[PATCH v7 00/10] Support ROHM BD79124 ADC

[PATCH v7 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:
v6 => v7:
 - Inline device_get_named_child_node_count()
 - Fix kernel-doc for fwnode_get_named_child_node_count()
 - Minor styling fixes
 More accurate changelog in individual patches.

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                       |   27 +
 drivers/iio/adc/Kconfig                       |   17 +
 drivers/iio/adc/Makefile                      |    3 +
 drivers/iio/adc/industrialio-adc.c            |   79 ++
 drivers/iio/adc/rohm-bd79124.c                | 1107 +++++++++++++++++
 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                      |   24 +
 13 files changed, 1449 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 v7 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 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:
v6 => v7:
 - Improve kerneldoc
 - Inline device_get_named_child_node_count() and change it to call
  fwnode_get_named_child_node_count() inside
 - Fix indentiation of the new macros
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/
---
 drivers/base/property.c  | 27 +++++++++++++++++++++++++++
 include/linux/property.h | 24 ++++++++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index c1392743df9c..83fa0d0ee1f5 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -945,6 +945,33 @@ 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. Potential
+ * 'number' -ending after the 'at sign' for scanned names is ignored.
+ * E.g.::
+ *   device_get_named_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);
+
 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..7411dfdaadc0 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,
@@ -210,6 +226,14 @@ 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);
+static inline unsigned int device_get_named_child_node_count(const struct device *dev,
+							     const char *name)
+{
+	return fwnode_get_named_child_node_count(dev_fwnode(dev), 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 v7 net-next 09/10] net: gianfar: Use device_get_child_node_count_named()

[Matti Vaittinen]

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We can avoid open-coding the loop construct which counts firmware child
nodes with a specific name by using the newly added
device_get_child_node_count_named().

The gianfar driver has such open-coded loop. Replace it with the
device_get_child_node_count_named().

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
---
Revision history:
v6 =>:
 - No changes
v5 (RFC) => v6:
 - Drop RFC
 - Adapt to changed function name.

It's fair to tell the pros and cons of this patch.
The simplification is there, but it's not a big one. It comes with a cost
of getting the property.h included in this driver which currently uses
exclusively the of_* APIs.

NOTE: This patch depends on the patch:
[2/10] "property: Add functions to iterate named child"

Compile-tested only!
---
 drivers/net/ethernet/freescale/gianfar.c | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c
index 435138f4699d..d4ee0fc843be 100644
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -97,6 +97,7 @@
 #include <linux/phy_fixed.h>
 #include <linux/of.h>
 #include <linux/of_net.h>
+#include <linux/property.h>
 
 #include "gianfar.h"
 
@@ -571,18 +572,6 @@ static int gfar_parse_group(struct device_node *np,
 	return 0;
 }
 
-static int gfar_of_group_count(struct device_node *np)
-{
-	struct device_node *child;
-	int num = 0;
-
-	for_each_available_child_of_node(np, child)
-		if (of_node_name_eq(child, "queue-group"))
-			num++;
-
-	return num;
-}
-
 /* Reads the controller's registers to determine what interface
  * connects it to the PHY.
  */
@@ -654,8 +643,10 @@ static int gfar_of_init(struct platform_device *ofdev, struct net_device **pdev)
 		num_rx_qs = 1;
 	} else { /* MQ_MG_MODE */
 		/* get the actual number of supported groups */
-		unsigned int num_grps = gfar_of_group_count(np);
+		unsigned int num_grps;
 
+		num_grps = device_get_named_child_node_count(&ofdev->dev,
+							     "queue-group");
 		if (num_grps == 0 || num_grps > MAXGROUPS) {
 			dev_err(&ofdev->dev, "Invalid # of int groups(%d)\n",
 				num_grps);
-- 
2.48.1


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Re: [PATCH v7 02/10] property: Add functions to iterate named child

[Andy Shevchenko]

On Thu, Mar 13, 2025 at 09:18:00AM +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 helpers for iterating and counting device's sub-nodes with certain
> name instead of open-coding this in every user.

LGTM,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
I haven't checked the rendered kernel-doc, though.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v7 net-next 09/10] net: gianfar: Use device_get_child_node_count_named()

[Andy Shevchenko]

On Thu, Mar 13, 2025 at 09:20:10AM +0200, Matti Vaittinen wrote:
> We can avoid open-coding the loop construct which counts firmware child
> nodes with a specific name by using the newly added
> device_get_child_node_count_named().
> 
> The gianfar driver has such open-coded loop. Replace it with the
> device_get_child_node_count_named().

FWIW,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v7 02/10] property: Add functions to iterate named child

[Marcelo Schmitt]

Hello,

LGTM, few minor comments inline.
With those sorted
Reviewed-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>

On 03/13, 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 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>
> ---
...
> +/**
> + * 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. Potential
> + * 'number' -ending after the 'at sign' for scanned names is ignored.
> + * E.g.::
> + *   device_get_named_child_node_count(dev, "channel");

The function being documented is fwnode_get_named_child_node_count().
Shouldn't the example be
   fwnode_get_named_child_node_count(fwnode, "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.
> + */
...
> +#define device_for_each_named_child_node(dev, child, name)		\
> +		device_for_each_child_node(dev, child)			\
> +			if (!fwnode_name_eq(child, name)) { } else

nitpicking: add only one tab for each indentation level.
	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
> +

nitpicking: instead of two tabs, only one tab before device_for_..._scoped().
	device_for_each_child_node_scoped(dev, child)		\
		if (!fwnode_name_eq(child, name)) { } else

Regards,
Marcelo