[PATCH 1/2] counter: Add support for Quadrature x4 with swapped inputs

[Jarkko Nikula <jarkko.nikula@linux.intel.com>]

Some Quadrature Encoders can swap phase inputs A and B internally. This
new function will allow drivers to configure input swap mode.

This was implemented by Felipe Balbi while he was working at Intel.

Signed-off-by: Felipe Balbi (Intel) <balbi@kernel.org>
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
 Documentation/ABI/testing/sysfs-bus-counter | 4 ++++
 drivers/counter/counter.c                   | 3 ++-
 include/linux/counter.h                     | 3 ++-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-counter b/Documentation/ABI/testing/sysfs-bus-counter
index 566bd99fe0a5..8f1e3de88c77 100644
--- a/Documentation/ABI/testing/sysfs-bus-counter
+++ b/Documentation/ABI/testing/sysfs-bus-counter
@@ -146,6 +146,10 @@ Description:
 			updates	the respective count. Quadrature encoding
 			determines the direction.
 
+		quadrature x4 swapped:
+			Same as quadrature x4, however Phase A and Phase B
+			signals are swapped.
+
 What:		/sys/bus/counter/devices/counterX/countY/name
 KernelVersion:	5.2
 Contact:	linux-iio@vger.kernel.org
diff --git a/drivers/counter/counter.c b/drivers/counter/counter.c
index 6a683d086008..11d357245b14 100644
--- a/drivers/counter/counter.c
+++ b/drivers/counter/counter.c
@@ -752,7 +752,8 @@ static const char *const counter_count_function_str[] = {
 	[COUNTER_COUNT_FUNCTION_QUADRATURE_X1_B] = "quadrature x1 b",
 	[COUNTER_COUNT_FUNCTION_QUADRATURE_X2_A] = "quadrature x2 a",
 	[COUNTER_COUNT_FUNCTION_QUADRATURE_X2_B] = "quadrature x2 b",
-	[COUNTER_COUNT_FUNCTION_QUADRATURE_X4] = "quadrature x4"
+	[COUNTER_COUNT_FUNCTION_QUADRATURE_X4] = "quadrature x4",
+	[COUNTER_COUNT_FUNCTION_QUADRATURE_X4_SWAPPED] = "quadrature x4 swapped"
 };
 
 static ssize_t counter_function_show(struct device *dev,
diff --git a/include/linux/counter.h b/include/linux/counter.h
index 9dbd5df4cd34..c3b4d263eb22 100644
--- a/include/linux/counter.h
+++ b/include/linux/counter.h
@@ -170,7 +170,8 @@ enum counter_count_function {
 	COUNTER_COUNT_FUNCTION_QUADRATURE_X1_B,
 	COUNTER_COUNT_FUNCTION_QUADRATURE_X2_A,
 	COUNTER_COUNT_FUNCTION_QUADRATURE_X2_B,
-	COUNTER_COUNT_FUNCTION_QUADRATURE_X4
+	COUNTER_COUNT_FUNCTION_QUADRATURE_X4,
+	COUNTER_COUNT_FUNCTION_QUADRATURE_X4_SWAPPED,
 };
 
 /**
-- 
2.30.2