[PATCH v2 0/8] iio: adc: new ti-ads112c14 driver

[PATCH v2 0/8] iio: adc: new ti-ads112c14 driver

[David Lechner]

This adds support for TI ADS112C14 and ADS122C14 ADC chips.

The closest thing we've seen to this in the kernel already is ads124s08.
However, that has a completely different register map and the DT
bindings are incomplete and the driver is extremely basic. So I've just
started from scratch here.

We've also had a similar submission recently for ADS1220 [1]. That chip
is in a similar situation to ads124s08 in that it has a different
register map (but the submitted DT bindings are better than the ones for
ads124s08, even if still a bit incomplete). And literally as I was
writing the previous sentence, another series [2]  was sent for yet
another similar family of chips (ADS1262). That one is even more complex
in the feature set than the ones I am working on. I was going to polish
up the driver a bit more before submitting it, but now it seems more
urgent to coordinate with the other two series to align on how we would
like to handle all of these.

[1]: https://lore.kernel.org/linux-iio/20260610151342.44274-1-zizuzacker@gmail.com/
[2]: https://lore.kernel.org/linux-iio/20260612-ads126x-v1-0-894c788d03ed@gmail.com/

All of these chips have in common that they are designed for use with
RTDs and thermocouples and so they look very similar to each other in
terms of wiring and feature set, even if the register maps are
different. They are in the gray area where we could either keep them
separate because they are just different enough, or we could do like
we've done before with ad_sigma_delta and have a bit of an abstraction
layer for the register differences and otherwise try to share as much
code as possible. Normally, I would lean towards keeping them separate,
but in this case, I'm considering trying to share code because the
devicetree bindings for the inputs is complex and is going to be mostly
the same across all of these chips.

If we decide to go the route of sharing code, we could still merge this
series as-is and then do the refactoring to add the abstraction layer in
a follow-up series that also adds support for the first of the other
chips.

This series includes just basic support for reading single measurements
from the ADC and gain selection via the scale attribute. I plan to
follow this up with additional series to add support for buffered reads,
filtering/oversampling configuration, event support, gpio controller
support and perhaps a few other things that are slipping my mind right
now.

The most interesting part about this (that I alluded to above) is the
way channels are handled. These are multipling ADCs with differential
and single-ended inputs. But what sets them apart from other similar
chips is that since they are designed for use with RTDs, there can also
be a current output required to excite the RTD and this current output
might be different for different channels. So the way I conceptualized
the channels is that the devicetree specifies the conditions needed
to take a particular measurement rather than being purely a physical
channel.

This makes things more flexible, but does make the driver a bit more
complex. For example, knowing when the current output needs to be
enabled or disabled. For now, I have chosen a lazy-enable where they
are not turned on until the first measurement is taken that requires
them, but then they stay on until another measurement is taken that
doesn't require them. This can lead to some oddness with the diagnostic
channels that may be measuring something that indirectly requires the
current output (i.e. the external reference voltage when it is connected
to a resistor rather than a power supply). This means you need to take
a measurement that requires the current output to be enabled before the
diagnostic channels will give accurate readings.

I have also pushed a branch to [3] that contains the start of some
documentation for this driver that can give some more insight into how
the implementation works. It still needs some work and also documents
some things that haven't been implemented yet, so I haven't included it
in this series yet.

[3]: https://github.com/dlech/linux/blob/b4/iio-adc-ti-ads122c14/Documentation/iio/ads112c14.rst

Signed-off-by: David Lechner <dlechner@baylibre.com>
---
Changes in v2:
- Added patches for adding properties to adc.yaml.
- Some of these are coming from: https://lore.kernel.org/linux-iio/20260622-new-channel-props-v2-0-aafd5369f253@gmail.com/
- For now, I have stuck with one channel per single-channel pin or
  diff-channels pin pair rather than some of the other ideas that were
  discussed. Handling burn out current enable will be handled in a later
  series. I'm leaning towards something like the _burnoutraw attribute
  that Jonathan suggested.
- See individual patches for details of changes (mostly renaming DT
  properties, fixing some driver bugs and style issues).
- Link to v1: https://patch.msgid.link/20260615-iio-adc-ti-ads122c14-v1-0-e6bdadf7cb2b@baylibre.com

---
David Lechner (TI) (5):
      dt-bindings: iio: adc: add input-channel-rotation property
      dt-bindings: iio: adc: add ti,ads122c14
      iio: adc: add ti-ads112c14 driver
      iio: adc: ti-ads112c14: implement gain on internal short SYS_MON channel
      iio: adc: ti-ads112c14: add measurement channel support

Kurt Borja (3):
      dt-bindings: iio: adc: Add reference-sources property
      dt-bindings: iio: adc: Add excitation current sources properties
      dt-bindings: iio: adc: Add burn-out current properties

 Documentation/devicetree/bindings/iio/adc/adc.yaml |   41 +
 .../devicetree/bindings/iio/adc/ti,ads112c14.yaml  |  205 ++++
 MAINTAINERS                                        |    7 +
 drivers/iio/adc/Kconfig                            |   12 +
 drivers/iio/adc/Makefile                           |    1 +
 drivers/iio/adc/ti-ads112c14.c                     | 1186 ++++++++++++++++++++
 6 files changed, 1452 insertions(+)
---
base-commit: 948efecf22e49aa4bf55bb73ec79a0ddcfd38571
change-id: 20260514-iio-adc-ti-ads122c14-d0b92479334e

Best regards,
--  
David Lechner (TI) <dlechner@baylibre.com>

[PATCH v2 1/8] dt-bindings: iio: adc: Add reference-sources property

[David Lechner]

From: Kurt Borja <kuurtb@gmail.com>

Some ADCs have configurable voltage reference sources for each channel.

Signed-off-by: Kurt Borja <kuurtb@gmail.com>
Signed-off-by: David Lechner (TI) <dlechner@baylibre.com>
---
v2 changes (compared to Kurt's RFC v2):
* Drop maxItems.
* Drop 2nd paragraph of description.
* Make reference-sources plural since it is an array.
---
 Documentation/devicetree/bindings/iio/adc/adc.yaml | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
index b9bc02b5b07a..12800737d4fb 100644
--- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
@@ -73,6 +73,14 @@ properties:
       device design and can interact with other characteristics such as
       settling time.
 
+  reference-sources:
+    $ref: /schemas/types.yaml#/definitions/string-array
+    minItems: 1
+    description:
+      Indicates the voltage reference source or sources for this channel. Some
+      ADCs usually allow choosing between internal reference sources or a pair
+      of external pins.
+
 anyOf:
   - oneOf:
       - required:

-- 
2.43.0

[PATCH v2 2/8] dt-bindings: iio: adc: Add excitation current sources properties

[David Lechner]

From: Kurt Borja <kuurtb@gmail.com>

Some ADCs incorporate current sources that provide excitation current to
resistive temperature devices (RTDs), thermistors, diodes and other
resistive sensors that require constant current biasing.

Signed-off-by: Kurt Borja <kuurtb@gmail.com>
Signed-off-by: David Lechner (TI) <dlechner@baylibre.com>
---
v2 changes (compared to Kurt's RFC v2):
* Make units nanoamps instead of microamps to fit known devices.
* Drop bit about allowing single value for multiple channels.
* Add bit about semantics of the array index.
---
 Documentation/devicetree/bindings/iio/adc/adc.yaml | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
index 12800737d4fb..860601ec5334 100644
--- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
@@ -81,6 +81,26 @@ properties:
       ADCs usually allow choosing between internal reference sources or a pair
       of external pins.
 
+  excitation-channels:
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    description:
+      Excitation current sources provide current to resistive temperature
+      devices (RTDs), thermistors, diodes and other resistive sensors that
+      require constant current biasing.
+
+      This array describes the mux configuration of the excitation current
+      sources.
+
+  excitation-current-nanoamp:
+    description:
+      Excitation current sources provide current to resistive temperature
+      devices (RTDs), thermistors, diodes and other resistive sensors that
+      require constant current biasing.
+
+      This array describes the current configuration of the excitation current
+      sources. The index in the array corresponds to the same index in the
+      excitation-channels array.
+
 anyOf:
   - oneOf:
       - required:

-- 
2.43.0

[PATCH v2 3/8] dt-bindings: iio: adc: Add burn-out current properties

[David Lechner]

From: Kurt Borja <kuurtb@gmail.com>

Some ADCs incorporate burn-out current sources that provide current to
the channel's input pins for open-circuit or short-circuit detection.

Signed-off-by: Kurt Borja <kuurtb@gmail.com>
Signed-off-by: David Lechner (TI) <dlechner@baylibre.com>
---
v2 changes (compared to Kurt's RFC v2):
* Changed units from microamps to nanoamps to fit known devices.
---
 Documentation/devicetree/bindings/iio/adc/adc.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
index 860601ec5334..9ec1f447b565 100644
--- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
@@ -101,6 +101,12 @@ properties:
       sources. The index in the array corresponds to the same index in the
       excitation-channels array.
 
+  burn-out-current-nanoamp:
+    maxItems: 1
+    description:
+      Burn-out current sources provide current to the channel's input pins for
+      open-circuit or short-circuit detection.
+
 anyOf:
   - oneOf:
       - required:

-- 
2.43.0

[PATCH v2 4/8] dt-bindings: iio: adc: add input-channel-rotation property

[David Lechner (TI)]

Add a generic input-channel-rotation property to adc.yaml. This is a
feature seen frequently in ADCs that are designed to measure resistive
loads, such as RTDs and strain gauges. Enabling this can reduce offset
errors by swapping the positive and negative input channels on every
other conversion. This can have side-effects in timing and filter
response, so it is not always desirable to enable this feature in some
applications. Therefore, it is best to make this a property that can be
enabled or disabled in the device tree.

Signed-off-by: David Lechner (TI) <dlechner@baylibre.com>
---
v2 changes:
* New patch.
---
 Documentation/devicetree/bindings/iio/adc/adc.yaml | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
index 9ec1f447b565..3d52c00922c9 100644
--- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
@@ -81,6 +81,13 @@ properties:
       ADCs usually allow choosing between internal reference sources or a pair
       of external pins.
 
+  input-channel-rotation:
+    type: boolean
+    description:
+      If set, the positive and negative input channels are allowed to be swapped
+      on every other conversion to reduce offset errors. This is also referred
+      to as "chop" in some datasheets.
+
   excitation-channels:
     $ref: /schemas/types.yaml#/definitions/uint32-array
     description:

-- 
2.43.0

[PATCH v2 5/8] dt-bindings: iio: adc: add ti,ads122c14

[David Lechner (TI)]

Add new bindings for ti,ads122c14 and similar devices.

This is an ADC that is primarily intended for use with temperature
sensors. There are a few unusual properties because of this. In
particular, the reference voltage source and current output requirements
can be different for each measurement, so these are included in the
channel bindings.

The REFP/REFN reference voltage is usually just connected to a resistor
that is being driven by the ADC's current outputs, so there is special
property for this case rather than requiring a regulator to be defined
to represent that.

ti,vref-source is reused from ti,tlv320adcx140.yaml (otherwise might
have preferred an enum of strings).

Signed-off-by: David Lechner (TI) <dlechner@baylibre.com>
---

v2 changes:
* Added ti, vendor prefix when appropriate.
* Others are now standardized properties from adc.yaml.
* Moved top-level unevaluatedProperties.
* Fixed some issues with the channel@ matching and reg property.
* Dropped description on bipolar property.
* Renamed currnet-chopping to input-channel-rotation.
* Drop header file and use string enum instead for reference-sources.
* Added burn-out-current-nanoamp property.
* Drop allOf: and just use oneOf: directly.
* Fix inconsistent indentation in the examples.
---
 .../devicetree/bindings/iio/adc/ti,ads112c14.yaml  | 205 +++++++++++++++++++++
 MAINTAINERS                                        |   6 +
 2 files changed, 211 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/ti,ads112c14.yaml b/Documentation/devicetree/bindings/iio/adc/ti,ads112c14.yaml
new file mode 100644
index 000000000000..59ee4d652a08
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/ti,ads112c14.yaml
@@ -0,0 +1,205 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/ti,ads112c14.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments' ADS112C14 and similar ADC chips
+
+description: |
+  Supports the following Texas Instruments' ADC chips:
+  - ADS112C14 (16-bit)
+  - ADS122C14 (24-bit)
+
+  https://www.ti.com/lit/ds/symlink/ads122c14.pdf
+
+  These chips are primarily designed for use with temperature sensors such as
+  RTDs and thermocouples. The channel bindings reflect this in that each channel
+  represents the conditions required to make a measurement rather than strictly
+  just the physical input channels.
+
+maintainers:
+  - David Lechner <dlechner@baylibre.com>
+
+properties:
+  compatible:
+    enum:
+      - ti,ads112c14
+      - ti,ads122c14
+
+  reg:
+    items:
+      - minimum: 0x40
+        maximum: 0x47
+
+  clocks:
+    maxItems: 1
+    description: Optional external clock connected to GPIO3 pin.
+
+  avdd-supply: true
+  dvdd-supply: true
+
+  refp-supply: true
+  refn-supply: true
+
+  ti,refp-refn-resistor-ohms:
+    description:
+      The resistance of the external resistor between REFP and REFN when using
+      resistor bridge driven by current outputs for RTD measurements.
+
+  interrupts:
+    minItems: 1
+    items:
+      - description: FAULT interrupt (GPIO2 pin)
+      - description: DRDY interrupt (GPIO3 pin)
+
+  interrupt-names:
+    minItems: 1
+    maxItems: 2
+    items:
+      enum: [fault, drdy]
+
+  gpio-controller: true
+  '#gpio-cells':
+    const: 2
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+patternProperties:
+  ^channel@[0-7a-f]$:
+    $ref: adc.yaml
+
+    unevaluatedProperties: false
+
+    properties:
+      reg:
+        items:
+          - maximum: 15 # arbitrary limit, channel@ can be any combination of AIN0-AIN7
+
+      single-channel:
+        maximum: 7
+
+      diff-channels:
+        items:
+          maximum: 7
+
+      bipolar: true
+
+      input-channel-rotation: true
+
+      excitation-channels:
+        maxItems: 2
+        items:
+          maximum: 7
+
+      excitation-current-nanoamp:
+        maxItems: 2
+        items:
+          enum: [1000, 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000,
+                 90000, 100000, 200000, 300000, 400000, 500000, 600000, 700000,
+                 800000, 900000, 1000000]
+
+      burn-out-current-nanoamp:
+        enum: [200, 1000, 10000]
+
+      reference-sources:
+        items:
+          - enum: [internal-2.5v, internal-1.25v, external, avdd]
+            default: internal-2.5v
+
+    dependencies:
+      excitation-channels: [ excitation-current-nanoamp ]
+      excitation-current-nanoamp: [ excitation-channels ]
+
+    oneOf:
+      - required: [ single-channel ]
+      - required: [ diff-channels ]
+
+unevaluatedProperties: false
+
+required:
+  - compatible
+  - avdd-supply
+  - dvdd-supply
+
+dependencies:
+  refn-supply: [ refp-supply ]
+
+oneOf:
+  - required: [ refp-supply ]
+  - required: [ "ti,refp-refn-resistor-ohms" ]
+  - properties:
+      refp-supply: false
+      refn-supply: false
+      ti,refp-refn-resistor-ohms: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@40 {
+            compatible = "ti,ads112c14";
+            reg = <0x40>;
+
+            avdd-supply = <&avdd>;
+            dvdd-supply = <&dvdd>;
+
+            /* 3-Wire RTD: Two IDACs, One Measurement (AIN1-AIN2) */
+
+            ti,refp-refn-resistor-ohms = <500>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            channel@0 {
+                reg = <0>;
+                diff-channels = <1>, <2>;
+                input-channel-rotation;
+                excitation-channels = <0>, <3>;
+                excitation-current-nanoamp = <500000>, <500000>;
+                reference-sources = "external";
+                label = "rtd";
+            };
+        };
+    };
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@40 {
+            compatible = "ti,ads112c14";
+            reg = <0x40>;
+
+            avdd-supply = <&avdd>;
+            dvdd-supply = <&dvdd>;
+
+            /* Resistive Bridge Measurement With a Thermistor for Temperature Compensation*/
+
+            refp-supply = <&avdd>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            channel@0 {
+                reg = <0>;
+                diff-channels = <6>, <7>;
+                bipolar;
+                reference-sources = "external";
+                label = "bridge";
+            };
+
+            channel@1 {
+                reg = <1>;
+                diff-channels = <1>, <2>;
+                reference-sources = "internal-2.5v";
+                label = "thermistor";
+            };
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 895a87b571c3..0ac9f44c7096 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26935,6 +26935,12 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/iio/adc/ti,ads1119.yaml
 F:	drivers/iio/adc/ti-ads1119.c
 
+TI ADS112C14 ADC DRIVER
+M:	David Lechner <dlechner@baylibre.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/adc/ti,ads112c14.yaml
+
 TI ADS1018 ADC DRIVER
 M:	Kurt Borja <kuurtb@gmail.com>
 L:	linux-iio@vger.kernel.org

-- 
2.43.0

[PATCH v2 6/8] iio: adc: add ti-ads112c14 driver

[David Lechner (TI)]

Add a new driver for the TI ADS112C14/ADS122C14 ADC chips.

This first step is adding a very basic driver that only supports power
on/reset and reading the system monitor channels.

ADS112C14_SYS_MON_CHANNEL_SHORT is the last channel rather than being in
logical order by address to keep the voltage channels together and in
case we find we need to add variants of this channel with different
voltage reference later.

Signed-off-by: David Lechner (TI) <dlechner@baylibre.com>
---

A few other notes for review that didn't seem worth putting in the
commit message:
* I intentionally did not use bulk regmap because later we may need to
  get the voltage of the avdd supply.
* I left some comments in the code where the code might look funny (e.g.
  to reduce future diff) or does not exactly match the datasheet, in
  which case later changes will address that.

v2 changes:
* Add some indent to register field macro defines.
* Drop ads112c14_internal_ref_uV array (use macros instead).
* Don't keep pointer to i2c client.
* Consistently check channel < 100 instead of >= 100 sometimes.
* Check return of i2c_get_match_data().
* Fix bug on checking -EREMOTEIO.
* Don't use &client->dev when we already have dev local variable.
* Make some changes to reduce diff in later patches.
---
 MAINTAINERS                    |   1 +
 drivers/iio/adc/Kconfig        |  12 +
 drivers/iio/adc/Makefile       |   1 +
 drivers/iio/adc/ti-ads112c14.c | 547 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 561 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 0ac9f44c7096..92746892f6b3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26940,6 +26940,7 @@ M:	David Lechner <dlechner@baylibre.com>
 L:	linux-iio@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/iio/adc/ti,ads112c14.yaml
+F:	drivers/iio/adc/ti-ads112c14.c
 
 TI ADS1018 ADC DRIVER
 M:	Kurt Borja <kuurtb@gmail.com>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 6fb0766ca27a..bfcaecc85f24 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1787,6 +1787,18 @@ config TI_ADS1119
          This driver can also be built as a module. If so, the module will be
          called ti-ads1119.
 
+config TI_ADS112C14
+	tristate "Texas Instruments ADS112C14/ADS122C14"
+	depends on I2C
+	select REGMAP
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for Texas Instruments ADS112C14,
+	  ADS122C14 ADC chips.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called ti-ads112c14.
+
 config TI_ADS124S08
 	tristate "Texas Instruments ADS124S08"
 	depends on SPI
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 707dd708912f..72f4c6b33ca8 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -153,6 +153,7 @@ obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
 obj-$(CONFIG_TI_ADS1018) += ti-ads1018.o
 obj-$(CONFIG_TI_ADS1100) += ti-ads1100.o
 obj-$(CONFIG_TI_ADS1119) += ti-ads1119.o
+obj-$(CONFIG_TI_ADS112C14) += ti-ads112c14.o
 obj-$(CONFIG_TI_ADS124S08) += ti-ads124s08.o
 obj-$(CONFIG_TI_ADS1298) += ti-ads1298.o
 obj-$(CONFIG_TI_ADS131E08) += ti-ads131e08.o
diff --git a/drivers/iio/adc/ti-ads112c14.c b/drivers/iio/adc/ti-ads112c14.c
new file mode 100644
index 000000000000..c61d47244732
--- /dev/null
+++ b/drivers/iio/adc/ti-ads112c14.c
@@ -0,0 +1,547 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * IIO driver for Texas Instruments ADS112C14 and similar ADCs.
+ *
+ * Copyright (C) 2026 Texas Instruments Incorporated - https://www.ti.com/
+ * Copyright (C) 2026 Baylibre Inc.
+ *
+ * Datasheet: https://www.ti.com/lit/ds/symlink/ads122c14.pdf
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/dev_printk.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/math64.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/sysfs.h>
+#include <linux/time64.h>
+#include <linux/types.h>
+#include <linux/unaligned.h>
+#include <linux/units.h>
+
+/* Datasheet t_d(RST) - time to wait after reset before next I2C use. */
+#define ADS112C14_DELAY_RESET_US 500
+
+#define ADS112C14_CMD_RDATA	0x00
+#define ADS112C14_CMD_RREG	0x40
+#define ADS112C14_CMD_WREG	0x80
+
+#define ADS112C14_REG_DEVICE_ID				0x00
+#define   ADS112C14_DEVICE_ID_BITS			GENMASK(3, 0)
+
+#define ADS112C14_REG_REVISION_ID			0x01
+
+#define ADS112C14_REG_STATUS_MSB			0x02
+#define   ADS112C14_STATUS_MSB_RESETN			BIT(7)
+#define   ADS112C14_STATUS_MSB_AVDD_UVN			BIT(6)
+#define   ADS112C14_STATUS_MSB_REF_UVN			BIT(5)
+#define   ADS112C14_STATUS_MSB_REG_MAP_CRC_FAULTN	BIT(3)
+#define   ADS112C14_STATUS_MSB_MEM_FAULTN		BIT(2)
+#define   ADS112C14_STATUS_MSB_REG_WRITE_FAULTN		BIT(1)
+#define   ADS112C14_STATUS_MSB_DRDY			BIT(0)
+
+#define ADS112C14_REG_STATUS_LSB			0x03
+#define   ADS112C14_STATUS_LSB_CONV_COUNT		GENMASK(7, 4)
+#define   ADS112C14_STATUS_LSB_GPIO3_DAT_IN		BIT(3)
+#define   ADS112C14_STATUS_LSB_GPIO2_DAT_IN		BIT(2)
+#define   ADS112C14_STATUS_LSB_GPIO1_DAT_IN		BIT(1)
+#define   ADS112C14_STATUS_LSB_GPIO0_DAT_IN		BIT(0)
+
+#define ADS112C14_REG_CONVERSION_CTRL			0x04
+#define   ADS112C14_CONVERSION_CTRL_RESET		GENMASK(7, 2)
+#define   ADS112C14_CONVERSION_CTRL_START		BIT(1)
+#define   ADS112C14_CONVERSION_CTRL_STOP		BIT(0)
+
+#define ADS112C14_REG_DEVICE_CFG			0x05
+#define   ADS112C14_DEVICE_CFG_PWDN			BIT(7)
+#define   ADS112C14_DEVICE_CFG_STBY_MODE		BIT(6)
+#define   ADS112C14_DEVICE_CFG_BOCS			GENMASK(5, 4)
+#define   ADS112C14_DEVICE_CFG_CLK_SEL			BIT(3)
+#define   ADS112C14_DEVICE_CFG_CONV_MODE		BIT(2)
+#define   ADS112C14_DEVICE_CFG_SPEED_MODE		GENMASK(1, 0)
+
+#define ADS112C14_REG_DATA_RATE_CFG			0x06
+#define   ADS112C14_DATA_RATE_CFG_DELAY			GENMASK(7, 4)
+#define   ADS112C14_DATA_RATE_CFG_GC_EN			BIT(3)
+#define   ADS112C14_DATA_RATE_CFG_FLTR_OSR		GENMASK(2, 0)
+
+#define ADS112C14_REG_MUX_CFG				0x07
+#define   ADS112C14_MUX_CFG_AINP			GENMASK(7, 4)
+#define   ADS112C14_MUX_CFG_AINN			GENMASK(3, 0)
+
+#define ADS112C14_REG_GAIN_CFG				0x08
+#define   ADS112C14_GAIN_CFG_SPARE			BIT(7)
+#define   ADS112C14_GAIN_CFG_SYS_MON			GENMASK(6, 4)
+#define   ADS112C14_GAIN_CFG_GAIN			GENMASK(3, 0)
+
+#define ADS112C14_REG_REFERENCE_CFG			0x09
+#define   ADS112C14_REFERENCE_CFG_REF_UV_EN		BIT(7)
+#define   ADS112C14_REFERENCE_CFG_REFP_BUF_EN		BIT(5)
+#define   ADS112C14_REFERENCE_CFG_REFN_BUF_EN		BIT(4)
+#define   ADS112C14_REFERENCE_CFG_REF_VAL		BIT(2)
+#define     ADS112C14_REFERENCE_CFG_REF_VAL_1_25V	  0
+#define     ADS112C14_REFERENCE_CFG_REF_VAL_2_5V	  1
+#define   ADS112C14_REFERENCE_CFG_REF_SEL		GENMASK(1, 0)
+
+#define ADS112C14_REG_DIGITAL_CFG			0x0A
+#define   ADS112C14_DIGITAL_CFG_REG_MAP_CRC_EN		BIT(6)
+#define   ADS112C14_DIGITAL_CFG_I2C_CRC_EN		BIT(5)
+#define   ADS112C14_DIGITAL_CFG_STATUS_EN		BIT(4)
+#define   ADS112C14_DIGITAL_CFG_FAULT_PIN_BEHAVIOR	BIT(3)
+#define   ADS112C14_DIGITAL_CFG_CODING			BIT(1)
+
+#define ADS112C14_REG_GPIO_CFG				0x0B
+#define   ADS112C14_GPIO_CFG_GPIO3_CFG			GENMASK(7, 6)
+#define   ADS112C14_GPIO_CFG_GPIO2_CFG			GENMASK(5, 4)
+#define   ADS112C14_GPIO_CFG_GPIO1_CFG			GENMASK(3, 2)
+#define   ADS112C14_GPIO_CFG_GPIO0_CFG			GENMASK(1, 0)
+
+#define ADS112C14_REG_GPIO_DATA_OUTPUT			0x0C
+#define   ADS112C14_GPIO_DATA_OUTPUT_GPIO3_SRC		BIT(7)
+#define   ADS112C14_GPIO_DATA_OUTPUT_GPIO2_SRC		BIT(6)
+#define   ADS112C14_GPIO_DATA_OUTPUT_GPIO3_DAT_OUT	BIT(3)
+#define   ADS112C14_GPIO_DATA_OUTPUT_GPIO2_DAT_OUT	BIT(2)
+#define   ADS112C14_GPIO_DATA_OUTPUT_GPIO1_DAT_OUT	BIT(1)
+#define   ADS112C14_GPIO_DATA_OUTPUT_GPIO0_DAT_OUT	BIT(0)
+
+#define ADS112C14_REG_IDAC_MAG_CFG			0x0D
+#define   ADS112C14_IDAC_MAG_CFG_I2MAG			GENMASK(7, 4)
+#define   ADS112C14_IDAC_MAG_CFG_I1MAG			GENMASK(3, 0)
+
+#define ADS112C14_REG_IDAC_MUX_CFG			0x0E
+#define   ADS112C14_IDAC_MUX_CFG_IUNIT			BIT(7)
+#define   ADS112C14_IDAC_MUX_CFG_I2MUX			GENMASK(6, 4)
+#define   ADS112C14_IDAC_MUX_CFG_I1MUX			GENMASK(2, 0)
+
+#define ADS112C14_REG_REG_MAP_CRC			0x0F
+
+#define ADS112C14_INT_REF0_mV				1250
+#define ADS112C14_INT_REF1_mV				2500
+
+static bool ads112c14_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case ADS112C14_REG_DEVICE_ID:
+	case ADS112C14_REG_REVISION_ID:
+	case ADS112C14_REG_STATUS_LSB:
+		return false;
+	default:
+		return true;
+	}
+}
+
+static bool ads112c14_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case ADS112C14_REG_STATUS_MSB:
+	case ADS112C14_REG_STATUS_LSB:
+	case ADS112C14_REG_CONVERSION_CTRL:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct reg_default ads112c14_reg_defaults[] = {
+	{ ADS112C14_REG_DEVICE_CFG, 0 },
+	{ ADS112C14_REG_DATA_RATE_CFG, 0 },
+	{ ADS112C14_REG_MUX_CFG, 0 },
+	{ ADS112C14_REG_GAIN_CFG, FIELD_PREP_CONST(ADS112C14_GAIN_CFG_GAIN, 1) },
+	{ ADS112C14_REG_REFERENCE_CFG, 0 },
+	{ ADS112C14_REG_DIGITAL_CFG, 0 },
+	{ ADS112C14_REG_GPIO_CFG, 0 },
+	{ ADS112C14_REG_GPIO_DATA_OUTPUT, 0 },
+	{ ADS112C14_REG_IDAC_MAG_CFG, 0 },
+	{ ADS112C14_REG_IDAC_MUX_CFG, FIELD_PREP_CONST(ADS112C14_IDAC_MUX_CFG_I2MUX, 1) },
+};
+
+static const struct regmap_config ads112c14_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.read_flag_mask = ADS112C14_CMD_RREG,
+	.write_flag_mask = ADS112C14_CMD_WREG,
+	.max_register = ADS112C14_REG_REG_MAP_CRC,
+	.writeable_reg = ads112c14_writeable_reg,
+	.volatile_reg = ads112c14_volatile_reg,
+	.reg_defaults = ads112c14_reg_defaults,
+	.num_reg_defaults = ARRAY_SIZE(ads112c14_reg_defaults),
+	.cache_type = REGCACHE_MAPLE,
+};
+
+struct ads112c14_chip_info {
+	const char *name;
+	u32 resolution_bits;
+};
+
+struct ads112c14_data {
+	const struct ads112c14_chip_info *chip_info;
+	struct regmap *regmap;
+};
+
+/* Fixed channels for system monitor measurements. */
+#define ADS112C14_SYS_MON_CHANNEL_TEMP		100
+#define ADS112C14_SYS_MON_CHANNEL_EXT_REF	101
+#define ADS112C14_SYS_MON_CHANNEL_AVDD		102
+#define ADS112C14_SYS_MON_CHANNEL_DVDD		103
+#define ADS112C14_SYS_MON_CHANNEL_SHORT		104
+
+static const struct iio_chan_spec ads112c14_sys_mon_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.indexed = 1,
+		.channel = ADS112C14_SYS_MON_CHANNEL_TEMP,
+		.address = 2,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
+				    | BIT(IIO_CHAN_INFO_SCALE)
+				    | BIT(IIO_CHAN_INFO_OFFSET),
+	},
+	{
+		.type = IIO_VOLTAGE,
+		.indexed = 1,
+		.channel = ADS112C14_SYS_MON_CHANNEL_EXT_REF,
+		.address = 3,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
+				    | BIT(IIO_CHAN_INFO_SCALE),
+	},
+	{
+		.type = IIO_VOLTAGE,
+		.indexed = 1,
+		.channel = ADS112C14_SYS_MON_CHANNEL_AVDD,
+		.address = 4,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
+				    | BIT(IIO_CHAN_INFO_SCALE),
+	},
+	{
+		.type = IIO_VOLTAGE,
+		.indexed = 1,
+		.channel = ADS112C14_SYS_MON_CHANNEL_DVDD,
+		.address = 5,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
+				    | BIT(IIO_CHAN_INFO_SCALE),
+	},
+	{
+		.type = IIO_VOLTAGE,
+		.indexed = 1,
+		.channel = ADS112C14_SYS_MON_CHANNEL_SHORT,
+		.channel2 = ADS112C14_SYS_MON_CHANNEL_SHORT,
+		.differential = 1,
+		.address = 1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
+				    | BIT(IIO_CHAN_INFO_SCALE),
+	},
+};
+
+static int ads112c14_prepare_sys_mon_channel(struct ads112c14_data *data,
+					     const struct iio_chan_spec *chan)
+{
+	int ret;
+
+	/* TODO: GAIN is useful for shorted PGA inputs. */
+	/* All SYS_MON channels use GAIN of 1 to keep it simple. */
+	ret = regmap_update_bits(data->regmap, ADS112C14_REG_GAIN_CFG,
+				 ADS112C14_GAIN_CFG_SYS_MON |
+				 ADS112C14_GAIN_CFG_GAIN,
+				 FIELD_PREP(ADS112C14_GAIN_CFG_SYS_MON, chan->address) |
+				 FIELD_PREP(ADS112C14_GAIN_CFG_GAIN, 1));
+	if (ret)
+		return ret;
+
+	/* All SYS_MON channels use signed data to keep it simple. */
+	ret = regmap_clear_bits(data->regmap, ADS112C14_REG_DIGITAL_CFG,
+				ADS112C14_DIGITAL_CFG_CODING);
+	if (ret)
+		return ret;
+
+	/*
+	 * REVISIT: if we implement regulator support for the REFOUT pin, we
+	 * might need to make this voltage match what is required by that. In
+	 * that case, we could also adjust GAIN so that we still get the same
+	 * range.
+	 */
+	/*
+	 * NB: SYS_MON channels ignore REF_SEL except for the shorted input
+	 * channel, so we set it here to internal reference to be consistent.
+	 * If we ever need to make a measurement of shorted input with other
+	 * reference source, we could add additional channels for that.
+	 */
+	ret = regmap_update_bits(data->regmap, ADS112C14_REG_REFERENCE_CFG,
+				 ADS112C14_REFERENCE_CFG_REF_VAL |
+				 ADS112C14_REFERENCE_CFG_REF_SEL,
+				 FIELD_PREP(ADS112C14_REFERENCE_CFG_REF_VAL,
+					    ADS112C14_REFERENCE_CFG_REF_VAL_2_5V) |
+				 FIELD_PREP(ADS112C14_REFERENCE_CFG_REF_SEL,
+					    ADS112C14_REFERENCE_CFG_REF_SEL_INTERNAL));
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ads112c14_single_conversion(struct ads112c14_data *data,
+				       const struct iio_chan_spec *chan,
+				       u8 *buf)
+{
+	struct i2c_client *client = to_i2c_client(regmap_get_device(data->regmap));
+	u32 reg_val;
+	int ret;
+
+	if (chan->channel < 100) {
+		/* Not implemented yet. */
+		return -EINVAL;
+	} else {
+		ret = ads112c14_prepare_sys_mon_channel(data, chan);
+		if (ret)
+			return ret;
+	}
+
+	ret = regmap_write(data->regmap, ADS112C14_REG_CONVERSION_CTRL,
+			   ADS112C14_CONVERSION_CTRL_START);
+	if (ret)
+		return ret;
+
+	ret = regmap_read_poll_timeout(data->regmap,
+				       ADS112C14_REG_STATUS_MSB, reg_val,
+				       FIELD_GET(ADS112C14_STATUS_MSB_DRDY, reg_val),
+				       1 * USEC_PER_MSEC, 100 * USEC_PER_MSEC);
+	if (ret)
+		return ret;
+
+	return i2c_smbus_read_i2c_block_data(client, ADS112C14_CMD_RDATA,
+					     BITS_TO_BYTES(data->chip_info->resolution_bits),
+					     buf);
+}
+
+static int ads112c14_read_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan, int *val,
+			      int *val2, long mask)
+{
+	struct ads112c14_data *data = iio_priv(indio_dev);
+	u32 vref_uV, fsr_bits;
+
+	/* Selecting V_REF source is not implemented yet. */
+	vref_uV = ADS112C14_INT_REF1_mV * (MICRO / MILLI);
+
+	if (chan->channel < 100) {
+		/* Not implemented yet. */
+		return -EINVAL;
+	} else {
+		/* All SYS_MON channels are using signed coding. */
+		fsr_bits = data->chip_info->resolution_bits - 1;
+	}
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW: {
+		u8 buf[3];
+		int ret;
+
+		if (!iio_device_claim_direct(indio_dev))
+			return -EBUSY;
+
+		ret = ads112c14_single_conversion(data, chan, buf);
+		iio_device_release_direct(indio_dev);
+		if (ret < 0)
+			return ret;
+
+		switch (data->chip_info->resolution_bits) {
+		case 16:
+			*val = get_unaligned_be16(buf);
+			break;
+		case 24:
+			*val = get_unaligned_be24(buf);
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		*val = sign_extend32(*val, fsr_bits);
+
+		return IIO_VAL_INT;
+	}
+	case IIO_CHAN_INFO_SCALE:
+		if (chan->type == IIO_TEMP) {
+			/* TS_TC (typical) = 405 uV/°C */
+			*val = MILLI * vref_uV / 405;
+			*val2 = fsr_bits;
+			return IIO_VAL_FRACTIONAL_LOG2;
+		}
+
+		*val = vref_uV / (MICRO / MILLI);
+		/*
+		 * Last 3 SYS_MON channels (ext ref, AVDD, DVDD) need to be
+		 * multiplied by 8 to account for internal attenuation of / 8.
+		 */
+		*val2 = fsr_bits - (chan->address >= 3 ? 3 : 0);
+		return IIO_VAL_FRACTIONAL_LOG2;
+	case IIO_CHAN_INFO_OFFSET:
+		/* Only the temperature channel has an offset. */
+		if (chan->type != IIO_TEMP)
+			return -EINVAL;
+		/*
+		 * Die temperature [°C] = 25°C + (Measured voltage – TS_Offset) / TS_TC
+		 * TS_TC (typical) = 405 uV/°C
+		 * TS_Offset (typical) = 119.5 mV
+		 */
+		*val = div_s64((s64)(25 * 405 - 119500) * BIT(fsr_bits), vref_uV);
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ads112c14_read_label(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan, char *label)
+{
+	const char *label_source;
+
+	/* System monitor channels. */
+	switch (chan->channel) {
+	case ADS112C14_SYS_MON_CHANNEL_TEMP:
+		label_source = "Internal temperature sensor";
+		break;
+	case ADS112C14_SYS_MON_CHANNEL_EXT_REF:
+		label_source = "External reference";
+		break;
+	case ADS112C14_SYS_MON_CHANNEL_AVDD:
+		label_source = "AVDD";
+		break;
+	case ADS112C14_SYS_MON_CHANNEL_DVDD:
+		label_source = "DVDD";
+		break;
+	case ADS112C14_SYS_MON_CHANNEL_SHORT:
+		label_source = "Internal short (internal reference source)";
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return sysfs_emit(label, "%s\n", label_source);
+}
+
+static const struct iio_info ads112c14_info = {
+	.read_raw = ads112c14_read_raw,
+	.read_label = ads112c14_read_label,
+};
+
+static int ads112c14_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	const struct ads112c14_chip_info *info;
+	struct iio_dev *indio_dev;
+	struct ads112c14_data *data;
+	u32 reg_val;
+	int ret;
+
+	info = i2c_get_match_data(client);
+	if (!info)
+		return dev_err_probe(dev, -EINVAL, "missing match data\n");
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	data->chip_info = info;
+
+	ret = devm_regulator_get_enable(dev, "dvdd");
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to get dvdd regulator\n");
+
+	ret = devm_regulator_get_enable(dev, "avdd");
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to get avdd regulator\n");
+
+	data->regmap = devm_regmap_init_i2c(client, &ads112c14_regmap_config);
+	if (IS_ERR(data->regmap))
+		return dev_err_probe(dev, PTR_ERR(data->regmap),
+				     "failed to init regmap\n");
+
+	/* Write magic reset value (0x16) to ensure known state.*/
+	ret = regmap_write(data->regmap, ADS112C14_REG_CONVERSION_CTRL,
+			   FIELD_PREP(ADS112C14_CONVERSION_CTRL_RESET, 0x16));
+	/*
+	 * The reset may cause an -EREMOTEIO error because of failing to get the
+	 * I2C ACK at the end of the message. The device still gets reset so it
+	 * is safe to ignore this error.
+	 */
+	if (ret == -EREMOTEIO)
+		ret = 0;
+	if (ret)
+		return ret;
+
+	fsleep(ADS112C14_DELAY_RESET_US);
+
+	ret = regmap_read(data->regmap, ADS112C14_REG_STATUS_MSB, &reg_val);
+	if (ret)
+		return ret;
+
+	if (FIELD_GET(ADS112C14_STATUS_MSB_RESETN, reg_val))
+		return dev_err_probe(dev, -EIO, "reset failed\n");
+
+	/*
+	 * Clear reset bit to prepare for next probe. And clear AVDD fault since
+	 * that happens on every reset.
+	 */
+	ret = regmap_write(data->regmap, ADS112C14_REG_STATUS_MSB,
+			   ADS112C14_STATUS_MSB_RESETN |
+			   ADS112C14_STATUS_MSB_AVDD_UVN);
+	if (ret)
+		return ret;
+
+	/* Place in single-shot conversion mode to make ready for raw read. */
+	ret = regmap_set_bits(data->regmap, ADS112C14_REG_DEVICE_CFG,
+			      ADS112C14_DEVICE_CFG_CONV_MODE);
+	if (ret)
+		return ret;
+
+	indio_dev->name = info->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = ads112c14_sys_mon_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ads112c14_sys_mon_channels);
+	indio_dev->info = &ads112c14_info;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct ads112c14_chip_info ads112c14_chip_info = {
+	.name = "ads112c14",
+	.resolution_bits = 16,
+};
+
+static const struct ads112c14_chip_info ads122c14_chip_info = {
+	.name = "ads122c14",
+	.resolution_bits = 24,
+};
+
+static const struct of_device_id ads112c14_of_match[] = {
+	{ .compatible = "ti,ads112c14", .data = &ads112c14_chip_info },
+	{ .compatible = "ti,ads122c14", .data = &ads122c14_chip_info },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ads112c14_of_match);
+
+static const struct i2c_device_id ads112c14_id[] = {
+	{ .name = "ads112c14", .driver_data = (kernel_ulong_t)&ads112c14_chip_info },
+	{ .name = "ads122c14", .driver_data = (kernel_ulong_t)&ads122c14_chip_info },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ads112c14_id);
+
+static struct i2c_driver ads112c14_driver = {
+	.driver = {
+		.name = "ads112c14",
+		.of_match_table = ads112c14_of_match,
+	},
+	.probe = ads112c14_probe,
+	.id_table = ads112c14_id,
+};
+module_i2c_driver(ads112c14_driver);
+
+MODULE_AUTHOR("David Lechner (TI) <dlechner@baylibre.com>");
+MODULE_DESCRIPTION("TI ADS112C14 I2C ADC driver");
+MODULE_LICENSE("GPL");

-- 
2.43.0

[PATCH v2 7/8] iio: adc: ti-ads112c14: implement gain on internal short SYS_MON channel

[David Lechner (TI)]

Implement support for the programmable gain amplifier on the internal
short SYS_MON channel. This channel is used for calibration, so it is
useful to be able to set the PGA to the same gain as the external
channels. The gain setting is implemented via the `_scale` attribute.

In the future, we may want to support different reference voltages for
this channel, so the scale_available table is populated during probe
rather than being a static table.

Signed-off-by: David Lechner (TI) <dlechner@baylibre.com>
---
v2 changes:
* Make some changes to reduce diff in next patch.
* Add some local variables to reduce line wrap.
---
 drivers/iio/adc/ti-ads112c14.c | 144 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 141 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/ti-ads112c14.c b/drivers/iio/adc/ti-ads112c14.c
index c61d47244732..0e775dbc8d50 100644
--- a/drivers/iio/adc/ti-ads112c14.c
+++ b/drivers/iio/adc/ti-ads112c14.c
@@ -124,6 +124,26 @@
 #define ADS112C14_INT_REF0_mV				1250
 #define ADS112C14_INT_REF1_mV				2500
 
+/* Available gains as tenths (x10) */
+static const u32 ads112c14_pga_gains_x10[] = {
+	5, /* 0.5 */
+	10, /* 1 */
+	20, /* 2 */
+	40, /* 4 */
+	50, /* 5 */
+	80, /* 8 */
+	100, /* 10 */
+	160, /* 16 */
+	200, /* 20 */
+	320, /* 32 */
+	500, /* 50 */
+	640, /* 64 */
+	1000, /* 100 */
+	1280, /* 128 */
+	2000, /* 200 */
+	2560, /* 256 */
+};
+
 static bool ads112c14_writeable_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
@@ -182,6 +202,8 @@ struct ads112c14_chip_info {
 struct ads112c14_data {
 	const struct ads112c14_chip_info *chip_info;
 	struct regmap *regmap;
+	u8 sys_mon_chan_short_gain_val;
+	int sys_mon_chan_short_scale_available[ARRAY_SIZE(ads112c14_pga_gains_x10)][2];
 };
 
 /* Fixed channels for system monitor measurements. */
@@ -234,21 +256,28 @@ static const struct iio_chan_spec ads112c14_sys_mon_channels[] = {
 		.address = 1,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)
 				    | BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_separate_available = BIT(IIO_CHAN_INFO_SCALE),
 	},
 };
 
 static int ads112c14_prepare_sys_mon_channel(struct ads112c14_data *data,
 					     const struct iio_chan_spec *chan)
 {
+	u32 gain_val;
 	int ret;
 
-	/* TODO: GAIN is useful for shorted PGA inputs. */
-	/* All SYS_MON channels use GAIN of 1 to keep it simple. */
+	/*
+	 * All SYS_MON channels use GAIN of 1 to keep it simple. Other than
+	 * the internal short channel, where it is useful in practice.
+	 */
+	gain_val = chan->channel == ADS112C14_SYS_MON_CHANNEL_SHORT ?
+		   data->sys_mon_chan_short_gain_val : 1;
+
 	ret = regmap_update_bits(data->regmap, ADS112C14_REG_GAIN_CFG,
 				 ADS112C14_GAIN_CFG_SYS_MON |
 				 ADS112C14_GAIN_CFG_GAIN,
 				 FIELD_PREP(ADS112C14_GAIN_CFG_SYS_MON, chan->address) |
-				 FIELD_PREP(ADS112C14_GAIN_CFG_GAIN, 1));
+				 FIELD_PREP(ADS112C14_GAIN_CFG_GAIN, gain_val));
 	if (ret)
 		return ret;
 
@@ -323,6 +352,7 @@ static int ads112c14_read_raw(struct iio_dev *indio_dev,
 {
 	struct ads112c14_data *data = iio_priv(indio_dev);
 	u32 vref_uV, fsr_bits;
+	int *scale_avail;
 
 	/* Selecting V_REF source is not implemented yet. */
 	vref_uV = ADS112C14_INT_REF1_mV * (MICRO / MILLI);
@@ -371,6 +401,17 @@ static int ads112c14_read_raw(struct iio_dev *indio_dev,
 			return IIO_VAL_FRACTIONAL_LOG2;
 		}
 
+		if (chan->channel == ADS112C14_SYS_MON_CHANNEL_SHORT) {
+			u8 idx = data->sys_mon_chan_short_gain_val;
+
+			scale_avail = data->sys_mon_chan_short_scale_available[idx];
+
+			*val = scale_avail[0];
+			*val2 = scale_avail[1];
+
+			return IIO_VAL_INT_PLUS_NANO;
+		}
+
 		*val = vref_uV / (MICRO / MILLI);
 		/*
 		 * Last 3 SYS_MON channels (ext ref, AVDD, DVDD) need to be
@@ -394,6 +435,69 @@ static int ads112c14_read_raw(struct iio_dev *indio_dev,
 	}
 }
 
+static int ads112c14_read_avail(struct iio_dev *indio_dev,
+				const struct iio_chan_spec *chan, const int **vals,
+				int *type, int *length, long mask)
+{
+	struct ads112c14_data *data = iio_priv(indio_dev);
+
+	if (chan->channel == ADS112C14_SYS_MON_CHANNEL_SHORT) {
+		*vals = (const int *)data->sys_mon_chan_short_scale_available;
+		*length = 2 * ARRAY_SIZE(data->sys_mon_chan_short_scale_available);
+		*type = IIO_VAL_INT_PLUS_NANO;
+		return IIO_AVAIL_LIST;
+	}
+
+	return -EINVAL;
+}
+
+static int ads112c14_write_raw(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan, int val,
+			       int val2, long mask)
+{
+	struct ads112c14_data *data = iio_priv(indio_dev);
+	const int (*scale_avail)[2];
+	u8 *gain_val;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE: {
+		if (chan->channel == ADS112C14_SYS_MON_CHANNEL_SHORT) {
+			scale_avail = data->sys_mon_chan_short_scale_available;
+			gain_val = &data->sys_mon_chan_short_gain_val;
+		} else {
+			return -EINVAL;
+		}
+
+		IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
+		if (IIO_DEV_ACQUIRE_FAILED(claim))
+			return -EBUSY;
+
+		for (u32 i = 0; i < ARRAY_SIZE(ads112c14_pga_gains_x10); i++) {
+			if (val == scale_avail[i][0] && val2 == scale_avail[i][1]) {
+				*gain_val = i;
+				return 0;
+			}
+		}
+
+		return -EINVAL;
+	}
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ads112c14_write_raw_get_fmt(struct iio_dev *indio_dev,
+				       struct iio_chan_spec const *chan,
+				       long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		return IIO_VAL_INT_PLUS_NANO;
+	default:
+		return IIO_VAL_INT_PLUS_MICRO;
+	}
+}
+
 static int ads112c14_read_label(struct iio_dev *indio_dev,
 				struct iio_chan_spec const *chan, char *label)
 {
@@ -425,9 +529,38 @@ static int ads112c14_read_label(struct iio_dev *indio_dev,
 
 static const struct iio_info ads112c14_info = {
 	.read_raw = ads112c14_read_raw,
+	.read_avail = ads112c14_read_avail,
+	.write_raw = ads112c14_write_raw,
+	.write_raw_get_fmt = ads112c14_write_raw_get_fmt,
 	.read_label = ads112c14_read_label,
 };
 
+static void ads112c14_populate_scale_available(int scale_avail[][2],
+					       u32 full_scale, u32 fsr_bits)
+{
+	for (u32 i = 0; i < ARRAY_SIZE(ads112c14_pga_gains_x10); i++) {
+		int *entry = scale_avail[i];
+		u64 gain_x10, nano_scale;
+
+		gain_x10 = ads112c14_pga_gains_x10[i];
+		nano_scale = div64_u64((u64)NANO * 10U * full_scale,
+				       gain_x10 * BIT(fsr_bits));
+		entry[0] = div_u64_rem(nano_scale, NANO, &entry[1]);
+	}
+}
+
+static void ads112c14_populate_tables(struct ads112c14_data *data)
+{
+	u32 full_scale, fsr_bits;
+
+	/* For now, assuming all sys_mon channels are using 2.5V reference. */
+	full_scale = ADS112C14_INT_REF1_mV;
+	fsr_bits = data->chip_info->resolution_bits - 1;
+
+	ads112c14_populate_scale_available(data->sys_mon_chan_short_scale_available,
+					   full_scale, fsr_bits);
+}
+
 static int ads112c14_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
@@ -483,6 +616,9 @@ static int ads112c14_probe(struct i2c_client *client)
 	if (FIELD_GET(ADS112C14_STATUS_MSB_RESETN, reg_val))
 		return dev_err_probe(dev, -EIO, "reset failed\n");
 
+	/* Default gain after reset is 1. */
+	data->sys_mon_chan_short_gain_val = 1;
+
 	/*
 	 * Clear reset bit to prepare for next probe. And clear AVDD fault since
 	 * that happens on every reset.
@@ -499,6 +635,8 @@ static int ads112c14_probe(struct i2c_client *client)
 	if (ret)
 		return ret;
 
+	ads112c14_populate_tables(data);
+
 	indio_dev->name = info->name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = ads112c14_sys_mon_channels;

-- 
2.43.0

[PATCH v2 8/8] iio: adc: ti-ads112c14: add measurement channel support

[David Lechner (TI)]

Add support for parsing devicetree properties for measurement channels
and doing direct reads on these.

There are quite a lot of conditions that have to be met for each
measurement to be made, so quite a bit of state and algorithms are
required to handle it.

Channels are created dynamically since the number of possibilities is
unreasonably large.

Signed-off-by: David Lechner (TI) <dlechner@baylibre.com>
---
v2 changes:
* Adapted for changes in DT bindings.
* Fixed bug in IDAC current register value calculation.
* Fix uninitialized variable bug.
* Fix bug in data->num_measurements calculation.
* Use IIO_RESISTANCE instead of IIO_VOLTAGE when external reference is
  used and it is a resistor rather than a voltage source.
* Fix bug with negative input mux selection on single-ended measurements.
* Fixed return checks of devm_regulator_get_enable_read_voltage().
---
 drivers/iio/adc/ti-ads112c14.c | 523 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 512 insertions(+), 11 deletions(-)

diff --git a/drivers/iio/adc/ti-ads112c14.c b/drivers/iio/adc/ti-ads112c14.c
index 0e775dbc8d50..05d9670c72a4 100644
--- a/drivers/iio/adc/ti-ads112c14.c
+++ b/drivers/iio/adc/ti-ads112c14.c
@@ -9,11 +9,14 @@
  */
 
 #include <linux/bitfield.h>
+#include <linux/cleanup.h>
 #include <linux/delay.h>
 #include <linux/dev_printk.h>
+#include <linux/device/devres.h>
 #include <linux/i2c.h>
 #include <linux/iio/iio.h>
 #include <linux/math64.h>
+#include <linux/minmax.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/property.h>
@@ -62,6 +65,10 @@
 #define   ADS112C14_DEVICE_CFG_PWDN			BIT(7)
 #define   ADS112C14_DEVICE_CFG_STBY_MODE		BIT(6)
 #define   ADS112C14_DEVICE_CFG_BOCS			GENMASK(5, 4)
+#define     ADS112C14_DEVICE_CFG_BOCS_DISABLED		  0
+#define     ADS112C14_DEVICE_CFG_BOCS_200_nA		  1
+#define     ADS112C14_DEVICE_CFG_BOCS_1_uA		  2
+#define     ADS112C14_DEVICE_CFG_BOCS_10_uA		  3
 #define   ADS112C14_DEVICE_CFG_CLK_SEL			BIT(3)
 #define   ADS112C14_DEVICE_CFG_CONV_MODE		BIT(2)
 #define   ADS112C14_DEVICE_CFG_SPEED_MODE		GENMASK(1, 0)
@@ -74,6 +81,7 @@
 #define ADS112C14_REG_MUX_CFG				0x07
 #define   ADS112C14_MUX_CFG_AINP			GENMASK(7, 4)
 #define   ADS112C14_MUX_CFG_AINN			GENMASK(3, 0)
+#define     ADS112C14_MUX_CFG_AIN_GND			  0x8
 
 #define ADS112C14_REG_GAIN_CFG				0x08
 #define   ADS112C14_GAIN_CFG_SPARE			BIT(7)
@@ -88,6 +96,9 @@
 #define     ADS112C14_REFERENCE_CFG_REF_VAL_1_25V	  0
 #define     ADS112C14_REFERENCE_CFG_REF_VAL_2_5V	  1
 #define   ADS112C14_REFERENCE_CFG_REF_SEL		GENMASK(1, 0)
+#define     ADS112C14_REFERENCE_CFG_REF_SEL_INTERNAL	  0
+#define     ADS112C14_REFERENCE_CFG_REF_SEL_EXTERNAL	  1
+#define     ADS112C14_REFERENCE_CFG_REF_SEL_AVDD	  2
 
 #define ADS112C14_REG_DIGITAL_CFG			0x0A
 #define   ADS112C14_DIGITAL_CFG_REG_MAP_CRC_EN		BIT(6)
@@ -124,6 +135,20 @@
 #define ADS112C14_INT_REF0_mV				1250
 #define ADS112C14_INT_REF1_mV				2500
 
+enum {
+	ADS112C14_VREF_SOURCE_INTERNAL_2_5V,
+	ADS112C14_VREF_SOURCE_INTERNAL_1_25V,
+	ADS112C14_VREF_SOURCE_EXTERNAL,
+	ADS112C14_VREF_SOURCE_AVDD,
+};
+
+static const char * const ads112c14_vref_source_names[] = {
+	[ADS112C14_VREF_SOURCE_INTERNAL_2_5V] = "internal-2.5v",
+	[ADS112C14_VREF_SOURCE_INTERNAL_1_25V] = "internal-1.25v",
+	[ADS112C14_VREF_SOURCE_EXTERNAL] = "external",
+	[ADS112C14_VREF_SOURCE_AVDD] = "avdd",
+};
+
 /* Available gains as tenths (x10) */
 static const u32 ads112c14_pga_gains_x10[] = {
 	5, /* 0.5 */
@@ -199,9 +224,32 @@ struct ads112c14_chip_info {
 	u32 resolution_bits;
 };
 
+struct ads112c14_measurement {
+	const char *label;
+	u32 vref_source;
+	u8 iunit;
+	u8 idac1_mag;
+	u8 idac2_mag;
+	u8 idac1_mux;
+	u8 idac2_mux;
+	u8 iadc_count;
+	u8 gain_val;
+	u8 burnout;
+	bool global_chop;
+	bool bipolar;
+	int scale_available[ARRAY_SIZE(ads112c14_pga_gains_x10)][2];
+};
+
 struct ads112c14_data {
 	const struct ads112c14_chip_info *chip_info;
 	struct regmap *regmap;
+	u32 avdd_uV;
+	u32 ext_ref_uV;
+	bool refp_is_avdd;
+	bool refn_is_gnd;
+	u32 ext_ref_ohms;
+	struct ads112c14_measurement *measurements;
+	u32 num_measurements;
 	u8 sys_mon_chan_short_gain_val;
 	int sys_mon_chan_short_scale_available[ARRAY_SIZE(ads112c14_pga_gains_x10)][2];
 };
@@ -260,12 +308,106 @@ static const struct iio_chan_spec ads112c14_sys_mon_channels[] = {
 	},
 };
 
+static int ads112c14_prepare_measurement_channel(struct ads112c14_data *data,
+						 const struct iio_chan_spec *chan)
+{
+	struct ads112c14_measurement *measurement = &data->measurements[chan->scan_index];
+	u32 refp_buf_en, refn_buf_en, ref_val, ref_sel;
+	int ret;
+
+	ret = regmap_write(data->regmap, ADS112C14_REG_MUX_CFG,
+			   FIELD_PREP(ADS112C14_MUX_CFG_AINP, chan->channel) |
+			   FIELD_PREP(ADS112C14_MUX_CFG_AINN, chan->channel2));
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(data->regmap, ADS112C14_REG_DIGITAL_CFG,
+				 ADS112C14_DIGITAL_CFG_CODING,
+				 FIELD_PREP(ADS112C14_DIGITAL_CFG_CODING,
+					    measurement->bipolar ? 0 : 1));
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(data->regmap, ADS112C14_REG_GAIN_CFG,
+				 ADS112C14_GAIN_CFG_SYS_MON | ADS112C14_GAIN_CFG_GAIN,
+				 FIELD_PREP(ADS112C14_GAIN_CFG_SYS_MON, 0) |
+				 FIELD_PREP(ADS112C14_GAIN_CFG_GAIN,
+					    measurement->gain_val));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(data->regmap, ADS112C14_REG_IDAC_MAG_CFG,
+			   FIELD_PREP(ADS112C14_IDAC_MAG_CFG_I2MAG,
+				      measurement->idac2_mag) |
+			   FIELD_PREP(ADS112C14_IDAC_MAG_CFG_I1MAG,
+				      measurement->idac1_mag));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(data->regmap, ADS112C14_REG_IDAC_MUX_CFG,
+			   FIELD_PREP(ADS112C14_IDAC_MUX_CFG_IUNIT,
+				      measurement->iunit) |
+			   FIELD_PREP(ADS112C14_IDAC_MUX_CFG_I2MUX,
+				      measurement->idac2_mux) |
+			   FIELD_PREP(ADS112C14_IDAC_MUX_CFG_I1MUX,
+				      measurement->idac1_mux));
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(data->regmap, ADS112C14_REG_DATA_RATE_CFG,
+				 ADS112C14_DATA_RATE_CFG_GC_EN,
+				 FIELD_PREP(ADS112C14_DATA_RATE_CFG_GC_EN,
+					    measurement->global_chop));
+	if (ret)
+		return ret;
+
+	refp_buf_en = !data->refp_is_avdd &&
+		      measurement->vref_source == ADS112C14_VREF_SOURCE_EXTERNAL;
+	refn_buf_en = !data->refn_is_gnd &&
+		      measurement->vref_source == ADS112C14_VREF_SOURCE_EXTERNAL;
+
+	ref_val = measurement->vref_source == ADS112C14_VREF_SOURCE_INTERNAL_2_5V ?
+		ADS112C14_REFERENCE_CFG_REF_VAL_2_5V :
+		ADS112C14_REFERENCE_CFG_REF_VAL_1_25V;
+
+	switch (measurement->vref_source) {
+	case ADS112C14_VREF_SOURCE_AVDD:
+		ref_sel = ADS112C14_REFERENCE_CFG_REF_SEL_AVDD;
+		break;
+	case ADS112C14_VREF_SOURCE_EXTERNAL:
+		ref_sel = ADS112C14_REFERENCE_CFG_REF_SEL_EXTERNAL;
+		break;
+	default:
+		ref_sel = ADS112C14_REFERENCE_CFG_REF_SEL_INTERNAL;
+		break;
+	}
+
+	return regmap_update_bits(data->regmap, ADS112C14_REG_REFERENCE_CFG,
+				  ADS112C14_REFERENCE_CFG_REFP_BUF_EN |
+				  ADS112C14_REFERENCE_CFG_REFN_BUF_EN |
+				  ADS112C14_REFERENCE_CFG_REF_VAL |
+				  ADS112C14_REFERENCE_CFG_REF_SEL,
+				  FIELD_PREP(ADS112C14_REFERENCE_CFG_REFP_BUF_EN,
+					     refp_buf_en) |
+				  FIELD_PREP(ADS112C14_REFERENCE_CFG_REFN_BUF_EN,
+					     refn_buf_en) |
+				  FIELD_PREP(ADS112C14_REFERENCE_CFG_REF_VAL,
+					     ref_val) |
+				  FIELD_PREP(ADS112C14_REFERENCE_CFG_REF_SEL,
+					     ref_sel));
+}
+
 static int ads112c14_prepare_sys_mon_channel(struct ads112c14_data *data,
 					     const struct iio_chan_spec *chan)
 {
 	u32 gain_val;
 	int ret;
 
+	/*
+	 * NB: IDAC registers are left as-is in case they are generating current
+	 * needed for the external reference measurement.
+	 */
+
 	/*
 	 * All SYS_MON channels use GAIN of 1 to keep it simple. Other than
 	 * the internal short channel, where it is useful in practice.
@@ -321,8 +463,9 @@ static int ads112c14_single_conversion(struct ads112c14_data *data,
 	int ret;
 
 	if (chan->channel < 100) {
-		/* Not implemented yet. */
-		return -EINVAL;
+		ret = ads112c14_prepare_measurement_channel(data, chan);
+		if (ret)
+			return ret;
 	} else {
 		ret = ads112c14_prepare_sys_mon_channel(data, chan);
 		if (ret)
@@ -351,6 +494,7 @@ static int ads112c14_read_raw(struct iio_dev *indio_dev,
 			      int *val2, long mask)
 {
 	struct ads112c14_data *data = iio_priv(indio_dev);
+	struct ads112c14_measurement *measurement = NULL;
 	u32 vref_uV, fsr_bits;
 	int *scale_avail;
 
@@ -358,8 +502,8 @@ static int ads112c14_read_raw(struct iio_dev *indio_dev,
 	vref_uV = ADS112C14_INT_REF1_mV * (MICRO / MILLI);
 
 	if (chan->channel < 100) {
-		/* Not implemented yet. */
-		return -EINVAL;
+		measurement = &data->measurements[chan->scan_index];
+		fsr_bits = data->chip_info->resolution_bits - measurement->bipolar;
 	} else {
 		/* All SYS_MON channels are using signed coding. */
 		fsr_bits = data->chip_info->resolution_bits - 1;
@@ -389,7 +533,8 @@ static int ads112c14_read_raw(struct iio_dev *indio_dev,
 			return -EINVAL;
 		}
 
-		*val = sign_extend32(*val, fsr_bits);
+		if (!measurement || measurement->bipolar)
+			*val = sign_extend32(*val, fsr_bits);
 
 		return IIO_VAL_INT;
 	}
@@ -401,6 +546,14 @@ static int ads112c14_read_raw(struct iio_dev *indio_dev,
 			return IIO_VAL_FRACTIONAL_LOG2;
 		}
 
+		if (chan->channel < 100) {
+			scale_avail = measurement->scale_available[measurement->gain_val];
+			*val = scale_avail[0];
+			*val2 = scale_avail[1];
+
+			return IIO_VAL_INT_PLUS_NANO;
+		}
+
 		if (chan->channel == ADS112C14_SYS_MON_CHANNEL_SHORT) {
 			u8 idx = data->sys_mon_chan_short_gain_val;
 
@@ -441,6 +594,16 @@ static int ads112c14_read_avail(struct iio_dev *indio_dev,
 {
 	struct ads112c14_data *data = iio_priv(indio_dev);
 
+	if (chan->channel < 100) {
+		struct ads112c14_measurement *measurement;
+
+		measurement = &data->measurements[chan->scan_index];
+		*vals = (const int *)measurement->scale_available;
+		*length = 2 * ARRAY_SIZE(measurement->scale_available);
+		*type = IIO_VAL_INT_PLUS_NANO;
+		return IIO_AVAIL_LIST;
+	}
+
 	if (chan->channel == ADS112C14_SYS_MON_CHANNEL_SHORT) {
 		*vals = (const int *)data->sys_mon_chan_short_scale_available;
 		*length = 2 * ARRAY_SIZE(data->sys_mon_chan_short_scale_available);
@@ -461,7 +624,13 @@ static int ads112c14_write_raw(struct iio_dev *indio_dev,
 
 	switch (mask) {
 	case IIO_CHAN_INFO_SCALE: {
-		if (chan->channel == ADS112C14_SYS_MON_CHANNEL_SHORT) {
+		if (chan->channel < 100) {
+			struct ads112c14_measurement *measurement;
+
+			measurement = &data->measurements[chan->scan_index];
+			scale_avail = measurement->scale_available;
+			gain_val = &measurement->gain_val;
+		} else if (chan->channel == ADS112C14_SYS_MON_CHANNEL_SHORT) {
 			scale_avail = data->sys_mon_chan_short_scale_available;
 			gain_val = &data->sys_mon_chan_short_gain_val;
 		} else {
@@ -501,8 +670,21 @@ static int ads112c14_write_raw_get_fmt(struct iio_dev *indio_dev,
 static int ads112c14_read_label(struct iio_dev *indio_dev,
 				struct iio_chan_spec const *chan, char *label)
 {
+	struct ads112c14_data *data = iio_priv(indio_dev);
 	const char *label_source;
 
+	/* measurement channels */
+	if (chan->channel < 100) {
+		struct ads112c14_measurement *measurement;
+
+		measurement = &data->measurements[chan->scan_index];
+
+		if (!measurement->label)
+			return -EINVAL;
+
+		return sysfs_emit(label, "%s\n", measurement->label);
+	}
+
 	/* System monitor channels. */
 	switch (chan->channel) {
 	case ADS112C14_SYS_MON_CHANNEL_TEMP:
@@ -535,6 +717,234 @@ static const struct iio_info ads112c14_info = {
 	.read_label = ads112c14_read_label,
 };
 
+static int ads112c14_populate_idac_mag(u32 current_nA, u8 *idac_mag)
+{
+	u32 current_uA = current_nA / (NANO / MICRO);
+
+	/* Convert microamps to IMAG bits */
+	if (current_uA == 1)
+		*idac_mag = 1;
+	else if (in_range(current_uA, 10, 100) && current_uA % 10 == 0)
+		*idac_mag = current_uA / 10 + 1;
+	else
+		return dev_err_probe(NULL, -EINVAL,
+				     "invalid excitation-current-nanoamp value\n");
+
+	return 0;
+}
+
+static int ads112c14_parse_channels(struct iio_dev *indio_dev,
+				    bool *need_avdd_ref, bool *need_ext_ref)
+{
+	struct ads112c14_data *data = iio_priv(indio_dev);
+	struct device *dev = indio_dev->dev.parent;
+	struct iio_chan_spec *channels;
+	u32 num_child_nodes, i, pair[2];
+	int ret;
+
+	*need_avdd_ref = false;
+	*need_ext_ref = false;
+
+	num_child_nodes = device_get_named_child_node_count(dev, "channel");
+
+	data->measurements = devm_kcalloc(dev, num_child_nodes,
+					  sizeof(*data->measurements), GFP_KERNEL);
+	if (!data->measurements)
+		return -ENOMEM;
+
+	channels = devm_kcalloc(dev, num_child_nodes +
+				ARRAY_SIZE(ads112c14_sys_mon_channels),
+				sizeof(*channels), GFP_KERNEL);
+	if (!channels)
+		return -ENOMEM;
+
+	i = 0;
+	device_for_each_named_child_node_scoped(dev, child, "channel") {
+		struct ads112c14_measurement *measurement = &data->measurements[i];
+		struct iio_chan_spec *spec = &channels[i];
+
+		if (!fwnode_device_is_available(child))
+			continue;
+
+		spec->indexed = 1;
+		spec->scan_index = i;
+		measurement->gain_val = 1;
+
+		fwnode_property_read_string(child, "label", &measurement->label);
+
+		if (fwnode_property_present(child, "single-channel")) {
+			ret = fwnode_property_read_u32(child, "single-channel",
+						       &pair[0]);
+			if (ret)
+				return dev_err_probe(dev, ret,
+						     "failed to read single-channel property\n");
+
+			if (pair[0] >= 8)
+				return dev_err_probe(dev, -EINVAL,
+						     "single-channel value must be between 0 and 7\n");
+
+			spec->channel = pair[0];
+			/* NB: channel2 is unused by iio core code in this case. */
+			spec->channel2 = ADS112C14_MUX_CFG_AIN_GND;
+		} else if (fwnode_property_present(child, "diff-channels")) {
+			ret = fwnode_property_read_u32_array(child, "diff-channels",
+							     pair, ARRAY_SIZE(pair));
+			if (ret)
+				return dev_err_probe(dev, ret,
+						     "failed to read diff-channels property\n");
+
+			if (pair[0] >= 8 || pair[1] >= 8)
+				return dev_err_probe(dev, -EINVAL,
+						     "diff-channels values must be between 0 and 7\n");
+
+			spec->differential = 1;
+			spec->channel = pair[0];
+			spec->channel2 = pair[1];
+		} else {
+			return dev_err_probe(dev, -EINVAL,
+					     "channel node missing channel type property\n");
+		}
+
+		if (fwnode_property_present(child, "excitation-channels")) {
+			ret = fwnode_property_count_u32(child, "excitation-channels");
+			if (ret < 0)
+				return dev_err_probe(dev, ret,
+						     "failed to read excitation-channels property\n");
+
+			if (ret < 1 || ret > 2)
+				return dev_err_probe(dev, -EINVAL,
+						     "excitation-channels property must have 1 or 2 values\n");
+
+			measurement->iadc_count = ret;
+			pair[1] = 0;
+
+			ret = fwnode_property_read_u32_array(child, "excitation-channels",
+							     pair, measurement->iadc_count);
+			if (ret)
+				return dev_err_probe(dev, ret,
+						     "failed to read excitation-channels property\n");
+
+			if (pair[0] >= 8 || pair[1] >= 8)
+				return dev_err_probe(dev, -EINVAL,
+						     "excitation-channels values must be between 0 and 7\n");
+
+			measurement->idac1_mux = pair[0];
+			measurement->idac2_mux = measurement->iadc_count > 1 ? pair[1] : 0;
+
+			ret = fwnode_property_read_u32_array(child, "excitation-current-nanoamp",
+							     pair, measurement->iadc_count);
+			if (ret)
+				return dev_err_probe(dev, ret,
+						     "failed to read excitation-current-nanoamp property\n");
+
+			if (pair[0] <= 100000 && (measurement->iadc_count == 1 || pair[1] <= 100000)) {
+				/*
+				 * If both values are 100uA or less, then we can
+				 * use IUNIT = 1uA for better precision.
+				 */
+				ret = ads112c14_populate_idac_mag(pair[0],
+								  &measurement->idac1_mag);
+				if (ret)
+					return ret;
+
+				if (measurement->iadc_count > 1) {
+					ret = ads112c14_populate_idac_mag(pair[1],
+									  &measurement->idac2_mag);
+					if (ret)
+						return ret;
+				}
+			} else {
+				/*
+				 * Otherwise, IUINT is 10uA (flag set) and so
+				 * IxMAG is 1/10 of the actual current.
+				 */
+				measurement->iunit = 1;
+
+				ret = ads112c14_populate_idac_mag(pair[0] / 10,
+								  &measurement->idac1_mag);
+				if (ret)
+					return ret;
+
+				if (measurement->iadc_count > 1) {
+					ret = ads112c14_populate_idac_mag(pair[1] / 10,
+									  &measurement->idac2_mag);
+					if (ret)
+						return ret;
+				}
+			}
+		}
+
+		measurement->global_chop = fwnode_property_read_bool(child,
+								     "input-channel-rotation");
+
+		if (fwnode_property_present(child, "burn-out-current-nanoamp")) {
+			u32 burnout_nA;
+
+			ret = fwnode_property_read_u32(child, "burn-out-current-nanoamp",
+						       &burnout_nA);
+			if (ret)
+				return dev_err_probe(dev, ret,
+						     "failed to read burn-out-current-nanoamp property\n");
+
+			switch (burnout_nA) {
+			case 200:
+				measurement->burnout = ADS112C14_DEVICE_CFG_BOCS_200_nA;
+				break;
+			case 1000:
+				measurement->burnout = ADS112C14_DEVICE_CFG_BOCS_1_uA;
+				break;
+			case 10000:
+				measurement->burnout = ADS112C14_DEVICE_CFG_BOCS_10_uA;
+				break;
+			default:
+				return dev_err_probe(dev, -EINVAL,
+						     "invalid burn-out-current-nanoamp value\n");
+			}
+		}
+
+		measurement->bipolar = fwnode_property_read_bool(child, "bipolar");
+
+		if (fwnode_property_present(child, "reference-sources")) {
+			ret = fwnode_property_match_property_string(child,
+				"reference-sources", ads112c14_vref_source_names,
+				ARRAY_SIZE(ads112c14_vref_source_names));
+			if (ret < 0)
+				return dev_err_probe(dev, ret,
+						     "invalid reference-sources value\n");
+
+			measurement->vref_source = ret;
+		}
+
+		if (measurement->vref_source == ADS112C14_VREF_SOURCE_AVDD)
+			*need_avdd_ref = true;
+		if (measurement->vref_source == ADS112C14_VREF_SOURCE_EXTERNAL)
+			*need_ext_ref = true;
+
+		spec->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE);
+		spec->info_mask_separate_available = BIT(IIO_CHAN_INFO_SCALE);
+
+		/*
+		 * If reference source is resistor rather than voltage supply,
+		 * then the measurement is effectively a resistance measurement.
+		 */
+		spec->type = (measurement->vref_source == ADS112C14_VREF_SOURCE_EXTERNAL &&
+			      data->ext_ref_ohms) ? IIO_RESISTANCE : IIO_VOLTAGE;
+
+		if (spec->type == IIO_RESISTANCE)
+			spec->differential = 0;
+
+		i++;
+	}
+
+	data->num_measurements = i;
+	memcpy(channels + i, ads112c14_sys_mon_channels, sizeof(ads112c14_sys_mon_channels));
+
+	indio_dev->channels = channels;
+	indio_dev->num_channels = i + ARRAY_SIZE(ads112c14_sys_mon_channels);
+
+	return 0;
+}
+
 static void ads112c14_populate_scale_available(int scale_avail[][2],
 					       u32 full_scale, u32 fsr_bits)
 {
@@ -553,6 +963,33 @@ static void ads112c14_populate_tables(struct ads112c14_data *data)
 {
 	u32 full_scale, fsr_bits;
 
+	for (u32 i = 0; i < data->num_measurements; i++) {
+		struct ads112c14_measurement *measurement = &data->measurements[i];
+
+		switch (measurement->vref_source) {
+		case ADS112C14_VREF_SOURCE_EXTERNAL:
+			if (data->ext_ref_ohms)
+				full_scale = data->ext_ref_ohms;
+			else
+				full_scale = data->ext_ref_uV / (MICRO / MILLI);
+			break;
+		case ADS112C14_VREF_SOURCE_AVDD:
+			full_scale = data->avdd_uV / (MICRO / MILLI);
+			break;
+		case ADS112C14_VREF_SOURCE_INTERNAL_1_25V:
+			full_scale = ADS112C14_INT_REF0_mV;
+			break;
+		default:
+			full_scale = ADS112C14_INT_REF1_mV;
+			break;
+		}
+
+		fsr_bits = data->chip_info->resolution_bits - measurement->bipolar;
+
+		ads112c14_populate_scale_available(measurement->scale_available,
+						   full_scale, fsr_bits);
+	}
+
 	/* For now, assuming all sys_mon channels are using 2.5V reference. */
 	full_scale = ADS112C14_INT_REF1_mV;
 	fsr_bits = data->chip_info->resolution_bits - 1;
@@ -567,6 +1004,9 @@ static int ads112c14_probe(struct i2c_client *client)
 	const struct ads112c14_chip_info *info;
 	struct iio_dev *indio_dev;
 	struct ads112c14_data *data;
+	bool need_avdd_ref, need_ext_ref;
+	u32 refp_uV = 0;
+	u32 refn_uV = 0;
 	u32 reg_val;
 	int ret;
 
@@ -581,13 +1021,76 @@ static int ads112c14_probe(struct i2c_client *client)
 	data = iio_priv(indio_dev);
 	data->chip_info = info;
 
+	if (device_property_present(dev, "ti,refp-refn-resistor-ohms")) {
+		ret = device_property_read_u32(dev, "ti,refp-refn-resistor-ohms",
+					       &data->ext_ref_ohms);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "failed to read ti,refp-refn-resistor-ohms property\n");
+	}
+
+	ret = ads112c14_parse_channels(indio_dev, &need_avdd_ref, &need_ext_ref);
+	if (ret)
+		return ret;
+
 	ret = devm_regulator_get_enable(dev, "dvdd");
 	if (ret)
 		return dev_err_probe(dev, ret, "failed to get dvdd regulator\n");
 
-	ret = devm_regulator_get_enable(dev, "avdd");
-	if (ret)
-		return dev_err_probe(dev, ret, "failed to get avdd regulator\n");
+	if (need_avdd_ref) {
+		ret = devm_regulator_get_enable_read_voltage(dev, "avdd");
+		if (ret < 0)
+			return dev_err_probe(dev, ret, "failed to get avdd voltage\n");
+
+		data->avdd_uV = ret;
+	} else {
+		ret = devm_regulator_get_enable(dev, "avdd");
+		if (ret)
+			return dev_err_probe(dev, ret, "failed to get avdd regulator\n");
+	}
+
+	if (device_property_present(dev, "refp-supply")) {
+		ret = devm_regulator_get_enable_read_voltage(dev, "refp");
+		if (ret < 0)
+			return dev_err_probe(dev, ret, "failed to get refp voltage\n");
+
+		refp_uV = ret;
+
+		struct fwnode_handle *refp_fwnode __free(fwnode_handle) =
+			fwnode_find_reference(dev->fwnode, "refp-supply", 0);
+		if (IS_ERR(refp_fwnode))
+			return dev_err_probe(dev, PTR_ERR(refp_fwnode),
+					     "failed to get refp fwnode\n");
+
+		struct fwnode_handle *avdd_fwnode __free(fwnode_handle) =
+			fwnode_find_reference(dev->fwnode, "avdd-supply", 0);
+		if (IS_ERR(avdd_fwnode))
+			return dev_err_probe(dev, PTR_ERR(avdd_fwnode),
+					     "failed to get avdd fwnode\n");
+
+		/* REFP buffer should not be enabled when connected to AVDD */
+		data->refp_is_avdd = refp_fwnode == avdd_fwnode;
+	}
+
+	if (device_property_present(dev, "refn-supply")) {
+		ret = devm_regulator_get_enable_read_voltage(dev, "refn");
+		if (ret < 0)
+			return dev_err_probe(dev, ret, "failed to get refn voltage\n");
+
+		refn_uV = ret;
+	} else {
+		data->refn_is_gnd = true;
+	}
+
+	data->ext_ref_uV = refp_uV - refn_uV;
+
+	if (data->ext_ref_uV && data->ext_ref_ohms)
+		return dev_err_probe(dev, -EINVAL,
+				     "ti,refp-refn-resistor-ohms property should not be present when refp-supply or refn-supply is present\n");
+
+	if (need_ext_ref && !data->ext_ref_uV && !data->ext_ref_ohms)
+		return dev_err_probe(dev, -EINVAL,
+				     "external reference measurements require either refp-supply or ti,refp-refn-resistor-ohms property\n");
 
 	data->regmap = devm_regmap_init_i2c(client, &ads112c14_regmap_config);
 	if (IS_ERR(data->regmap))
@@ -639,8 +1142,6 @@ static int ads112c14_probe(struct i2c_client *client)
 
 	indio_dev->name = info->name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
-	indio_dev->channels = ads112c14_sys_mon_channels;
-	indio_dev->num_channels = ARRAY_SIZE(ads112c14_sys_mon_channels);
 	indio_dev->info = &ads112c14_info;
 
 	return devm_iio_device_register(dev, indio_dev);

-- 
2.43.0

Re: [PATCH v2 6/8] iio: adc: add ti-ads112c14 driver

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] Short I2C reads lead to the use of uninitialized stack memory for ADC readings.
- [High] The driver inadvertently sets the device into Continuous Conversion mode instead of the intended Single-Shot mode.
--

commit 610f816911f47ce29d3c83f300222d6ab72f8820
Author: David Lechner (TI) <dlechner@baylibre.com>

iio: adc: add ti-ads112c14 driver

Add a new driver for the TI ADS112C14/ADS122C14 ADC chips.

This first step is adding a very basic driver that only supports power
on/reset and reading the system monitor channels.

> diff --git a/drivers/iio/adc/ti-ads112c14.c b/drivers/iio/adc/ti-ads112c14.c
> new file mode 100644
> index 0000000000000..c61d472447325
> --- /dev/null
> +++ b/drivers/iio/adc/ti-ads112c14.c

[ ... ]

> +static int ads112c14_single_conversion(struct ads112c14_data *data,
> +				       const struct iio_chan_spec *chan,
> +				       u8 *buf)
> +{

[ ... ]

> +	return i2c_smbus_read_i2c_block_data(client, ADS112C14_CMD_RDATA,
> +					     BITS_TO_BYTES(data->chip_info->resolution_bits),
> +					     buf);
> +}
> +
> +static int ads112c14_read_raw(struct iio_dev *indio_dev,
> +			      struct iio_chan_spec const *chan, int *val,
> +			      int *val2, long mask)
> +{

[ ... ]

> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW: {
> +		u8 buf[3];
> +		int ret;
> +
> +		if (!iio_device_claim_direct(indio_dev))
> +			return -EBUSY;
> +
> +		ret = ads112c14_single_conversion(data, chan, buf);
> +		iio_device_release_direct(indio_dev);
> +		if (ret < 0)
> +			return ret;

[Severity: High]
Does this code handle short I2C reads correctly?

i2c_smbus_read_i2c_block_data() returns the positive byte count on success.
If the device returns fewer bytes than requested, ret will be positive but
less than BITS_TO_BYTES(data->chip_info->resolution_bits).

Since ads112c14_read_raw() only checks if (ret < 0), won't a short read
bypass error handling and cause it to process uninitialized stack memory from
buf, leading to an information leak and corrupted ADC readings?

> +
> +		switch (data->chip_info->resolution_bits) {
> +		case 16:
> +			*val = get_unaligned_be16(buf);

[ ... ]

> +static int ads112c14_probe(struct i2c_client *client)
> +{

[ ... ]

> +	/* Place in single-shot conversion mode to make ready for raw read. */
> +	ret = regmap_set_bits(data->regmap, ADS112C14_REG_DEVICE_CFG,
> +			      ADS112C14_DEVICE_CFG_CONV_MODE);

[Severity: High]
Does setting ADS112C14_DEVICE_CFG_CONV_MODE actually put the device into
continuous conversion mode instead of the intended single-shot mode?

According to the comment, the intention is to use single-shot mode (which is
typically the default value of 0). Setting the bit to 1 appears to enable
continuous conversion mode, which could cause hardware race conditions and
corrupted data when multiplexer settings are changed for new sysfs readings.

> +	if (ret)
> +		return ret;
> +
> +	indio_dev->name = info->name;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260625-iio-adc-ti-ads122c14-v2-0-ceb9b0b561cb@baylibre.com?part=6

Re: [PATCH v2 7/8] iio: adc: ti-ads112c14: implement gain on internal short SYS_MON channel

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Unlocked concurrent accesses to `gain_val` variables can result in data races and potentially corrupted scale values being returned to userspace.
--

commit d2600e3b47039aca86a7fafcbbec65c4180a38f5
Author: David Lechner (TI) <dlechner@baylibre.com>

iio: adc: ti-ads112c14: implement gain on internal short SYS_MON channel

Implement support for the programmable gain amplifier on the internal short
SYS_MON channel. This channel is used for calibration, so it is useful to be
able to set the PGA to the same gain as the external channels.

> diff --git a/drivers/iio/adc/ti-ads112c14.c b/drivers/iio/adc/ti-ads112c14.c
> index c61d472447325..0e775dbc8d50b 100644
> --- a/drivers/iio/adc/ti-ads112c14.c
> +++ b/drivers/iio/adc/ti-ads112c14.c
[ ... ]
> @@ -371,6 +401,17 @@ static int ads112c14_read_raw(struct iio_dev *indio_dev,
>  			return IIO_VAL_FRACTIONAL_LOG2;
>  		}
>  
> +		if (chan->channel == ADS112C14_SYS_MON_CHANNEL_SHORT) {
> +			u8 idx = data->sys_mon_chan_short_gain_val;
> +
> +			scale_avail = data->sys_mon_chan_short_scale_available[idx];
> +
> +			*val = scale_avail[0];
> +			*val2 = scale_avail[1];
> +
> +			return IIO_VAL_INT_PLUS_NANO;
> +		}
> +

[Severity: Medium]
Is it possible for a concurrent write from ads112c14_write_raw() to cause a
data race here?

Since this read side in ads112c14_read_raw() does not acquire the IIO direct
mode lock or use READ_ONCE(), the compiler could reload 
data->sys_mon_chan_short_gain_val.

If the value gets reloaded between the assignments of *val and *val2, the
function might fetch the integer and fractional parts from different gain
configurations, returning a corrupted scale to userspace.

[ ... ]
> +static int ads112c14_write_raw(struct iio_dev *indio_dev,
> +			       struct iio_chan_spec const *chan, int val,
> +			       int val2, long mask)
> +{
[ ... ]
> +		IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
> +		if (IIO_DEV_ACQUIRE_FAILED(claim))
> +			return -EBUSY;
> +
> +		for (u32 i = 0; i < ARRAY_SIZE(ads112c14_pga_gains_x10); i++) {
> +			if (val == scale_avail[i][0] && val2 == scale_avail[i][1]) {
> +				*gain_val = i;
> +				return 0;
> +			}
> +		}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260625-iio-adc-ti-ads122c14-v2-0-ceb9b0b561cb@baylibre.com?part=7

Re: [PATCH v2 8/8] iio: adc: ti-ads112c14: add measurement channel support

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 4 potential issue(s) to consider:

New issues:
- [Medium] The parsed burnout current configuration (`measurement->burnout`) is never applied to the hardware.
- [Medium] Directly checking `fwnode_find_reference` for `avdd-supply` bypasses the regulator framework's dummy fallback, causing probe to fail if the supply is omitted from the devicetree.
- [Medium] Calculation of `ext_ref_uV` can underflow, leading to garbage scaling values and bypassing validation checks.

Pre-existing issues:
- [High] Short reads from `i2c_smbus_read_i2c_block_data()` are not correctly identified as errors, exposing uninitialized kernel stack memory to userspace.
--

commit 61a17369383e7866b0adf6d21770ae99f4aca379
Author: David Lechner (TI) <dlechner@baylibre.com>

iio: adc: ti-ads112c14: add measurement channel support
    
Add support for parsing devicetree properties for measurement channels
and doing direct reads on these.
    
Channels are created dynamically since the number of possibilities is
unreasonably large.

> diff --git a/drivers/iio/adc/ti-ads112c14.c b/drivers/iio/adc/ti-ads112c14.c
> --- a/drivers/iio/adc/ti-ads112c14.c
> +++ b/drivers/iio/adc/ti-ads112c14.c
> @@ -308,106 +463,6 @@ static int ads112c14_prepare_measurement_channel(struct ads112c14_data *data,
>  						 const struct iio_chan_spec *chan)
>  {
>  	struct ads112c14_measurement *measurement = &data->measurements[chan->scan_index];
>  	u32 refp_buf_en, refn_buf_en, ref_val, ref_sel;
>  	int ret;
>  

[ ... ]

>  	ret = regmap_update_bits(data->regmap, ADS112C14_REG_DATA_RATE_CFG,
>  				 ADS112C14_DATA_RATE_CFG_GC_EN,
>  				 FIELD_PREP(ADS112C14_DATA_RATE_CFG_GC_EN,
>  					    measurement->global_chop));
>  	if (ret)
>  		return ret;

[Severity: Medium]
Is the burnout configuration supposed to be applied to the hardware here?

The parsed burn-out-current-nanoamp is saved to measurement->burnout in
ads112c14_parse_channels(), but this function does not appear to write it
to the ADS112C14_REG_DEVICE_CFG register. This might cause the feature to
be silently ignored even when configured in the devicetree.

[ ... ]

> @@ -494,7 +670,6 @@ static int ads112c14_read_raw(struct iio_dev *indio_dev,
>  	case IIO_CHAN_INFO_RAW: {
>  		u8 buf[3];
>  		int ret;
>  
>  		if (!iio_device_claim_direct(indio_dev))
>  			return -EBUSY;
>  
>  		ret = ads112c14_single_conversion(data, chan, buf);
>  		iio_device_release_direct(indio_dev);
>  		if (ret < 0)
>  			return ret;
>  
>  		switch (data->chip_info->resolution_bits) {
>  		case 16:
>  			*val = get_unaligned_be16(buf);

[Severity: High]
This isn't a bug introduced by this patch, but does this adequately handle
short reads?

The i2c_smbus_read_i2c_block_data() function called by
ads112c14_single_conversion() returns the positive number of bytes read on
success. If a short read occurs, ret will be positive and bypass the
ret < 0 check. 

Could this proceed to process a partially uninitialized buf array and expose
kernel stack memory to userspace?

[ ... ]

> @@ -1021,76 +1142,6 @@ static int ads112c14_probe(struct i2c_client *client)
>  	if (device_property_present(dev, "refp-supply")) {
>  		ret = devm_regulator_get_enable_read_voltage(dev, "refp");
>  		if (ret < 0)
>  			return dev_err_probe(dev, ret, "failed to get refp voltage\n");
>  
>  		refp_uV = ret;
>  
>  		struct fwnode_handle *refp_fwnode __free(fwnode_handle) =
>  			fwnode_find_reference(dev->fwnode, "refp-supply", 0);
>  		if (IS_ERR(refp_fwnode))
>  			return dev_err_probe(dev, PTR_ERR(refp_fwnode),
>  					     "failed to get refp fwnode\n");
>  
>  		struct fwnode_handle *avdd_fwnode __free(fwnode_handle) =
>  			fwnode_find_reference(dev->fwnode, "avdd-supply", 0);
>  		if (IS_ERR(avdd_fwnode))
>  			return dev_err_probe(dev, PTR_ERR(avdd_fwnode),
>  					     "failed to get avdd fwnode\n");

[Severity: Medium]
Will this rigidly fail the probe if the avdd-supply is absent?

By directly using fwnode_find_reference(), it seems we bypass the regulator
framework's dummy fallback. If the devicetree omits avdd-supply, this
appears to return -ENOENT and fail unconditionally rather than treating
the missing reference as simply not matching refp_fwnode.

>  
>  		/* REFP buffer should not be enabled when connected to AVDD */
>  		data->refp_is_avdd = refp_fwnode == avdd_fwnode;
>  	}
>  
>  	if (device_property_present(dev, "refn-supply")) {
>  		ret = devm_regulator_get_enable_read_voltage(dev, "refn");
>  		if (ret < 0)
>  			return dev_err_probe(dev, ret, "failed to get refn voltage\n");
>  
>  		refn_uV = ret;
>  	} else {
>  		data->refn_is_gnd = true;
>  	}
>  
>  	data->ext_ref_uV = refp_uV - refn_uV;
>  
>  	if (data->ext_ref_uV && data->ext_ref_ohms)
>  		return dev_err_probe(dev, -EINVAL,
>  				     "ti,refp-refn-resistor-ohms property should not be present when refp-supply or refn-supply is present\n");
>  
>  	if (need_ext_ref && !data->ext_ref_uV && !data->ext_ref_ohms)
>  		return dev_err_probe(dev, -EINVAL,
>  				     "external reference measurements require either refp-supply or ti,refp-refn-resistor-ohms property\n");

[Severity: Medium]
Can this subtraction underflow if refp-supply is missing but refn-supply is
present?

If refp_uV is 0 and refn_uV is greater than 0, subtracting them as unsigned
32-bit integers will wrap to a large positive number. This seems like it
would bypass the subsequent !data->ext_ref_uV validation check and lead to
incorrect values when computing full_scale in ads112c14_populate_tables().

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260625-iio-adc-ti-ads122c14-v2-0-ceb9b0b561cb@baylibre.com?part=8

Re: [PATCH v2 5/8] dt-bindings: iio: adc: add ti,ads122c14

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 6 potential issue(s) to consider:
- [High] The pattern property regex for channel nodes `^channel@[0-7a-f]$` omits digits 8 and 9, rejecting valid node addresses.
- [High] The `burn-out-current-nanoamp` property applies an `enum` constraint directly to an array, which will fail DT validation.
- [Medium] The commit message explicitly claims to reuse the custom 'ti,vref-source' property, but the code actually implements the standard 'reference-sources' property instead.
- [Medium] The JSON schema reference `$ref: adc.yaml` is missing the `#` fragment or the absolute path.
- [Medium] The `reference-sources` property lacks a `maxItems` constraint and leaves subsequent elements unvalidated.
- [Low] Strict index ordering in `interrupts` clashes with unordered `interrupt-names`, causing invalid semantics if only one interrupt is used.
--

commit de052c7080b8c89f1a3c4b730b190d119eacb414
Author: David Lechner (TI) <dlechner@baylibre.com>

dt-bindings: iio: adc: add ti,ads122c14

Add new bindings for ti,ads122c14 and similar devices primarily intended for
use with temperature sensors. These bindings introduce channel-specific
properties to handle per-measurement reference voltage and current output
requirements.

> ti,vref-source is reused from ti,tlv320adcx140.yaml (otherwise might
> have preferred an enum of strings).

[Severity: Medium]
The commit message explicitly states it reuses the 'ti,vref-source' property,
but the schema actually implements the standard 'reference-sources' property
instead. Should the commit message be updated to match the implementation?

> diff --git a/Documentation/devicetree/bindings/iio/adc/ti,ads112c14.yaml b/Documentation/devicetree/bindings/iio/adc/ti,ads112c14.yaml
> new file mode 100644
> index 0000000000000..59ee4d652a087
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/ti,ads112c14.yaml

[ ... ]

> +  interrupts:
> +    minItems: 1
> +    items:
> +      - description: FAULT interrupt (GPIO2 pin)
> +      - description: DRDY interrupt (GPIO3 pin)
> +
> +  interrupt-names:
> +    minItems: 1
> +    maxItems: 2
> +    items:
> +      enum: [fault, drdy]

[Severity: Low]
If a device tree specifies only the DRDY interrupt at index 0, does the strict
ordering in the interrupts list (which expects FAULT at index 0) clash with
the unordered interrupt-names definition?

[ ... ]

> +patternProperties:
> +  ^channel@[0-7a-f]$:
> +    $ref: adc.yaml

[Severity: Medium]
Does the JSON schema reference here need a '#' fragment or an absolute path
to ensure it resolves properly across all tooling versions during validation?

[Severity: High]
Does the regex pattern ^channel@[0-7a-f]$ omit digits 8 and 9? The reg
property below has a maximum of 15, so a device tree legitimately using
channel@8 or channel@9 would fail schema validation.

> +
> +    unevaluatedProperties: false
> +
> +    properties:
> +      reg:
> +        items:
> +          - maximum: 15 # arbitrary limit, channel@ can be any combination of AIN0-AIN7

[ ... ]

> +      burn-out-current-nanoamp:
> +        enum: [200, 1000, 10000]

[Severity: High]
Because device tree properties are parsed as arrays, will applying an enum
constraint directly to the property without using the 'items' keyword cause
dt_binding_check to always fail?

> +
> +      reference-sources:
> +        items:
> +          - enum: [internal-2.5v, internal-1.25v, external, avdd]
> +            default: internal-2.5v

[Severity: Medium]
Is a maxItems constraint needed for this array? Without it, JSON Schema only
applies the list validation to the first element, meaning additional items
in the array might silently pass without being checked.

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260625-iio-adc-ti-ads122c14-v2-0-ceb9b0b561cb@baylibre.com?part=5