[PATCH v6 00/10] Support ROHM BD79124 ADC

[PATCH v6 00/10] Support ROHM BD79124 ADC

[Matti Vaittinen]

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Support ROHM BD79124 ADC.

This series adds also couple of IIO ADC helper functions for parsing the
channel information from the device tree. There are also new helpers
included for iterating and counting firmware child nodes with a specific
name.

Series does also convert couple of drivers to use these helpers. The
rzg2l_adc and the sun20i-gpadc are converted to use the new ADC helper.

The gianfar driver under net and the thp7312 under media/i2c are added as
first users of the newly added "named child node" -helpers.

There has been some discussion about how useful these ADC helpers are,
and whether they should support also differential and single ended channel
configurations. This version does not include support for those - with the
benefit of reduced complexity and easier to use API.

NOTE: Patches 4,5,9 and 10 are untested as I lack of relevant HW.
They have been compile tested only.

The ROHM BD79124 ADC itself is quite usual stuff. 12-bit, 8-channel ADC
with threshold monitoring.

Except that:
 - each ADC input pin can be configured as a general purpose output.
 - manually starting an ADC conversion and reading the result would
   require the I2C _master_ to do clock stretching(!) for the duration
   of the conversion... Let's just say this is not well supported.
 - IC supports 'autonomous measurement mode' and storing latest results
   to the result registers. This mode is used by the driver due to the
   "peculiar" I2C when doing manual reads.

Furthermore, the ADC uses this continuous autonomous measuring,
and the IC keeps producing new 'out of window' IRQs if measurements are
out of window - the driver disables the event for 1 seconds when sending
it to user. This prevents generating storm of events

Revision history:
v5 => v6:
 - Drop applied patch
 - Add *_for_each_named_child_* iterators
 - Add a patch converting the thp7312 driver to use the new helper
 - Styling and minor things pointed by reviewers

v4 => v5: Fixes as per various review comments. Most notably:
 - Drop the patch making the TI's ADC driver to respect device tree.
 - Add (RFC) patch converting gianfar driver to use new name child-node
   counting API as suggested by Andy.
 - Add fwnode_get_child_node_count_named() as suggested by Rob.
 - rebase to v6.14-rc5
 More accurate changelog in individual patches.

v3 => v4:
 - Drop the ADC helper support for differential channels
 - Drop the ADC helper for getting only channel IDs by fwnode.
 - "Promote" the function counting the number of child nodes with a
   specific name to the property.h (As suggested by Jonathan).
 - Add ADC helpers to a namespace.
 - Rebase on v6.14-rc3
 - More minor changes described in individual patches.

v2 => v3:
 - Restrict BD79124 channel numbers as suggested by Conor and add
   Conor's Reviewed-by tag.
 - Support differential and single-ended inputs
 - Convert couple of existing drivers to use the added ADC helpers
 - Minor fixes based on reviews
Link to v2:
https://lore.kernel.org/all/cover.1738761899.git.mazziesaccount@gmail.com/

RFC v1 => v2:
 - Drop MFD and pinmux.
 - Automatically re-enable events after 1 second.
 - Export fwnode parsing helpers for finding the ADC channels.

---

Matti Vaittinen (10):
  dt-bindings: ROHM BD79124 ADC/GPO
  property: Add functions to iterate named child
  iio: adc: add helpers for parsing ADC nodes
  iio: adc: rzg2l_adc: Use adc-helpers
  iio: adc: sun20i-gpadc: Use adc-helpers
  iio: adc: Support ROHM BD79124 ADC
  MAINTAINERS: Add IIO ADC helpers
  MAINTAINERS: Add ROHM BD79124 ADC/GPO
  net: gianfar: Use device_get_child_node_count_named()
  media: thp7312: Use helper for iterating named child nodes

 .../bindings/iio/adc/rohm,bd79124.yaml        |  114 ++
 MAINTAINERS                                   |   12 +
 drivers/base/property.c                       |   54 +
 drivers/iio/adc/Kconfig                       |   17 +
 drivers/iio/adc/Makefile                      |    3 +
 drivers/iio/adc/industrialio-adc.c            |   79 ++
 drivers/iio/adc/rohm-bd79124.c                | 1106 +++++++++++++++++
 drivers/iio/adc/rzg2l_adc.c                   |   38 +-
 drivers/iio/adc/sun20i-gpadc-iio.c            |   38 +-
 drivers/media/i2c/thp7312.c                   |    8 +-
 drivers/net/ethernet/freescale/gianfar.c      |   17 +-
 include/linux/iio/adc-helpers.h               |   27 +
 include/linux/property.h                      |   20 +
 13 files changed, 1471 insertions(+), 62 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/rohm,bd79124.yaml
 create mode 100644 drivers/iio/adc/industrialio-adc.c
 create mode 100644 drivers/iio/adc/rohm-bd79124.c
 create mode 100644 include/linux/iio/adc-helpers.h


base-commit: 7eb172143d5508b4da468ed59ee857c6e5e01da6
-- 
2.48.1


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[PATCH v6 01/10] dt-bindings: ROHM BD79124 ADC/GPO

[Matti Vaittinen]

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Add binding document for the ROHM BD79124 ADC / GPO.

ROHM BD79124 is a 8-channel, 12-bit ADC. The input pins can also be used
as general purpose outputs.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
---
Revision history:
v3 =>
 - No changes
v2 => v3:
 - Restrict channel numbers to 0-7 as suggested by Conor
RFC v1 => v2:
 - drop MFD and represent directly as ADC
 - drop pinmux and treat all non ADC channel pins as GPOs
---
 .../bindings/iio/adc/rohm,bd79124.yaml        | 114 ++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/rohm,bd79124.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/rohm,bd79124.yaml b/Documentation/devicetree/bindings/iio/adc/rohm,bd79124.yaml
new file mode 100644
index 000000000000..503285823376
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/rohm,bd79124.yaml
@@ -0,0 +1,114 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/rohm,bd79124.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ROHM BD79124 ADC/GPO
+
+maintainers:
+  - Matti Vaittinen <mazziesaccount@gmail.com>
+
+description: |
+  The ROHM BD79124 is a 12-bit, 8-channel, SAR ADC. The ADC supports
+  an automatic measurement mode, with an alarm interrupt for out-of-window
+  measurements. ADC input pins can be also configured as general purpose
+  outputs.
+
+properties:
+  compatible:
+    const: rohm,bd79124
+
+  reg:
+    description:
+      I2C slave address.
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 1
+    description:
+      The pin number.
+
+  vdd-supply: true
+
+  iovdd-supply: true
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+patternProperties:
+  "^channel@[0-7]+$":
+    type: object
+    $ref: /schemas/iio/adc/adc.yaml#
+    description: Represents ADC channel.
+
+    properties:
+      reg:
+        description: AIN pin number
+        minimum: 0
+        maximum: 7
+
+    required:
+      - reg
+
+    additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - iovdd-supply
+  - vdd-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/leds/common.h>
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        adc: adc@10 {
+            compatible = "rohm,bd79124";
+            reg = <0x10>;
+
+            interrupt-parent = <&gpio1>;
+            interrupts = <29 8>;
+
+            vdd-supply = <&dummyreg>;
+            iovdd-supply = <&dummyreg>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            channel@0 {
+                reg = <0>;
+            };
+            channel@1 {
+                reg = <1>;
+            };
+            channel@2 {
+                reg = <2>;
+            };
+            channel@3 {
+                reg = <3>;
+            };
+            channel@4 {
+                reg = <4>;
+            };
+            channel@5 {
+                reg = <5>;
+            };
+            channel@6 {
+                reg = <6>;
+            };
+        };
+    };
-- 
2.48.1


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[PATCH v6 02/10] property: Add functions to iterate named child

[Matti Vaittinen]

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There are a few use-cases where child nodes with a specific name need to
be parsed. Code like:

fwnode_for_each_child_node()
	if (fwnode_name_eq())
		...

can be found from a various drivers/subsystems. Adding a macro for this
can simplify things a bit.

In a few cases the data from the found nodes is later added to an array,
which is allocated based on the number of found nodes. One example of
such use is the IIO subsystem's ADC channel nodes, where the relevant
nodes are named as channel[@N].

Add a helpers for iterating and counting device's sub-nodes with certain
name instead, of open-coding this in every user.

Suggested-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
---
Revision history:
v5 => v6:
 - Add helpers to also iterate through the nodes.
v4 => v5:
 - Use given name instead of string 'channel' when counting the nodes
 - Add also fwnode_get_child_node_count_named() as suggested by Rob.
v3 => v4:
 - New patch as suggested by Jonathan, see discussion in:
https://lore.kernel.org/lkml/20250223161338.5c896280@jic23-huawei/

Please note, the checkpatch.pl was not happy about the for_each...()
macros. I tried to make them to follow the existing convention. I am
open to suggestions how to improve.

---
 drivers/base/property.c  | 54 ++++++++++++++++++++++++++++++++++++++++
 include/linux/property.h | 20 +++++++++++++++
 2 files changed, 74 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index c1392743df9c..335262a894f4 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -945,6 +945,60 @@ unsigned int device_get_child_node_count(const struct device *dev)
 }
 EXPORT_SYMBOL_GPL(device_get_child_node_count);
 
+/**
+ * fwnode_get_named_child_node_count - number of child nodes with given name
+ * @fwnode: Node which child nodes are counted.
+ * @name: String to match child node name against.
+ *
+ * Scan child nodes and count all the nodes with a specific name. Return the
+ * number of found nodes. Potential '@number' -ending for scanned names is
+ * ignored. Eg,
+ * device_get_child_node_count(dev, "channel");
+ * would match all the nodes:
+ * channel { }, channel@0 {}, channel@0xabba {}...
+ *
+ * Return: the number of child nodes with a matching name for a given device.
+ */
+unsigned int fwnode_get_named_child_node_count(const struct fwnode_handle *fwnode,
+					       const char *name)
+{
+	struct fwnode_handle *child;
+	unsigned int count = 0;
+
+	fwnode_for_each_named_child_node(fwnode, child, name)
+		count++;
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(fwnode_get_named_child_node_count);
+
+/**
+ * device_get_named_child_node_count - number of child nodes with given name
+ * @dev: Device to count the child nodes for.
+ * @name: String to match child node name against.
+ *
+ * Scan device's child nodes and find all the nodes with a specific name and
+ * return the number of found nodes. Potential '@number' -ending for scanned
+ * names is ignored. Eg,
+ * device_get_child_node_count(dev, "channel");
+ * would match all the nodes:
+ * channel { }, channel@0 {}, channel@0xabba {}...
+ *
+ * Return: the number of child nodes with a matching name for a given device.
+ */
+unsigned int device_get_named_child_node_count(const struct device *dev,
+					       const char *name)
+{
+	struct fwnode_handle *child;
+	unsigned int count = 0;
+
+	device_for_each_named_child_node(dev, child, name)
+		count++;
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(device_get_named_child_node_count);
+
 bool device_dma_supported(const struct device *dev)
 {
 	return fwnode_call_bool_op(dev_fwnode(dev), device_dma_supported);
diff --git a/include/linux/property.h b/include/linux/property.h
index e214ecd241eb..6dd9ae83e9a5 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -167,10 +167,18 @@ struct fwnode_handle *fwnode_get_next_available_child_node(
 	for (child = fwnode_get_next_child_node(fwnode, NULL); child;	\
 	     child = fwnode_get_next_child_node(fwnode, child))
 
+#define fwnode_for_each_named_child_node(fwnode, child, name)		\
+		fwnode_for_each_child_node(fwnode, child)		\
+			if (!fwnode_name_eq(child, name)) { } else
+
 #define fwnode_for_each_available_child_node(fwnode, child)		       \
 	for (child = fwnode_get_next_available_child_node(fwnode, NULL); child;\
 	     child = fwnode_get_next_available_child_node(fwnode, child))
 
+#define fwnode_for_each_available_named_child_node(fwnode, child, name)	\
+		fwnode_for_each_available_child_node(fwnode, child)	\
+			if (!fwnode_name_eq(child, name)) { } else
+
 struct fwnode_handle *device_get_next_child_node(const struct device *dev,
 						 struct fwnode_handle *child);
 
@@ -178,11 +186,19 @@ struct fwnode_handle *device_get_next_child_node(const struct device *dev,
 	for (child = device_get_next_child_node(dev, NULL); child;	\
 	     child = device_get_next_child_node(dev, child))
 
+#define device_for_each_named_child_node(dev, child, name)		\
+		device_for_each_child_node(dev, child)			\
+			if (!fwnode_name_eq(child, name)) { } else
+
 #define device_for_each_child_node_scoped(dev, child)			\
 	for (struct fwnode_handle *child __free(fwnode_handle) =	\
 		device_get_next_child_node(dev, NULL);			\
 	     child; child = device_get_next_child_node(dev, child))
 
+#define device_for_each_named_child_node_scoped(dev, child, name)	\
+		device_for_each_child_node_scoped(dev, child)		\
+			if (!fwnode_name_eq(child, name)) { } else
+
 struct fwnode_handle *fwnode_get_named_child_node(const struct fwnode_handle *fwnode,
 						  const char *childname);
 struct fwnode_handle *device_get_named_child_node(const struct device *dev,
@@ -209,6 +225,10 @@ int fwnode_irq_get(const struct fwnode_handle *fwnode, unsigned int index);
 int fwnode_irq_get_byname(const struct fwnode_handle *fwnode, const char *name);
 
 unsigned int device_get_child_node_count(const struct device *dev);
+unsigned int fwnode_get_named_child_node_count(const struct fwnode_handle *fwnode,
+					       const char *name);
+unsigned int device_get_named_child_node_count(const struct device *dev,
+					       const char *name);
 
 static inline int device_property_read_u8(const struct device *dev,
 					  const char *propname, u8 *val)
-- 
2.48.1


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[PATCH v6 03/10] iio: adc: add helpers for parsing ADC nodes

[Matti Vaittinen]

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There are ADC ICs which may have some of the AIN pins usable for other
functions. These ICs may have some of the AIN pins wired so that they
should not be used for ADC.

(Preferred?) way for marking pins which can be used as ADC inputs is to
add corresponding channels@N nodes in the device tree as described in
the ADC binding yaml.

Add couple of helper functions which can be used to retrieve the channel
information from the device node.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>

---
Revision history:
v5 => v6:
 - Adapt to changed fwnode helper names
 - Fix spelling
v4 => v5:
 - Inline iio_adc_device_num_channels()
 - Fix Indenting function parameters
 - Combine the max channel ID checks.
v3 => v4:
 - Drop diff-channel support
 - Drop iio_adc_device_channels_by_property()
 - Add IIO_DEVICE namespace
 - Move industrialio-adc.o to top of the Makefile
 - Some styling as suggested by Andy
 - Re-consider included headers
v2 => v3: Mostly based on review comments by Jonathan
 - Support differential and single-ended channels
 - Rename iio_adc_device_get_channels() as
   iio_adc_device_channels_by_property()
 - Improve spelling
 - Drop support for cases where DT comes from parent device's node
 - Decrease loop indent by reverting node name check conditions
 - Don't set 'chan->indexed' by number of channels to keep the
   interface consistent no matter how many channels are connected.
 - Fix ID range check and related comment
RFC v1 => v2:
 - New patch
---
 drivers/iio/adc/Kconfig            |  3 ++
 drivers/iio/adc/Makefile           |  2 +
 drivers/iio/adc/industrialio-adc.c | 79 ++++++++++++++++++++++++++++++
 include/linux/iio/adc-helpers.h    | 27 ++++++++++
 4 files changed, 111 insertions(+)
 create mode 100644 drivers/iio/adc/industrialio-adc.c
 create mode 100644 include/linux/iio/adc-helpers.h

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 849c90203071..37b70a65da6f 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -6,6 +6,9 @@
 
 menu "Analog to digital converters"
 
+config IIO_ADC_HELPER
+	tristate
+
 config AB8500_GPADC
 	bool "ST-Ericsson AB8500 GPADC driver"
 	depends on AB8500_CORE && REGULATOR_AB8500
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index ee19afba62b7..1c410f483029 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -3,6 +3,8 @@
 # Makefile for IIO ADC drivers
 #
 
+obj-$(CONFIG_IIO_ADC_HELPER) += industrialio-adc.o
+
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_AB8500_GPADC) += ab8500-gpadc.o
 obj-$(CONFIG_AD_SIGMA_DELTA) += ad_sigma_delta.o
diff --git a/drivers/iio/adc/industrialio-adc.c b/drivers/iio/adc/industrialio-adc.c
new file mode 100644
index 000000000000..6cfb001c74b9
--- /dev/null
+++ b/drivers/iio/adc/industrialio-adc.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Helpers for parsing common ADC information from a firmware node.
+ *
+ * Copyright (c) 2025 Matti Vaittinen <mazziesaccount@gmail.com>
+ */
+
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/types.h>
+
+#include <linux/iio/adc-helpers.h>
+#include <linux/iio/iio.h>
+
+/**
+ * devm_iio_adc_device_alloc_chaninfo_se - allocate and fill iio_chan_spec for ADC
+ *
+ * Scan the device node for single-ended ADC channel information. Channel ID is
+ * expected to be found from the "reg" property. Allocate and populate the
+ * iio_chan_spec structure corresponding to channels that are found. The memory
+ * for iio_chan_spec structure will be freed upon device detach.
+ *
+ * @dev:		Pointer to the ADC device.
+ * @template:		Template iio_chan_spec from which the fields of all
+ *			found and allocated channels are initialized.
+ * @max_chan_id:	Maximum value of a channel ID. Use -1 if no checking
+ *			is required.
+ * @cs:			Location where pointer to allocated iio_chan_spec
+ *			should be stored.
+ *
+ * Return:	Number of found channels on success. Negative value to indicate
+ *		failure.
+ */
+int devm_iio_adc_device_alloc_chaninfo_se(struct device *dev,
+					  const struct iio_chan_spec *template,
+					  int max_chan_id,
+					  struct iio_chan_spec **cs)
+{
+	struct iio_chan_spec *chan_array, *chan;
+	int num_chan = 0, ret;
+
+	num_chan = iio_adc_device_num_channels(dev);
+	if (num_chan < 1)
+		return num_chan;
+
+	chan_array = devm_kcalloc(dev, num_chan, sizeof(*chan_array),
+				  GFP_KERNEL);
+	if (!chan_array)
+		return -ENOMEM;
+
+	chan = &chan_array[0];
+
+	device_for_each_named_child_node_scoped(dev, child, "channel") {
+		u32 ch;
+
+		ret = fwnode_property_read_u32(child, "reg", &ch);
+		if (ret)
+			return ret;
+
+		if (max_chan_id != -1 && ch > max_chan_id)
+			return -ERANGE;
+
+		*chan = *template;
+		chan->channel = ch;
+		chan++;
+	}
+
+	*cs = chan_array;
+
+	return num_chan;
+}
+EXPORT_SYMBOL_NS_GPL(devm_iio_adc_device_alloc_chaninfo_se, "IIO_DRIVER");
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Matti Vaittinen <mazziesaccount@gmail.com>");
+MODULE_DESCRIPTION("IIO ADC fwnode parsing helpers");
diff --git a/include/linux/iio/adc-helpers.h b/include/linux/iio/adc-helpers.h
new file mode 100644
index 000000000000..56b092a2a4c4
--- /dev/null
+++ b/include/linux/iio/adc-helpers.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/*
+ * The industrial I/O ADC firmware property parsing helpers
+ *
+ * Copyright (c) 2025 Matti Vaittinen <mazziesaccount@gmail.com>
+ */
+
+#ifndef _INDUSTRIAL_IO_ADC_HELPERS_H_
+#define _INDUSTRIAL_IO_ADC_HELPERS_H_
+
+#include <linux/property.h>
+
+struct device;
+struct iio_chan_spec;
+
+static inline int iio_adc_device_num_channels(struct device *dev)
+{
+	return device_get_named_child_node_count(dev, "channel");
+}
+
+int devm_iio_adc_device_alloc_chaninfo_se(struct device *dev,
+					  const struct iio_chan_spec *template,
+					  int max_chan_id,
+					  struct iio_chan_spec **cs);
+
+#endif /* _INDUSTRIAL_IO_ADC_HELPERS_H_ */
-- 
2.48.1


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[PATCH v6 07/10] MAINTAINERS: Add IIO ADC helpers

[Matti Vaittinen]

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Add undersigned as a maintainer for the IIO ADC helpers.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
---
Revision history:
v2 =>
 - No changes
RFC v1 => v2:
 - New patch
---
 MAINTAINERS | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 8e0736dc2ee0..5b96fb864227 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11208,6 +11208,13 @@ L:	linux-media@vger.kernel.org
 S:	Maintained
 F:	drivers/media/rc/iguanair.c
 
+IIO ADC HELPERS
+M:	Matti Vaittinen <mazziesaccount@gmail.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	drivers/iio/adc/industrialio-adc.c
+F:	include/linux/iio/adc-helpers.h
+
 IIO BACKEND FRAMEWORK
 M:	Nuno Sa <nuno.sa@analog.com>
 R:	Olivier Moysan <olivier.moysan@foss.st.com>
-- 
2.48.1


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Re: [PATCH v6 02/10] property: Add functions to iterate named child

[Andy Shevchenko]

On Mon, Mar 10, 2025 at 02:55:53PM +0200, Matti Vaittinen wrote:
> There are a few use-cases where child nodes with a specific name need to
> be parsed. Code like:
> 
> fwnode_for_each_child_node()
> 	if (fwnode_name_eq())
> 		...
> 
> can be found from a various drivers/subsystems. Adding a macro for this
> can simplify things a bit.
> 
> In a few cases the data from the found nodes is later added to an array,
> which is allocated based on the number of found nodes. One example of
> such use is the IIO subsystem's ADC channel nodes, where the relevant
> nodes are named as channel[@N].
> 
> Add a helpers for iterating and counting device's sub-nodes with certain
> name instead, of open-coding this in every user.

Almost good, I doubt we need the exported function for the device as it can be
derived from the fwnode_*() API by supplying dev_fwnode(dev).

Perhaps we want also this for the completeness (other comments are below):

 From f52dbbe97ff0cdf835eef29506e482433f0a50a9 Mon Sep 17 00:00:00 2001
 From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
 Date: Mon, 10 Mar 2025 16:20:35 +0200
 Subject: [PATCH 1/1] device property: Split fwnode_get_child_node_count()

The new helper is introduced to allow counting the child firmware nodes
of their parent without requiring a device to be passed. This also makes
the fwnode and device property API more symmetrical with the rest.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/base/property.c  | 12 ++++++------
 include/linux/property.h |  7 ++++++-
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index c1392743df9c..805f75b35115 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -928,22 +928,22 @@ bool fwnode_device_is_available(const struct fwnode_handle *fwnode)
 EXPORT_SYMBOL_GPL(fwnode_device_is_available);
 
 /**
- * device_get_child_node_count - return the number of child nodes for device
- * @dev: Device to count the child nodes for
+ * fwnode_get_child_node_count - return the number of child nodes for a given firmware node
+ * @fwnode: Pointer to the parent firmware node
  *
- * Return: the number of child nodes for a given device.
+ * Return: the number of child nodes for a given firmware node.
  */
-unsigned int device_get_child_node_count(const struct device *dev)
+unsigned int fwnode_get_child_node_count(const struct fwnode_handle *fwnode)
 {
 	struct fwnode_handle *child;
 	unsigned int count = 0;
 
-	device_for_each_child_node(dev, child)
+	fwnode_for_each_child_node(fwnode, child)
 		count++;
 
 	return count;
 }
-EXPORT_SYMBOL_GPL(device_get_child_node_count);
+EXPORT_SYMBOL_GPL(fwnode_get_child_node_count);
 
 bool device_dma_supported(const struct device *dev)
 {
diff --git a/include/linux/property.h b/include/linux/property.h
index e214ecd241eb..bc5bfc98176b 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -208,7 +208,12 @@ DEFINE_FREE(fwnode_handle, struct fwnode_handle *, fwnode_handle_put(_T))
 int fwnode_irq_get(const struct fwnode_handle *fwnode, unsigned int index);
 int fwnode_irq_get_byname(const struct fwnode_handle *fwnode, const char *name);
 
-unsigned int device_get_child_node_count(const struct device *dev);
+unsigned int fwnode_get_child_node_count(const struct fwnode_handle *fwnode);
+
+static inline unsigned int device_get_child_node_count(const struct device *dev)
+{
+	return fwnode_get_child_node_count(dev_fwnode(dev));
+}
 
 static inline int device_property_read_u8(const struct device *dev,
 					  const char *propname, u8 *val)

...

> Please note, the checkpatch.pl was not happy about the for_each...()
> macros. I tried to make them to follow the existing convention. I am
> open to suggestions how to improve.

checkpatch is known for false-positives and/or false-negatives.

...

> +/**
> + * fwnode_get_named_child_node_count - number of child nodes with given name
> + * @fwnode: Node which child nodes are counted.
> + * @name: String to match child node name against.
> + *
> + * Scan child nodes and count all the nodes with a specific name. Return the

You already have a return section below. Perhaps rephrase somehow?

> + * number of found nodes. Potential '@number' -ending for scanned names is

Not sure how this "'@foo' -ending" part is being rendered in HTML/PDF...
Also kernel-doc might be not happy with the @ character followed by an
immediate text as it might be misinterpreted as a reference to a parameter.

> + * ignored. Eg,

E.g.,

(because it's the phrase in Latin: exempli gratia)

> + * device_get_child_node_count(dev, "channel");

Shift right to make sure it's not a text, but a code, better even to use reST
approach, i.e. (note additional leading space(s) and double colon):

 * ignored. E.g.::
 *
 *   fwnode_get_child_node_count(dev, "channel"); // you have a copy'n'paste typo
 *
 * would match all the nodes::
 *
 *   ...
 *

> + * would match all the nodes:
> + * channel { }, channel@0 {}, channel@0xabba {}...
> + *
> + * Return: the number of child nodes with a matching name for a given device.
> + */

...

> +/**
> + * device_get_named_child_node_count - number of child nodes with given name
> + * @dev: Device to count the child nodes for.
> + * @name: String to match child node name against.
> + *
> + * Scan device's child nodes and find all the nodes with a specific name and
> + * return the number of found nodes. Potential '@number' -ending for scanned
> + * names is ignored. Eg,
> + * device_get_child_node_count(dev, "channel");
> + * would match all the nodes:
> + * channel { }, channel@0 {}, channel@0xabba {}...
> + *
> + * Return: the number of child nodes with a matching name for a given device.

Similar comments as per above.

> + */

...

> +#define fwnode_for_each_named_child_node(fwnode, child, name)		\
> +		fwnode_for_each_child_node(fwnode, child)		\

One TAB too much.

> +			if (!fwnode_name_eq(child, name)) { } else

Ditto.

Note, I believe this won't get v6.15-rc1, so there will be for_each_if()
available and these will become

#define fwnode_for_each_named_child_node(fwnode, child, name)	\
	fwnode_for_each_child_node(fwnode, child)		\
		for_each_if(fwnode_name_eq(child, name))

and so on...

...

>  unsigned int device_get_child_node_count(const struct device *dev);
> +unsigned int fwnode_get_named_child_node_count(const struct fwnode_handle *fwnode,
> +					       const char *name);
> +unsigned int device_get_named_child_node_count(const struct device *dev,
> +					       const char *name);

I would add a blank line.

unsigned int device_get_child_node_count(const struct device *dev);
// here is a blank line
unsigned int device_get_named_child_node_count(const struct device *dev,
					       const char *name);
unsigned int fwnode_get_named_child_node_count(const struct fwnode_handle *fwnode,
					       const char *name);

But see above the proposed additional patch that you may include in your next
version.

>  static inline int device_property_read_u8(const struct device *dev,
>  					  const char *propname, u8 *val)

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 02/10] property: Add functions to iterate named child

[Andy Shevchenko]

On Mon, Mar 10, 2025 at 02:55:53PM +0200, Matti Vaittinen wrote:
> There are a few use-cases where child nodes with a specific name need to
> be parsed. Code like:
> 
> fwnode_for_each_child_node()
> 	if (fwnode_name_eq())
> 		...
> 
> can be found from a various drivers/subsystems. Adding a macro for this
> can simplify things a bit.
> 
> In a few cases the data from the found nodes is later added to an array,
> which is allocated based on the number of found nodes. One example of
> such use is the IIO subsystem's ADC channel nodes, where the relevant
> nodes are named as channel[@N].
> 
> Add a helpers for iterating and counting device's sub-nodes with certain
> name instead, of open-coding this in every user.

> Please note, the checkpatch.pl was not happy about the for_each...()
> macros. I tried to make them to follow the existing convention. I am
> open to suggestions how to improve.

You also may update .clang-format.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v6 02/10] property: Add functions to iterate named child

[Sakari Ailus]

Moi,

On Mon, Mar 10, 2025 at 02:55:53PM +0200, Matti Vaittinen wrote:
> Please note, the checkpatch.pl was not happy about the for_each...()
> macros. I tried to make them to follow the existing convention. I am
> open to suggestions how to improve.

checkpatch.pl isn't always handling macros as well as it might. (It's just
hard to parse C using regular expressions and in practice some
simplifications end up being made.)

-- 
Sakari Ailus

Re: [PATCH v6 02/10] property: Add functions to iterate named child

[Jonathan Cameron]

> 
> > +			if (!fwnode_name_eq(child, name)) { } else  
> 
> Ditto.
> 
> Note, I believe this won't get v6.15-rc1, so there will be for_each_if()
> available and these will become

Unless this cycle goes long (i.e. an rc8) very unlikely I'll sneak
the series in now due to lack of time to soak in next.

> 
> #define fwnode_for_each_named_child_node(fwnode, child, name)	\
> 	fwnode_for_each_child_node(fwnode, child)		\
> 		for_each_if(fwnode_name_eq(child, name))
> 
> and so on...

Nice - first time I've seen this :)

Jonathan

Re: [PATCH v6 00/10] Support ROHM BD79124 ADC

[Jonathan Cameron]

On Mon, 10 Mar 2025 14:53:50 +0200
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> Support ROHM BD79124 ADC.
> 
> This series adds also couple of IIO ADC helper functions for parsing the
> channel information from the device tree. There are also new helpers
> included for iterating and counting firmware child nodes with a specific
> name.
> 
> Series does also convert couple of drivers to use these helpers. The
> rzg2l_adc and the sun20i-gpadc are converted to use the new ADC helper.
> 
> The gianfar driver under net and the thp7312 under media/i2c are added as
> first users of the newly added "named child node" -helpers.
> 
> There has been some discussion about how useful these ADC helpers are,
> and whether they should support also differential and single ended channel
> configurations. This version does not include support for those - with the
> benefit of reduced complexity and easier to use API.
> 
> NOTE: Patches 4,5,9 and 10 are untested as I lack of relevant HW.
> They have been compile tested only.
This probably wants an update.  Also, 00/10? There are only 8 that I can see.

Jonathan

Re: [PATCH v6 00/10] Support ROHM BD79124 ADC

[Matti Vaittinen]

On 10/03/2025 22:27, Jonathan Cameron wrote:
> On Mon, 10 Mar 2025 14:53:50 +0200
> Matti Vaittinen <mazziesaccount@gmail.com> wrote:
> 
>> Support ROHM BD79124 ADC.
>>
>> This series adds also couple of IIO ADC helper functions for parsing the
>> channel information from the device tree. There are also new helpers
>> included for iterating and counting firmware child nodes with a specific
>> name.
>>
>> Series does also convert couple of drivers to use these helpers. The
>> rzg2l_adc and the sun20i-gpadc are converted to use the new ADC helper.
>>
>> The gianfar driver under net and the thp7312 under media/i2c are added as
>> first users of the newly added "named child node" -helpers.
>>
>> There has been some discussion about how useful these ADC helpers are,
>> and whether they should support also differential and single ended channel
>> configurations. This version does not include support for those - with the
>> benefit of reduced complexity and easier to use API.
>>
>> NOTE: Patches 4,5,9 and 10 are untested as I lack of relevant HW.
>> They have been compile tested only.
> This probably wants an update.  Also, 00/10? There are only 8 that I can see.

That's odd.
There should be 10 in total. And the 4, 5, 9 and 10 was updated.

9/10:
https://lore.kernel.org/all/1c4b9b4ceb1995bce76a0ddef0e04ad0d1d81190.1741610847.git.mazziesaccount@gmail.com/

10/10:
https://lore.kernel.org/all/ab79cf4415d21ff2854fee4f4189fac555c30b7a.1741610847.git.mazziesaccount@gmail.com/

Perhaps it's because of the "net-next" in subject?

Yours,
	-- Matti

Re: [PATCH v6 02/10] property: Add functions to iterate named child

[Matti Vaittinen]

Hi Andy,

Thanks for the review.

On 10/03/2025 16:25, Andy Shevchenko wrote:
> On Mon, Mar 10, 2025 at 02:55:53PM +0200, Matti Vaittinen wrote:

...

>> +#define fwnode_for_each_named_child_node(fwnode, child, name)		\
>> +		fwnode_for_each_child_node(fwnode, child)		\
> 
> One TAB too much.
> 
>> +			if (!fwnode_name_eq(child, name)) { } else
> 
> Ditto.
> 
> Note, I believe this won't get v6.15-rc1, so there will be for_each_if()
> available and these will become

I'll use for_each_if() if I'll have to rebase this to the v6.15-rc1.

> But see above the proposed additional patch that you may include in your next
> version.

Seems like you sent it as it's own series. I believe it's better that way.

Yours,
	-- Matti

Re: [PATCH v6 00/10] Support ROHM BD79124 ADC

[Jonathan Cameron]

On Tue, 11 Mar 2025 07:49:35 +0200
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> On 10/03/2025 22:27, Jonathan Cameron wrote:
> > On Mon, 10 Mar 2025 14:53:50 +0200
> > Matti Vaittinen <mazziesaccount@gmail.com> wrote:
> >   
> >> Support ROHM BD79124 ADC.
> >>
> >> This series adds also couple of IIO ADC helper functions for parsing the
> >> channel information from the device tree. There are also new helpers
> >> included for iterating and counting firmware child nodes with a specific
> >> name.
> >>
> >> Series does also convert couple of drivers to use these helpers. The
> >> rzg2l_adc and the sun20i-gpadc are converted to use the new ADC helper.
> >>
> >> The gianfar driver under net and the thp7312 under media/i2c are added as
> >> first users of the newly added "named child node" -helpers.
> >>
> >> There has been some discussion about how useful these ADC helpers are,
> >> and whether they should support also differential and single ended channel
> >> configurations. This version does not include support for those - with the
> >> benefit of reduced complexity and easier to use API.
> >>
> >> NOTE: Patches 4,5,9 and 10 are untested as I lack of relevant HW.
> >> They have been compile tested only.  
> > This probably wants an update.  Also, 00/10? There are only 8 that I can see.  
> 
> That's odd.
> There should be 10 in total. And the 4, 5, 9 and 10 was updated.
> 
> 9/10:
> https://lore.kernel.org/all/1c4b9b4ceb1995bce76a0ddef0e04ad0d1d81190.1741610847.git.mazziesaccount@gmail.com/
> 
> 10/10:
> https://lore.kernel.org/all/ab79cf4415d21ff2854fee4f4189fac555c30b7a.1741610847.git.mazziesaccount@gmail.com/
> 
> Perhaps it's because of the "net-next" in subject?
> 
Nope. My filters broke the series up into different directories.

Thanks,

Jonathan

> Yours,
> 	-- Matti