[PATCH v5 00/10] Support ROHM BD79124 ADC

[PATCH v5 00/10] Support ROHM BD79124 ADC

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 4904 bytes --]

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 two helpers
included for counting number of 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 is added as an RFC patch to use the newly
added firmware child node counting function.

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.

patch 6/10 is small simplification for the ti-ads7924, and it can be
taken independently from the rest of the series.

NOTE: Patches 4...6 and the patch 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:
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.
 Changes which were not proposed by reviewers:
 - rebase to v6.14-rc5
 - Do not include all recipients to all of the patches.
 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 count named child nodes
  iio: adc: add helpers for parsing ADC nodes
  iio: adc: rzg2l_adc: Use adc-helpers
  iio: adc: sun20i-gpadc: Use adc-helpers
  iio: adc: ti-ads7924 Drop unnecessary function parameters
  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()

 .../bindings/iio/adc/rohm,bd79124.yaml        |  114 ++
 MAINTAINERS                                   |   12 +
 drivers/base/property.c                       |   57 +
 drivers/iio/adc/Kconfig                       |   17 +
 drivers/iio/adc/Makefile                      |    3 +
 drivers/iio/adc/industrialio-adc.c            |   82 ++
 drivers/iio/adc/rohm-bd79124.c                | 1108 +++++++++++++++++
 drivers/iio/adc/rzg2l_adc.c                   |   38 +-
 drivers/iio/adc/sun20i-gpadc-iio.c            |   38 +-
 drivers/iio/adc/ti-ads7924.c                  |    7 +-
 drivers/net/ethernet/freescale/gianfar.c      |   17 +-
 include/linux/iio/adc-helpers.h               |   27 +
 include/linux/property.h                      |    4 +
 13 files changed, 1462 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


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH v5 01/10] dt-bindings: ROHM BD79124 ADC/GPO

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 3475 bytes --]

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


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH v5 02/10] property: Add functions to count named child nodes

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 4178 bytes --]

There are some use-cases where child nodes with a specific name need to
be parsed. In a few cases the data from the found nodes is 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 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:
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  | 57 ++++++++++++++++++++++++++++++++++++++++
 include/linux/property.h |  4 +++
 2 files changed, 61 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index c1392743df9c..3faf02b99cff 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -945,6 +945,63 @@ unsigned int device_get_child_node_count(const struct device *dev)
 }
 EXPORT_SYMBOL_GPL(device_get_child_node_count);
 
+/**
+ * fwnode_get_child_node_count_named - 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_child_node_count_named(const struct fwnode_handle *fwnode,
+					       const char *name)
+{
+	struct fwnode_handle *child;
+	unsigned int count = 0;
+
+	fwnode_for_each_child_node(fwnode, child)
+		if (fwnode_name_eq(child, name))
+			count++;
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(fwnode_get_child_node_count_named);
+
+/**
+ * device_get_child_node_count_named - 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_child_node_count_named(const struct device *dev,
+					       const char *name)
+{
+	const struct fwnode_handle *fwnode = dev_fwnode(dev);
+
+	if (!fwnode)
+		return -EINVAL;
+
+	if (IS_ERR(fwnode))
+		return PTR_ERR(fwnode);
+
+	return fwnode_get_child_node_count_named(fwnode, name);
+}
+EXPORT_SYMBOL_GPL(device_get_child_node_count_named);
+
 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..269ab539515b 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -209,6 +209,10 @@ 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_child_node_count_named(const struct fwnode_handle *fwnode,
+					       const char *name);
+unsigned int device_get_child_node_count_named(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


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH v5 03/10] iio: adc: add helpers for parsing ADC nodes

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 6220 bytes --]

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:
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 | 82 ++++++++++++++++++++++++++++++
 include/linux/iio/adc-helpers.h    | 27 ++++++++++
 4 files changed, 114 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..7bdae5330224
--- /dev/null
+++ b/drivers/iio/adc/industrialio-adc.c
@@ -0,0 +1,82 @@
+// 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 succes. 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_child_node_scoped(dev, child) {
+		u32 ch;
+
+		if (!fwnode_name_eq(child, "channel"))
+			continue;
+
+		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..403a70b109ec
--- /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_child_node_count_named(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


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH v5 04/10] iio: adc: rzg2l_adc: Use adc-helpers

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 4843 bytes --]

The new devm_iio_adc_device_alloc_chaninfo() -helper is intended to help
drivers avoid open-coding the for_each_node -loop for getting the
channel IDs. The helper provides standard way to detect the ADC channel
nodes (by the node name), and a standard way to convert the "reg"
-propereties to channel identification numbers, used in the struct
iio_chan_spec. Furthermore, the helper can optionally check the found
channel IDs are smaller than given maximum. This is useful for callers
which later use the IDs for example for indexing a channel data array.

The original driver treated all found child nodes as channel nodes. The
new helper requires channel nodes to be named channel[@N]. This should
help avoid problems with devices which may contain also other but ADC
child nodes. Quick grep from arch/* with the rzg2l_adc's compatible
string didn't reveal any in-tree .dts with channel nodes named
otherwise. Also, same grep shows all the .dts seem to have channel IDs
between 0..num of channels.

Use the new helper.

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

---
Revision history:
v4 => v5:
 - Drop the diff-channel stuff from the commit message
v3 => v4:
 - Adapt to 'drop diff-channel support' changes to ADC-helpers
 - select ADC helpers in the Kconfig
 - Rebased to 6.14-rc3 => channel type can no longer come from the
   template.

v2 => v3:
 - New patch

The change is compile tested only!! Testing before applying is highly
appreciated (as always!).
---
 drivers/iio/adc/Kconfig     |  1 +
 drivers/iio/adc/rzg2l_adc.c | 38 +++++++++++++++++--------------------
 2 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 37b70a65da6f..e4933de0c366 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1222,6 +1222,7 @@ config RICHTEK_RTQ6056
 config RZG2L_ADC
 	tristate "Renesas RZ/G2L ADC driver"
 	depends on ARCH_RZG2L || COMPILE_TEST
+	select IIO_ADC_HELPER
 	help
 	  Say yes here to build support for the ADC found in Renesas
 	  RZ/G2L family.
diff --git a/drivers/iio/adc/rzg2l_adc.c b/drivers/iio/adc/rzg2l_adc.c
index 883c167c0670..51c87b1bdc98 100644
--- a/drivers/iio/adc/rzg2l_adc.c
+++ b/drivers/iio/adc/rzg2l_adc.c
@@ -11,6 +11,7 @@
 #include <linux/cleanup.h>
 #include <linux/completion.h>
 #include <linux/delay.h>
+#include <linux/iio/adc-helpers.h>
 #include <linux/iio/iio.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
@@ -324,21 +325,30 @@ static irqreturn_t rzg2l_adc_isr(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static const struct iio_chan_spec rzg2l_adc_chan_template = {
+	.indexed = 1,
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+};
+
 static int rzg2l_adc_parse_properties(struct platform_device *pdev, struct rzg2l_adc *adc)
 {
 	const struct rzg2l_adc_hw_params *hw_params = adc->hw_params;
 	struct iio_chan_spec *chan_array;
 	struct rzg2l_adc_data *data;
-	unsigned int channel;
 	int num_channels;
-	int ret;
 	u8 i;
 
 	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
 
-	num_channels = device_get_child_node_count(&pdev->dev);
+	num_channels = devm_iio_adc_device_alloc_chaninfo_se(&pdev->dev,
+						&rzg2l_adc_chan_template,
+						hw_params->num_channels - 1,
+						&chan_array);
+	if (num_channels < 0)
+		return num_channels;
+
 	if (!num_channels)
 		return dev_err_probe(&pdev->dev, -ENODEV, "no channel children\n");
 
@@ -346,26 +356,11 @@ static int rzg2l_adc_parse_properties(struct platform_device *pdev, struct rzg2l
 		return dev_err_probe(&pdev->dev, -EINVAL,
 				     "num of channel children out of range\n");
 
-	chan_array = devm_kcalloc(&pdev->dev, num_channels, sizeof(*chan_array),
-				  GFP_KERNEL);
-	if (!chan_array)
-		return -ENOMEM;
-
-	i = 0;
-	device_for_each_child_node_scoped(&pdev->dev, fwnode) {
-		ret = fwnode_property_read_u32(fwnode, "reg", &channel);
-		if (ret)
-			return ret;
-
-		if (channel >= hw_params->num_channels)
-			return -EINVAL;
+	for (i = 0; i < num_channels; i++) {
+		int channel = chan_array[i].channel;
 
-		chan_array[i].type = rzg2l_adc_channels[channel].type;
-		chan_array[i].indexed = 1;
-		chan_array[i].channel = channel;
-		chan_array[i].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
 		chan_array[i].datasheet_name = rzg2l_adc_channels[channel].name;
-		i++;
+		chan_array[i].type = rzg2l_adc_channels[channel].type;
 	}
 
 	data->num_channels = num_channels;
@@ -626,3 +621,4 @@ module_platform_driver(rzg2l_adc_driver);
 MODULE_AUTHOR("Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>");
 MODULE_DESCRIPTION("Renesas RZ/G2L ADC driver");
 MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS("IIO_DRIVER");
-- 
2.48.1


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH v5 05/10] iio: adc: sun20i-gpadc: Use adc-helpers

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 4837 bytes --]

The new devm_iio_adc_device_alloc_chaninfo() -helper is intended to help
drivers avoid open-coding the for_each_node -loop for getting the
channel IDs. The helper provides standard way to detect the ADC channel
nodes (by the node name), and a standard way to convert the "reg"
-propereties to channel identification numbers, used in the struct
iio_chan_spec. Furthermore, the helper can optionally check the found
channel IDs are smaller than given maximum. This is useful for callers
which later use the IDs for example for indexing a channel data array.

The original driver treated all found child nodes as channel nodes. The
new helper requires channel nodes to be named channel[@N]. This should
help avoid problems with devices which may contain also other but ADC
child nodes. Quick grep from arch/* with the sun20i-gpadc's compatible
string didn't reveal any in-tree .dts with channel nodes named
otherwise. Also, same grep shows all the in-tree .dts seem to have
channel IDs between 0..num of channels.

Use the new helper.

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

---
Revision history:
v4 => v5:
 - Drop the diff-channel stuff from the commit message
v3 => v4:
 - Adapt to 'drop diff-channel support' changes to ADC-helpers
 - select ADC helpers in the Kconfig
v2 => v3:
 - New patch

I picked the sun20i-gpadc in this series because it has a straightforward
approach for populating the struct iio_chan_spec. Everything else except
the .channel can use 'template'-data.

This makes the sun20i-gpadc well suited to be an example user of this new
helper. I hope this patch helps to evaluate whether these helpers are worth
the hassle.

The change is compile tested only!! Testing before applying is highly
appreciated (as always!). Also, even though I tried to audit the dts
files for the reg-properties in the channel nodes, use of references
didn't make it easy. I can't guarantee I didn't miss anything.
---
 drivers/iio/adc/Kconfig            |  1 +
 drivers/iio/adc/sun20i-gpadc-iio.c | 38 ++++++++++++------------------
 2 files changed, 16 insertions(+), 23 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index e4933de0c366..0993008a1586 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1357,6 +1357,7 @@ config SUN4I_GPADC
 config SUN20I_GPADC
 	tristate "Allwinner D1/T113s/T507/R329 and similar GPADCs driver"
 	depends on ARCH_SUNXI || COMPILE_TEST
+	select IIO_ADC_HELPER
 	help
 	  Say yes here to build support for Allwinner (D1, T113, T507 and R329)
 	  SoCs GPADC. This ADC provides up to 16 channels.
diff --git a/drivers/iio/adc/sun20i-gpadc-iio.c b/drivers/iio/adc/sun20i-gpadc-iio.c
index 136b8d9c294f..bf1db2a3de9b 100644
--- a/drivers/iio/adc/sun20i-gpadc-iio.c
+++ b/drivers/iio/adc/sun20i-gpadc-iio.c
@@ -15,6 +15,7 @@
 #include <linux/property.h>
 #include <linux/reset.h>
 
+#include <linux/iio/adc-helpers.h>
 #include <linux/iio/iio.h>
 
 #define SUN20I_GPADC_DRIVER_NAME	"sun20i-gpadc"
@@ -149,37 +150,27 @@ static void sun20i_gpadc_reset_assert(void *data)
 	reset_control_assert(rst);
 }
 
+static const struct iio_chan_spec sun20i_gpadc_chan_template = {
+	.type = IIO_VOLTAGE,
+	.indexed = 1,
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+};
+
 static int sun20i_gpadc_alloc_channels(struct iio_dev *indio_dev,
 				       struct device *dev)
 {
-	unsigned int channel;
-	int num_channels, i, ret;
+	int num_channels;
 	struct iio_chan_spec *channels;
 
-	num_channels = device_get_child_node_count(dev);
+	num_channels = devm_iio_adc_device_alloc_chaninfo_se(dev,
+				&sun20i_gpadc_chan_template, -1, &channels);
+	if (num_channels < 0)
+		return num_channels;
+
 	if (num_channels == 0)
 		return dev_err_probe(dev, -ENODEV, "no channel children\n");
 
-	channels = devm_kcalloc(dev, num_channels, sizeof(*channels),
-				GFP_KERNEL);
-	if (!channels)
-		return -ENOMEM;
-
-	i = 0;
-	device_for_each_child_node_scoped(dev, node) {
-		ret = fwnode_property_read_u32(node, "reg", &channel);
-		if (ret)
-			return dev_err_probe(dev, ret, "invalid channel number\n");
-
-		channels[i].type = IIO_VOLTAGE;
-		channels[i].indexed = 1;
-		channels[i].channel = channel;
-		channels[i].info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
-		channels[i].info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
-
-		i++;
-	}
-
 	indio_dev->channels = channels;
 	indio_dev->num_channels = num_channels;
 
@@ -271,3 +262,4 @@ module_platform_driver(sun20i_gpadc_driver);
 MODULE_DESCRIPTION("ADC driver for sunxi platforms");
 MODULE_AUTHOR("Maksim Kiselev <bigunclemax@gmail.com>");
 MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_DRIVER");
-- 
2.48.1


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH v5 06/10] iio: adc: ti-ads7924 Drop unnecessary function parameters

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 1739 bytes --]

Device pointer is the only variable which is used by the
ads7924_get_channels_config() and which is declared outside this
function. Still, the function gets the iio_device and i2c_client as
parameters. The sole caller of this function (probe) already has the
device pointer which it can directly pass to the function.

Simplify code by passing the device pointer directly as a parameter
instead of digging it from the iio_device's private data.

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

---
Revision history:
v4 => No changes

This commit is compile-tested only! All further testing is appreciated.
---
 drivers/iio/adc/ti-ads7924.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/ti-ads7924.c b/drivers/iio/adc/ti-ads7924.c
index 66b54c0d75aa..b1f745f75dbe 100644
--- a/drivers/iio/adc/ti-ads7924.c
+++ b/drivers/iio/adc/ti-ads7924.c
@@ -251,11 +251,8 @@ static const struct iio_info ads7924_info = {
 	.read_raw = ads7924_read_raw,
 };
 
-static int ads7924_get_channels_config(struct i2c_client *client,
-				       struct iio_dev *indio_dev)
+static int ads7924_get_channels_config(struct device *dev)
 {
-	struct ads7924_data *priv = iio_priv(indio_dev);
-	struct device *dev = priv->dev;
 	struct fwnode_handle *node;
 	int num_channels = 0;
 
@@ -380,7 +377,7 @@ static int ads7924_probe(struct i2c_client *client)
 	indio_dev->num_channels = ARRAY_SIZE(ads7924_channels);
 	indio_dev->info = &ads7924_info;
 
-	ret = ads7924_get_channels_config(client, indio_dev);
+	ret = ads7924_get_channels_config(dev);
 	if (ret < 0)
 		return dev_err_probe(dev, ret,
 				     "failed to get channels configuration\n");
-- 
2.48.1


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH v5 07/10] iio: adc: Support ROHM BD79124 ADC

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 36644 bytes --]

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. The window is configurable for each channel.

The I2C protocol for manual start of the measurement and data reading is
somewhat peculiar. It requires the master to do clock stretching after
sending the I2C slave-address until the slave has captured the data.
Needless to say this is not well suopported by the I2C controllers.

Thus the driver does not support the BD79124's manual measurement mode
but implements the measurements using automatic measurement mode relying
on the BD79124's ability of storing latest measurements into register.

The driver does also support configuring the threshold events for
detecting the out-of-window events.

The BD79124 keeps asserting IRQ for as long as the measured voltage is
out of the configured window. Thus the driver masks the received event
for a fixed duration (1 second) when an event is handled. This prevents
the user-space from choking on the events

The ADC input pins can be also configured as general purpose outputs.
Those pins which don't have corresponding ADC channel node in the
device-tree will be controllable as GPO.

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

---
Revision history:
v4 => v5:
 - Drop unused interval defines
 - Append unit to interval define and drop a comment
 - Drop parenthesis around bitwise negation operation ~
 - Use proper block comment style
 - Improve the documentation of the re-enabling the events by moving
   comment explaining early return to the point of the return, and
   by adding own comment for the reason of locking before calling the
   re-enabling
 - Indenting
 - Drop unused struct bd79124_reg_init
 - Drop bd79124_init_mux() wrapper and call the regmap_write() directly
v3 => v4:
 - Adapt to 'drop diff-channel support' changes to ADC-helpers
 - Don't parse fwnode in GPIO valid-mask callback but use pin config
   cached at probe()
 - Drop use of iio_adc_device_channels_by_property()
 - Open code the bd79124_reg_init loop (as suggested by Jonathan)
 - Use devm variant of mutex_init()
 - Styling
v2 => v3:
 - Fix uninitialized return value reported by the kernel test robot
 - Fix indent
 - Adapt to adc-helper changes supporting also single-ended and
   differential channels
RFC v1 => v2:
 - Add event throttling (constant delay of 1 sec)
 - rename variable 'd' to 'data'
 - Use ADC helpers to detect pins used for ADC
 - bd79124 drop MFD and pinmux && handle GPO in this driver
 - Drop adc suffix from the IIO file name
---
 drivers/iio/adc/Kconfig        |   12 +
 drivers/iio/adc/Makefile       |    1 +
 drivers/iio/adc/rohm-bd79124.c | 1108 ++++++++++++++++++++++++++++++++
 3 files changed, 1121 insertions(+)
 create mode 100644 drivers/iio/adc/rohm-bd79124.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 0993008a1586..74d749c0cd8f 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1191,6 +1191,18 @@ config RN5T618_ADC
 	  This driver can also be built as a module. If so, the module
 	  will be called rn5t618-adc.
 
+config ROHM_BD79124
+	tristate "Rohm BD79124 ADC driver"
+	depends on I2C
+	select REGMAP_I2C
+	select IIO_ADC_HELPER
+	help
+	  Say yes here to build support for the ROHM BD79124 ADC. The
+	  ROHM BD79124 is a 12-bit, 8-channel, SAR ADC. The ADC supports
+	  also an automatic measurement mode, with an alarm interrupt for
+	  out-of-window measurements. The window is configurable for each
+	  channel.
+
 config ROCKCHIP_SARADC
 	tristate "Rockchip SARADC driver"
 	depends on ARCH_ROCKCHIP || COMPILE_TEST
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 1c410f483029..3e10af9ec4c4 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -109,6 +109,7 @@ obj-$(CONFIG_QCOM_VADC_COMMON) += qcom-vadc-common.o
 obj-$(CONFIG_RCAR_GYRO_ADC) += rcar-gyroadc.o
 obj-$(CONFIG_RICHTEK_RTQ6056) += rtq6056.o
 obj-$(CONFIG_RN5T618_ADC) += rn5t618-adc.o
+obj-$(CONFIG_ROHM_BD79124) += rohm-bd79124.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_RZG2L_ADC) += rzg2l_adc.o
 obj-$(CONFIG_SC27XX_ADC) += sc27xx_adc.o
diff --git a/drivers/iio/adc/rohm-bd79124.c b/drivers/iio/adc/rohm-bd79124.c
new file mode 100644
index 000000000000..466c7decf8fc
--- /dev/null
+++ b/drivers/iio/adc/rohm-bd79124.c
@@ -0,0 +1,1108 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ROHM ADC driver for BD79124 ADC/GPO device
+ * https://fscdn.rohm.com/en/products/databook/datasheet/ic/data_converter/dac/bd79124muf-c-e.pdf
+ *
+ * Copyright (c) 2025, ROHM Semiconductor.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitmap.h>
+#include <linux/bits.h>
+#include <linux/byteorder/generic.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/devm-helpers.h>
+#include <linux/err.h>
+#include <linux/gpio/driver.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+#include <linux/iio/events.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/adc-helpers.h>
+
+#define BD79124_I2C_MULTI_READ		0x30
+#define BD79124_I2C_MULTI_WRITE		0x28
+#define BD79124_REG_MAX			0xaf
+
+#define BD79124_REG_SYSTEM_STATUS	0x0
+#define BD79124_REG_GEN_CFG		0x01
+#define BD79124_REG_OPMODE_CFG		0x04
+#define BD79124_REG_PINCFG		0x05
+#define BD79124_REG_GPO_VAL		0x0B
+#define BD79124_REG_SEQUENCE_CFG	0x10
+#define BD79124_REG_MANUAL_CHANNELS	0x11
+#define BD79124_REG_AUTO_CHANNELS	0x12
+#define BD79124_REG_ALERT_CH_SEL	0x14
+#define BD79124_REG_EVENT_FLAG		0x18
+#define BD79124_REG_EVENT_FLAG_HI	0x1a
+#define BD79124_REG_EVENT_FLAG_LO	0x1c
+#define BD79124_REG_HYSTERESIS_CH0	0x20
+#define BD79124_REG_EVENTCOUNT_CH0	0x22
+#define BD79124_REG_RECENT_CH0_LSB	0xa0
+#define BD79124_REG_RECENT_CH7_MSB	0xaf
+
+#define BD79124_ADC_BITS 12
+#define BD79124_MASK_CONV_MODE GENMASK(6, 5)
+#define BD79124_MASK_AUTO_INTERVAL GENMASK(1, 0)
+#define BD79124_CONV_MODE_MANSEQ 0
+#define BD79124_CONV_MODE_AUTO 1
+#define BD79124_INTERVAL_750_US 0
+
+#define BD79124_MASK_DWC_EN BIT(4)
+#define BD79124_MASK_STATS_EN BIT(5)
+#define BD79124_MASK_SEQ_START BIT(4)
+#define BD79124_MASK_SEQ_MODE GENMASK(1, 0)
+#define BD79124_MASK_SEQ_MANUAL 0
+#define BD79124_MASK_SEQ_SEQ 1
+
+#define BD79124_MASK_HYSTERESIS GENMASK(3, 0)
+#define BD79124_LOW_LIMIT_MIN 0
+#define BD79124_HIGH_LIMIT_MAX GENMASK(11, 0)
+
+/*
+ * The high limit, low limit and last measurement result are each stored in
+ * 2 consequtive registers. 4 bits are in the high bits of the 1.st register
+ * and 8 bits in the next register.
+ *
+ * These macros return the address of the 1.st reg for the given channel
+ */
+#define BD79124_GET_HIGH_LIMIT_REG(ch) (BD79124_REG_HYSTERESIS_CH0 + (ch) * 4)
+#define BD79124_GET_LOW_LIMIT_REG(ch) (BD79124_REG_EVENTCOUNT_CH0 + (ch) * 4)
+#define BD79124_GET_LIMIT_REG(ch, dir) ((dir) == IIO_EV_DIR_RISING ?		\
+		BD79124_GET_HIGH_LIMIT_REG(ch) : BD79124_GET_LOW_LIMIT_REG(ch))
+#define BD79124_GET_RECENT_RES_REG(ch) (BD79124_REG_RECENT_CH0_LSB + (ch) * 2)
+
+/*
+ * The hysteresis for a channel is stored in the same register where the
+ * 4 bits of high limit reside.
+ */
+#define BD79124_GET_HYSTERESIS_REG(ch) BD79124_GET_HIGH_LIMIT_REG(ch)
+
+#define BD79124_MAX_NUM_CHANNELS 8
+
+struct bd79124_data {
+	s64 timestamp;
+	struct regmap *map;
+	struct device *dev;
+	int vmax;
+	/*
+	 * Keep measurement status so read_raw() knows if the measurement needs
+	 * to be started.
+	 */
+	int alarm_monitored[BD79124_MAX_NUM_CHANNELS];
+	/*
+	 * The BD79124 does not allow disabling/enabling limit separately for
+	 * one direction only. Hence, we do the disabling by changing the limit
+	 * to maximum/minimum measurable value. This means we need to cache
+	 * the limit in order to maintain it over the time limit is disabled.
+	 */
+	u16 alarm_r_limit[BD79124_MAX_NUM_CHANNELS];
+	u16 alarm_f_limit[BD79124_MAX_NUM_CHANNELS];
+	/* Bitmask of disabled events (for rate limiting) for each channel. */
+	int alarm_suppressed[BD79124_MAX_NUM_CHANNELS];
+	/*
+	 * The BD79124 is configured to run the measurements in the background.
+	 * This is done for the event monitoring as well as for the read_raw().
+	 * Protect the measurement starting/stopping using a mutex.
+	 */
+	struct mutex mutex;
+	struct delayed_work alm_enable_work;
+	struct gpio_chip gc;
+	u8 gpio_valid_mask;
+};
+
+/* Read-only regs */
+static const struct regmap_range bd79124_ro_ranges[] = {
+	{
+		.range_min = BD79124_REG_EVENT_FLAG,
+		.range_max = BD79124_REG_EVENT_FLAG,
+	}, {
+		.range_min = BD79124_REG_RECENT_CH0_LSB,
+		.range_max = BD79124_REG_RECENT_CH7_MSB,
+	},
+};
+
+static const struct regmap_access_table bd79124_ro_regs = {
+	.no_ranges	= &bd79124_ro_ranges[0],
+	.n_no_ranges	= ARRAY_SIZE(bd79124_ro_ranges),
+};
+
+static const struct regmap_range bd79124_volatile_ranges[] = {
+	{
+		.range_min = BD79124_REG_RECENT_CH0_LSB,
+		.range_max = BD79124_REG_RECENT_CH7_MSB,
+	}, {
+		.range_min = BD79124_REG_EVENT_FLAG,
+		.range_max = BD79124_REG_EVENT_FLAG,
+	}, {
+		.range_min = BD79124_REG_EVENT_FLAG_HI,
+		.range_max = BD79124_REG_EVENT_FLAG_HI,
+	}, {
+		.range_min = BD79124_REG_EVENT_FLAG_LO,
+		.range_max = BD79124_REG_EVENT_FLAG_LO,
+	}, {
+		.range_min = BD79124_REG_SYSTEM_STATUS,
+		.range_max = BD79124_REG_SYSTEM_STATUS,
+	},
+};
+
+static const struct regmap_access_table bd79124_volatile_regs = {
+	.yes_ranges	= &bd79124_volatile_ranges[0],
+	.n_yes_ranges	= ARRAY_SIZE(bd79124_volatile_ranges),
+};
+
+static const struct regmap_range bd79124_precious_ranges[] = {
+	{
+		.range_min = BD79124_REG_EVENT_FLAG_HI,
+		.range_max = BD79124_REG_EVENT_FLAG_HI,
+	}, {
+		.range_min = BD79124_REG_EVENT_FLAG_LO,
+		.range_max = BD79124_REG_EVENT_FLAG_LO,
+	},
+};
+
+static const struct regmap_access_table bd79124_precious_regs = {
+	.yes_ranges	= &bd79124_precious_ranges[0],
+	.n_yes_ranges	= ARRAY_SIZE(bd79124_precious_ranges),
+};
+
+static const struct regmap_config bd79124_regmap = {
+	.reg_bits		= 16,
+	.val_bits		= 8,
+	.read_flag_mask		= BD79124_I2C_MULTI_READ,
+	.write_flag_mask	= BD79124_I2C_MULTI_WRITE,
+	.max_register		= BD79124_REG_MAX,
+	.cache_type		= REGCACHE_MAPLE,
+	.volatile_table		= &bd79124_volatile_regs,
+	.wr_table		= &bd79124_ro_regs,
+	.precious_table		= &bd79124_precious_regs,
+};
+
+static int bd79124gpo_direction_get(struct gpio_chip *gc, unsigned int offset)
+{
+	return GPIO_LINE_DIRECTION_OUT;
+}
+
+static void bd79124gpo_set(struct gpio_chip *gc, unsigned int offset, int value)
+{
+	struct bd79124_data *data = gpiochip_get_data(gc);
+
+	if (value)
+		regmap_set_bits(data->map, BD79124_REG_GPO_VAL, BIT(offset));
+	else
+		regmap_clear_bits(data->map, BD79124_REG_GPO_VAL, BIT(offset));
+}
+
+static void bd79124gpo_set_multiple(struct gpio_chip *gc, unsigned long *mask,
+				   unsigned long *bits)
+{
+	int ret, val;
+	struct bd79124_data *data = gpiochip_get_data(gc);
+
+	/* Ensure all GPIOs in 'mask' are set to be GPIOs */
+	ret = regmap_read(data->map, BD79124_REG_PINCFG, &val);
+	if (ret)
+		return;
+
+	if ((val & *mask) != *mask) {
+		dev_dbg(data->dev, "Invalid mux config. Can't set value.\n");
+		/* Do not set value for pins configured as ADC inputs */
+		*mask &= val;
+	}
+
+	regmap_update_bits(data->map, BD79124_REG_GPO_VAL, *mask, *bits);
+}
+
+static int bd79124_init_valid_mask(struct gpio_chip *gc,
+				   unsigned long *valid_mask,
+				   unsigned int ngpios)
+{
+	struct bd79124_data *data = gpiochip_get_data(gc);
+
+	*valid_mask = data->gpio_valid_mask;
+
+	return 0;
+}
+
+/* Template for GPIO chip */
+static const struct gpio_chip bd79124gpo_chip = {
+	.label			= "bd79124-gpo",
+	.get_direction		= bd79124gpo_direction_get,
+	.set			= bd79124gpo_set,
+	.set_multiple		= bd79124gpo_set_multiple,
+	.init_valid_mask	= bd79124_init_valid_mask,
+	.can_sleep		= true,
+	.ngpio			= 8,
+	.base			= -1,
+};
+
+struct bd79124_raw {
+	u8 bit0_3; /* Is set in high bits of the byte */
+	u8 bit4_11;
+};
+#define BD79124_RAW_TO_INT(r) ((r.bit4_11 << 4) | (r.bit0_3 >> 4))
+
+/*
+ * The high and low limits as well as the recent result values are stored in
+ * the same way in 2 consequent registers. The first register contains 4 bits
+ * of the value. These bits are stored in the high bits [7:4] of register, but
+ * they represent the low bits [3:0] of the value.
+ * The value bits [11:4] are stored in the next register.
+ *
+ * Read data from register and convert to integer.
+ */
+static int bd79124_read_reg_to_int(struct bd79124_data *data, int reg,
+				   unsigned int *val)
+{
+	int ret;
+	struct bd79124_raw raw;
+
+	ret = regmap_bulk_read(data->map, reg, &raw, sizeof(raw));
+	if (ret) {
+		dev_dbg(data->dev, "bulk_read failed %d\n", ret);
+
+		return ret;
+	}
+
+	*val = BD79124_RAW_TO_INT(raw);
+
+	return 0;
+}
+
+/*
+ * The high and low limits as well as the recent result values are stored in
+ * the same way in 2 consequent registers. The first register contains 4 bits
+ * of the value. These bits are stored in the high bits [7:4] of register, but
+ * they represent the low bits [3:0] of the value.
+ * The value bits [11:4] are stored in the next regoster.
+ *
+ * Conver the integer to register format and write it using rmw cycle.
+ */
+static int bd79124_write_int_to_reg(struct bd79124_data *data, int reg,
+				    unsigned int val)
+{
+	struct bd79124_raw raw;
+	int ret, tmp;
+
+	raw.bit4_11 = (u8)(val >> 4);
+	raw.bit0_3 = (u8)(val << 4);
+
+	ret = regmap_read(data->map, reg, &tmp);
+	if (ret)
+		return ret;
+
+	raw.bit0_3 |= (0xf & tmp);
+
+	return regmap_bulk_write(data->map, reg, &raw, sizeof(raw));
+}
+
+static const struct iio_event_spec bd79124_events[] = {
+	{
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_RISING,
+		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
+				 BIT(IIO_EV_INFO_ENABLE),
+	},
+	{
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_FALLING,
+		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
+				 BIT(IIO_EV_INFO_ENABLE),
+	},
+	{
+		.type = IIO_EV_TYPE_THRESH,
+		.dir = IIO_EV_DIR_EITHER,
+		.mask_separate = BIT(IIO_EV_INFO_HYSTERESIS),
+	},
+};
+
+static const struct iio_chan_spec bd79124_chan_template_noirq = {
+	.type = IIO_VOLTAGE,
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+	.indexed = 1,
+};
+
+static const struct iio_chan_spec bd79124_chan_template = {
+	.type = IIO_VOLTAGE,
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+	.indexed = 1,
+	.event_spec = bd79124_events,
+	.num_event_specs = ARRAY_SIZE(bd79124_events),
+};
+
+static int bd79124_read_event_value(struct iio_dev *iio_dev,
+				    const struct iio_chan_spec *chan,
+				    enum iio_event_type type,
+				    enum iio_event_direction dir,
+				    enum iio_event_info info, int *val,
+				    int *val2)
+{
+	struct bd79124_data *data = iio_priv(iio_dev);
+	int ret, reg;
+
+	if (chan->channel >= BD79124_MAX_NUM_CHANNELS)
+		return -EINVAL;
+
+	switch (info) {
+	case IIO_EV_INFO_VALUE:
+		if (dir == IIO_EV_DIR_RISING)
+			*val = data->alarm_r_limit[chan->channel];
+		else if (dir == IIO_EV_DIR_FALLING)
+			*val = data->alarm_f_limit[chan->channel];
+		else
+			return -EINVAL;
+
+		return IIO_VAL_INT;
+
+	case IIO_EV_INFO_HYSTERESIS:
+		reg = BD79124_GET_HYSTERESIS_REG(chan->channel);
+		ret = regmap_read(data->map, reg, val);
+		if (ret)
+			return ret;
+		/* Mask the non hysteresis bits */
+		*val &= BD79124_MASK_HYSTERESIS;
+		/*
+		 * The data-sheet says the hysteresis register value needs to be
+		 * sifted left by 3 (or multiplied by 8, depending on the
+		 * page :] )
+		 */
+		*val <<= 3;
+
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int bd79124_start_measurement(struct bd79124_data *data, int chan)
+{
+	int val, ret, regval;
+
+	/* See if already started */
+	ret = regmap_read(data->map, BD79124_REG_AUTO_CHANNELS, &val);
+	if (val & BIT(chan))
+		return 0;
+
+	ret = regmap_clear_bits(data->map, BD79124_REG_SEQUENCE_CFG,
+				BD79124_MASK_SEQ_START);
+	if (ret)
+		return ret;
+
+	/* Add the channel to measured channels */
+	ret = regmap_write(data->map, BD79124_REG_AUTO_CHANNELS, val | BIT(chan));
+	if (ret)
+		return ret;
+
+	ret = regmap_set_bits(data->map, BD79124_REG_SEQUENCE_CFG,
+			      BD79124_MASK_SEQ_START);
+	if (ret)
+		return ret;
+
+	/*
+	 * Start the measurement at the background. Don't bother checking if
+	 * it was started, regmap has cache.
+	 */
+	regval = FIELD_PREP(BD79124_MASK_CONV_MODE, BD79124_CONV_MODE_AUTO);
+
+	return regmap_update_bits(data->map, BD79124_REG_OPMODE_CFG,
+				BD79124_MASK_CONV_MODE, regval);
+}
+
+static int bd79124_stop_measurement(struct bd79124_data *data, int chan)
+{
+	int val, ret;
+
+	/* See if already stopped */
+	ret = regmap_read(data->map, BD79124_REG_AUTO_CHANNELS, &val);
+	if (!(val & BIT(chan)))
+		return 0;
+
+	ret = regmap_clear_bits(data->map, BD79124_REG_SEQUENCE_CFG,
+				BD79124_MASK_SEQ_START);
+
+	/* Clear the channel from the measured channels */
+	ret = regmap_write(data->map, BD79124_REG_AUTO_CHANNELS,
+			   ~BIT(chan) & val);
+	if (ret)
+		return ret;
+
+	/*
+	 * Stop background conversion for power saving if it was the last
+	 * channel
+	 */
+	if (!(~BIT(chan) & val)) {
+		int regval = FIELD_PREP(BD79124_MASK_CONV_MODE,
+					BD79124_CONV_MODE_MANSEQ);
+
+		ret = regmap_update_bits(data->map, BD79124_REG_OPMODE_CFG,
+					 BD79124_MASK_CONV_MODE, regval);
+		if (ret)
+			return ret;
+	}
+
+	return regmap_set_bits(data->map, BD79124_REG_SEQUENCE_CFG,
+			       BD79124_MASK_SEQ_START);
+}
+
+static int bd79124_read_event_config(struct iio_dev *iio_dev,
+				     const struct iio_chan_spec *chan,
+				     enum iio_event_type type,
+				     enum iio_event_direction dir)
+{
+	struct bd79124_data *data = iio_priv(iio_dev);
+
+	if (chan->channel >= BD79124_MAX_NUM_CHANNELS)
+		return -EINVAL;
+
+	return (data->alarm_monitored[chan->channel] & BIT(dir));
+}
+
+static int bd79124_disable_event(struct bd79124_data *data,
+			enum iio_event_direction dir, int channel)
+{
+	int dir_bit = BIT(dir), reg;
+	unsigned int limit;
+
+	guard(mutex)(&data->mutex);
+	/*
+	 * Set thresholds either to 0 or to 2^12 - 1 as appropriate to prevent
+	 * alerts and thus disable event generation.
+	 */
+	if (dir == IIO_EV_DIR_RISING) {
+		reg = BD79124_GET_HIGH_LIMIT_REG(channel);
+		limit = BD79124_HIGH_LIMIT_MAX;
+	} else if (dir == IIO_EV_DIR_FALLING) {
+		reg = BD79124_GET_LOW_LIMIT_REG(channel);
+		limit = BD79124_LOW_LIMIT_MIN;
+	} else {
+		return -EINVAL;
+	}
+
+	data->alarm_monitored[channel] &= ~dir_bit;
+	/*
+	 * Stop measurement if there is no more events to monitor.
+	 * We don't bother checking the retval because the limit
+	 * setting should in any case effectively disable the alarm.
+	 */
+	if (!data->alarm_monitored[channel]) {
+		bd79124_stop_measurement(data, channel);
+		regmap_clear_bits(data->map, BD79124_REG_ALERT_CH_SEL,
+			       BIT(channel));
+	}
+
+	return bd79124_write_int_to_reg(data, reg, limit);
+}
+
+static int bd79124_enable_event(struct bd79124_data *data,
+		enum iio_event_direction dir, unsigned int channel)
+{
+	int dir_bit = BIT(dir);
+	int reg;
+	u16 *limit;
+	int ret;
+
+	guard(mutex)(&data->mutex);
+	/* Set channel to be measured */
+	ret = bd79124_start_measurement(data, channel);
+	if (ret)
+		return ret;
+
+	data->alarm_monitored[channel] |= dir_bit;
+
+	/* Add the channel to the list of monitored channels */
+	ret = regmap_set_bits(data->map, BD79124_REG_ALERT_CH_SEL,
+			      BIT(channel));
+	if (ret)
+		return ret;
+
+	if (dir == IIO_EV_DIR_RISING) {
+		limit = &data->alarm_f_limit[channel];
+		reg = BD79124_GET_HIGH_LIMIT_REG(channel);
+	} else {
+		limit = &data->alarm_f_limit[channel];
+		reg = BD79124_GET_LOW_LIMIT_REG(channel);
+	}
+	/*
+	 * Don't write the new limit to the hardware if we are in the
+	 * rate-limit period. The timer which re-enables the event will set
+	 * the limit.
+	 */
+	if (!(data->alarm_suppressed[channel] & dir_bit)) {
+		ret = bd79124_write_int_to_reg(data, reg, *limit);
+		if (ret)
+			return ret;
+	}
+
+	/*
+	 * Enable comparator. Trust the regmap cache, no need to check
+	 * if it was already enabled.
+	 *
+	 * We could do this in the hw-init, but there may be users who
+	 * never enable alarms and for them it makes sense to not
+	 * enable the comparator at probe.
+	 */
+	return regmap_set_bits(data->map, BD79124_REG_GEN_CFG,
+				      BD79124_MASK_DWC_EN);
+
+}
+
+static int bd79124_write_event_config(struct iio_dev *iio_dev,
+				      const struct iio_chan_spec *chan,
+				      enum iio_event_type type,
+				      enum iio_event_direction dir, bool state)
+{
+	struct bd79124_data *data = iio_priv(iio_dev);
+
+	if (chan->channel >= BD79124_MAX_NUM_CHANNELS)
+		return -EINVAL;
+
+	if (state)
+		return bd79124_enable_event(data, dir, chan->channel);
+
+	return bd79124_disable_event(data, dir, chan->channel);
+}
+
+static int bd79124_write_event_value(struct iio_dev *iio_dev,
+				     const struct iio_chan_spec *chan,
+				     enum iio_event_type type,
+				     enum iio_event_direction dir,
+				     enum iio_event_info info, int val,
+				     int val2)
+{
+	struct bd79124_data *data = iio_priv(iio_dev);
+	int reg;
+
+	if (chan->channel >= BD79124_MAX_NUM_CHANNELS)
+		return -EINVAL;
+
+	switch (info) {
+	case IIO_EV_INFO_VALUE:
+		if (dir == IIO_EV_DIR_RISING) {
+			guard(mutex)(&data->mutex);
+
+			data->alarm_r_limit[chan->channel] = val;
+			reg = BD79124_GET_HIGH_LIMIT_REG(chan->channel);
+		} else if (dir == IIO_EV_DIR_FALLING) {
+			guard(mutex)(&data->mutex);
+
+			data->alarm_f_limit[chan->channel] = val;
+			reg = BD79124_GET_LOW_LIMIT_REG(chan->channel);
+		} else {
+			return -EINVAL;
+		}
+		/*
+		 * We don't want to enable the alarm if it is not enabled or
+		 * if it is suppressed. In that case skip writing to the
+		 * register.
+		 */
+		if (!(data->alarm_monitored[chan->channel] & BIT(dir)) ||
+		    data->alarm_suppressed[chan->channel] & BIT(dir))
+			return 0;
+
+		return bd79124_write_int_to_reg(data, reg, val);
+
+	case IIO_EV_INFO_HYSTERESIS:
+		reg = BD79124_GET_HYSTERESIS_REG(chan->channel);
+		val >>= 3;
+
+		return regmap_update_bits(data->map, reg, BD79124_MASK_HYSTERESIS,
+					  val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int bd79124_single_chan_seq(struct bd79124_data *data, int chan, int *old)
+{
+	int ret;
+
+	ret = regmap_clear_bits(data->map, BD79124_REG_SEQUENCE_CFG,
+				BD79124_MASK_SEQ_START);
+	if (ret)
+		return ret;
+
+	/*
+	 * It may be we have some channels monitored for alarms so we want to
+	 * cache the old config and return it when the single channel
+	 * measurement has been completed.
+	 */
+	ret = regmap_read(data->map, BD79124_REG_AUTO_CHANNELS, old);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(data->map, BD79124_REG_AUTO_CHANNELS, BIT(chan));
+	if (ret)
+		return ret;
+
+	/* Restart the sequencer */
+	return regmap_set_bits(data->map, BD79124_REG_SEQUENCE_CFG,
+			      BD79124_MASK_SEQ_START);
+}
+
+static int bd79124_single_chan_seq_end(struct bd79124_data *data, int old)
+{
+	int ret;
+
+	ret = regmap_clear_bits(data->map, BD79124_REG_SEQUENCE_CFG,
+				BD79124_MASK_SEQ_START);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(data->map, BD79124_REG_AUTO_CHANNELS, old);
+	if (ret)
+		return ret;
+
+	return regmap_set_bits(data->map, BD79124_REG_SEQUENCE_CFG,
+			      BD79124_MASK_SEQ_START);
+}
+
+static int bd79124_read_raw(struct iio_dev *iio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long m)
+{
+	struct bd79124_data *data = iio_priv(iio_dev);
+	int ret;
+
+	if (chan->channel >= BD79124_MAX_NUM_CHANNELS)
+		return -EINVAL;
+
+	switch (m) {
+	case IIO_CHAN_INFO_RAW:
+	{
+		int old_chan_cfg, tmp;
+		int regval;
+
+		guard(mutex)(&data->mutex);
+
+		/*
+		 * Start the automatic conversion. This is needed here if no
+		 * events have been enabled.
+		 */
+		regval = FIELD_PREP(BD79124_MASK_CONV_MODE,
+				    BD79124_CONV_MODE_AUTO);
+		ret = regmap_update_bits(data->map, BD79124_REG_OPMODE_CFG,
+					 BD79124_MASK_CONV_MODE, regval);
+		if (ret)
+			return ret;
+
+		ret = bd79124_single_chan_seq(data, chan->channel, &old_chan_cfg);
+		if (ret)
+			return ret;
+
+		/* The maximum conversion time is 6 uS. */
+		udelay(6);
+
+		ret = bd79124_read_reg_to_int(data,
+				BD79124_GET_RECENT_RES_REG(chan->channel),
+				val);
+		/*
+		 * Return the old chan config even if data reading failed in
+		 * order to re-enable the event monitoring.
+		 */
+		tmp = bd79124_single_chan_seq_end(data, old_chan_cfg);
+		if (tmp)
+			dev_err(data->dev,
+				"Failed to return config. Alarms may be disabled\n");
+
+		if (ret)
+			return ret;
+
+		return IIO_VAL_INT;
+	}
+	case IIO_CHAN_INFO_SCALE:
+		*val = data->vmax / 1000;
+		*val2 = BD79124_ADC_BITS;
+		return IIO_VAL_FRACTIONAL_LOG2;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info bd79124_info = {
+	.read_raw = bd79124_read_raw,
+	.read_event_config = &bd79124_read_event_config,
+	.write_event_config = &bd79124_write_event_config,
+	.read_event_value = &bd79124_read_event_value,
+	.write_event_value = &bd79124_write_event_value,
+};
+
+static void bd79124_re_enable_lo(struct bd79124_data *data, unsigned int channel)
+{
+	int ret, evbit = BIT(IIO_EV_DIR_FALLING);
+
+	/*
+	 * We should not re-enable the event if user has disabled it while
+	 * rate-limiting was enabled.
+	 */
+	if (!(data->alarm_suppressed[channel] & evbit))
+		return;
+
+	data->alarm_suppressed[channel] &= ~evbit;
+
+	if (!(data->alarm_monitored[channel] & evbit))
+		return;
+
+	ret = bd79124_write_int_to_reg(data, BD79124_GET_LOW_LIMIT_REG(channel),
+				       data->alarm_f_limit[channel]);
+	if (ret)
+		dev_warn(data->dev, "Low limit enabling failed for channel%d\n",
+			 channel);
+}
+
+static void bd79124_re_enable_hi(struct bd79124_data *data, unsigned int channel)
+{
+	int ret, evbit = BIT(IIO_EV_DIR_RISING);
+
+	/*
+	 * We should not re-enable the event if user has disabled it while
+	 * rate-limiting was enabled.
+	 */
+	if (!(data->alarm_suppressed[channel] & evbit))
+		return;
+
+	data->alarm_suppressed[channel] &= ~evbit;
+
+	if (!(data->alarm_monitored[channel] & evbit))
+		return;
+
+	ret = bd79124_write_int_to_reg(data, BD79124_GET_HIGH_LIMIT_REG(channel),
+				       data->alarm_r_limit[channel]);
+	if (ret)
+		dev_warn(data->dev, "High limit enabling failed for channel%d\n",
+			 channel);
+}
+
+static void bd79124_alm_enable_worker(struct work_struct *work)
+{
+	int i;
+	struct bd79124_data *data = container_of(work, struct bd79124_data,
+						 alm_enable_work.work);
+
+	/* Take the mutex so there is no race with user disabling the alarm */
+	guard(mutex)(&data->mutex);
+	for (i = 0; i < BD79124_MAX_NUM_CHANNELS; i++) {
+		bd79124_re_enable_hi(data, i);
+		bd79124_re_enable_lo(data, i);
+	}
+}
+
+static int __bd79124_event_ratelimit(struct bd79124_data *data, int reg,
+				     unsigned int limit)
+{
+	int ret;
+
+	if (limit > BD79124_HIGH_LIMIT_MAX)
+		return -EINVAL;
+
+	ret = bd79124_write_int_to_reg(data, reg, limit);
+	if (ret)
+		return ret;
+
+	/*
+	 * We use 1 sec 'grace period'. At the moment I see no reason to make
+	 * this user configurable. We need an ABI for this if configuration is
+	 * needed.
+	 */
+	schedule_delayed_work(&data->alm_enable_work,
+			      msecs_to_jiffies(1000));
+
+	return 0;
+}
+
+static int bd79124_event_ratelimit_hi(struct bd79124_data *data,
+				      unsigned int channel)
+{
+	guard(mutex)(&data->mutex);
+	data->alarm_suppressed[channel] |= BIT(IIO_EV_DIR_RISING);
+
+	return __bd79124_event_ratelimit(data,
+					 BD79124_GET_HIGH_LIMIT_REG(channel),
+					 BD79124_HIGH_LIMIT_MAX);
+}
+
+static int bd79124_event_ratelimit_lo(struct bd79124_data *data,
+				      unsigned int channel)
+{
+	guard(mutex)(&data->mutex);
+	data->alarm_suppressed[channel] |= BIT(IIO_EV_DIR_FALLING);
+
+	return __bd79124_event_ratelimit(data,
+					 BD79124_GET_LOW_LIMIT_REG(channel),
+					 BD79124_LOW_LIMIT_MIN);
+}
+
+static irqreturn_t bd79124_event_handler(int irq, void *priv)
+{
+	int ret, i_hi, i_lo, i;
+	struct iio_dev *iio_dev = priv;
+	struct bd79124_data *data = iio_priv(iio_dev);
+
+	/*
+	 * Return IRQ_NONE if bailing-out without acking. This allows the IRQ
+	 * subsystem to disable the offending IRQ line if we get a hardware
+	 * problem. This behaviour has saved my poor bottom a few times in the
+	 * past as, instead of getting unusably unresponsive, the system has
+	 * spilled out the magic words "...nobody cared".
+	 */
+	ret = regmap_read(data->map, BD79124_REG_EVENT_FLAG_HI, &i_hi);
+	if (ret)
+		return IRQ_NONE;
+
+	ret = regmap_read(data->map, BD79124_REG_EVENT_FLAG_LO, &i_lo);
+	if (ret)
+		return IRQ_NONE;
+
+	if (!i_lo && !i_hi)
+		return IRQ_NONE;
+
+	for (i = 0; i < BD79124_MAX_NUM_CHANNELS; i++) {
+		u64 ecode;
+
+		if (BIT(i) & i_hi) {
+			ecode = IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE, i,
+						     IIO_EV_TYPE_THRESH,
+						     IIO_EV_DIR_RISING);
+
+			iio_push_event(iio_dev, ecode, data->timestamp);
+			/*
+			 * The BD79124 keeps the IRQ asserted for as long as
+			 * the voltage exceeds the threshold. It causes the IRQ
+			 * to keep firing.
+			 *
+			 * Disable the event for the channel and schedule the
+			 * re-enabling the event later to prevent storm of
+			 * events.
+			 */
+			ret = bd79124_event_ratelimit_hi(data, i);
+			if (ret)
+				return IRQ_NONE;
+		}
+		if (BIT(i) & i_lo) {
+			ecode = IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE, i,
+						     IIO_EV_TYPE_THRESH,
+						     IIO_EV_DIR_FALLING);
+
+			iio_push_event(iio_dev, ecode, data->timestamp);
+			ret = bd79124_event_ratelimit_lo(data, i);
+			if (ret)
+				return IRQ_NONE;
+		}
+	}
+
+	ret = regmap_write(data->map, BD79124_REG_EVENT_FLAG_HI, i_hi);
+	if (ret)
+		return IRQ_NONE;
+
+	ret = regmap_write(data->map, BD79124_REG_EVENT_FLAG_LO, i_lo);
+	if (ret)
+		return IRQ_NONE;
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t bd79124_irq_handler(int irq, void *priv)
+{
+	struct iio_dev *iio_dev = priv;
+	struct bd79124_data *data = iio_priv(iio_dev);
+
+	data->timestamp = iio_get_time_ns(iio_dev);
+
+	return IRQ_WAKE_THREAD;
+}
+
+static int bd79124_chan_init(struct bd79124_data *data, int channel)
+{
+	int ret;
+
+	ret = regmap_write(data->map, BD79124_GET_HIGH_LIMIT_REG(channel), 4095);
+	if (ret)
+		return ret;
+
+	return regmap_write(data->map, BD79124_GET_LOW_LIMIT_REG(channel), 0);
+}
+
+static int bd79124_get_gpio_pins(const struct iio_chan_spec *cs, int num_channels)
+{
+	int i, gpio_channels;
+
+	/*
+	 * Let's initialize the mux config to say that all 8 channels are
+	 * GPIOs. Then we can just loop through the iio_chan_spec and clear the
+	 * bits for found ADC channels.
+	 */
+	gpio_channels = GENMASK(7, 0);
+	for (i = 0; i < num_channels; i++)
+		gpio_channels &= ~BIT(cs[i].channel);
+
+	return gpio_channels;
+}
+
+static int bd79124_hw_init(struct bd79124_data *data, int gpio_pins)
+{
+	int ret, regval, i;
+
+	ret = regmap_write(data->map, BD79124_REG_PINCFG, gpio_pins);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < BD79124_MAX_NUM_CHANNELS; i++) {
+		ret = bd79124_chan_init(data, i);
+		if (ret)
+			return ret;
+		data->alarm_r_limit[i] = 4095;
+	}
+	/* Stop auto sequencer */
+	ret = regmap_clear_bits(data->map, BD79124_REG_SEQUENCE_CFG,
+				BD79124_MASK_SEQ_START);
+	if (ret)
+		return ret;
+
+	/* Enable writing the measured values to the regsters */
+	ret = regmap_set_bits(data->map, BD79124_REG_GEN_CFG,
+			      BD79124_MASK_STATS_EN);
+	if (ret)
+		return ret;
+
+	/* Set no channels to be auto-measured */
+	ret = regmap_write(data->map, BD79124_REG_AUTO_CHANNELS, 0x0);
+	if (ret)
+		return ret;
+
+	/* Set no channels to be manually measured */
+	ret = regmap_write(data->map, BD79124_REG_MANUAL_CHANNELS, 0x0);
+	if (ret)
+		return ret;
+
+	regval = FIELD_PREP(BD79124_MASK_AUTO_INTERVAL, BD79124_INTERVAL_750_US);
+	ret = regmap_update_bits(data->map, BD79124_REG_OPMODE_CFG,
+				 BD79124_MASK_AUTO_INTERVAL, regval);
+	if (ret)
+		return ret;
+
+	/* Sequencer mode to auto */
+	ret = regmap_set_bits(data->map, BD79124_REG_SEQUENCE_CFG,
+			      BD79124_MASK_SEQ_SEQ);
+	if (ret)
+		return ret;
+
+	/* Don't start the measurement */
+	regval = FIELD_PREP(BD79124_MASK_CONV_MODE, BD79124_CONV_MODE_MANSEQ);
+	return regmap_update_bits(data->map, BD79124_REG_OPMODE_CFG,
+				  BD79124_MASK_CONV_MODE, regval);
+
+}
+
+static int bd79124_probe(struct i2c_client *i2c)
+{
+	struct bd79124_data *data;
+	struct iio_dev *iio_dev;
+	const struct iio_chan_spec *template;
+	struct iio_chan_spec *cs;
+	struct device *dev = &i2c->dev;
+	int gpio_pins, ret;
+
+	iio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!iio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(iio_dev);
+	data->dev = dev;
+	data->map = devm_regmap_init_i2c(i2c, &bd79124_regmap);
+	if (IS_ERR(data->map))
+		return dev_err_probe(dev, PTR_ERR(data->map),
+				     "Failed to initialize Regmap\n");
+
+	ret = devm_regulator_get_enable_read_voltage(dev, "vdd");
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to get the Vdd\n");
+
+	data->vmax = ret;
+
+	ret = devm_regulator_get_enable(dev, "iovdd");
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to enable I/O voltage\n");
+
+	ret = devm_delayed_work_autocancel(dev, &data->alm_enable_work,
+					   bd79124_alm_enable_worker);
+	if (ret)
+		return ret;
+
+	if (i2c->irq) {
+		template = &bd79124_chan_template;
+	} else {
+		template = &bd79124_chan_template_noirq;
+		dev_dbg(dev, "No IRQ found, events disabled\n");
+	}
+	ret = devm_iio_adc_device_alloc_chaninfo_se(dev, template,
+					BD79124_MAX_NUM_CHANNELS - 1, &cs);
+	if (ret < 0)
+		return ret;
+
+	iio_dev->channels = cs;
+	iio_dev->num_channels = ret;
+	iio_dev->info = &bd79124_info;
+	iio_dev->name = "bd79124";
+	iio_dev->modes = INDIO_DIRECT_MODE;
+
+	gpio_pins = bd79124_get_gpio_pins(iio_dev->channels,
+					  iio_dev->num_channels);
+	ret = bd79124_hw_init(data, gpio_pins);
+	if (ret)
+		return ret;
+
+	data->gpio_valid_mask = gpio_pins;
+	data->gc = bd79124gpo_chip;
+	data->gc.parent = dev;
+	devm_mutex_init(dev, &data->mutex);
+
+	ret = devm_gpiochip_add_data(dev, &data->gc, data);
+	if (ret)
+		return dev_err_probe(dev, ret, "gpio init Failed\n");
+
+	if (i2c->irq > 0) {
+		ret = devm_request_threaded_irq(dev, i2c->irq,
+				bd79124_irq_handler, &bd79124_event_handler,
+				IRQF_ONESHOT, "adc-thresh-alert", iio_dev);
+		if (ret)
+			return dev_err_probe(data->dev, ret,
+					     "Failed to register IRQ\n");
+	}
+
+	return devm_iio_device_register(data->dev, iio_dev);
+}
+
+static const struct of_device_id bd79124_of_match[] = {
+	{ .compatible = "rohm,bd79124" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, bd79124_of_match);
+
+static const struct i2c_device_id bd79124_id[] = {
+	{ "bd79124", },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, bd79124_id);
+
+static struct i2c_driver bd79124_driver = {
+	.driver = {
+		.name = "bd79124",
+		.of_match_table = bd79124_of_match,
+	},
+	.probe = bd79124_probe,
+	.id_table = bd79124_id,
+};
+module_i2c_driver(bd79124_driver);
+
+MODULE_AUTHOR("Matti Vaittinen <mazziesaccount@gmail.com>");
+MODULE_DESCRIPTION("Driver for ROHM BD79124 ADC");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_DRIVER");
-- 
2.48.1


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH v5 08/10] MAINTAINERS: Add IIO ADC helpers

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 782 bytes --]

Add undersigned as a maintainer for the IIO ADC helpers.

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


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH v5 09/10] MAINTAINERS: Add ROHM BD79124 ADC/GPO

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 767 bytes --]

Add undersigned as a maintainer for the ROHM BD79124 ADC/GPO driver.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
---
Revision history:
RFC v1 => v2:
 - Drop MFD and pinmux drivers
---
 MAINTAINERS | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 5b96fb864227..2e4416b59930 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -20547,6 +20547,11 @@ S:	Supported
 F:	drivers/power/supply/bd99954-charger.c
 F:	drivers/power/supply/bd99954-charger.h
 
+ROHM BD79124 ADC / GPO IC
+M:	Matti Vaittinen <mazziesaccount@gmail.com>
+S:	Supported
+F:	drivers/iio/adc/rohm-bd79124.c
+
 ROHM BH1745 COLOUR SENSOR
 M:	Mudit Sharma <muditsharma.info@gmail.com>
 L:	linux-iio@vger.kernel.org
-- 
2.48.1


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH RFC net-next v5 10/10] net: gianfar: Use device_get_child_node_count_named()

[Matti Vaittinen]

[-- Attachment #1: Type: text/plain, Size: 2231 bytes --]

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>
---
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 count named child nodes"

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..dfe012a5bc0a 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_child_node_count_named(&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


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: [PATCH v5 02/10] property: Add functions to count named child nodes

[Heikki Krogerus]

Hi,

> +/**
> + * fwnode_get_child_node_count_named - 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_child_node_count_named(const struct fwnode_handle *fwnode,
> +					       const char *name)
> +{
> +	struct fwnode_handle *child;
> +	unsigned int count = 0;
> +
> +	fwnode_for_each_child_node(fwnode, child)
> +		if (fwnode_name_eq(child, name))
> +			count++;
> +
> +	return count;
> +}
> +EXPORT_SYMBOL_GPL(fwnode_get_child_node_count_named);
> +
> +/**
> + * device_get_child_node_count_named - 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_child_node_count_named(const struct device *dev,
> +					       const char *name)
> +{
> +	const struct fwnode_handle *fwnode = dev_fwnode(dev);
> +
> +	if (!fwnode)
> +		return -EINVAL;
> +
> +	if (IS_ERR(fwnode))
> +		return PTR_ERR(fwnode);
> +
> +	return fwnode_get_child_node_count_named(fwnode, name);
> +}
> +EXPORT_SYMBOL_GPL(device_get_child_node_count_named);

Sorry if I missed something in the v4 thread, but why not do all the
checks in fwnode_get_child_node_count_named(), and make this an inline
function?

        static inline unsigned int
        device_get_child_node_count_named(const struct device *dev, const char *name)
        {
                return fwnode_get_child_node_count_named(dev_fwnode(fwnode), name);
        }

thanks,

-- 
heikki

Re: [PATCH RFC net-next v5 10/10] net: gianfar: Use device_get_child_node_count_named()

[Andy Shevchenko]

On Mon, Mar 03, 2025 at 01:34:49PM +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().

...

> 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.

I think it's a good step to the right direction. We might convert the rest
(at least I don't see much impediments while briefly looking into the code).

...

What about the second loop (in gfar_of_init)?
I mean perhaps we want to have fwnode_for_each_named_child_node()
and its device variant that may be also reused in the IIO code and here.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v5 02/10] property: Add functions to count named child nodes

[Andy Shevchenko]

On Mon, Mar 03, 2025 at 01:31:45PM +0200, Matti Vaittinen wrote:
> There are some use-cases where child nodes with a specific name need to
> be parsed. In a few cases the data from the found nodes is 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 counting device's sub-nodes with certain name instead
> of open-coding this in every user.

...

> +unsigned int fwnode_get_child_node_count_named(const struct fwnode_handle *fwnode,
> +					       const char *name)
> +{
> +	struct fwnode_handle *child;
> +	unsigned int count = 0;

> +	fwnode_for_each_child_node(fwnode, child)
> +		if (fwnode_name_eq(child, name))

I would expect this to be a separate macro

	fwnode_for_each_named_child_node()

(and its device variant) that gives us more consistent approach.

> +			count++;

And the above looks like missing {}, which won't be needed with the other
suggestion in place.

> +	return count;
> +}

> +	if (!fwnode)
> +		return -EINVAL;
> +
> +	if (IS_ERR(fwnode))
> +		return PTR_ERR(fwnode);

I expect that this will return 0 or number of nodes. Why do we need an error code?
If it's really required, it should be in the fwnode API above.

Also do we care about secondary fwnodes?

> +	return fwnode_get_child_node_count_named(fwnode, name);
> +}

...

> +unsigned int fwnode_get_child_node_count_named(const struct fwnode_handle *fwnode,
> +					       const char *name);

To me the following name sounds better: fwnode_get_named_child_node_count().

> +unsigned int device_get_child_node_count_named(const struct device *dev,
> +					       const char *name);

In the similar way.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v5 02/10] property: Add functions to count named child nodes

[Andy Shevchenko]

On Mon, Mar 03, 2025 at 01:50:13PM +0200, Heikki Krogerus wrote:

...

> > +unsigned int device_get_child_node_count_named(const struct device *dev,
> > +					       const char *name)
> > +{
> > +	const struct fwnode_handle *fwnode = dev_fwnode(dev);
> > +
> > +	if (!fwnode)
> > +		return -EINVAL;
> > +
> > +	if (IS_ERR(fwnode))
> > +		return PTR_ERR(fwnode);
> > +
> > +	return fwnode_get_child_node_count_named(fwnode, name);
> > +}
> > +EXPORT_SYMBOL_GPL(device_get_child_node_count_named);
> 
> Sorry if I missed something in the v4 thread, but why not do all the
> checks in fwnode_get_child_node_count_named(), and make this an inline
> function?

+1, or drop the checks and make it return 0 depending on the follow up use cases.

>         static inline unsigned int
>         device_get_child_node_count_named(const struct device *dev, const char *name)
>         {
>                 return fwnode_get_child_node_count_named(dev_fwnode(fwnode), name);
>         }

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH RFC net-next v5 10/10] net: gianfar: Use device_get_child_node_count_named()

[Matti Vaittinen]

On 03/03/2025 13:51, Andy Shevchenko wrote:
> On Mon, Mar 03, 2025 at 01:34:49PM +0200, Matti Vaittinen wrote:

> 
> What about the second loop (in gfar_of_init)?
> I mean perhaps we want to have fwnode_for_each_named_child_node()
> and its device variant that may be also reused in the IIO code and here.
> 

I agree the fwnode_for_each_named_child_node() would be useful. I think 
I said that already during the previous review rounds. There is plenty 
of code which could be converted to use it.

This, however, is far more than I am willing to do in the context of a 
simple IIO driver addition. The "BD79124 ADC suupport" is already now 10 
patches, 2 of which are directly related to it.

I propose adding the for_each_named_child_node() as a separate series 
with bunch of users appended. That's be plenty of beans to count for 
those who like following the statistics :)

Yours,
	-- Matti

Re: [PATCH RFC net-next v5 10/10] net: gianfar: Use device_get_child_node_count_named()

[Andy Shevchenko]

On Mon, Mar 03, 2025 at 02:13:30PM +0200, Matti Vaittinen wrote:
> On 03/03/2025 13:51, Andy Shevchenko wrote:
> > On Mon, Mar 03, 2025 at 01:34:49PM +0200, Matti Vaittinen wrote:
> 
> > What about the second loop (in gfar_of_init)?
> > I mean perhaps we want to have fwnode_for_each_named_child_node()
> > and its device variant that may be also reused in the IIO code and here.
> 
> I agree the fwnode_for_each_named_child_node() would be useful. I think I
> said that already during the previous review rounds. There is plenty of code
> which could be converted to use it.


> This, however, is far more than I am willing to do in the context of a
> simple IIO driver addition. The "BD79124 ADC suupport" is already now 10
> patches, 2 of which are directly related to it.

But you already will have at least one user (IIO code) and second as in RFC.
I do not ask you to _add_ patches.

> I propose adding the for_each_named_child_node() as a separate series with
> bunch of users appended. That's be plenty of beans to count for those who
> like following the statistics :)

It would sound like an unneeded churn as we first introduce something that we
already know needs a refactoring.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v5 03/10] iio: adc: add helpers for parsing ADC nodes

[David Lechner]

On Mon, Mar 3, 2025 at 12:32 PM Matti Vaittinen
<mazziesaccount@gmail.com> wrote:
>
> 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:
> 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 | 82 ++++++++++++++++++++++++++++++
>  include/linux/iio/adc-helpers.h    | 27 ++++++++++
>  4 files changed, 114 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..7bdae5330224
> --- /dev/null
> +++ b/drivers/iio/adc/industrialio-adc.c
> @@ -0,0 +1,82 @@
> +// 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 succes. Negative value to indicate

s/succes/success/

> + *             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_child_node_scoped(dev, child) {
> +               u32 ch;
> +
> +               if (!fwnode_name_eq(child, "channel"))
> +                       continue;
> +
> +               ret = fwnode_property_read_u32(child, "reg", &ch);
> +               if (ret)
> +                       return ret;
> +
> +               if (max_chan_id != -1 && ch > max_chan_id)
> +                       return -ERANGE;
> +

Should we use return dev_err_probe() on these to help with debugging a bad dtb?

> +               *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");

We can make this less verbose by setting #define
DEFAULT_SYMBOL_NAMESPACE at the start of the file. Then we can just do
EXPORT_SYMBOL_GPL() throughout the rest of the file.

Also, I would prefer if the namespace matched config name (IIO_ADC_HELPER).

> +
> +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..403a70b109ec
> --- /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_child_node_count_named(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);
> +

There are some different opinions on this, but on the last patch I did
introducing a new namespace, the consensus seems to be that putting
the MODULE_IMPORT_NS() in the header file was convenient so that users
of the API don't have to remember to both include the header and add
the import macro.

> +#endif /* _INDUSTRIAL_IO_ADC_HELPERS_H_ */
> --
> 2.48.1
>

Re: [PATCH v5 03/10] iio: adc: add helpers for parsing ADC nodes

[Andy Shevchenko]

On Tue, Mar 04, 2025 at 10:25:03AM +0100, David Lechner wrote:
> On Mon, Mar 3, 2025 at 12:32 PM Matti Vaittinen
> <mazziesaccount@gmail.com> wrote:

...

> There are some different opinions on this, but on the last patch I did
> introducing a new namespace,

> the consensus

Hmm... I may not call that "the consensus"...

> seems to be that putting
> the MODULE_IMPORT_NS() in the header file was convenient so that users
> of the API don't have to remember to both include the header and add
> the import macro.

Which I am against because it will diminish the point of prevention of
the APIs abuse along with a potential to have the stale headers in
the file when the code is moved somewhere else..

So, please do not do that. We have only two abusers currently:
the PWM and SPI OFFLOAD.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v5 03/10] iio: adc: add helpers for parsing ADC nodes

[Matti Vaittinen]

Thanks for the review David.

On 04/03/2025 11:25, David Lechner wrote:
> On Mon, Mar 3, 2025 at 12:32 PM Matti Vaittinen
> <mazziesaccount@gmail.com> wrote:
>>
>> 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>
>>
>> ---

>> + *
>> + * Return:     Number of found channels on succes. Negative value to indicate
> 
> s/succes/success/

Thanks!

>> +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_child_node_scoped(dev, child) {
>> +               u32 ch;
>> +
>> +               if (!fwnode_name_eq(child, "channel"))
>> +                       continue;
>> +
>> +               ret = fwnode_property_read_u32(child, "reg", &ch);
>> +               if (ret)
>> +                       return ret;
>> +
>> +               if (max_chan_id != -1 && ch > max_chan_id)
>> +                       return -ERANGE;
>> +
> 
> Should we use return dev_err_probe() on these to help with debugging a bad dtb?
> 

I am not fan of using dev_err_probe() in a 'library code'. This is 
because we never know if there'll be some odd use-case where this is not 
called from the probe.

All in all, I'd leave adding most of the debugs to the callers - 
especially because we do not expect to have bad device-trees after the 
initial 'development stage' of a board. The board 'development stage' 
should really reveal bugs which prevent the channels from being 
registered - and after the DT is correct, these debug prints become 
unnecessary (albeit minor) binary bloat.

>> +               *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");
> 
> We can make this less verbose by setting #define
> DEFAULT_SYMBOL_NAMESPACE at the start of the file. Then we can just do
> EXPORT_SYMBOL_GPL() throughout the rest of the file.

I am not sure what to think of this. I use the good old 'ctrl + ]' in my 
editor when I need to check how a function was supposed to be used. That 
jumps to the spot of code where the function is. I'd like to see the 
namespace mentioned there in order to not accidentally miss the fact the 
function belongs to one.

OTOH, I do like simplifications. Yet, the added simplification might not 
warrant the namespace not being visible in the function definition.

> Also, I would prefer if the namespace matched config name (IIO_ADC_HELPER).

I had some lengthy discussion about this with Andy and Jonathan during 
earlier review versions. In short, I don't like the idea of very 
fragmented namespaces in IIO, which will just complicate the drivers 
without providing any obvious benefit.

https://lore.kernel.org/all/20250222174842.57c091c5@jic23-huawei/

>> +
>> +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);
>> +
> 
> There are some different opinions on this, but on the last patch I did
> introducing a new namespace, the consensus seems to be that putting
> the MODULE_IMPORT_NS() in the header file was convenient so that users
> of the API don't have to remember to both include the header and add
> the import macro.
> 

I do like this suggestion, and I believe this would be the balance 
between getting the benefit of hiding part of the symbols - while not 
unnecessarily complicating the callers. I know some people are opposing 
it though. My personal opinion is that having the MODULE_IMPORT_NS() in 
a header would be neatly simplifying the calling code with very little 
harm, especially here where including the header hardly has use-cases 
outside the IIO ADC.

Unfortunately, the "safety" seems to often be a synonym for just "making 
it intentionally hard". As Finnish people say: "Kärsi, kärsi, 
kirkkaamman kruunun saat". :)
(Roughly translated as "Suffer, suffer, you will get a brighter crown").

Let's hear what Jonathan thinks of your suggestion.

Thanks!
	-- Matti

Re: [PATCH v5 03/10] iio: adc: add helpers for parsing ADC nodes

[Jonathan Cameron]

On Wed, 5 Mar 2025 12:54:33 +0200
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> Thanks for the review David.
> 
> On 04/03/2025 11:25, David Lechner wrote:
> > On Mon, Mar 3, 2025 at 12:32 PM Matti Vaittinen
> > <mazziesaccount@gmail.com> wrote:  
> >>
> >> 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>
> >>
> >> ---  
> 
> >> + *
> >> + * Return:     Number of found channels on succes. Negative value to indicate  
> > 
> > s/succes/success/  
> 
> Thanks!
> 
> >> +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_child_node_scoped(dev, child) {
> >> +               u32 ch;
> >> +
> >> +               if (!fwnode_name_eq(child, "channel"))
> >> +                       continue;
> >> +
> >> +               ret = fwnode_property_read_u32(child, "reg", &ch);
> >> +               if (ret)
> >> +                       return ret;
> >> +
> >> +               if (max_chan_id != -1 && ch > max_chan_id)
> >> +                       return -ERANGE;
> >> +  
> > 
> > Should we use return dev_err_probe() on these to help with debugging a bad dtb?
> >   
> 
> I am not fan of using dev_err_probe() in a 'library code'. This is 
> because we never know if there'll be some odd use-case where this is not 
> called from the probe.
> 
> All in all, I'd leave adding most of the debugs to the callers - 
> especially because we do not expect to have bad device-trees after the 
> initial 'development stage' of a board. The board 'development stage' 
> should really reveal bugs which prevent the channels from being 
> registered - and after the DT is correct, these debug prints become 
> unnecessary (albeit minor) binary bloat.
> 
> >> +               *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");  
> > 
> > We can make this less verbose by setting #define
> > DEFAULT_SYMBOL_NAMESPACE at the start of the file. Then we can just do
> > EXPORT_SYMBOL_GPL() throughout the rest of the file.  
> 
> I am not sure what to think of this. I use the good old 'ctrl + ]' in my 
> editor when I need to check how a function was supposed to be used. That 
> jumps to the spot of code where the function is. I'd like to see the 
> namespace mentioned there in order to not accidentally miss the fact the 
> function belongs to one.
> 
> OTOH, I do like simplifications. Yet, the added simplification might not 
> warrant the namespace not being visible in the function definition.
> 
> > Also, I would prefer if the namespace matched config name (IIO_ADC_HELPER).  
> 
> I had some lengthy discussion about this with Andy and Jonathan during 
> earlier review versions. In short, I don't like the idea of very 
> fragmented namespaces in IIO, which will just complicate the drivers 
> without providing any obvious benefit.
> 
> https://lore.kernel.org/all/20250222174842.57c091c5@jic23-huawei/
> 
> >> +
> >> +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);
> >> +  
> > 
> > There are some different opinions on this, but on the last patch I did
> > introducing a new namespace, the consensus seems to be that putting
> > the MODULE_IMPORT_NS() in the header file was convenient so that users
> > of the API don't have to remember to both include the header and add
> > the import macro.
> >   
> 
> I do like this suggestion, and I believe this would be the balance 
> between getting the benefit of hiding part of the symbols - while not 
> unnecessarily complicating the callers. I know some people are opposing 
> it though. My personal opinion is that having the MODULE_IMPORT_NS() in 
> a header would be neatly simplifying the calling code with very little 
> harm, especially here where including the header hardly has use-cases 
> outside the IIO ADC.
> 
> Unfortunately, the "safety" seems to often be a synonym for just "making 
> it intentionally hard". As Finnish people say: "Kärsi, kärsi, 
> kirkkaamman kruunun saat". :)
> (Roughly translated as "Suffer, suffer, you will get a brighter crown").
> 
> Let's hear what Jonathan thinks of your suggestion.

For this particular case my intent was that all the IIO exports that
are suitable for use in simple IIO drives will be in this namespace,
we just haven't started that conversion yet.

As such, having it defined from a header for this helper isn't a good
thing to do.  Generally I prefer to see in driver code what namespaces
are involved but do understand the other viewpoint. In this case I
definitely don't think it is appropriate unless we go for a specific namespace
for just this helper.

Jonathan

> 
> Thanks!
> 	-- Matti
> 

Re: [PATCH v5 04/10] iio: adc: rzg2l_adc: Use adc-helpers

[Jonathan Cameron]

On Mon, 3 Mar 2025 13:32:29 +0200
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> The new devm_iio_adc_device_alloc_chaninfo() -helper is intended to help
> drivers avoid open-coding the for_each_node -loop for getting the
> channel IDs. The helper provides standard way to detect the ADC channel
> nodes (by the node name), and a standard way to convert the "reg"
> -propereties to channel identification numbers, used in the struct
spell check: properties

> iio_chan_spec. Furthermore, the helper can optionally check the found
> channel IDs are smaller than given maximum. This is useful for callers
> which later use the IDs for example for indexing a channel data array.
> 
> The original driver treated all found child nodes as channel nodes. The
> new helper requires channel nodes to be named channel[@N]. This should
> help avoid problems with devices which may contain also other but ADC
> child nodes. Quick grep from arch/* with the rzg2l_adc's compatible
> string didn't reveal any in-tree .dts with channel nodes named
> otherwise. Also, same grep shows all the .dts seem to have channel IDs
> between 0..num of channels.
> 
> Use the new helper.
> 
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Code looks good to me.

J

Re: [PATCH v5 05/10] iio: adc: sun20i-gpadc: Use adc-helpers

[Jonathan Cameron]

On Mon, 3 Mar 2025 13:33:02 +0200
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> The new devm_iio_adc_device_alloc_chaninfo() -helper is intended to help
> drivers avoid open-coding the for_each_node -loop for getting the
> channel IDs. The helper provides standard way to detect the ADC channel
> nodes (by the node name), and a standard way to convert the "reg"
> -propereties to channel identification numbers, used in the struct

same typo.

> iio_chan_spec. Furthermore, the helper can optionally check the found
> channel IDs are smaller than given maximum. This is useful for callers
> which later use the IDs for example for indexing a channel data array.
> 
> The original driver treated all found child nodes as channel nodes. The
> new helper requires channel nodes to be named channel[@N]. This should
> help avoid problems with devices which may contain also other but ADC
> child nodes. Quick grep from arch/* with the sun20i-gpadc's compatible
> string didn't reveal any in-tree .dts with channel nodes named
> otherwise. Also, same grep shows all the in-tree .dts seem to have
> channel IDs between 0..num of channels.
> 
> Use the new helper.
> 
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> 
Otherwise LGTM

Re: [PATCH v5 06/10] iio: adc: ti-ads7924 Drop unnecessary function parameters

[Jonathan Cameron]

On Mon, 3 Mar 2025 13:33:21 +0200
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> Device pointer is the only variable which is used by the
> ads7924_get_channels_config() and which is declared outside this
> function. Still, the function gets the iio_device and i2c_client as
> parameters. The sole caller of this function (probe) already has the
> device pointer which it can directly pass to the function.
> 
> Simplify code by passing the device pointer directly as a parameter
> instead of digging it from the iio_device's private data.
> 
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Now an unrelated change, so I'll pick this up to avoid confusion in
any future versions.

Applied to the togreg branch of iio.git

Thanks,

Jonathan

> 
> ---
> Revision history:
> v4 => No changes
> 
> This commit is compile-tested only! All further testing is appreciated.
> ---
>  drivers/iio/adc/ti-ads7924.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/iio/adc/ti-ads7924.c b/drivers/iio/adc/ti-ads7924.c
> index 66b54c0d75aa..b1f745f75dbe 100644
> --- a/drivers/iio/adc/ti-ads7924.c
> +++ b/drivers/iio/adc/ti-ads7924.c
> @@ -251,11 +251,8 @@ static const struct iio_info ads7924_info = {
>  	.read_raw = ads7924_read_raw,
>  };
>  
> -static int ads7924_get_channels_config(struct i2c_client *client,
> -				       struct iio_dev *indio_dev)
> +static int ads7924_get_channels_config(struct device *dev)
>  {
> -	struct ads7924_data *priv = iio_priv(indio_dev);
> -	struct device *dev = priv->dev;
>  	struct fwnode_handle *node;
>  	int num_channels = 0;
>  
> @@ -380,7 +377,7 @@ static int ads7924_probe(struct i2c_client *client)
>  	indio_dev->num_channels = ARRAY_SIZE(ads7924_channels);
>  	indio_dev->info = &ads7924_info;
>  
> -	ret = ads7924_get_channels_config(client, indio_dev);
> +	ret = ads7924_get_channels_config(dev);
>  	if (ret < 0)
>  		return dev_err_probe(dev, ret,
>  				     "failed to get channels configuration\n");

Re: [PATCH v5 07/10] iio: adc: Support ROHM BD79124 ADC

[Jonathan Cameron]

On Mon, 3 Mar 2025 13:33:39 +0200
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> 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. The window is configurable for each channel.
> 
> The I2C protocol for manual start of the measurement and data reading is
> somewhat peculiar. It requires the master to do clock stretching after
> sending the I2C slave-address until the slave has captured the data.
> Needless to say this is not well suopported by the I2C controllers.
> 
> Thus the driver does not support the BD79124's manual measurement mode
> but implements the measurements using automatic measurement mode relying
> on the BD79124's ability of storing latest measurements into register.
> 
> The driver does also support configuring the threshold events for
> detecting the out-of-window events.
> 
> The BD79124 keeps asserting IRQ for as long as the measured voltage is
> out of the configured window. Thus the driver masks the received event
> for a fixed duration (1 second) when an event is handled. This prevents
> the user-space from choking on the events
> 
> The ADC input pins can be also configured as general purpose outputs.
> Those pins which don't have corresponding ADC channel node in the
> device-tree will be controllable as GPO.
> 
> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Hi Matti

Just a few really trivial comments.  If all else in the
set was resolved I'd probably have applied with a tweak or two

Thanks,

Jonathan

>  obj-$(CONFIG_SC27XX_ADC) += sc27xx_adc.o
> diff --git a/drivers/iio/adc/rohm-bd79124.c b/drivers/iio/adc/rohm-bd79124.c
> new file mode 100644
> index 000000000000..466c7decf8fc
> --- /dev/null
> +++ b/drivers/iio/adc/rohm-bd79124.c
> @@ -0,0 +1,1108 @@
...

> +
> +/* Read-only regs */

Given naming this is pretty obvious. I would drop the comment
and any others that don't add much meaning.

> +static const struct regmap_range bd79124_ro_ranges[] = {



> +static int bd79124_read_event_value(struct iio_dev *iio_dev,
> +				    const struct iio_chan_spec *chan,
> +				    enum iio_event_type type,
> +				    enum iio_event_direction dir,
> +				    enum iio_event_info info, int *val,
> +				    int *val2)
> +{
> +	struct bd79124_data *data = iio_priv(iio_dev);
> +	int ret, reg;
> +
> +	if (chan->channel >= BD79124_MAX_NUM_CHANNELS)
> +		return -EINVAL;
> +
> +	switch (info) {
> +	case IIO_EV_INFO_VALUE:
> +		if (dir == IIO_EV_DIR_RISING)
> +			*val = data->alarm_r_limit[chan->channel];
> +		else if (dir == IIO_EV_DIR_FALLING)
> +			*val = data->alarm_f_limit[chan->channel];
> +		else
> +			return -EINVAL;
> +
> +		return IIO_VAL_INT;
> +
> +	case IIO_EV_INFO_HYSTERESIS:
> +		reg = BD79124_GET_HYSTERESIS_REG(chan->channel);
> +		ret = regmap_read(data->map, reg, val);
> +		if (ret)
> +			return ret;
> +		/* Mask the non hysteresis bits */
> +		*val &= BD79124_MASK_HYSTERESIS;
> +		/*
> +		 * The data-sheet says the hysteresis register value needs to be
> +		 * sifted left by 3 (or multiplied by 8, depending on the
> +		 * page :] )

We don't really need this comment on the oddity of the way the datasheet
describes things in the final driver as effect is same in either case.
It did make me smile though ;)


> +		 */
> +		*val <<= 3;
> +
> +		return IIO_VAL_INT;
> +	default:
> +		return -EINVAL;
> +	}
> +}

> +
> +static int bd79124_disable_event(struct bd79124_data *data,
> +			enum iio_event_direction dir, int channel)
> +{
> +	int dir_bit = BIT(dir), reg;

I'd rather this one was split as I find it hard to read lines that
mix setting of some variables and not others.

> +	unsigned int limit;
> +
>
> +static int bd79124_enable_event(struct bd79124_data *data,
> +		enum iio_event_direction dir, unsigned int channel)
> +{
> +	int dir_bit = BIT(dir);
> +	int reg;
> +	u16 *limit;
> +	int ret;

Trivial but might as well but ret and reg on same line.


> +
> +}


>

Re: [PATCH v5 02/10] property: Add functions to count named child nodes

[Matti Vaittinen]

On 03/03/2025 13:59, Andy Shevchenko wrote:
> On Mon, Mar 03, 2025 at 01:31:45PM +0200, Matti Vaittinen wrote:

...

> 
>> +	return count;
>> +}
> 
>> +	if (!fwnode)
>> +		return -EINVAL;
>> +
>> +	if (IS_ERR(fwnode))
>> +		return PTR_ERR(fwnode);
> 
> I expect that this will return 0 or number of nodes. Why do we need an error code?
> If it's really required, it should be in the fwnode API above.
> 
> Also do we care about secondary fwnodes?

We have the device_get_child_node_count(). 
device_get_child_node_count_named() should follow the same logic.

> 
>> +	return fwnode_get_child_node_count_named(fwnode, name);
>> +}
> 
> ...
> 
>> +unsigned int fwnode_get_child_node_count_named(const struct fwnode_handle *fwnode,
>> +					       const char *name);
> 
> To me the following name sounds better: fwnode_get_named_child_node_count().

Agree.

> 
>> +unsigned int device_get_child_node_count_named(const struct device *dev,
>> +					       const char *name);
> 
> In the similar way.
> 

Re: [PATCH v5 03/10] iio: adc: add helpers for parsing ADC nodes

[Matti Vaittinen]

On 08/03/2025 18:29, Jonathan Cameron wrote:
> On Wed, 5 Mar 2025 12:54:33 +0200
> Matti Vaittinen <mazziesaccount@gmail.com> wrote:
> 
>> Thanks for the review David.
>>
>> On 04/03/2025 11:25, David Lechner wrote:
>>> On Mon, Mar 3, 2025 at 12:32 PM Matti Vaittinen
>>> <mazziesaccount@gmail.com> wrote:
>>>>
>>>> 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>
>>>>
>>>> ---
>>
>>>> + *
>>>> + * Return:     Number of found channels on succes. Negative value to indicate
>>>
>>> s/succes/success/
>>
>> Thanks!
>>
>>>> +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_child_node_scoped(dev, child) {
>>>> +               u32 ch;
>>>> +
>>>> +               if (!fwnode_name_eq(child, "channel"))
>>>> +                       continue;
>>>> +
>>>> +               ret = fwnode_property_read_u32(child, "reg", &ch);
>>>> +               if (ret)
>>>> +                       return ret;
>>>> +
>>>> +               if (max_chan_id != -1 && ch > max_chan_id)
>>>> +                       return -ERANGE;
>>>> +
>>>
>>> Should we use return dev_err_probe() on these to help with debugging a bad dtb?
>>>    
>>
>> I am not fan of using dev_err_probe() in a 'library code'. This is
>> because we never know if there'll be some odd use-case where this is not
>> called from the probe.
>>
>> All in all, I'd leave adding most of the debugs to the callers -
>> especially because we do not expect to have bad device-trees after the
>> initial 'development stage' of a board. The board 'development stage'
>> should really reveal bugs which prevent the channels from being
>> registered - and after the DT is correct, these debug prints become
>> unnecessary (albeit minor) binary bloat.
>>
>>>> +               *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");
>>>
>>> We can make this less verbose by setting #define
>>> DEFAULT_SYMBOL_NAMESPACE at the start of the file. Then we can just do
>>> EXPORT_SYMBOL_GPL() throughout the rest of the file.
>>
>> I am not sure what to think of this. I use the good old 'ctrl + ]' in my
>> editor when I need to check how a function was supposed to be used. That
>> jumps to the spot of code where the function is. I'd like to see the
>> namespace mentioned there in order to not accidentally miss the fact the
>> function belongs to one.
>>
>> OTOH, I do like simplifications. Yet, the added simplification might not
>> warrant the namespace not being visible in the function definition.
>>
>>> Also, I would prefer if the namespace matched config name (IIO_ADC_HELPER).
>>
>> I had some lengthy discussion about this with Andy and Jonathan during
>> earlier review versions. In short, I don't like the idea of very
>> fragmented namespaces in IIO, which will just complicate the drivers
>> without providing any obvious benefit.
>>
>> https://lore.kernel.org/all/20250222174842.57c091c5@jic23-huawei/
>>
>>>> +
>>>> +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);
>>>> +
>>>
>>> There are some different opinions on this, but on the last patch I did
>>> introducing a new namespace, the consensus seems to be that putting
>>> the MODULE_IMPORT_NS() in the header file was convenient so that users
>>> of the API don't have to remember to both include the header and add
>>> the import macro.
>>>    
>>
>> I do like this suggestion, and I believe this would be the balance
>> between getting the benefit of hiding part of the symbols - while not
>> unnecessarily complicating the callers. I know some people are opposing
>> it though. My personal opinion is that having the MODULE_IMPORT_NS() in
>> a header would be neatly simplifying the calling code with very little
>> harm, especially here where including the header hardly has use-cases
>> outside the IIO ADC.
>>
>> Unfortunately, the "safety" seems to often be a synonym for just "making
>> it intentionally hard". As Finnish people say: "Kärsi, kärsi,
>> kirkkaamman kruunun saat". :)
>> (Roughly translated as "Suffer, suffer, you will get a brighter crown").
>>
>> Let's hear what Jonathan thinks of your suggestion.
> 
> For this particular case my intent was that all the IIO exports that
> are suitable for use in simple IIO drives will be in this namespace,
> we just haven't started that conversion yet.
> 
> As such, having it defined from a header for this helper isn't a good
> thing to do.

Hmm. I agree.

>  Generally I prefer to see in driver code what namespaces
> are involved but do understand the other viewpoint. In this case I
> definitely don't think it is appropriate unless we go for a specific namespace
> for just this helper.

I suppose having the MODULE_IMPORT_NS() in the header would actually 
make the more fine-grained namespaces (like IIO_ADC_HELPERS, IIO_GTS, 
...) much more usable. That'd relieved the drivers from explicitly 
listing multiple namespaces while nicely limiting the visibility.

If IIO was my territory, I might want to ask people to go with that 
approach - but I am quite happy being a freeloade.. errm, I mean, 
bystander ;)

Thanks!

Yours,
	-- Matti

Re: [PATCH v5 02/10] property: Add functions to count named child nodes

[Andy Shevchenko]

On Mon, Mar 10, 2025 at 08:23:15AM +0200, Matti Vaittinen wrote:
> On 03/03/2025 13:59, Andy Shevchenko wrote:
> > On Mon, Mar 03, 2025 at 01:31:45PM +0200, Matti Vaittinen wrote:

...

> > Also do we care about secondary fwnodes?
> 
> We have the device_get_child_node_count().
> device_get_child_node_count_named() should follow the same logic.

Okay, so we don't care about them right now.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v5 07/10] iio: adc: Support ROHM BD79124 ADC

[Matti Vaittinen]

On 08/03/2025 18:44, Jonathan Cameron wrote:
> On Mon, 3 Mar 2025 13:33:39 +0200
> Matti Vaittinen <mazziesaccount@gmail.com> wrote:
> 
>> 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. The window is configurable for each channel.
>>
>> The I2C protocol for manual start of the measurement and data reading is
>> somewhat peculiar. It requires the master to do clock stretching after
>> sending the I2C slave-address until the slave has captured the data.
>> Needless to say this is not well suopported by the I2C controllers.
>>
>> Thus the driver does not support the BD79124's manual measurement mode
>> but implements the measurements using automatic measurement mode relying
>> on the BD79124's ability of storing latest measurements into register.
>>
>> The driver does also support configuring the threshold events for
>> detecting the out-of-window events.
>>
>> The BD79124 keeps asserting IRQ for as long as the measured voltage is
>> out of the configured window. Thus the driver masks the received event
>> for a fixed duration (1 second) when an event is handled. This prevents
>> the user-space from choking on the events
>>
>> The ADC input pins can be also configured as general purpose outputs.
>> Those pins which don't have corresponding ADC channel node in the
>> device-tree will be controllable as GPO.
>>
>> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
> Hi Matti
> 
> Just a few really trivial comments.  If all else in the
> set was resolved I'd probably have applied with a tweak or two
> 
> Thanks,
> 
> Jonathan
> 
>>   obj-$(CONFIG_SC27XX_ADC) += sc27xx_adc.o
>> diff --git a/drivers/iio/adc/rohm-bd79124.c b/drivers/iio/adc/rohm-bd79124.c
>> new file mode 100644
>> index 000000000000..466c7decf8fc
>> --- /dev/null
>> +++ b/drivers/iio/adc/rohm-bd79124.c
>> @@ -0,0 +1,1108 @@
> ...
> 
>> +
>> +/* Read-only regs */
> 
> Given naming this is pretty obvious.
 > I would drop the comment

I will drop this, although I am not sure it is as self explatonary as 
one thinks. I've seen people getting this wrong because the logic of 
regmap-ranges is kind of reversed. (Eg, read-only is done by adding 
range to wr_tables and not to rd_tables - as a no-range).

Thanks for the review, and rest of the comments just agreed with.

-- Matti

Re: [PATCH v5 03/10] iio: adc: add helpers for parsing ADC nodes

[Jonathan Cameron]

On Mon, 10 Mar 2025 09:41:00 +0200
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> On 08/03/2025 18:29, Jonathan Cameron wrote:
> > On Wed, 5 Mar 2025 12:54:33 +0200
> > Matti Vaittinen <mazziesaccount@gmail.com> wrote:
> >   
> >> Thanks for the review David.
> >>
> >> On 04/03/2025 11:25, David Lechner wrote:  
> >>> On Mon, Mar 3, 2025 at 12:32 PM Matti Vaittinen
> >>> <mazziesaccount@gmail.com> wrote:  
> >>>>
> >>>> 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>
> >>>>
> >>>> ---  
> >>  
> >>>> + *
> >>>> + * Return:     Number of found channels on succes. Negative value to indicate  
> >>>
> >>> s/succes/success/  
> >>
> >> Thanks!
> >>  
> >>>> +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_child_node_scoped(dev, child) {
> >>>> +               u32 ch;
> >>>> +
> >>>> +               if (!fwnode_name_eq(child, "channel"))
> >>>> +                       continue;
> >>>> +
> >>>> +               ret = fwnode_property_read_u32(child, "reg", &ch);
> >>>> +               if (ret)
> >>>> +                       return ret;
> >>>> +
> >>>> +               if (max_chan_id != -1 && ch > max_chan_id)
> >>>> +                       return -ERANGE;
> >>>> +  
> >>>
> >>> Should we use return dev_err_probe() on these to help with debugging a bad dtb?
> >>>      
> >>
> >> I am not fan of using dev_err_probe() in a 'library code'. This is
> >> because we never know if there'll be some odd use-case where this is not
> >> called from the probe.
> >>
> >> All in all, I'd leave adding most of the debugs to the callers -
> >> especially because we do not expect to have bad device-trees after the
> >> initial 'development stage' of a board. The board 'development stage'
> >> should really reveal bugs which prevent the channels from being
> >> registered - and after the DT is correct, these debug prints become
> >> unnecessary (albeit minor) binary bloat.
> >>  
> >>>> +               *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");  
> >>>
> >>> We can make this less verbose by setting #define
> >>> DEFAULT_SYMBOL_NAMESPACE at the start of the file. Then we can just do
> >>> EXPORT_SYMBOL_GPL() throughout the rest of the file.  
> >>
> >> I am not sure what to think of this. I use the good old 'ctrl + ]' in my
> >> editor when I need to check how a function was supposed to be used. That
> >> jumps to the spot of code where the function is. I'd like to see the
> >> namespace mentioned there in order to not accidentally miss the fact the
> >> function belongs to one.
> >>
> >> OTOH, I do like simplifications. Yet, the added simplification might not
> >> warrant the namespace not being visible in the function definition.
> >>  
> >>> Also, I would prefer if the namespace matched config name (IIO_ADC_HELPER).  
> >>
> >> I had some lengthy discussion about this with Andy and Jonathan during
> >> earlier review versions. In short, I don't like the idea of very
> >> fragmented namespaces in IIO, which will just complicate the drivers
> >> without providing any obvious benefit.
> >>
> >> https://lore.kernel.org/all/20250222174842.57c091c5@jic23-huawei/
> >>  
> >>>> +
> >>>> +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);
> >>>> +  
> >>>
> >>> There are some different opinions on this, but on the last patch I did
> >>> introducing a new namespace, the consensus seems to be that putting
> >>> the MODULE_IMPORT_NS() in the header file was convenient so that users
> >>> of the API don't have to remember to both include the header and add
> >>> the import macro.
> >>>      
> >>
> >> I do like this suggestion, and I believe this would be the balance
> >> between getting the benefit of hiding part of the symbols - while not
> >> unnecessarily complicating the callers. I know some people are opposing
> >> it though. My personal opinion is that having the MODULE_IMPORT_NS() in
> >> a header would be neatly simplifying the calling code with very little
> >> harm, especially here where including the header hardly has use-cases
> >> outside the IIO ADC.
> >>
> >> Unfortunately, the "safety" seems to often be a synonym for just "making
> >> it intentionally hard". As Finnish people say: "Kärsi, kärsi,
> >> kirkkaamman kruunun saat". :)
> >> (Roughly translated as "Suffer, suffer, you will get a brighter crown").
> >>
> >> Let's hear what Jonathan thinks of your suggestion.  
> > 
> > For this particular case my intent was that all the IIO exports that
> > are suitable for use in simple IIO drives will be in this namespace,
> > we just haven't started that conversion yet.
> > 
> > As such, having it defined from a header for this helper isn't a good
> > thing to do.  
> 
> Hmm. I agree.
> 
> >  Generally I prefer to see in driver code what namespaces
> > are involved but do understand the other viewpoint. In this case I
> > definitely don't think it is appropriate unless we go for a specific namespace
> > for just this helper.  
> 
> I suppose having the MODULE_IMPORT_NS() in the header would actually 
> make the more fine-grained namespaces (like IIO_ADC_HELPERS, IIO_GTS, 
> ...) much more usable. That'd relieved the drivers from explicitly 
> listing multiple namespaces while nicely limiting the visibility.
> 
> If IIO was my territory, I might want to ask people to go with that 
> approach - but I am quite happy being a freeloade.. errm, I mean, 
> bystander ;)
> 
It relieves the burden but I'd still prefer explicit opt in to namespaces
unless there is general agreement on the approach of doing it in headers
which there has not been so far.

Jonathan

> Thanks!
> 
> Yours,
> 	-- Matti

Re: [PATCH v5 07/10] iio: adc: Support ROHM BD79124 ADC

[Jonathan Cameron]

On Mon, 10 Mar 2025 10:46:45 +0200
Matti Vaittinen <mazziesaccount@gmail.com> wrote:

> On 08/03/2025 18:44, Jonathan Cameron wrote:
> > On Mon, 3 Mar 2025 13:33:39 +0200
> > Matti Vaittinen <mazziesaccount@gmail.com> wrote:
> >   
> >> 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. The window is configurable for each channel.
> >>
> >> The I2C protocol for manual start of the measurement and data reading is
> >> somewhat peculiar. It requires the master to do clock stretching after
> >> sending the I2C slave-address until the slave has captured the data.
> >> Needless to say this is not well suopported by the I2C controllers.
> >>
> >> Thus the driver does not support the BD79124's manual measurement mode
> >> but implements the measurements using automatic measurement mode relying
> >> on the BD79124's ability of storing latest measurements into register.
> >>
> >> The driver does also support configuring the threshold events for
> >> detecting the out-of-window events.
> >>
> >> The BD79124 keeps asserting IRQ for as long as the measured voltage is
> >> out of the configured window. Thus the driver masks the received event
> >> for a fixed duration (1 second) when an event is handled. This prevents
> >> the user-space from choking on the events
> >>
> >> The ADC input pins can be also configured as general purpose outputs.
> >> Those pins which don't have corresponding ADC channel node in the
> >> device-tree will be controllable as GPO.
> >>
> >> Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>  
> > Hi Matti
> > 
> > Just a few really trivial comments.  If all else in the
> > set was resolved I'd probably have applied with a tweak or two
> > 
> > Thanks,
> > 
> > Jonathan
> >   
> >>   obj-$(CONFIG_SC27XX_ADC) += sc27xx_adc.o
> >> diff --git a/drivers/iio/adc/rohm-bd79124.c b/drivers/iio/adc/rohm-bd79124.c
> >> new file mode 100644
> >> index 000000000000..466c7decf8fc
> >> --- /dev/null
> >> +++ b/drivers/iio/adc/rohm-bd79124.c
> >> @@ -0,0 +1,1108 @@  
> > ...
> >   
> >> +
> >> +/* Read-only regs */  
> > 
> > Given naming this is pretty obvious.
>  > I would drop the comment  
> 
> I will drop this, although I am not sure it is as self explatonary as 
> one thinks. I've seen people getting this wrong because the logic of 
> regmap-ranges is kind of reversed. (Eg, read-only is done by adding 
> range to wr_tables and not to rd_tables - as a no-range).
It's obvious in the structure naming + how it is used. I agree
the interface in general is non obvious.

Jonathan

> 
> Thanks for the review, and rest of the comments just agreed with.
> 
> -- Matti