsdm-dai {
-          compatible = "st,stm32h7-dfsdm-dai";
-          #sound-dai-cells = <0>;
-          io-channels = <&dfsdm0 0>;
-        };
-      };
-
-      dfsdm_pdm1: filter@1 {
-        compatible = "st,stm32-dfsdm-adc";
-        reg = <1>;
-        interrupts = <GIC_SPI 111 IRQ_TYPE_LEVEL_HIGH>;
-        dmas = <&dmamux1 102 0x400 0x01>;
-        dma-names = "rx";
-        #io-channel-cells = <1>;
-        st,adc-channels = <2 3>;
-        st,adc-channel-names = "in2", "in3";
-        st,adc-channel-types = "SPI_R", "SPI_R";
-        st,adc-channel-clk-src = "CLKOUT_F", "CLKOUT_F";
-        io-channels = <&sd_adc2 &sd_adc3>;
-        st,filter-order = <1>;
-      };
-    };
-
 ...
-- 
2.25.1

[RFC v2 04/11] dt-bindings: iio: adc: add scaling support to sd modulator

[Olivier Moysan]

Add scaling support to SD modulator.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 .../bindings/iio/adc/sigma-delta-modulator.yaml          | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/sigma-delta-modulator.yaml b/Documentation/devicetree/bindings/iio/adc/sigma-delta-modulator.yaml
index cab0d425eaa4..bcc446c6428c 100644
--- a/Documentation/devicetree/bindings/iio/adc/sigma-delta-modulator.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/sigma-delta-modulator.yaml
@@ -18,12 +18,15 @@ properties:
       - sd-modulator
       - ads1201
 
-  '#io-channel-cells':
+  '#io-backend-cells':
     const: 0
 
+  vref-supply:
+    description: Phandle to the SD modulator reference voltage.
+
 required:
   - compatible
-  - '#io-channel-cells'
+  - '#io-backend-cells'
 
 additionalProperties: false
 
@@ -31,7 +34,7 @@ examples:
   - |
     ads1202: adc {
       compatible = "sd-modulator";
-      #io-channel-cells = <0>;
+      #io-backend-cells = <0>;
     };
 
 ...
-- 
2.25.1

[RFC v2 09/11] ARM: dts: stm32: adopt new dfsdm bindings on stm32mp151

[Olivier Moysan]

Adapt STM32MP151 device tree to match DFSDM new bindings.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 arch/arm/boot/dts/st/stm32mp151.dtsi | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/arm/boot/dts/st/stm32mp151.dtsi b/arch/arm/boot/dts/st/stm32mp151.dtsi
index 61508917521c..338457357248 100644
--- a/arch/arm/boot/dts/st/stm32mp151.dtsi
+++ b/arch/arm/boot/dts/st/stm32mp151.dtsi
@@ -970,7 +970,8 @@ dfsdm: dfsdm@4400d000 {
 
 			dfsdm0: filter@0 {
 				compatible = "st,stm32-dfsdm-adc";
-				#io-channel-cells = <1>;
+				#address-cells = <1>;
+				#size-cells = <0>;
 				reg = <0>;
 				interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
 				dmas = <&dmamux1 101 0x400 0x01>;
@@ -980,7 +981,8 @@ dfsdm0: filter@0 {
 
 			dfsdm1: filter@1 {
 				compatible = "st,stm32-dfsdm-adc";
-				#io-channel-cells = <1>;
+				#address-cells = <1>;
+				#size-cells = <0>;
 				reg = <1>;
 				interrupts = <GIC_SPI 111 IRQ_TYPE_LEVEL_HIGH>;
 				dmas = <&dmamux1 102 0x400 0x01>;
@@ -990,7 +992,8 @@ dfsdm1: filter@1 {
 
 			dfsdm2: filter@2 {
 				compatible = "st,stm32-dfsdm-adc";
-				#io-channel-cells = <1>;
+				#address-cells = <1>;
+				#size-cells = <0>;
 				reg = <2>;
 				interrupts = <GIC_SPI 112 IRQ_TYPE_LEVEL_HIGH>;
 				dmas = <&dmamux1 103 0x400 0x01>;
@@ -1000,7 +1003,8 @@ dfsdm2: filter@2 {
 
 			dfsdm3: filter@3 {
 				compatible = "st,stm32-dfsdm-adc";
-				#io-channel-cells = <1>;
+				#address-cells = <1>;
+				#size-cells = <0>;
 				reg = <3>;
 				interrupts = <GIC_SPI 113 IRQ_TYPE_LEVEL_HIGH>;
 				dmas = <&dmamux1 104 0x400 0x01>;
@@ -1010,7 +1014,8 @@ dfsdm3: filter@3 {
 
 			dfsdm4: filter@4 {
 				compatible = "st,stm32-dfsdm-adc";
-				#io-channel-cells = <1>;
+				#address-cells = <1>;
+				#size-cells = <0>;
 				reg = <4>;
 				interrupts = <GIC_SPI 115 IRQ_TYPE_LEVEL_HIGH>;
 				dmas = <&dmamux1 91 0x400 0x01>;
@@ -1020,7 +1025,8 @@ dfsdm4: filter@4 {
 
 			dfsdm5: filter@5 {
 				compatible = "st,stm32-dfsdm-adc";
-				#io-channel-cells = <1>;
+				#address-cells = <1>;
+				#size-cells = <0>;
 				reg = <5>;
 				interrupts = <GIC_SPI 126 IRQ_TYPE_LEVEL_HIGH>;
 				dmas = <&dmamux1 92 0x400 0x01>;
-- 
2.25.1

[RFC v2 10/11] ARM: dts: stm32: add dfsdm pins muxing on stm32mp15

[Olivier Moysan]

Add STM32 DFSDM pin muxings to STM32MP15.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 arch/arm/boot/dts/st/stm32mp15-pinctrl.dtsi | 39 +++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/arch/arm/boot/dts/st/stm32mp15-pinctrl.dtsi b/arch/arm/boot/dts/st/stm32mp15-pinctrl.dtsi
index 05c9c4f8064c..f4dd46c176f9 100644
--- a/arch/arm/boot/dts/st/stm32mp15-pinctrl.dtsi
+++ b/arch/arm/boot/dts/st/stm32mp15-pinctrl.dtsi
@@ -188,6 +188,45 @@ pins {
 		};
 	};
 
+	dfsdm_clkout_pins_a: dfsdm-clkout-pins-0 {
+		pins {
+			pinmux = <STM32_PINMUX('B', 13, AF3)>; /* DFSDM_CKOUT */
+			bias-disable;
+			drive-push-pull;
+			slew-rate = <0>;
+		};
+	};
+
+	dfsdm_clkout_sleep_pins_a: dfsdm-clkout-sleep-pins-0 {
+		pins {
+			pinmux = <STM32_PINMUX('B', 13, ANALOG)>; /* DFSDM_CKOUT */
+		};
+	};
+
+	dfsdm_data1_pins_a: dfsdm-data1-pins-0 {
+		pins {
+			pinmux = <STM32_PINMUX('C', 3, AF3)>; /* DFSDM_DATA1 */
+		};
+	};
+
+	dfsdm_data1_sleep_pins_a: dfsdm-data1-sleep-pins-0 {
+		pins {
+			pinmux = <STM32_PINMUX('C', 3, ANALOG)>; /* DFSDM_DATA1 */
+		};
+	};
+
+	dfsdm_data3_pins_a: dfsdm-data3-pins-0 {
+		pins {
+			pinmux = <STM32_PINMUX('F', 13, AF6)>; /* DFSDM_DATA3 */
+		};
+	};
+
+	dfsdm_data3_sleep_pins_a: dfsdm-data3-sleep-pins-0 {
+		pins {
+			pinmux = <STM32_PINMUX('F', 13, ANALOG)>; /* DFSDM_DATA3 */
+		};
+	};
+
 	ethernet0_rgmii_pins_a: rgmii-0 {
 		pins1 {
 			pinmux = <STM32_PINMUX('G', 5, AF11)>, /* ETH_RGMII_CLK125 */
-- 
2.25.1

[RFC v2 11/11] ARM: dts: stm32: add dfsdm iio support on stm32mp157c-ev

[Olivier Moysan]

This DT is an example of backend iio device used for STM32 DFSDM.
DFSDM filter1 has a single input channel, while filter0 is configured
to support scan mode with two input channels.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 arch/arm/boot/dts/st/stm32mp157c-ev1.dts | 68 ++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/arch/arm/boot/dts/st/stm32mp157c-ev1.dts b/arch/arm/boot/dts/st/stm32mp157c-ev1.dts
index af3800501875..edeac26f39a4 100644
--- a/arch/arm/boot/dts/st/stm32mp157c-ev1.dts
+++ b/arch/arm/boot/dts/st/stm32mp157c-ev1.dts
@@ -73,6 +73,27 @@ panel_backlight: panel-backlight {
 		default-on;
 		status = "okay";
 	};
+
+	sd_adc0: sd-adc0 {
+		compatible = "sd-modulator";
+		#io-backend-cells = <0>;
+		vref-supply = <&v3v3>;
+		status = "okay";
+	};
+
+	sd_adc1: sd-adc1 {
+		compatible = "sd-modulator";
+		#io-backend-cells = <0>;
+		vref-supply = <&v3v3>;
+		status = "okay";
+	};
+
+	sd_adc2: sd-adc2 {
+		compatible = "sd-modulator";
+		#io-backend-cells = <0>;
+		vref-supply = <&v3v3>;
+		status = "okay";
+	};
 };
 
 &cec {
@@ -99,6 +120,53 @@ dcmi_0: endpoint {
 	};
 };
 
+&dfsdm {
+	pinctrl-names = "default", "sleep";
+	pinctrl-0 = <&dfsdm_clkout_pins_a
+		     &dfsdm_data1_pins_a &dfsdm_data3_pins_a>;
+	pinctrl-1 = <&dfsdm_clkout_sleep_pins_a
+		     &dfsdm_data1_sleep_pins_a &dfsdm_data3_sleep_pins_a>;
+	spi-max-frequency = <2048000>;
+	status = "okay";
+
+	dfsdm0: filter@0 {
+		compatible = "st,stm32-dfsdm-adc";
+		st,filter-order = <3>;
+		status = "okay";
+
+		channel@0 {
+			reg = <0>;
+			label = "in0";
+			st,adc-channel-types = "SPI_F";
+			st,adc-channel-clk-src = "CLKOUT";
+			st,adc-alt-channel;
+			io-backends = <&sd_adc0>;
+		};
+
+		channel@1 {
+			reg = <1>;
+			label = "in1";
+			st,adc-channel-types = "SPI_R";
+			st,adc-channel-clk-src = "CLKOUT";
+			io-backends = <&sd_adc1>;
+		};
+	};
+
+	dfsdm1: filter@1 {
+		compatible = "st,stm32-dfsdm-adc";
+		st,filter-order = <3>;
+		status = "okay";
+
+		channel@3 {
+			reg = <3>;
+			label = "in3";
+			st,adc-channel-types = "SPI_R";
+			st,adc-channel-clk-src = "CLKOUT";
+			io-backends = <&sd_adc2>;
+		};
+	};
+};
+
 &dsi {
 	phy-dsi-supply = <&reg18>;
 	#address-cells = <1>;
-- 
2.25.1

Re: [RFC v2 03/11] dt-bindings: iio: stm32-dfsdm-adc: add scaling support

[Rob Herring]

On Thu, Jul 27, 2023 at 05:03:14PM +0200, Olivier Moysan wrote:
> Add scaling support to STM32 DFSDM.
> 
> This introduces the following changes:

Why?

> - Add ADC generic channel binding and remove support of deprecated
> channel bindings.

When was it deprecated?

> - DFSDM is now implemented as a channel provider, so remove io-channels
> properties.
> - Add iio-backend property to connect DFSDM to an SD modulator.

io-backends

All sorts of ABI issues with this change. Please explain why you don't 
care.

> 
> Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
> ---
>  .../bindings/iio/adc/st,stm32-dfsdm-adc.yaml  | 189 ++++++------------
>  1 file changed, 63 insertions(+), 126 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
> index 1970503389aa..128545cedc7f 100644
> --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
> @@ -85,22 +85,14 @@ patternProperties:
>          description: Specifies the DFSDM filter instance used.
>          maxItems: 1
>  
> -      interrupts:
> -        maxItems: 1
> +      '#address-cells':
> +        const: 1
>  
> -      st,adc-channels:
> -        description: |
> -          List of single-ended channels muxed for this ADC.
> -          On stm32h7 and stm32mp1:
> -          - For st,stm32-dfsdm-adc: up to 8 channels numbered from 0 to 7.
> -          - For st,stm32-dfsdm-dmic: 1 channel numbered from 0 to 7.
> -        $ref: /schemas/types.yaml#/definitions/uint32-array
> -        items:
> -          minimum: 0
> -          maximum: 7
> +      '#size-cells':
> +        const: 0
>  
> -      st,adc-channel-names:
> -        description: List of single-ended channel names.
> +      interrupts:
> +        maxItems: 1
>  
>        st,filter-order:
>          description: |
> @@ -111,39 +103,6 @@ patternProperties:
>          $ref: /schemas/types.yaml#/definitions/uint32
>          maximum: 5
>  
> -      "#io-channel-cells":
> -        const: 1
> -
> -      st,adc-channel-types:
> -        description: |
> -          Single-ended channel input type.
> -          - "SPI_R": SPI with data on rising edge (default)
> -          - "SPI_F": SPI with data on falling edge
> -          - "MANCH_R": manchester codec, rising edge = logic 0, falling edge = logic 1
> -          - "MANCH_F": manchester codec, rising edge = logic 1, falling edge = logic 0
> -        items:
> -          enum: [ SPI_R, SPI_F, MANCH_R, MANCH_F ]
> -        $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> -
> -      st,adc-channel-clk-src:
> -        description: |
> -          Conversion clock source.
> -          - "CLKIN": external SPI clock (CLKIN x)
> -          - "CLKOUT": internal SPI clock (CLKOUT) (default)
> -          - "CLKOUT_F": internal SPI clock divided by 2 (falling edge).
> -          - "CLKOUT_R": internal SPI clock divided by 2 (rising edge).
> -        items:
> -          enum: [ CLKIN, CLKOUT, CLKOUT_F, CLKOUT_R ]
> -        $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> -
> -      st,adc-alt-channel:
> -        description:
> -          Must be defined if two sigma delta modulators are
> -          connected on same SPI input.
> -          If not set, channel n is connected to SPI input n.
> -          If set, channel n is connected to SPI input n + 1.
> -        type: boolean
> -
>        st,filter0-sync:
>          description:
>            Set to 1 to synchronize with DFSDM filter instance 0.
> @@ -157,14 +116,68 @@ patternProperties:
>          items:
>            - const: rx
>  
> +    patternProperties:
> +      "^channel@([0-9]|1[0-9])$":
> +        type: object
> +        $ref: "adc.yaml"
> +        description: Represents the external channels which are connected to the DFSDM.
> +
> +        properties:
> +          reg:
> +            items:
> +              minimum: 0
> +              maximum: 19
> +
> +          label:
> +            description: |
> +              Unique name to identify channel.
> +
> +          st,adc-channel-types:
> +            description: |
> +              Single-ended channel input type.
> +              - "SPI_R": SPI with data on rising edge (default)
> +              - "SPI_F": SPI with data on falling edge
> +              - "MANCH_R": manchester codec, rising edge = logic 0, falling edge = logic 1
> +              - "MANCH_F": manchester codec, rising edge = logic 1, falling edge = logic 0
> +            items:
> +              enum: [ SPI_R, SPI_F, MANCH_R, MANCH_F ]
> +            $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> +
> +          st,adc-channel-clk-src:
> +            description: |
> +              Conversion clock source.
> +              - "CLKIN": external SPI clock (CLKIN x)
> +              - "CLKOUT": internal SPI clock (CLKOUT) (default)
> +              - "CLKOUT_F": internal SPI clock divided by 2 (falling edge).
> +              - "CLKOUT_R": internal SPI clock divided by 2 (rising edge).
> +            items:
> +              enum: [ CLKIN, CLKOUT, CLKOUT_F, CLKOUT_R ]
> +            $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> +
> +          st,adc-alt-channel:
> +            description:
> +              Must be defined if two sigma delta modulators are
> +              connected on same SPI input.
> +              If not set, channel n is connected to SPI input n.
> +              If set, channel n is connected to SPI input n + 1.
> +            type: boolean
> +
> +          io-backends:
> +            description: |
> +              phandle to an external sigma delta modulator or internal ADC output.
> +            $ref: /schemas/types.yaml#/definitions/phandle
> +
> +        required:
> +          - reg
> +          - io-backends
> +
> +        additionalProperties: false
> +
>      required:
>        - compatible
>        - reg
>        - interrupts
> -      - st,adc-channels
> -      - st,adc-channel-names
>        - st,filter-order
> -      - "#io-channel-cells"
>  
>      allOf:
>        - if:
> @@ -175,14 +188,6 @@ patternProperties:
>  
>          then:
>            properties:
> -            st,adc-channels:
> -              minItems: 1
> -              maxItems: 8
> -
> -            st,adc-channel-names:
> -              minItems: 1
> -              maxItems: 8
> -
>              st,adc-channel-types:
>                minItems: 1
>                maxItems: 8
> @@ -191,14 +196,6 @@ patternProperties:
>                minItems: 1
>                maxItems: 8
>  
> -            io-channels:
> -              description:
> -                From common IIO binding. Used to pipe external sigma delta
> -                modulator or internal ADC output to DFSDM channel.
> -
> -          required:
> -            - io-channels
> -
>        - if:
>            properties:
>              compatible:
> @@ -207,12 +204,6 @@ patternProperties:
>  
>          then:
>            properties:
> -            st,adc-channels:
> -              maxItems: 1
> -
> -            st,adc-channel-names:
> -              maxItems: 1
> -
>              st,adc-channel-types:
>                maxItems: 1
>  
> @@ -237,15 +228,9 @@ patternProperties:
>                  "#sound-dai-cells":
>                    const: 0
>  
> -                io-channels:
> -                  description:
> -                    From common IIO binding. Used to pipe external sigma delta
> -                    modulator or internal ADC output to DFSDM channel.
> -
>                required:
>                  - compatible
>                  - "#sound-dai-cells"
> -                - io-channels
>  
>  allOf:
>    - if:
> @@ -278,52 +263,4 @@ allOf:
>                  minimum: 0
>                  maximum: 5
>  
> -examples:
> -  - |
> -    #include <dt-bindings/interrupt-controller/arm-gic.h>
> -    #include <dt-bindings/clock/stm32mp1-clks.h>
> -    dfsdm: dfsdm@4400d000 {
> -      compatible = "st,stm32mp1-dfsdm";
> -      reg = <0x4400d000 0x800>;
> -      clocks = <&rcc DFSDM_K>, <&rcc ADFSDM_K>;
> -      clock-names = "dfsdm", "audio";
> -      #address-cells = <1>;
> -      #size-cells = <0>;
> -
> -      dfsdm0: filter@0 {
> -        compatible = "st,stm32-dfsdm-dmic";
> -        reg = <0>;
> -        interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
> -        dmas = <&dmamux1 101 0x400 0x01>;
> -        dma-names = "rx";
> -        #io-channel-cells = <1>;
> -        st,adc-channels = <1>;
> -        st,adc-channel-names = "dmic0";
> -        st,adc-channel-types = "SPI_R";
> -        st,adc-channel-clk-src = "CLKOUT";
> -        st,filter-order = <5>;
> -
> -        asoc_pdm0: dfsdm-dai {
> -          compatible = "st,stm32h7-dfsdm-dai";
> -          #sound-dai-cells = <0>;
> -          io-channels = <&dfsdm0 0>;
> -        };
> -      };
> -
> -      dfsdm_pdm1: filter@1 {
> -        compatible = "st,stm32-dfsdm-adc";
> -        reg = <1>;
> -        interrupts = <GIC_SPI 111 IRQ_TYPE_LEVEL_HIGH>;
> -        dmas = <&dmamux1 102 0x400 0x01>;
> -        dma-names = "rx";
> -        #io-channel-cells = <1>;
> -        st,adc-channels = <2 3>;
> -        st,adc-channel-names = "in2", "in3";
> -        st,adc-channel-types = "SPI_R", "SPI_R";
> -        st,adc-channel-clk-src = "CLKOUT_F", "CLKOUT_F";
> -        io-channels = <&sd_adc2 &sd_adc3>;
> -        st,filter-order = <1>;
> -      };
> -    };
> -
>  ...
> -- 
> 2.25.1
> 

Re: [RFC v2 03/11] dt-bindings: iio: stm32-dfsdm-adc: add scaling support

[Olivier MOYSAN]

Hi Rob,

On 8/11/23 19:10, Rob Herring wrote:
> On Thu, Jul 27, 2023 at 05:03:14PM +0200, Olivier Moysan wrote:
>> Add scaling support to STM32 DFSDM.
>>
>> This introduces the following changes:
> 
> Why?
> 

This RFC is an attempt to support scaling through a change in DFSDM 
topology.

These changes have some impacts on DFSDM and sd modulator bindings.
To keep things simple in this RFC, I skipped legacy support, to put the 
emphasis on the new bindings proposal.
There are two changes here: adoption of the generic IIO bindings and new 
"io-backends" property. This needs to be put in two separate patches at 
the end, I think (as already done for driver patches)

Anyway, the current bindings would become deprecated with these changes. 
I still have to consider how to support these legacy bindings for next 
step, However.

BRs
Olivier

>> - Add ADC generic channel binding and remove support of deprecated
>> channel bindings.
> 
> When was it deprecated?
> 
>> - DFSDM is now implemented as a channel provider, so remove io-channels
>> properties.
>> - Add iio-backend property to connect DFSDM to an SD modulator.
> 
> io-backends
> 
> All sorts of ABI issues with this change. Please explain why you don't
> care.
> 
>>
>> Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
>> ---
>>   .../bindings/iio/adc/st,stm32-dfsdm-adc.yaml  | 189 ++++++------------
>>   1 file changed, 63 insertions(+), 126 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
>> index 1970503389aa..128545cedc7f 100644
>> --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
>> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-dfsdm-adc.yaml
>> @@ -85,22 +85,14 @@ patternProperties:
>>           description: Specifies the DFSDM filter instance used.
>>           maxItems: 1
>>   
>> -      interrupts:
>> -        maxItems: 1
>> +      '#address-cells':
>> +        const: 1
>>   
>> -      st,adc-channels:
>> -        description: |
>> -          List of single-ended channels muxed for this ADC.
>> -          On stm32h7 and stm32mp1:
>> -          - For st,stm32-dfsdm-adc: up to 8 channels numbered from 0 to 7.
>> -          - For st,stm32-dfsdm-dmic: 1 channel numbered from 0 to 7.
>> -        $ref: /schemas/types.yaml#/definitions/uint32-array
>> -        items:
>> -          minimum: 0
>> -          maximum: 7
>> +      '#size-cells':
>> +        const: 0
>>   
>> -      st,adc-channel-names:
>> -        description: List of single-ended channel names.
>> +      interrupts:
>> +        maxItems: 1
>>   
>>         st,filter-order:
>>           description: |
>> @@ -111,39 +103,6 @@ patternProperties:
>>           $ref: /schemas/types.yaml#/definitions/uint32
>>           maximum: 5
>>   
>> -      "#io-channel-cells":
>> -        const: 1
>> -
>> -      st,adc-channel-types:
>> -        description: |
>> -          Single-ended channel input type.
>> -          - "SPI_R": SPI with data on rising edge (default)
>> -          - "SPI_F": SPI with data on falling edge
>> -          - "MANCH_R": manchester codec, rising edge = logic 0, falling edge = logic 1
>> -          - "MANCH_F": manchester codec, rising edge = logic 1, falling edge = logic 0
>> -        items:
>> -          enum: [ SPI_R, SPI_F, MANCH_R, MANCH_F ]
>> -        $ref: /schemas/types.yaml#/definitions/non-unique-string-array
>> -
>> -      st,adc-channel-clk-src:
>> -        description: |
>> -          Conversion clock source.
>> -          - "CLKIN": external SPI clock (CLKIN x)
>> -          - "CLKOUT": internal SPI clock (CLKOUT) (default)
>> -          - "CLKOUT_F": internal SPI clock divided by 2 (falling edge).
>> -          - "CLKOUT_R": internal SPI clock divided by 2 (rising edge).
>> -        items:
>> -          enum: [ CLKIN, CLKOUT, CLKOUT_F, CLKOUT_R ]
>> -        $ref: /schemas/types.yaml#/definitions/non-unique-string-array
>> -
>> -      st,adc-alt-channel:
>> -        description:
>> -          Must be defined if two sigma delta modulators are
>> -          connected on same SPI input.
>> -          If not set, channel n is connected to SPI input n.
>> -          If set, channel n is connected to SPI input n + 1.
>> -        type: boolean
>> -
>>         st,filter0-sync:
>>           description:
>>             Set to 1 to synchronize with DFSDM filter instance 0.
>> @@ -157,14 +116,68 @@ patternProperties:
>>           items:
>>             - const: rx
>>   
>> +    patternProperties:
>> +      "^channel@([0-9]|1[0-9])$":
>> +        type: object
>> +        $ref: "adc.yaml"
>> +        description: Represents the external channels which are connected to the DFSDM.
>> +
>> +        properties:
>> +          reg:
>> +            items:
>> +              minimum: 0
>> +              maximum: 19
>> +
>> +          label:
>> +            description: |
>> +              Unique name to identify channel.
>> +
>> +          st,adc-channel-types:
>> +            description: |
>> +              Single-ended channel input type.
>> +              - "SPI_R": SPI with data on rising edge (default)
>> +              - "SPI_F": SPI with data on falling edge
>> +              - "MANCH_R": manchester codec, rising edge = logic 0, falling edge = logic 1
>> +              - "MANCH_F": manchester codec, rising edge = logic 1, falling edge = logic 0
>> +            items:
>> +              enum: [ SPI_R, SPI_F, MANCH_R, MANCH_F ]
>> +            $ref: /schemas/types.yaml#/definitions/non-unique-string-array
>> +
>> +          st,adc-channel-clk-src:
>> +            description: |
>> +              Conversion clock source.
>> +              - "CLKIN": external SPI clock (CLKIN x)
>> +              - "CLKOUT": internal SPI clock (CLKOUT) (default)
>> +              - "CLKOUT_F": internal SPI clock divided by 2 (falling edge).
>> +              - "CLKOUT_R": internal SPI clock divided by 2 (rising edge).
>> +            items:
>> +              enum: [ CLKIN, CLKOUT, CLKOUT_F, CLKOUT_R ]
>> +            $ref: /schemas/types.yaml#/definitions/non-unique-string-array
>> +
>> +          st,adc-alt-channel:
>> +            description:
>> +              Must be defined if two sigma delta modulators are
>> +              connected on same SPI input.
>> +              If not set, channel n is connected to SPI input n.
>> +              If set, channel n is connected to SPI input n + 1.
>> +            type: boolean
>> +
>> +          io-backends:
>> +            description: |
>> +              phandle to an external sigma delta modulator or internal ADC output.
>> +            $ref: /schemas/types.yaml#/definitions/phandle
>> +
>> +        required:
>> +          - reg
>> +          - io-backends
>> +
>> +        additionalProperties: false
>> +
>>       required:
>>         - compatible
>>         - reg
>>         - interrupts
>> -      - st,adc-channels
>> -      - st,adc-channel-names
>>         - st,filter-order
>> -      - "#io-channel-cells"
>>   
>>       allOf:
>>         - if:
>> @@ -175,14 +188,6 @@ patternProperties:
>>   
>>           then:
>>             properties:
>> -            st,adc-channels:
>> -              minItems: 1
>> -              maxItems: 8
>> -
>> -            st,adc-channel-names:
>> -              minItems: 1
>> -              maxItems: 8
>> -
>>               st,adc-channel-types:
>>                 minItems: 1
>>                 maxItems: 8
>> @@ -191,14 +196,6 @@ patternProperties:
>>                 minItems: 1
>>                 maxItems: 8
>>   
>> -            io-channels:
>> -              description:
>> -                From common IIO binding. Used to pipe external sigma delta
>> -                modulator or internal ADC output to DFSDM channel.
>> -
>> -          required:
>> -            - io-channels
>> -
>>         - if:
>>             properties:
>>               compatible:
>> @@ -207,12 +204,6 @@ patternProperties:
>>   
>>           then:
>>             properties:
>> -            st,adc-channels:
>> -              maxItems: 1
>> -
>> -            st,adc-channel-names:
>> -              maxItems: 1
>> -
>>               st,adc-channel-types:
>>                 maxItems: 1
>>   
>> @@ -237,15 +228,9 @@ patternProperties:
>>                   "#sound-dai-cells":
>>                     const: 0
>>   
>> -                io-channels:
>> -                  description:
>> -                    From common IIO binding. Used to pipe external sigma delta
>> -                    modulator or internal ADC output to DFSDM channel.
>> -
>>                 required:
>>                   - compatible
>>                   - "#sound-dai-cells"
>> -                - io-channels
>>   
>>   allOf:
>>     - if:
>> @@ -278,52 +263,4 @@ allOf:
>>                   minimum: 0
>>                   maximum: 5
>>   
>> -examples:
>> -  - |
>> -    #include <dt-bindings/interrupt-controller/arm-gic.h>
>> -    #include <dt-bindings/clock/stm32mp1-clks.h>
>> -    dfsdm: dfsdm@4400d000 {
>> -      compatible = "st,stm32mp1-dfsdm";
>> -      reg = <0x4400d000 0x800>;
>> -      clocks = <&rcc DFSDM_K>, <&rcc ADFSDM_K>;
>> -      clock-names = "dfsdm", "audio";
>> -      #address-cells = <1>;
>> -      #size-cells = <0>;
>> -
>> -      dfsdm0: filter@0 {
>> -        compatible = "st,stm32-dfsdm-dmic";
>> -        reg = <0>;
>> -        interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
>> -        dmas = <&dmamux1 101 0x400 0x01>;
>> -        dma-names = "rx";
>> -        #io-channel-cells = <1>;
>> -        st,adc-channels = <1>;
>> -        st,adc-channel-names = "dmic0";
>> -        st,adc-channel-types = "SPI_R";
>> -        st,adc-channel-clk-src = "CLKOUT";
>> -        st,filter-order = <5>;
>> -
>> -        asoc_pdm0: dfsdm-dai {
>> -          compatible = "st,stm32h7-dfsdm-dai";
>> -          #sound-dai-cells = <0>;
>> -          io-channels = <&dfsdm0 0>;
>> -        };
>> -      };
>> -
>> -      dfsdm_pdm1: filter@1 {
>> -        compatible = "st,stm32-dfsdm-adc";
>> -        reg = <1>;
>> -        interrupts = <GIC_SPI 111 IRQ_TYPE_LEVEL_HIGH>;
>> -        dmas = <&dmamux1 102 0x400 0x01>;
>> -        dma-names = "rx";
>> -        #io-channel-cells = <1>;
>> -        st,adc-channels = <2 3>;
>> -        st,adc-channel-names = "in2", "in3";
>> -        st,adc-channel-types = "SPI_R", "SPI_R";
>> -        st,adc-channel-clk-src = "CLKOUT_F", "CLKOUT_F";
>> -        io-channels = <&sd_adc2 &sd_adc3>;
>> -        st,filter-order = <1>;
>> -      };
>> -    };
>> -
>>   ...
>> -- 
>> 2.25.1
>>