linux-kernel - [PATCH 2/8] dt-bindings: iio: adc: ad7606: Add iio backend bindings

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Message-Id: <20240815-ad7606_add_iio_backend_support-v1-2-cea3e11b1aa4@baylibre.com>
Date: Thu, 15 Aug 2024 12:11:56 +0000
From: Guillaume Stols <gstols@...libre.com>
To: Uwe Kleine-König <ukleinek@...nel.org>, 
 Lars-Peter Clausen <lars@...afoo.de>, 
 Michael Hennerich <Michael.Hennerich@...log.com>, 
 Jonathan Cameron <jic23@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, Jonathan Corbet <corbet@....net>
Cc: linux-pwm@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Michael Hennerich <michael.hennerich@...log.com>, 
 linux-fbdev@...r.kernel.org, linux-iio@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-doc@...r.kernel.org, 
 Guillaume Stols <gstols@...libre.com>, 
 20240705211452.1157967-2-u.kleine-koenig@...libre.com, 
 20240712171821.1470833-2-u.kleine-koenig@...libre.com, 
 cover.1721040875.git.u.kleine-koenig@...libre.com, aardelean@...libre.com
Subject: [PATCH 2/8] dt-bindings: iio: adc: ad7606: Add iio backend
 bindings

Add the required properties for iio-backend support, as well as an
example and the conditions to mutually exclude interruption and
conversion trigger with iio-backend.
The iio-backend's function is to controls the communication, and thus the
interruption pin won't be available anymore.
As a consequence, the conversion pin must be controlled externally since
we will miss information about when every single conversion cycle (i.e
conversion + data transfert) ends, hence a PWM is introduced to trigger
the conversions.

Signed-off-by: Guillaume Stols <gstols@...libre.com>
---
 .../devicetree/bindings/iio/adc/adi,ad7606.yaml    | 75 +++++++++++++++++++++-
 1 file changed, 72 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml
index c0008d36320f..4b324f7e3207 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml
@@ -114,13 +114,28 @@ properties:
       assumed that the pins are hardwired to VDD.
     type: boolean

+  pwms:
+    description:
+      In case the conversion is triggered by a PWM instead of a GPIO plugged to
+      the CONVST pin, the PWM must be referenced.
+    minItems: 1
+    maxItems: 2
+
+  pwm-names:
+    minItems: 1
+    maxItems: 2
+
+  io-backends:
+    description:
+      A reference to the iio-backend, which is responsible handling the BUSY
+      pin's falling edge and communication.
+      An example of backend can be found at
+      http://analogdevicesinc.github.io/hdl/library/axi_ad7606x/index.html
+
 required:
   - compatible
-  - reg
   - avcc-supply
   - vdrive-supply
-  - interrupts
-  - adi,conversion-start-gpios

 # This checks if reg is a chipselect so the device is on an SPI
 # bus, the if-clause will fail if reg is a tuple such as for a
@@ -137,6 +152,35 @@ then:
         - spi-cpol

 allOf:
+  # Communication is handled either by the backend or an interrupt.
+  - if:
+      properties:
+        pwms: false
+    then:
+      required:
+        - adi,conversion-start-gpios
+
+  - if:
+      properties:
+        adi,conversion-start-gpios: false
+    then:
+      required:
+        - pwms
+
+  - if:
+      properties:
+        interrupts: false
+    then:
+      required:
+        - io-backends
+
+  - if:
+      properties:
+        io-backends: false
+    then:
+      required:
+        - interrupts
+
   - if:
       properties:
         compatible:
@@ -178,12 +222,37 @@ allOf:
         adi,sw-mode: false
     else:
       properties:
+        pwms:
+          maxItems: 1
+        pwm-names:
+          maxItems: 1
         adi,conversion-start-gpios:
           maxItems: 1

 unevaluatedProperties: false

 examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    / {
+        adi_adc {
+                compatible = "adi,ad7606b";
+
+                pwms = <&axi_pwm_gen 0 0>;
+
+                avcc-supply = <&adc_vref>;
+                vdrive-supply = <&vdd_supply>;
+
+                reset-gpios = <&gpio0 91 GPIO_ACTIVE_HIGH>;
+                standby-gpios = <&gpio0 90 GPIO_ACTIVE_LOW>;
+                adi,range-gpios = <&gpio0 89 GPIO_ACTIVE_HIGH>;
+                adi,oversampling-ratio-gpios = <&gpio0 88 GPIO_ACTIVE_HIGH
+                                                &gpio0 87 GPIO_ACTIVE_HIGH
+                                                &gpio0 86 GPIO_ACTIVE_HIGH>;
+                io-backends = <&iio_backend>;
+        };
+    };
+
   - |
     #include <dt-bindings/gpio/gpio.h>
     #include <dt-bindings/interrupt-controller/irq.h>

-- 
2.34.1