dt-bindings: iio: adc: Add DT binding document for PMIC5 ADC

PMIC5 ADC has support for clients to measure voltage and current
on inputs connected to the PMIC. Clients include reading voltage
phone power and on board system thermistors for thermal management.
ADC5 on certain PMIC has support to read battery current.

This change adds documentation.

Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 58 insertions, 19 deletions

diff --git a/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
index 0fb46137f936..8498f11d06cd 100644
--- a/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
+++ b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
@@ -1,7 +1,9 @@
-Qualcomm's SPMI PMIC voltage ADC
+Qualcomm's SPMI PMIC ADC
 
-SPMI PMIC voltage ADC (VADC) provides interface to clients to read
-voltage. The VADC is a 15-bit sigma-delta ADC.
+- SPMI PMIC voltage ADC (VADC) provides interface to clients to read
+  voltage. The VADC is a 15-bit sigma-delta ADC.
+- SPMI PMIC5 voltage ADC (ADC) provides interface to clients to read
+  voltage. The VADC is a 16-bit sigma-delta ADC.
 
 VADC node:
 
@@ -9,6 +11,8 @@ VADC node:
     Usage: required
     Value type: <string>
     Definition: Should contain "qcom,spmi-vadc".
+                Should contain "qcom,spmi-adc5" for PMIC5 ADC driver.
+                Should contain "qcom,spmi-adc-rev2" for PMIC rev2 ADC driver.
 
 - reg:
     Usage: required
@@ -45,13 +49,26 @@ Channel node properties:
     Definition: ADC channel number.
             See include/dt-bindings/iio/qcom,spmi-vadc.h
 
+- label:
+    Usage: required for "qcom,spmi-adc5" and "qcom,spmi-adc-rev2"
+    Value type: <empty>
+    Definition: ADC input of the platform as seen in the schematics.
+            For thermistor inputs connected to generic AMUX or GPIO inputs
+            these can vary across platform for the same pins. Hence select
+            the platform schematics name for this channel.
+
 - qcom,decimation:
     Usage: optional
     Value type: <u32>
     Definition: This parameter is used to decrease ADC sampling rate.
             Quicker measurements can be made by reducing decimation ratio.
-            Valid values are 512, 1024, 2048, 4096.
-            If property is not found, default value of 512 will be used.
+            - For compatible property "qcom,spmi-vadc", valid values are
+              512, 1024, 2048, 4096. If property is not found, default value
+              of 512 will be used.
+            - For compatible property "qcom,spmi-adc5", valid values are 250, 420
+              and 840. If property is not found, default value of 840 is used.
+            - For compatible property "qcom,spmi-adc-rev2", valid values are 256,
+              512 and 1024. If property is not present, default value is 1024.
 
 - qcom,pre-scaling:
     Usage: optional
@@ -66,21 +83,38 @@ Channel node properties:
 - qcom,ratiometric:
     Usage: optional
     Value type: <empty>
-    Definition: Channel calibration type. If this property is specified
-            VADC will use the VDD reference (1.8V) and GND for channel
-            calibration. If property is not found, channel will be
-            calibrated with 0.625V and 1.25V reference channels, also
-            known as absolute calibration.
+    Definition: Channel calibration type.
+            - For compatible property "qcom,spmi-vadc", if this property is
+              specified VADC will use the VDD reference (1.8V) and GND for
+              channel calibration. If property is not found, channel will be
+              calibrated with 0.625V and 1.25V reference channels, also
+              known as absolute calibration.
+            - For compatible property "qcom,spmi-adc5" and "qcom,spmi-adc-rev2",
+              if this property is specified VADC will use the VDD reference
+              (1.875V) and GND for channel calibration. If property is not found,
+              channel will be calibrated with 0V and 1.25V reference channels,
+              also known as absolute calibration.
 
 - qcom,hw-settle-time:
     Usage: optional
     Value type: <u32>
     Definition: Time between AMUX getting configured and the ADC starting
-            conversion. Delay = 100us * (value) for value < 11, and
-            2ms * (value - 10) otherwise.
-            Valid values are: 0, 100, 200, 300, 400, 500, 600, 700, 800,
-            900 us and 1, 2, 4, 6, 8, 10 ms
-            If property is not found, channel will use 0us.
+            conversion. The 'hw_settle_time' is an index used from valid values
+            and programmed in hardware to achieve the hardware settling delay.
+            - For compatible property "qcom,spmi-vadc" and "qcom,spmi-adc-rev2",
+              Delay = 100us * (hw_settle_time) for hw_settle_time < 11,
+              and 2ms * (hw_settle_time - 10) otherwise.
+              Valid values are: 0, 100, 200, 300, 400, 500, 600, 700, 800,
+              900 us and 1, 2, 4, 6, 8, 10 ms.
+              If property is not found, channel will use 0us.
+            - For compatible property "qcom,spmi-adc5", delay = 15us for
+              value 0, 100us * (value) for values < 11,
+              and 2ms * (value - 10) otherwise.
+              Valid values are: 15, 100, 200, 300, 400, 500, 600, 700, 800,
+              900 us and 1, 2, 4, 6, 8, 10 ms
+              Certain controller digital versions have valid values of
+              15, 100, 200, 300, 400, 500, 600, 700, 1, 2, 4, 8, 16, 32, 64, 128 ms
+              If property is not found, channel will use 15us.
 
 - qcom,avg-samples:
     Usage: optional
@@ -89,13 +123,18 @@ Channel node properties:
             Averaging provides the option to obtain a single measurement
             from the ADC that is an average of multiple samples. The value
             selected is 2^(value).
-            Valid values are: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512
-            If property is not found, 1 sample will be used.
+            - For compatible property "qcom,spmi-vadc", valid values
+              are: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512
+              If property is not found, 1 sample will be used.
+            - For compatible property "qcom,spmi-adc5" and "qcom,spmi-adc-rev2",
+              valid values are: 1, 2, 4, 8, 16
+              If property is not found, 1 sample will be used.
 
 NOTE:
 
-Following channels, also known as reference point channels, are used for
-result calibration and their channel configuration nodes should be defined:
+For compatible property "qcom,spmi-vadc" following channels, also known as
+reference point channels, are used for result calibration and their channel
+configuration nodes should be defined:
 VADC_REF_625MV and/or VADC_SPARE1(based on PMIC version) VADC_REF_1250MV,
 VADC_GND_REF and VADC_VDD_VADC.