[PATCH v10 03/12] dt-bindings: iio: adc: ad7768-1: add trigger-sources property

[Jonathan Santos <Jonathan.Santos@analog.com>]

In addition to GPIO synchronization, The AD7768-1 also supports
synchronization over SPI, which use is recommended when the GPIO
cannot provide a pulse synchronous with the base MCLK signal. It
consists of looping back the SYNC_OUT to the SYNC_IN pin and send
a command via SPI to trigger the synchronization.

Introduce the 'trigger-sources' property to enable SPI-based
synchronization via SYNC_OUT pin, along with additional optional
entries for GPIO3 and DRDY pins.

Also create #trigger-source-cells property to differentiate the trigger
sources provided by the ADC. To improve readability, create a
adi,ad7768-1.h header with the macros for the cell values.

While at it, add description to the interrupts property.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: David Lechner <dlechner@baylirbe.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v10 Changes:
* None.

v9 Changes:
* No changes.

v8 Changes:
* No changes. I have decided to keep the 'dependencies' section header
  since Rob said it is ok for this case.

v7 Changes:
* added new file to the MAINTAINERS entry.
* Made interrupts description more concise.
* Added dependencies to constrain the use of trigger-sources and
  adi,sync-in-gpios properties at the same time.

v6 Changes:
* Removed references to offload.
* Changed trigger-sources-cells description. Each cell value indicates
  a gpio line from the ADC.
* Added adi,ad7768-1.h header with macros for the trigger source cells.
* Removed offload trigger entry from trigger-sources.

v5 Changes:
* Include START pin and DRDY in the trigger-sources description.
* Fixed "#trigger-source-cells" value and description.
* sync-in-gpios is represented in the trigger-sources property.

v4 Changes:
* none

v3 Changes:
* Fixed dt-bindings errors.
* Trigger-source is set as an alternative to sync-in-gpios, so we
  don't break the previous ABI.
* increased maxItems from trigger-sources to 2.

v2 Changes:
* Patch added as replacement for adi,sync-in-spi patch.
* addressed the request for a description to interrupts property.
---
 .../bindings/iio/adc/adi,ad7768-1.yaml        | 39 ++++++++++++++++++-
 MAINTAINERS                                   |  1 +
 include/dt-bindings/iio/adc/adi,ad7768-1.h    | 10 +++++
 3 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 include/dt-bindings/iio/adc/adi,ad7768-1.h

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
index 3ce59d4d065f..9a6df931edc3 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
@@ -26,7 +26,26 @@ properties:
   clock-names:
     const: mclk
 
+  trigger-sources:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    minItems: 1
+    maxItems: 2
+    description: |
+      A list of phandles referencing trigger source providers. Each entry
+      represents a trigger source for the ADC:
+
+        - First entry specifies the device responsible for driving the
+          synchronization (SYNC_IN) pin, as an alternative to adi,sync-in-gpios.
+          This can be a `gpio-trigger` or another `ad7768-1` device. If the
+          device's own SYNC_OUT pin is internally connected to its SYNC_IN pin,
+          reference the device itself or omit this property.
+        - Second entry optionally defines a GPIO3 pin used as a START signal trigger.
+
+      Use the accompanying trigger source cell to identify the type of each entry.
+
   interrupts:
+    description:
+      DRDY (Data Ready) pin, which signals conversion results are available.
     maxItems: 1
 
   '#address-cells':
@@ -57,6 +76,15 @@ properties:
   "#io-channel-cells":
     const: 1
 
+  "#trigger-source-cells":
+    description: |
+      Cell indicates the trigger output signal: 0 = SYNC_OUT, 1 = GPIO3,
+      2 = DRDY.
+
+      For better readability, macros for these values are available in
+      dt-bindings/iio/adc/adi,ad7768-1.h.
+    const: 1
+
 required:
   - compatible
   - reg
@@ -65,7 +93,16 @@ required:
   - vref-supply
   - spi-cpol
   - spi-cpha
-  - adi,sync-in-gpios
+
+dependencies:
+  adi,sync-in-gpios:
+    not:
+      required:
+        - trigger-sources
+  trigger-sources:
+    not:
+      required:
+        - adi,sync-in-gpios
 
 patternProperties:
   "^channel@([0-9]|1[0-5])$":
diff --git a/MAINTAINERS b/MAINTAINERS
index d5d14fc69ac0..426e63e761da 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1452,6 +1452,7 @@ S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
 F:	drivers/iio/adc/ad7768-1.c
+F:	include/dt-bindings/iio/adc/adi,ad7768-1.h
 
 ANALOG DEVICES INC AD7780 DRIVER
 M:	Michael Hennerich <Michael.Hennerich@analog.com>
diff --git a/include/dt-bindings/iio/adc/adi,ad7768-1.h b/include/dt-bindings/iio/adc/adi,ad7768-1.h
new file mode 100644
index 000000000000..34d92856a50b
--- /dev/null
+++ b/include/dt-bindings/iio/adc/adi,ad7768-1.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
+
+#ifndef _DT_BINDINGS_ADI_AD7768_1_H
+#define _DT_BINDINGS_ADI_AD7768_1_H
+
+#define AD7768_TRIGGER_SOURCE_SYNC_OUT  0
+#define AD7768_TRIGGER_SOURCE_GPIO3     1
+#define AD7768_TRIGGER_SOURCE_DRDY      2
+
+#endif /* _DT_BINDINGS_ADI_AD7768_1_H */
-- 
2.34.1