[PATCH v3 0/7] iio: adc: stm32-adc: add internal channels support

[PATCH v3 0/7] iio: adc: stm32-adc: add internal channels support

[Olivier Moysan]

This patchset adds support of ADC2 internal channels VDDCORE, VREFINT and VBAT
on STM32MP15x SoCs. The generic IIO channel bindings is also introduced here
to provide this feature. The legacy channel binding is kept for backward compatibility.

Changes in v2:
- Add 'deprecated' to channels legacy properties in ADC bindings
- Add set/clr service for common registers, to make code more generic in
  internal channels enable/disable services.
- Expose vrefint channel as a processed channel to return
  the actual value of vrefp.
- Minor code improvements

Changes in v3:
- fix vrefint sampling time check.

Olivier Moysan (7):
  dt-bindings: iio: stm32-adc: add generic channel binding
  dt-bindings: iio: stm32-adc: add nvmem support for vrefint internal
    channel
  iio: adc: stm32-adc: split channel init into several routines
  iio: adc: stm32-adc: add support of generic channels binding
  iio: adc: stm32-adc: add support of internal channels
  iio: adc: stm32-adc: add vrefint calibration support
  iio: adc: stm32-adc: use generic binding for sample-time

 .../bindings/iio/adc/st,stm32-adc.yaml        | 108 ++++-
 drivers/iio/adc/stm32-adc-core.h              |   8 +
 drivers/iio/adc/stm32-adc.c                   | 426 ++++++++++++++++--
 3 files changed, 487 insertions(+), 55 deletions(-)

-- 
2.17.1

[PATCH v3 1/7] dt-bindings: iio: stm32-adc: add generic channel binding

[Olivier Moysan]

Add ADC generic channel binding. This binding should
be used as an alternate to legacy channel properties
whenever possible.
ADC generic channel binding allows to identify supported
internal channels through the following reserved label names:
"vddcore", "vrefint" and "vbat".
This binding also allows to set a different sampling time
for each channel.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 .../bindings/iio/adc/st,stm32-adc.yaml        | 100 ++++++++++++++++--
 1 file changed, 93 insertions(+), 7 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml
index a58334c3bb76..1c13921b0556 100644
--- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml
@@ -222,6 +222,12 @@ patternProperties:
       '#io-channel-cells':
         const: 1
 
+      '#address-cells':
+        const: 1
+
+      '#size-cells':
+        const: 0
+
       interrupts:
         description: |
           IRQ Line for the ADC instance. Valid values are:
@@ -256,6 +262,7 @@ patternProperties:
             - 20 channels, numbered from 0 to 19 (for in0..in19) on stm32h7 and
               stm32mp1.
         $ref: /schemas/types.yaml#/definitions/uint32-array
+        deprecated: true
 
       st,adc-diff-channels:
         description: |
@@ -265,7 +272,9 @@ patternProperties:
           <vinp vinn>, <vinp vinn>,... vinp and vinn are numbered from 0 to 19.
 
           Note: At least one of "st,adc-channels" or "st,adc-diff-channels" is
-          required. Both properties can be used together. Some channels can be
+          required if no adc generic channel is defined. These legacy channel
+          properties are exclusive with adc generic channel bindings.
+          Both properties can be used together. Some channels can be
           used as single-ended and some other ones as differential (mixed). But
           channels can't be configured both as single-ended and differential.
         $ref: /schemas/types.yaml#/definitions/uint32-matrix
@@ -279,6 +288,7 @@ patternProperties:
                 "vinn" indicates negative input number
               minimum: 0
               maximum: 19
+        deprecated: true
 
       st,min-sample-time-nsecs:
         description:
@@ -289,6 +299,42 @@ patternProperties:
           list, to set sample time resp. for all channels, or independently for
           each channel.
         $ref: /schemas/types.yaml#/definitions/uint32-array
+        deprecated: true
+
+    patternProperties:
+      "^channel@([0-9]|1[0-9])$":
+        type: object
+        $ref: "adc.yaml"
+        description: |
+          Represents the external channels which are connected to the ADC.
+
+        properties:
+          reg:
+            items:
+              minimum: 0
+              maximum: 19
+
+          label:
+            description: |
+              Unique name to identify which channel this is.
+              Reserved label names "vddcore", "vrefint" and "vbat"
+              are used to identify internal channels with matching names.
+
+          diff-channels:
+            $ref: /schemas/types.yaml#/definitions/uint32-array
+            items:
+              minimum: 0
+              maximum: 19
+
+          st,min-sample-time-nsecs:
+            $ref: /schemas/types.yaml#/definitions/uint32
+            description: |
+              Minimum sampling time in nanoseconds. Depending on hardware (board)
+              e.g. high/low analog input source impedance, fine tune of ADC
+              sampling time may be recommended.
+
+        required:
+          - reg
 
     allOf:
       - if:
@@ -369,12 +415,6 @@ patternProperties:
 
     additionalProperties: false
 
-    anyOf:
-      - required:
-          - st,adc-channels
-      - required:
-          - st,adc-diff-channels
-
     required:
       - compatible
       - reg
@@ -451,4 +491,50 @@ examples:
         // other adc child node follow...
       };
 
+  - |
+    // Example 3: with stm32mp157c to setup ADC2 with:
+    // - internal channels 13, 14, 15.
+      #include <dt-bindings/interrupt-controller/arm-gic.h>
+      #include <dt-bindings/clock/stm32mp1-clks.h>
+      adc122: adc@48003000 {
+        compatible = "st,stm32mp1-adc-core";
+        reg = <0x48003000 0x400>;
+        interrupts = <GIC_SPI 18 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 90 IRQ_TYPE_LEVEL_HIGH>;
+        clocks = <&rcc ADC12>, <&rcc ADC12_K>;
+        clock-names = "bus", "adc";
+        booster-supply = <&booster>;
+        vdd-supply = <&vdd>;
+        vdda-supply = <&vdda>;
+        vref-supply = <&vref>;
+        st,syscfg = <&syscfg>;
+        interrupt-controller;
+        #interrupt-cells = <1>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+        adc@100 {
+          compatible = "st,stm32mp1-adc";
+          #io-channel-cells = <1>;
+          reg = <0x100>;
+          interrupts = <1>;
+          #address-cells = <1>;
+          #size-cells = <0>;
+          channel@13 {
+            reg = <13>;
+            label = "vrefint";
+            st,min-sample-time-nsecs = <9000>;
+          };
+          channel@14 {
+            reg = <14>;
+            label = "vddcore";
+            st,min-sample-time-nsecs = <9000>;
+          };
+          channel@15 {
+            reg = <15>;
+            label = "vbat";
+            st,min-sample-time-nsecs = <9000>;
+          };
+        };
+      };
+
 ...
-- 
2.17.1

[PATCH v3 2/7] dt-bindings: iio: stm32-adc: add nvmem support for vrefint internal channel

[Olivier Moysan]

Add support of nvmem. This allows to retrieve calibration data from OTP
for vrefint internal channel.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Acked-by: Rob Herring <robh@kernel.org>
---
 .../devicetree/bindings/iio/adc/st,stm32-adc.yaml         | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml
index 1c13921b0556..6a5d0181e784 100644
--- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml
@@ -301,6 +301,14 @@ patternProperties:
         $ref: /schemas/types.yaml#/definitions/uint32-array
         deprecated: true
 
+      nvmem-cells:
+        items:
+          - description: Phandle to the calibration vrefint data provided by otp
+
+      nvmem-cell-names:
+        items:
+          - const: vrefint
+
     patternProperties:
       "^channel@([0-9]|1[0-9])$":
         type: object
-- 
2.17.1

[PATCH v3 3/7] iio: adc: stm32-adc: split channel init into several routines

[Olivier Moysan]

Split stm32_adc_chan_of_init channel initialization function into
several routines to increase readability and prepare channel
generic binding handling.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 drivers/iio/adc/stm32-adc.c | 131 ++++++++++++++++++++++++------------
 1 file changed, 87 insertions(+), 44 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 5088de835bb1..2f137d14f141 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -194,6 +194,7 @@ struct stm32_adc_cfg {
  * @smpr_val:		sampling time settings (e.g. smpr1 / smpr2)
  * @cal:		optional calibration data on some devices
  * @chan_name:		channel name array
+ * @num_diff:		number of differential channels
  */
 struct stm32_adc {
 	struct stm32_adc_common	*common;
@@ -217,6 +218,7 @@ struct stm32_adc {
 	u32			smpr_val[2];
 	struct stm32_adc_calib	cal;
 	char			chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ];
+	u32			num_diff;
 };
 
 struct stm32_adc_diff_channel {
@@ -1706,17 +1708,11 @@ static void stm32_adc_chan_init_one(struct iio_dev *indio_dev,
 	}
 }
 
-static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
+static int stm32_adc_get_legacy_chan_count(struct iio_dev *indio_dev, struct stm32_adc *adc)
 {
 	struct device_node *node = indio_dev->dev.of_node;
-	struct stm32_adc *adc = iio_priv(indio_dev);
 	const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
-	struct stm32_adc_diff_channel diff[STM32_ADC_CH_MAX];
-	struct property *prop;
-	const __be32 *cur;
-	struct iio_chan_spec *channels;
-	int scan_index = 0, num_channels = 0, num_diff = 0, ret, i;
-	u32 val, smp = 0;
+	int num_channels = 0, ret;
 
 	ret = of_property_count_u32_elems(node, "st,adc-channels");
 	if (ret > adc_info->max_channels) {
@@ -1727,41 +1723,54 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 	}
 
 	ret = of_property_count_elems_of_size(node, "st,adc-diff-channels",
-					      sizeof(*diff));
+					      sizeof(struct stm32_adc_diff_channel));
 	if (ret > adc_info->max_channels) {
 		dev_err(&indio_dev->dev, "Bad st,adc-diff-channels?\n");
 		return -EINVAL;
 	} else if (ret > 0) {
-		int size = ret * sizeof(*diff) / sizeof(u32);
-
-		num_diff = ret;
+		adc->num_diff = ret;
 		num_channels += ret;
+	}
+
+	return num_channels;
+}
+
+static int stm32_adc_legacy_chan_init(struct iio_dev *indio_dev,
+				      struct stm32_adc *adc,
+				      struct iio_chan_spec *channels)
+{
+	struct device_node *node = indio_dev->dev.of_node;
+	const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
+	struct stm32_adc_diff_channel diff[STM32_ADC_CH_MAX];
+	u32 num_diff = adc->num_diff;
+	int size = num_diff * sizeof(*diff) / sizeof(u32);
+	int scan_index = 0, val, ret, i;
+	struct property *prop;
+	const __be32 *cur;
+
+	if (num_diff) {
 		ret = of_property_read_u32_array(node, "st,adc-diff-channels",
 						 (u32 *)diff, size);
-		if (ret)
+		if (ret) {
+			dev_err(&indio_dev->dev, "Failed to get diff channels %d\n", ret);
 			return ret;
-	}
+		}
 
-	if (!num_channels) {
-		dev_err(&indio_dev->dev, "No channels configured\n");
-		return -ENODATA;
-	}
+		for (i = 0; i < num_diff; i++) {
+			if (diff[i].vinp >= adc_info->max_channels ||
+			    diff[i].vinn >= adc_info->max_channels) {
+				dev_err(&indio_dev->dev, "Invalid channel in%d-in%d\n",
+					diff[i].vinp, diff[i].vinn);
+				return -EINVAL;
+			}
 
-	/* Optional sample time is provided either for each, or all channels */
-	ret = of_property_count_u32_elems(node, "st,min-sample-time-nsecs");
-	if (ret > 1 && ret != num_channels) {
-		dev_err(&indio_dev->dev, "Invalid st,min-sample-time-nsecs\n");
-		return -EINVAL;
+			stm32_adc_chan_init_one(indio_dev, &channels[scan_index],
+						diff[i].vinp, diff[i].vinn,
+						scan_index, true);
+			scan_index++;
+		}
 	}
 
-	if (timestamping)
-		num_channels++;
-
-	channels = devm_kcalloc(&indio_dev->dev, num_channels,
-				sizeof(struct iio_chan_spec), GFP_KERNEL);
-	if (!channels)
-		return -ENOMEM;
-
 	of_property_for_each_u32(node, "st,adc-channels", prop, cur, val) {
 		if (val >= adc_info->max_channels) {
 			dev_err(&indio_dev->dev, "Invalid channel %d\n", val);
@@ -1771,8 +1780,7 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 		/* Channel can't be configured both as single-ended & diff */
 		for (i = 0; i < num_diff; i++) {
 			if (val == diff[i].vinp) {
-				dev_err(&indio_dev->dev,
-					"channel %d miss-configured\n",	val);
+				dev_err(&indio_dev->dev, "channel %d misconfigured\n",	val);
 				return -EINVAL;
 			}
 		}
@@ -1781,19 +1789,54 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 		scan_index++;
 	}
 
-	for (i = 0; i < num_diff; i++) {
-		if (diff[i].vinp >= adc_info->max_channels ||
-		    diff[i].vinn >= adc_info->max_channels) {
-			dev_err(&indio_dev->dev, "Invalid channel in%d-in%d\n",
-				diff[i].vinp, diff[i].vinn);
-			return -EINVAL;
-		}
-		stm32_adc_chan_init_one(indio_dev, &channels[scan_index],
-					diff[i].vinp, diff[i].vinn, scan_index,
-					true);
-		scan_index++;
+	return scan_index;
+}
+
+static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
+{
+	struct device_node *node = indio_dev->dev.of_node;
+	struct stm32_adc *adc = iio_priv(indio_dev);
+	const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
+	struct iio_chan_spec *channels;
+	int scan_index = 0, num_channels = 0, ret, i;
+	u32 smp = 0;
+
+	ret = stm32_adc_get_legacy_chan_count(indio_dev, adc);
+	if (ret < 0)
+		return ret;
+	num_channels = ret;
+
+	if (!num_channels) {
+		dev_err(&indio_dev->dev, "No channels configured\n");
+		return -ENODATA;
 	}
 
+	if (num_channels > adc_info->max_channels) {
+		dev_err(&indio_dev->dev, "Channel number [%d] exceeds %d\n",
+			num_channels, adc_info->max_channels);
+		return -EINVAL;
+	}
+
+	/* Optional sample time is provided either for each, or all channels */
+	ret = of_property_count_u32_elems(node, "st,min-sample-time-nsecs");
+	if (ret > 1 && ret != num_channels) {
+		dev_err(&indio_dev->dev, "Invalid st,min-sample-time-nsecs\n");
+		return -EINVAL;
+	}
+
+	if (timestamping)
+		num_channels++;
+
+	channels = devm_kcalloc(&indio_dev->dev, num_channels,
+				sizeof(struct iio_chan_spec), GFP_KERNEL);
+	if (!channels)
+		return -ENOMEM;
+
+	ret = stm32_adc_legacy_chan_init(indio_dev, adc, channels);
+	if (ret < 0)
+		return ret;
+	scan_index = ret;
+
 	for (i = 0; i < scan_index; i++) {
 		/*
 		 * Using of_property_read_u32_index(), smp value will only be
-- 
2.17.1

[PATCH v3 4/7] iio: adc: stm32-adc: add support of generic channels binding

[Olivier Moysan]

Add support of generic IIO channel binding:
./devicetree/bindings/iio/adc/adc.yaml
Keep support of st,adc-channels and st,adc-diff-channels
for backward compatibility.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 drivers/iio/adc/stm32-adc.c | 95 +++++++++++++++++++++++++++++++++----
 1 file changed, 86 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 2f137d14f141..85d09cbd41ae 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -35,7 +35,7 @@
 #define STM32H7_BOOST_CLKRATE		20000000UL
 
 #define STM32_ADC_CH_MAX		20	/* max number of channels */
-#define STM32_ADC_CH_SZ			10	/* max channel name size */
+#define STM32_ADC_CH_SZ			16	/* max channel name size */
 #define STM32_ADC_MAX_SQ		16	/* SQ1..SQ16 */
 #define STM32_ADC_MAX_SMP		7	/* SMPx range is [0..7] */
 #define STM32_ADC_TIMEOUT_US		100000
@@ -1792,6 +1792,73 @@ static int stm32_adc_legacy_chan_init(struct iio_dev *indio_dev,
 	return scan_index;
 }
 
+static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
+				       struct stm32_adc *adc,
+				       struct iio_chan_spec *channels)
+{
+	struct device_node *node = indio_dev->dev.of_node;
+	const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
+	struct device_node *child;
+	const char *name;
+	int val, scan_index = 0, ret;
+	bool differential;
+	u32 vin[2];
+
+	for_each_available_child_of_node(node, child) {
+		ret = of_property_read_u32(child, "reg", &val);
+		if (ret) {
+			dev_err(&indio_dev->dev, "Missing channel index %d\n", ret);
+			goto err;
+		}
+
+		ret = of_property_read_string(child, "label", &name);
+		/* label is optional */
+		if (!ret) {
+			if (strlen(name) >= STM32_ADC_CH_SZ) {
+				dev_err(&indio_dev->dev, "Label %s exceeds %d characters\n",
+					name, STM32_ADC_CH_SZ);
+				return -EINVAL;
+			}
+			strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
+		} else if (ret != -EINVAL) {
+			dev_err(&indio_dev->dev, "Invalid label %d\n", ret);
+			goto err;
+		}
+
+		if (val >= adc_info->max_channels) {
+			dev_err(&indio_dev->dev, "Invalid channel %d\n", val);
+			ret = -EINVAL;
+			goto err;
+		}
+
+		differential = false;
+		ret = of_property_read_u32_array(child, "diff-channels", vin, 2);
+		/* diff-channels is optional */
+		if (!ret) {
+			differential = true;
+			if (vin[0] != val || vin[1] >= adc_info->max_channels) {
+				dev_err(&indio_dev->dev, "Invalid channel in%d-in%d\n",
+					vin[0], vin[1]);
+				goto err;
+			}
+		} else if (ret != -EINVAL) {
+			dev_err(&indio_dev->dev, "Invalid diff-channels property %d\n", ret);
+			goto err;
+		}
+
+		stm32_adc_chan_init_one(indio_dev, &channels[scan_index], val,
+					vin[1], scan_index, differential);
+		scan_index++;
+	}
+
+	return scan_index;
+
+err:
+	of_node_put(child);
+
+	return ret;
+}
+
 static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 {
 	struct device_node *node = indio_dev->dev.of_node;
@@ -1800,15 +1867,22 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 	struct iio_chan_spec *channels;
 	int scan_index = 0, num_channels = 0, ret, i;
 	u32 smp = 0;
+	bool legacy = false;
 
-	ret = stm32_adc_get_legacy_chan_count(indio_dev, adc);
-	if (ret < 0)
-		return ret;
-	num_channels = ret;
-
+	num_channels = of_get_available_child_count(node);
+	/* If no channels have been found, fallback to channels legacy properties. */
 	if (!num_channels) {
-		dev_err(&indio_dev->dev, "No channels configured\n");
-		return -ENODATA;
+		legacy = true;
+
+		ret = stm32_adc_get_legacy_chan_count(indio_dev, adc);
+		if (!ret) {
+			dev_err(indio_dev->dev.parent, "No channel found\n");
+			return -ENODATA;
+		} else if (ret < 0) {
+			return ret;
+		}
+
+		num_channels = ret;
 	}
 
 	if (num_channels > adc_info->max_channels) {
@@ -1832,7 +1906,10 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 	if (!channels)
 		return -ENOMEM;
 
-	ret = stm32_adc_legacy_chan_init(indio_dev, adc, channels);
+	if (legacy)
+		ret = stm32_adc_legacy_chan_init(indio_dev, adc, channels);
+	else
+		ret = stm32_adc_generic_chan_init(indio_dev, adc, channels);
 	if (ret < 0)
 		return ret;
 	scan_index = ret;
-- 
2.17.1

[PATCH v3 5/7] iio: adc: stm32-adc: add support of internal channels

[Olivier Moysan]

Add support of ADC2 internal channels VDDCORE, VREFINT and VBAT.
The reserved label name "vddcore", "vrefint" and "vbat" must
be used in Device Tree channel node, to enable the corresponding
internal channel.

Note: This patch does not provide support of internal channels
for F4 and H7.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 drivers/iio/adc/stm32-adc-core.h |   8 ++
 drivers/iio/adc/stm32-adc.c      | 142 ++++++++++++++++++++++++++++++-
 2 files changed, 147 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc-core.h b/drivers/iio/adc/stm32-adc-core.h
index 2322809bfd2f..7c924f463f67 100644
--- a/drivers/iio/adc/stm32-adc-core.h
+++ b/drivers/iio/adc/stm32-adc-core.h
@@ -102,6 +102,9 @@
 #define STM32H7_ADC_CALFACT		0xC4
 #define STM32H7_ADC_CALFACT2		0xC8
 
+/* STM32MP1 - ADC2 instance option register */
+#define STM32MP1_ADC2_OR		0xD0
+
 /* STM32H7 - common registers for all ADC instances */
 #define STM32H7_ADC_CSR			(STM32_ADCX_COMN_OFFSET + 0x00)
 #define STM32H7_ADC_CCR			(STM32_ADCX_COMN_OFFSET + 0x08)
@@ -168,11 +171,16 @@ enum stm32h7_adc_dmngt {
 #define STM32H7_EOC_MST			BIT(2)
 
 /* STM32H7_ADC_CCR - bit fields */
+#define STM32H7_VBATEN			BIT(24)
+#define STM32H7_VREFEN			BIT(22)
 #define STM32H7_PRESC_SHIFT		18
 #define STM32H7_PRESC_MASK		GENMASK(21, 18)
 #define STM32H7_CKMODE_SHIFT		16
 #define STM32H7_CKMODE_MASK		GENMASK(17, 16)
 
+/* STM32MP1_ADC2_OR - bit fields */
+#define STM32MP1_VDDCOREEN		BIT(0)
+
 /**
  * struct stm32_adc_common - stm32 ADC driver common data (for all instances)
  * @base:		control registers base cpu addr
diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 85d09cbd41ae..5a7ac45a0725 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -77,6 +77,30 @@ enum stm32_adc_extsel {
 	STM32_EXT20,
 };
 
+enum stm32_adc_int_ch {
+	STM32_ADC_INT_CH_NONE = -1,
+	STM32_ADC_INT_CH_VDDCORE,
+	STM32_ADC_INT_CH_VREFINT,
+	STM32_ADC_INT_CH_VBAT,
+	STM32_ADC_INT_CH_NB,
+};
+
+/**
+ * struct stm32_adc_ic - ADC internal channels
+ * @name:	name of the internal channel
+ * @idx:	internal channel enum index
+ */
+struct stm32_adc_ic {
+	const char *name;
+	u32 idx;
+};
+
+static const struct stm32_adc_ic stm32_adc_ic[STM32_ADC_INT_CH_NB] = {
+	{ "vddcore", STM32_ADC_INT_CH_VDDCORE },
+	{ "vrefint", STM32_ADC_INT_CH_VREFINT },
+	{ "vbat", STM32_ADC_INT_CH_VBAT },
+};
+
 /**
  * struct stm32_adc_trig_info - ADC trigger info
  * @name:		name of the trigger, corresponding to its source
@@ -126,6 +150,9 @@ struct stm32_adc_regs {
  * @res:		resolution selection register & bitfield
  * @smpr:		smpr1 & smpr2 registers offset array
  * @smp_bits:		smpr1 & smpr2 index and bitfields
+ * @or_vdd:		option register & vddcore bitfield
+ * @ccr_vbat:		common register & vbat bitfield
+ * @ccr_vref:		common register & vrefint bitfield
  */
 struct stm32_adc_regspec {
 	const u32 dr;
@@ -139,6 +166,9 @@ struct stm32_adc_regspec {
 	const struct stm32_adc_regs res;
 	const u32 smpr[2];
 	const struct stm32_adc_regs *smp_bits;
+	const struct stm32_adc_regs or_vdd;
+	const struct stm32_adc_regs ccr_vbat;
+	const struct stm32_adc_regs ccr_vref;
 };
 
 struct stm32_adc;
@@ -195,6 +225,7 @@ struct stm32_adc_cfg {
  * @cal:		optional calibration data on some devices
  * @chan_name:		channel name array
  * @num_diff:		number of differential channels
+ * @int_ch:		internal channel indexes array
  */
 struct stm32_adc {
 	struct stm32_adc_common	*common;
@@ -219,6 +250,7 @@ struct stm32_adc {
 	struct stm32_adc_calib	cal;
 	char			chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ];
 	u32			num_diff;
+	int			int_ch[STM32_ADC_INT_CH_NB];
 };
 
 struct stm32_adc_diff_channel {
@@ -451,6 +483,24 @@ static const struct stm32_adc_regspec stm32h7_adc_regspec = {
 	.smp_bits = stm32h7_smp_bits,
 };
 
+static const struct stm32_adc_regspec stm32mp1_adc_regspec = {
+	.dr = STM32H7_ADC_DR,
+	.ier_eoc = { STM32H7_ADC_IER, STM32H7_EOCIE },
+	.ier_ovr = { STM32H7_ADC_IER, STM32H7_OVRIE },
+	.isr_eoc = { STM32H7_ADC_ISR, STM32H7_EOC },
+	.isr_ovr = { STM32H7_ADC_ISR, STM32H7_OVR },
+	.sqr = stm32h7_sq,
+	.exten = { STM32H7_ADC_CFGR, STM32H7_EXTEN_MASK, STM32H7_EXTEN_SHIFT },
+	.extsel = { STM32H7_ADC_CFGR, STM32H7_EXTSEL_MASK,
+		    STM32H7_EXTSEL_SHIFT },
+	.res = { STM32H7_ADC_CFGR, STM32H7_RES_MASK, STM32H7_RES_SHIFT },
+	.smpr = { STM32H7_ADC_SMPR1, STM32H7_ADC_SMPR2 },
+	.smp_bits = stm32h7_smp_bits,
+	.or_vdd = { STM32MP1_ADC2_OR, STM32MP1_VDDCOREEN },
+	.ccr_vbat = { STM32H7_ADC_CCR, STM32H7_VBATEN },
+	.ccr_vref = { STM32H7_ADC_CCR, STM32H7_VREFEN },
+};
+
 /*
  * STM32 ADC registers access routines
  * @adc: stm32 adc instance
@@ -489,6 +539,16 @@ static void stm32_adc_set_bits(struct stm32_adc *adc, u32 reg, u32 bits)
 	spin_unlock_irqrestore(&adc->lock, flags);
 }
 
+static void stm32_adc_set_bits_common(struct stm32_adc *adc, u32 reg, u32 bits)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&adc->lock, flags);
+	writel_relaxed(readl_relaxed(adc->common->base + reg) | bits,
+		       adc->common->base + reg);
+	spin_unlock_irqrestore(&adc->lock, flags);
+}
+
 static void stm32_adc_clr_bits(struct stm32_adc *adc, u32 reg, u32 bits)
 {
 	unsigned long flags;
@@ -498,6 +558,16 @@ static void stm32_adc_clr_bits(struct stm32_adc *adc, u32 reg, u32 bits)
 	spin_unlock_irqrestore(&adc->lock, flags);
 }
 
+static void stm32_adc_clr_bits_common(struct stm32_adc *adc, u32 reg, u32 bits)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&adc->lock, flags);
+	writel_relaxed(readl_relaxed(adc->common->base + reg) & ~bits,
+		       adc->common->base + reg);
+	spin_unlock_irqrestore(&adc->lock, flags);
+}
+
 /**
  * stm32_adc_conv_irq_enable() - Enable end of conversion interrupt
  * @adc: stm32 adc instance
@@ -579,6 +649,60 @@ static int stm32_adc_hw_start(struct device *dev)
 	return ret;
 }
 
+static void stm32_adc_int_ch_enable(struct iio_dev *indio_dev)
+{
+	struct stm32_adc *adc = iio_priv(indio_dev);
+	u32 i;
+
+	for (i = 0; i < STM32_ADC_INT_CH_NB; i++) {
+		if (adc->int_ch[i] == STM32_ADC_INT_CH_NONE)
+			continue;
+
+		switch (i) {
+		case STM32_ADC_INT_CH_VDDCORE:
+			dev_dbg(&indio_dev->dev, "Enable VDDCore\n");
+			stm32_adc_set_bits(adc, adc->cfg->regs->or_vdd.reg,
+					   adc->cfg->regs->or_vdd.mask);
+			break;
+		case STM32_ADC_INT_CH_VREFINT:
+			dev_dbg(&indio_dev->dev, "Enable VREFInt\n");
+			stm32_adc_set_bits_common(adc, adc->cfg->regs->ccr_vref.reg,
+						  adc->cfg->regs->ccr_vref.mask);
+			break;
+		case STM32_ADC_INT_CH_VBAT:
+			dev_dbg(&indio_dev->dev, "Enable VBAT\n");
+			stm32_adc_set_bits_common(adc, adc->cfg->regs->ccr_vbat.reg,
+						  adc->cfg->regs->ccr_vbat.mask);
+			break;
+		}
+	}
+}
+
+static void stm32_adc_int_ch_disable(struct stm32_adc *adc)
+{
+	u32 i;
+
+	for (i = 0; i < STM32_ADC_INT_CH_NB; i++) {
+		if (adc->int_ch[i] == STM32_ADC_INT_CH_NONE)
+			continue;
+
+		switch (i) {
+		case STM32_ADC_INT_CH_VDDCORE:
+			stm32_adc_clr_bits(adc, adc->cfg->regs->or_vdd.reg,
+					   adc->cfg->regs->or_vdd.mask);
+			break;
+		case STM32_ADC_INT_CH_VREFINT:
+			stm32_adc_clr_bits_common(adc, adc->cfg->regs->ccr_vref.reg,
+						  adc->cfg->regs->ccr_vref.mask);
+			break;
+		case STM32_ADC_INT_CH_VBAT:
+			stm32_adc_clr_bits_common(adc, adc->cfg->regs->ccr_vbat.reg,
+						  adc->cfg->regs->ccr_vbat.mask);
+			break;
+		}
+	}
+}
+
 /**
  * stm32f4_adc_start_conv() - Start conversions for regular channels.
  * @indio_dev: IIO device instance
@@ -947,11 +1071,13 @@ static int stm32h7_adc_prepare(struct iio_dev *indio_dev)
 		goto pwr_dwn;
 	calib = ret;
 
+	stm32_adc_int_ch_enable(indio_dev);
+
 	stm32_adc_writel(adc, STM32H7_ADC_DIFSEL, adc->difsel);
 
 	ret = stm32h7_adc_enable(indio_dev);
 	if (ret)
-		goto pwr_dwn;
+		goto ch_disable;
 
 	/* Either restore or read calibration result for future reference */
 	if (calib)
@@ -967,6 +1093,8 @@ static int stm32h7_adc_prepare(struct iio_dev *indio_dev)
 
 disable:
 	stm32h7_adc_disable(indio_dev);
+ch_disable:
+	stm32_adc_int_ch_disable(adc);
 pwr_dwn:
 	stm32h7_adc_enter_pwr_down(adc);
 
@@ -978,6 +1106,7 @@ static void stm32h7_adc_unprepare(struct iio_dev *indio_dev)
 	struct stm32_adc *adc = iio_priv(indio_dev);
 
 	stm32h7_adc_disable(indio_dev);
+	stm32_adc_int_ch_disable(adc);
 	stm32h7_adc_enter_pwr_down(adc);
 }
 
@@ -1800,7 +1929,7 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
 	const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
 	struct device_node *child;
 	const char *name;
-	int val, scan_index = 0, ret;
+	int val, scan_index = 0, ret, i;
 	bool differential;
 	u32 vin[2];
 
@@ -1820,6 +1949,10 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
 				return -EINVAL;
 			}
 			strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
+			for (i = 0; i < STM32_ADC_INT_CH_NB; i++) {
+				if (!strncmp(stm32_adc_ic[i].name, name, STM32_ADC_CH_SZ))
+					adc->int_ch[i] = val;
+			}
 		} else if (ret != -EINVAL) {
 			dev_err(&indio_dev->dev, "Invalid label %d\n", ret);
 			goto err;
@@ -1869,6 +2002,9 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 	u32 smp = 0;
 	bool legacy = false;
 
+	for (i = 0; i < STM32_ADC_INT_CH_NB; i++)
+		adc->int_ch[i] = STM32_ADC_INT_CH_NONE;
+
 	num_channels = of_get_available_child_count(node);
 	/* If no channels have been found, fallback to channels legacy properties. */
 	if (!num_channels) {
@@ -2219,7 +2355,7 @@ static const struct stm32_adc_cfg stm32h7_adc_cfg = {
 };
 
 static const struct stm32_adc_cfg stm32mp1_adc_cfg = {
-	.regs = &stm32h7_adc_regspec,
+	.regs = &stm32mp1_adc_regspec,
 	.adc_info = &stm32h7_adc_info,
 	.trigs = stm32h7_adc_trigs,
 	.has_vregready = true,
-- 
2.17.1

[PATCH v3 6/7] iio: adc: stm32-adc: add vrefint calibration support

[Olivier Moysan]

Add support of vrefint calibration.
If a channel is labeled as vrefint, get vrefint calibration
from non volatile memory for this channel.
vrefint channel is exposed as a processed channel returning
the actual value of vrefp:
vrefp = 3.3 x vrefint_cal / vrefint_data

A conversion on vrefint channel allows to update scale
factor according to vrefint deviation, compared to vrefint
calibration value.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 drivers/iio/adc/stm32-adc.c | 74 ++++++++++++++++++++++++++++++++++---
 1 file changed, 68 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 5a7ac45a0725..d89115809b37 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -21,6 +21,7 @@
 #include <linux/io.h>
 #include <linux/iopoll.h>
 #include <linux/module.h>
+#include <linux/nvmem-consumer.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/of.h>
@@ -41,6 +42,7 @@
 #define STM32_ADC_TIMEOUT_US		100000
 #define STM32_ADC_TIMEOUT	(msecs_to_jiffies(STM32_ADC_TIMEOUT_US / 1000))
 #define STM32_ADC_HW_STOP_DELAY_MS	100
+#define STM32_ADC_VREFINT_VOLTAGE	3300
 
 #define STM32_DMA_BUFFER_SIZE		PAGE_SIZE
 
@@ -137,6 +139,16 @@ struct stm32_adc_regs {
 	int shift;
 };
 
+/**
+ * struct stm32_adc_vrefint - stm32 ADC internal reference voltage data
+ * @vrefint_cal:	vrefint calibration value from nvmem
+ * @vrefint_data:	vrefint actual value
+ */
+struct stm32_adc_vrefint {
+	u32 vrefint_cal;
+	u32 vrefint_data;
+};
+
 /**
  * struct stm32_adc_regspec - stm32 registers definition
  * @dr:			data register offset
@@ -186,6 +198,7 @@ struct stm32_adc;
  * @unprepare:		optional unprepare routine (disable, power-down)
  * @irq_clear:		routine to clear irqs
  * @smp_cycles:		programmable sampling time (ADC clock cycles)
+ * @ts_vrefint_ns:	vrefint minimum sampling time in ns
  */
 struct stm32_adc_cfg {
 	const struct stm32_adc_regspec	*regs;
@@ -199,6 +212,7 @@ struct stm32_adc_cfg {
 	void (*unprepare)(struct iio_dev *);
 	void (*irq_clear)(struct iio_dev *indio_dev, u32 msk);
 	const unsigned int *smp_cycles;
+	const unsigned int ts_vrefint_ns;
 };
 
 /**
@@ -223,6 +237,7 @@ struct stm32_adc_cfg {
  * @pcsel:		bitmask to preselect channels on some devices
  * @smpr_val:		sampling time settings (e.g. smpr1 / smpr2)
  * @cal:		optional calibration data on some devices
+ * @vrefint:		internal reference voltage data
  * @chan_name:		channel name array
  * @num_diff:		number of differential channels
  * @int_ch:		internal channel indexes array
@@ -248,6 +263,7 @@ struct stm32_adc {
 	u32			pcsel;
 	u32			smpr_val[2];
 	struct stm32_adc_calib	cal;
+	struct stm32_adc_vrefint vrefint;
 	char			chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ];
 	u32			num_diff;
 	int			int_ch[STM32_ADC_INT_CH_NB];
@@ -1343,6 +1359,7 @@ static int stm32_adc_read_raw(struct iio_dev *indio_dev,
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
+	case IIO_CHAN_INFO_PROCESSED:
 		ret = iio_device_claim_direct_mode(indio_dev);
 		if (ret)
 			return ret;
@@ -1350,6 +1367,10 @@ static int stm32_adc_read_raw(struct iio_dev *indio_dev,
 			ret = stm32_adc_single_conv(indio_dev, chan, val);
 		else
 			ret = -EINVAL;
+
+		if (mask == IIO_CHAN_INFO_PROCESSED && adc->vrefint.vrefint_cal)
+			*val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / *val;
+
 		iio_device_release_direct_mode(indio_dev);
 		return ret;
 
@@ -1819,7 +1840,10 @@ static void stm32_adc_chan_init_one(struct iio_dev *indio_dev,
 	chan->datasheet_name = name;
 	chan->scan_index = scan_index;
 	chan->indexed = 1;
-	chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
+	if (chan->channel == adc->int_ch[STM32_ADC_INT_CH_VREFINT])
+		chan->info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED);
+	else
+		chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
 	chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
 					 BIT(IIO_CHAN_INFO_OFFSET);
 	chan->scan_type.sign = 'u';
@@ -1921,6 +1945,36 @@ static int stm32_adc_legacy_chan_init(struct iio_dev *indio_dev,
 	return scan_index;
 }
 
+static int stm32_adc_populate_int_ch(struct iio_dev *indio_dev, const char *ch_name,
+				     int chan)
+{
+	struct stm32_adc *adc = iio_priv(indio_dev);
+	u16 vrefint;
+	int i, ret;
+
+	for (i = 0; i < STM32_ADC_INT_CH_NB; i++) {
+		if (!strncmp(stm32_adc_ic[i].name, ch_name, STM32_ADC_CH_SZ)) {
+			adc->int_ch[i] = chan;
+
+			if (stm32_adc_ic[i].idx != STM32_ADC_INT_CH_VREFINT)
+				continue;
+
+			/* Get calibration data for vrefint channel */
+			ret = nvmem_cell_read_u16(&indio_dev->dev, "vrefint", &vrefint);
+			if (ret && ret != -ENOENT && ret != -EOPNOTSUPP) {
+				dev_err(&indio_dev->dev, "nvmem access error %d\n", ret);
+				return ret;
+			}
+			if (ret == -ENOENT)
+				dev_dbg(&indio_dev->dev, "vrefint calibration not found\n");
+			else
+				adc->vrefint.vrefint_cal = vrefint;
+		}
+	}
+
+	return 0;
+}
+
 static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
 				       struct stm32_adc *adc,
 				       struct iio_chan_spec *channels)
@@ -1929,7 +1983,7 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
 	const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
 	struct device_node *child;
 	const char *name;
-	int val, scan_index = 0, ret, i;
+	int val, scan_index = 0, ret;
 	bool differential;
 	u32 vin[2];
 
@@ -1949,10 +2003,9 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
 				return -EINVAL;
 			}
 			strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
-			for (i = 0; i < STM32_ADC_INT_CH_NB; i++) {
-				if (!strncmp(stm32_adc_ic[i].name, name, STM32_ADC_CH_SZ))
-					adc->int_ch[i] = val;
-			}
+			ret = stm32_adc_populate_int_ch(indio_dev, name, val);
+			if (ret)
+				goto err;
 		} else if (ret != -EINVAL) {
 			dev_err(&indio_dev->dev, "Invalid label %d\n", ret);
 			goto err;
@@ -2059,6 +2112,14 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 		 */
 		of_property_read_u32_index(node, "st,min-sample-time-nsecs",
 					   i, &smp);
+
+		/*
+		 * For vrefint channel, ensure that the sampling time cannot
+		 * be lower than the one specified in the datasheet
+		 */
+		if (channels[i].channel == adc->int_ch[STM32_ADC_INT_CH_VREFINT])
+			smp = max(smp, adc->cfg->ts_vrefint_ns);
+
 		/* Prepare sampling time settings */
 		stm32_adc_smpr_init(adc, channels[i].channel, smp);
 	}
@@ -2365,6 +2426,7 @@ static const struct stm32_adc_cfg stm32mp1_adc_cfg = {
 	.unprepare = stm32h7_adc_unprepare,
 	.smp_cycles = stm32h7_adc_smp_cycles,
 	.irq_clear = stm32h7_adc_irq_clear,
+	.ts_vrefint_ns = 4300,
 };
 
 static const struct of_device_id stm32_adc_of_match[] = {
-- 
2.17.1

[PATCH v3 7/7] iio: adc: stm32-adc: use generic binding for sample-time

[Olivier Moysan]

Add st,min-sample-time-nsecs to channel generic binding.
Sample time can be defined par channel node. If a channel
is configured as differential, the same sample time applies
for both inputs.
Keep support of legacy st,min-sample-time-nsecs property
for backward compatibility.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
 drivers/iio/adc/stm32-adc.c | 70 ++++++++++++++++++++++---------------
 1 file changed, 41 insertions(+), 29 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index d89115809b37..3f1739b0a7b6 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -1809,6 +1809,13 @@ static void stm32_adc_smpr_init(struct stm32_adc *adc, int channel, u32 smp_ns)
 	u32 period_ns, shift = smpr->shift, mask = smpr->mask;
 	unsigned int smp, r = smpr->reg;
 
+	/*
+	 * For vrefint channel, ensure that the sampling time cannot
+	 * be lower than the one specified in the datasheet
+	 */
+	if (channel == adc->int_ch[STM32_ADC_INT_CH_VREFINT])
+		smp_ns = max(smp_ns, adc->cfg->ts_vrefint_ns);
+
 	/* Determine sampling time (ADC clock cycles) */
 	period_ns = NSEC_PER_SEC / adc->common->rate;
 	for (smp = 0; smp <= STM32_ADC_MAX_SMP; smp++)
@@ -1885,6 +1892,13 @@ static int stm32_adc_get_legacy_chan_count(struct iio_dev *indio_dev, struct stm
 		num_channels += ret;
 	}
 
+	/* Optional sample time is provided either for each, or all channels */
+	ret = of_property_count_u32_elems(node, "st,min-sample-time-nsecs");
+	if (ret > 1 && ret != num_channels) {
+		dev_err(&indio_dev->dev, "Invalid st,min-sample-time-nsecs\n");
+		return -EINVAL;
+	}
+
 	return num_channels;
 }
 
@@ -1900,6 +1914,7 @@ static int stm32_adc_legacy_chan_init(struct iio_dev *indio_dev,
 	int scan_index = 0, val, ret, i;
 	struct property *prop;
 	const __be32 *cur;
+	u32 smp = 0;
 
 	if (num_diff) {
 		ret = of_property_read_u32_array(node, "st,adc-diff-channels",
@@ -1942,6 +1957,19 @@ static int stm32_adc_legacy_chan_init(struct iio_dev *indio_dev,
 		scan_index++;
 	}
 
+	for (i = 0; i < scan_index; i++) {
+		/*
+		 * Using of_property_read_u32_index(), smp value will only be
+		 * modified if valid u32 value can be decoded. This allows to
+		 * get either no value, 1 shared value for all indexes, or one
+		 * value per channel.
+		 */
+		of_property_read_u32_index(node, "st,min-sample-time-nsecs", i, &smp);
+
+		/* Prepare sampling time settings */
+		stm32_adc_smpr_init(adc, channels[i].channel, smp);
+	}
+
 	return scan_index;
 }
 
@@ -2034,6 +2062,19 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
 
 		stm32_adc_chan_init_one(indio_dev, &channels[scan_index], val,
 					vin[1], scan_index, differential);
+
+		ret = of_property_read_u32(child, "st,min-sample-time-nsecs", &val);
+		/* st,min-sample-time-nsecs is optional */
+		if (!ret) {
+			stm32_adc_smpr_init(adc, channels[scan_index].channel, val);
+			if (differential)
+				stm32_adc_smpr_init(adc, vin[1], val);
+		} else if (ret != -EINVAL) {
+			dev_err(&indio_dev->dev, "Invalid st,min-sample-time-nsecs property %d\n",
+				ret);
+			goto err;
+		}
+
 		scan_index++;
 	}
 
@@ -2052,7 +2093,6 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 	const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
 	struct iio_chan_spec *channels;
 	int scan_index = 0, num_channels = 0, ret, i;
-	u32 smp = 0;
 	bool legacy = false;
 
 	for (i = 0; i < STM32_ADC_INT_CH_NB; i++)
@@ -2080,13 +2120,6 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 		return -EINVAL;
 	}
 
-	/* Optional sample time is provided either for each, or all channels */
-	ret = of_property_count_u32_elems(node, "st,min-sample-time-nsecs");
-	if (ret > 1 && ret != num_channels) {
-		dev_err(&indio_dev->dev, "Invalid st,min-sample-time-nsecs\n");
-		return -EINVAL;
-	}
-
 	if (timestamping)
 		num_channels++;
 
@@ -2103,27 +2136,6 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
 		return ret;
 	scan_index = ret;
 
-	for (i = 0; i < scan_index; i++) {
-		/*
-		 * Using of_property_read_u32_index(), smp value will only be
-		 * modified if valid u32 value can be decoded. This allows to
-		 * get either no value, 1 shared value for all indexes, or one
-		 * value per channel.
-		 */
-		of_property_read_u32_index(node, "st,min-sample-time-nsecs",
-					   i, &smp);
-
-		/*
-		 * For vrefint channel, ensure that the sampling time cannot
-		 * be lower than the one specified in the datasheet
-		 */
-		if (channels[i].channel == adc->int_ch[STM32_ADC_INT_CH_VREFINT])
-			smp = max(smp, adc->cfg->ts_vrefint_ns);
-
-		/* Prepare sampling time settings */
-		stm32_adc_smpr_init(adc, channels[i].channel, smp);
-	}
-
 	if (timestamping) {
 		struct iio_chan_spec *timestamp = &channels[scan_index];
 
-- 
2.17.1

Re: [PATCH v3 0/7] iio: adc: stm32-adc: add internal channels support

[Jonathan Cameron]

On Fri, 24 Sep 2021 10:34:03 +0200
Olivier Moysan <olivier.moysan@foss.st.com> wrote:

> This patchset adds support of ADC2 internal channels VDDCORE, VREFINT and VBAT
> on STM32MP15x SoCs. The generic IIO channel bindings is also introduced here
> to provide this feature. The legacy channel binding is kept for backward compatibility.

Hi Olivier,

I had a read through and am happy with how this looks now.
I'll leave it on the list for a while longer because Rob may well want to take
a final look at patch 1.

Obviously input from other people also welcome!

If it looks like I have forgotten it in a few weeks feel free to poke me.

Thanks,

Jonathan

> 
> Changes in v2:
> - Add 'deprecated' to channels legacy properties in ADC bindings
> - Add set/clr service for common registers, to make code more generic in
>   internal channels enable/disable services.
> - Expose vrefint channel as a processed channel to return
>   the actual value of vrefp.
> - Minor code improvements
> 
> Changes in v3:
> - fix vrefint sampling time check.
> 
> Olivier Moysan (7):
>   dt-bindings: iio: stm32-adc: add generic channel binding
>   dt-bindings: iio: stm32-adc: add nvmem support for vrefint internal
>     channel
>   iio: adc: stm32-adc: split channel init into several routines
>   iio: adc: stm32-adc: add support of generic channels binding
>   iio: adc: stm32-adc: add support of internal channels
>   iio: adc: stm32-adc: add vrefint calibration support
>   iio: adc: stm32-adc: use generic binding for sample-time
> 
>  .../bindings/iio/adc/st,stm32-adc.yaml        | 108 ++++-
>  drivers/iio/adc/stm32-adc-core.h              |   8 +
>  drivers/iio/adc/stm32-adc.c                   | 426 ++++++++++++++++--
>  3 files changed, 487 insertions(+), 55 deletions(-)
> 

Re: [Linux-stm32] [PATCH v3 5/7] iio: adc: stm32-adc: add support of internal channels

[Fabrice Gasnier]

On 9/24/21 10:34 AM, Olivier Moysan wrote:
> Add support of ADC2 internal channels VDDCORE, VREFINT and VBAT.
> The reserved label name "vddcore", "vrefint" and "vbat" must
> be used in Device Tree channel node, to enable the corresponding
> internal channel.
> 
> Note: This patch does not provide support of internal channels
> for F4 and H7.
> 
> Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
> ---
>  drivers/iio/adc/stm32-adc-core.h |   8 ++
>  drivers/iio/adc/stm32-adc.c      | 142 ++++++++++++++++++++++++++++++-
>  2 files changed, 147 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/adc/stm32-adc-core.h b/drivers/iio/adc/stm32-adc-core.h
> index 2322809bfd2f..7c924f463f67 100644
> --- a/drivers/iio/adc/stm32-adc-core.h
> +++ b/drivers/iio/adc/stm32-adc-core.h
> @@ -102,6 +102,9 @@
>  #define STM32H7_ADC_CALFACT		0xC4
>  #define STM32H7_ADC_CALFACT2		0xC8
>  
> +/* STM32MP1 - ADC2 instance option register */
> +#define STM32MP1_ADC2_OR		0xD0
> +
>  /* STM32H7 - common registers for all ADC instances */
>  #define STM32H7_ADC_CSR			(STM32_ADCX_COMN_OFFSET + 0x00)
>  #define STM32H7_ADC_CCR			(STM32_ADCX_COMN_OFFSET + 0x08)
> @@ -168,11 +171,16 @@ enum stm32h7_adc_dmngt {
>  #define STM32H7_EOC_MST			BIT(2)
>  
>  /* STM32H7_ADC_CCR - bit fields */
> +#define STM32H7_VBATEN			BIT(24)
> +#define STM32H7_VREFEN			BIT(22)
>  #define STM32H7_PRESC_SHIFT		18
>  #define STM32H7_PRESC_MASK		GENMASK(21, 18)
>  #define STM32H7_CKMODE_SHIFT		16
>  #define STM32H7_CKMODE_MASK		GENMASK(17, 16)
>  
> +/* STM32MP1_ADC2_OR - bit fields */
> +#define STM32MP1_VDDCOREEN		BIT(0)
> +
>  /**
>   * struct stm32_adc_common - stm32 ADC driver common data (for all instances)
>   * @base:		control registers base cpu addr
> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> index 85d09cbd41ae..5a7ac45a0725 100644
> --- a/drivers/iio/adc/stm32-adc.c
> +++ b/drivers/iio/adc/stm32-adc.c
> @@ -77,6 +77,30 @@ enum stm32_adc_extsel {
>  	STM32_EXT20,
>  };
>  
> +enum stm32_adc_int_ch {
> +	STM32_ADC_INT_CH_NONE = -1,
> +	STM32_ADC_INT_CH_VDDCORE,
> +	STM32_ADC_INT_CH_VREFINT,
> +	STM32_ADC_INT_CH_VBAT,
> +	STM32_ADC_INT_CH_NB,
> +};
> +
> +/**
> + * struct stm32_adc_ic - ADC internal channels
> + * @name:	name of the internal channel
> + * @idx:	internal channel enum index
> + */
> +struct stm32_adc_ic {
> +	const char *name;
> +	u32 idx;
> +};
> +
> +static const struct stm32_adc_ic stm32_adc_ic[STM32_ADC_INT_CH_NB] = {
> +	{ "vddcore", STM32_ADC_INT_CH_VDDCORE },
> +	{ "vrefint", STM32_ADC_INT_CH_VREFINT },
> +	{ "vbat", STM32_ADC_INT_CH_VBAT },
> +};
> +
>  /**
>   * struct stm32_adc_trig_info - ADC trigger info
>   * @name:		name of the trigger, corresponding to its source
> @@ -126,6 +150,9 @@ struct stm32_adc_regs {
>   * @res:		resolution selection register & bitfield
>   * @smpr:		smpr1 & smpr2 registers offset array
>   * @smp_bits:		smpr1 & smpr2 index and bitfields
> + * @or_vdd:		option register & vddcore bitfield
> + * @ccr_vbat:		common register & vbat bitfield
> + * @ccr_vref:		common register & vrefint bitfield
>   */
>  struct stm32_adc_regspec {
>  	const u32 dr;
> @@ -139,6 +166,9 @@ struct stm32_adc_regspec {
>  	const struct stm32_adc_regs res;
>  	const u32 smpr[2];
>  	const struct stm32_adc_regs *smp_bits;
> +	const struct stm32_adc_regs or_vdd;
> +	const struct stm32_adc_regs ccr_vbat;
> +	const struct stm32_adc_regs ccr_vref;
>  };
>  
>  struct stm32_adc;
> @@ -195,6 +225,7 @@ struct stm32_adc_cfg {
>   * @cal:		optional calibration data on some devices
>   * @chan_name:		channel name array
>   * @num_diff:		number of differential channels
> + * @int_ch:		internal channel indexes array
>   */
>  struct stm32_adc {
>  	struct stm32_adc_common	*common;
> @@ -219,6 +250,7 @@ struct stm32_adc {
>  	struct stm32_adc_calib	cal;
>  	char			chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ];
>  	u32			num_diff;
> +	int			int_ch[STM32_ADC_INT_CH_NB];
>  };
>  
>  struct stm32_adc_diff_channel {
> @@ -451,6 +483,24 @@ static const struct stm32_adc_regspec stm32h7_adc_regspec = {
>  	.smp_bits = stm32h7_smp_bits,
>  };
>  
> +static const struct stm32_adc_regspec stm32mp1_adc_regspec = {
> +	.dr = STM32H7_ADC_DR,
> +	.ier_eoc = { STM32H7_ADC_IER, STM32H7_EOCIE },
> +	.ier_ovr = { STM32H7_ADC_IER, STM32H7_OVRIE },
> +	.isr_eoc = { STM32H7_ADC_ISR, STM32H7_EOC },
> +	.isr_ovr = { STM32H7_ADC_ISR, STM32H7_OVR },
> +	.sqr = stm32h7_sq,
> +	.exten = { STM32H7_ADC_CFGR, STM32H7_EXTEN_MASK, STM32H7_EXTEN_SHIFT },
> +	.extsel = { STM32H7_ADC_CFGR, STM32H7_EXTSEL_MASK,
> +		    STM32H7_EXTSEL_SHIFT },
> +	.res = { STM32H7_ADC_CFGR, STM32H7_RES_MASK, STM32H7_RES_SHIFT },
> +	.smpr = { STM32H7_ADC_SMPR1, STM32H7_ADC_SMPR2 },
> +	.smp_bits = stm32h7_smp_bits,
> +	.or_vdd = { STM32MP1_ADC2_OR, STM32MP1_VDDCOREEN },
> +	.ccr_vbat = { STM32H7_ADC_CCR, STM32H7_VBATEN },
> +	.ccr_vref = { STM32H7_ADC_CCR, STM32H7_VREFEN },
> +};
> +
>  /*
>   * STM32 ADC registers access routines
>   * @adc: stm32 adc instance
> @@ -489,6 +539,16 @@ static void stm32_adc_set_bits(struct stm32_adc *adc, u32 reg, u32 bits)
>  	spin_unlock_irqrestore(&adc->lock, flags);
>  }
>  
> +static void stm32_adc_set_bits_common(struct stm32_adc *adc, u32 reg, u32 bits)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&adc->lock, flags);

Hi Olivier,

Sorry, I missed it in earlier version. I think there's no need for
protection against IRQs on "common" registers here.

But, this "common" register is touched in stm32-adc-core driver, in the
probe and pm routines. So maybe a lock in the adc->common structure
could be added here, instead of private (child only) adc lock?

> +	writel_relaxed(readl_relaxed(adc->common->base + reg) | bits,
> +		       adc->common->base + reg);
> +	spin_unlock_irqrestore(&adc->lock, flags);
> +}
> +
>  static void stm32_adc_clr_bits(struct stm32_adc *adc, u32 reg, u32 bits)
>  {
>  	unsigned long flags;
> @@ -498,6 +558,16 @@ static void stm32_adc_clr_bits(struct stm32_adc *adc, u32 reg, u32 bits)
>  	spin_unlock_irqrestore(&adc->lock, flags);
>  }
>  
> +static void stm32_adc_clr_bits_common(struct stm32_adc *adc, u32 reg, u32 bits)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&adc->lock, flags);

same here

Thanks,
Fabrice

> +	writel_relaxed(readl_relaxed(adc->common->base + reg) & ~bits,
> +		       adc->common->base + reg);
> +	spin_unlock_irqrestore(&adc->lock, flags);
> +}
> +
>  /**
>   * stm32_adc_conv_irq_enable() - Enable end of conversion interrupt
>   * @adc: stm32 adc instance
> @@ -579,6 +649,60 @@ static int stm32_adc_hw_start(struct device *dev)
>  	return ret;
>  }
>  
> +static void stm32_adc_int_ch_enable(struct iio_dev *indio_dev)
> +{
> +	struct stm32_adc *adc = iio_priv(indio_dev);
> +	u32 i;
> +
> +	for (i = 0; i < STM32_ADC_INT_CH_NB; i++) {
> +		if (adc->int_ch[i] == STM32_ADC_INT_CH_NONE)
> +			continue;
> +
> +		switch (i) {
> +		case STM32_ADC_INT_CH_VDDCORE:
> +			dev_dbg(&indio_dev->dev, "Enable VDDCore\n");
> +			stm32_adc_set_bits(adc, adc->cfg->regs->or_vdd.reg,
> +					   adc->cfg->regs->or_vdd.mask);
> +			break;
> +		case STM32_ADC_INT_CH_VREFINT:
> +			dev_dbg(&indio_dev->dev, "Enable VREFInt\n");
> +			stm32_adc_set_bits_common(adc, adc->cfg->regs->ccr_vref.reg,
> +						  adc->cfg->regs->ccr_vref.mask);
> +			break;
> +		case STM32_ADC_INT_CH_VBAT:
> +			dev_dbg(&indio_dev->dev, "Enable VBAT\n");
> +			stm32_adc_set_bits_common(adc, adc->cfg->regs->ccr_vbat.reg,
> +						  adc->cfg->regs->ccr_vbat.mask);
> +			break;
> +		}
> +	}
> +}
> +
> +static void stm32_adc_int_ch_disable(struct stm32_adc *adc)
> +{
> +	u32 i;
> +
> +	for (i = 0; i < STM32_ADC_INT_CH_NB; i++) {
> +		if (adc->int_ch[i] == STM32_ADC_INT_CH_NONE)
> +			continue;
> +
> +		switch (i) {
> +		case STM32_ADC_INT_CH_VDDCORE:
> +			stm32_adc_clr_bits(adc, adc->cfg->regs->or_vdd.reg,
> +					   adc->cfg->regs->or_vdd.mask);
> +			break;
> +		case STM32_ADC_INT_CH_VREFINT:
> +			stm32_adc_clr_bits_common(adc, adc->cfg->regs->ccr_vref.reg,
> +						  adc->cfg->regs->ccr_vref.mask);
> +			break;
> +		case STM32_ADC_INT_CH_VBAT:
> +			stm32_adc_clr_bits_common(adc, adc->cfg->regs->ccr_vbat.reg,
> +						  adc->cfg->regs->ccr_vbat.mask);
> +			break;
> +		}
> +	}
> +}
> +
>  /**
>   * stm32f4_adc_start_conv() - Start conversions for regular channels.
>   * @indio_dev: IIO device instance
> @@ -947,11 +1071,13 @@ static int stm32h7_adc_prepare(struct iio_dev *indio_dev)
>  		goto pwr_dwn;
>  	calib = ret;
>  
> +	stm32_adc_int_ch_enable(indio_dev);
> +
>  	stm32_adc_writel(adc, STM32H7_ADC_DIFSEL, adc->difsel);
>  
>  	ret = stm32h7_adc_enable(indio_dev);
>  	if (ret)
> -		goto pwr_dwn;
> +		goto ch_disable;
>  
>  	/* Either restore or read calibration result for future reference */
>  	if (calib)
> @@ -967,6 +1093,8 @@ static int stm32h7_adc_prepare(struct iio_dev *indio_dev)
>  
>  disable:
>  	stm32h7_adc_disable(indio_dev);
> +ch_disable:
> +	stm32_adc_int_ch_disable(adc);
>  pwr_dwn:
>  	stm32h7_adc_enter_pwr_down(adc);
>  
> @@ -978,6 +1106,7 @@ static void stm32h7_adc_unprepare(struct iio_dev *indio_dev)
>  	struct stm32_adc *adc = iio_priv(indio_dev);
>  
>  	stm32h7_adc_disable(indio_dev);
> +	stm32_adc_int_ch_disable(adc);
>  	stm32h7_adc_enter_pwr_down(adc);
>  }
>  
> @@ -1800,7 +1929,7 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
>  	const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
>  	struct device_node *child;
>  	const char *name;
> -	int val, scan_index = 0, ret;
> +	int val, scan_index = 0, ret, i;
>  	bool differential;
>  	u32 vin[2];
>  
> @@ -1820,6 +1949,10 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
>  				return -EINVAL;
>  			}
>  			strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
> +			for (i = 0; i < STM32_ADC_INT_CH_NB; i++) {
> +				if (!strncmp(stm32_adc_ic[i].name, name, STM32_ADC_CH_SZ))
> +					adc->int_ch[i] = val;
> +			}
>  		} else if (ret != -EINVAL) {
>  			dev_err(&indio_dev->dev, "Invalid label %d\n", ret);
>  			goto err;
> @@ -1869,6 +2002,9 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping)
>  	u32 smp = 0;
>  	bool legacy = false;
>  
> +	for (i = 0; i < STM32_ADC_INT_CH_NB; i++)
> +		adc->int_ch[i] = STM32_ADC_INT_CH_NONE;
> +
>  	num_channels = of_get_available_child_count(node);
>  	/* If no channels have been found, fallback to channels legacy properties. */
>  	if (!num_channels) {
> @@ -2219,7 +2355,7 @@ static const struct stm32_adc_cfg stm32h7_adc_cfg = {
>  };
>  
>  static const struct stm32_adc_cfg stm32mp1_adc_cfg = {
> -	.regs = &stm32h7_adc_regspec,
> +	.regs = &stm32mp1_adc_regspec,
>  	.adc_info = &stm32h7_adc_info,
>  	.trigs = stm32h7_adc_trigs,
>  	.has_vregready = true,
> 

Re: [PATCH v3 0/7] iio: adc: stm32-adc: add internal channels support

[Fabrice Gasnier]

On 9/24/21 10:34 AM, Olivier Moysan wrote:
> This patchset adds support of ADC2 internal channels VDDCORE, VREFINT and VBAT
> on STM32MP15x SoCs. The generic IIO channel bindings is also introduced here
> to provide this feature. The legacy channel binding is kept for backward compatibility.
> 
> Changes in v2:
> - Add 'deprecated' to channels legacy properties in ADC bindings
> - Add set/clr service for common registers, to make code more generic in
>   internal channels enable/disable services.
> - Expose vrefint channel as a processed channel to return
>   the actual value of vrefp.
> - Minor code improvements
> 
> Changes in v3:
> - fix vrefint sampling time check.
> 
> Olivier Moysan (7):
>   dt-bindings: iio: stm32-adc: add generic channel binding
>   dt-bindings: iio: stm32-adc: add nvmem support for vrefint internal
>     channel
>   iio: adc: stm32-adc: split channel init into several routines
>   iio: adc: stm32-adc: add support of generic channels binding
>   iio: adc: stm32-adc: add support of internal channels


Hi Olivier,

I've one remark on patch "... add support of internal channels".

For the other patches, you can add my
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>

Thanks!
Fabrice

>   iio: adc: stm32-adc: add vrefint calibration support
>   iio: adc: stm32-adc: use generic binding for sample-time>
>  .../bindings/iio/adc/st,stm32-adc.yaml        | 108 ++++-
>  drivers/iio/adc/stm32-adc-core.h              |   8 +
>  drivers/iio/adc/stm32-adc.c                   | 426 ++++++++++++++++--
>  3 files changed, 487 insertions(+), 55 deletions(-)
> 

Re: [PATCH v3 1/7] dt-bindings: iio: stm32-adc: add generic channel binding

[Rob Herring]

On Fri, Sep 24, 2021 at 10:34:04AM +0200, Olivier Moysan wrote:
> Add ADC generic channel binding. This binding should
> be used as an alternate to legacy channel properties
> whenever possible.
> ADC generic channel binding allows to identify supported
> internal channels through the following reserved label names:
> "vddcore", "vrefint" and "vbat".
> This binding also allows to set a different sampling time
> for each channel.
> 
> Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
> ---
>  .../bindings/iio/adc/st,stm32-adc.yaml        | 100 ++++++++++++++++--
>  1 file changed, 93 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml
> index a58334c3bb76..1c13921b0556 100644
> --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.yaml
> @@ -222,6 +222,12 @@ patternProperties:
>        '#io-channel-cells':
>          const: 1
>  
> +      '#address-cells':
> +        const: 1
> +
> +      '#size-cells':
> +        const: 0
> +
>        interrupts:
>          description: |
>            IRQ Line for the ADC instance. Valid values are:
> @@ -256,6 +262,7 @@ patternProperties:
>              - 20 channels, numbered from 0 to 19 (for in0..in19) on stm32h7 and
>                stm32mp1.
>          $ref: /schemas/types.yaml#/definitions/uint32-array
> +        deprecated: true
>  
>        st,adc-diff-channels:
>          description: |
> @@ -265,7 +272,9 @@ patternProperties:
>            <vinp vinn>, <vinp vinn>,... vinp and vinn are numbered from 0 to 19.
>  
>            Note: At least one of "st,adc-channels" or "st,adc-diff-channels" is
> -          required. Both properties can be used together. Some channels can be
> +          required if no adc generic channel is defined. These legacy channel
> +          properties are exclusive with adc generic channel bindings.
> +          Both properties can be used together. Some channels can be
>            used as single-ended and some other ones as differential (mixed). But
>            channels can't be configured both as single-ended and differential.
>          $ref: /schemas/types.yaml#/definitions/uint32-matrix
> @@ -279,6 +288,7 @@ patternProperties:
>                  "vinn" indicates negative input number
>                minimum: 0
>                maximum: 19
> +        deprecated: true
>  
>        st,min-sample-time-nsecs:
>          description:
> @@ -289,6 +299,42 @@ patternProperties:
>            list, to set sample time resp. for all channels, or independently for
>            each channel.
>          $ref: /schemas/types.yaml#/definitions/uint32-array
> +        deprecated: true
> +
> +    patternProperties:
> +      "^channel@([0-9]|1[0-9])$":
> +        type: object
> +        $ref: "adc.yaml"

You need 'additionalProperties: false' here. Or unevaluatedProperties if 
there are properties used and defined in adc.yaml, but not here.

> +        description: |

Don't need '|' unless you need to maintain formatting (line breaks).

> +          Represents the external channels which are connected to the ADC.
> +
> +        properties:
> +          reg:
> +            items:
> +              minimum: 0
> +              maximum: 19
> +
> +          label:
> +            description: |
> +              Unique name to identify which channel this is.
> +              Reserved label names "vddcore", "vrefint" and "vbat"
> +              are used to identify internal channels with matching names.
> +
> +          diff-channels:
> +            $ref: /schemas/types.yaml#/definitions/uint32-array
> +            items:
> +              minimum: 0
> +              maximum: 19
> +
> +          st,min-sample-time-nsecs:

Use standard unit suffix (-ns).

> +            $ref: /schemas/types.yaml#/definitions/uint32

And then drop this.

> +            description: |
> +              Minimum sampling time in nanoseconds. Depending on hardware (board)
> +              e.g. high/low analog input source impedance, fine tune of ADC
> +              sampling time may be recommended.
> +
> +        required:
> +          - reg
>  
>      allOf:
>        - if:
> @@ -369,12 +415,6 @@ patternProperties:
>  
>      additionalProperties: false
>  
> -    anyOf:
> -      - required:
> -          - st,adc-channels
> -      - required:
> -          - st,adc-diff-channels
> -
>      required:
>        - compatible
>        - reg
> @@ -451,4 +491,50 @@ examples:
>          // other adc child node follow...
>        };
>  
> +  - |
> +    // Example 3: with stm32mp157c to setup ADC2 with:
> +    // - internal channels 13, 14, 15.
> +      #include <dt-bindings/interrupt-controller/arm-gic.h>
> +      #include <dt-bindings/clock/stm32mp1-clks.h>
> +      adc122: adc@48003000 {
> +        compatible = "st,stm32mp1-adc-core";
> +        reg = <0x48003000 0x400>;
> +        interrupts = <GIC_SPI 18 IRQ_TYPE_LEVEL_HIGH>,
> +                     <GIC_SPI 90 IRQ_TYPE_LEVEL_HIGH>;
> +        clocks = <&rcc ADC12>, <&rcc ADC12_K>;
> +        clock-names = "bus", "adc";
> +        booster-supply = <&booster>;
> +        vdd-supply = <&vdd>;
> +        vdda-supply = <&vdda>;
> +        vref-supply = <&vref>;
> +        st,syscfg = <&syscfg>;
> +        interrupt-controller;
> +        #interrupt-cells = <1>;
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +        adc@100 {
> +          compatible = "st,stm32mp1-adc";
> +          #io-channel-cells = <1>;
> +          reg = <0x100>;
> +          interrupts = <1>;
> +          #address-cells = <1>;
> +          #size-cells = <0>;
> +          channel@13 {
> +            reg = <13>;
> +            label = "vrefint";
> +            st,min-sample-time-nsecs = <9000>;
> +          };
> +          channel@14 {
> +            reg = <14>;
> +            label = "vddcore";
> +            st,min-sample-time-nsecs = <9000>;
> +          };
> +          channel@15 {
> +            reg = <15>;
> +            label = "vbat";
> +            st,min-sample-time-nsecs = <9000>;
> +          };
> +        };
> +      };
> +
>  ...
> -- 
> 2.17.1
> 
>