[PATCH v3 2/3] misc: servo-pwm: Add sysfs entries to control motor angle

[Angelo Compagnucci <angelo.compagnucci@gmail.com>]

Servo motor can be moved between 0 and degrees angle.

Add 'angle' sysfs attribute:
  *read*: Current motor position.
  *write*: Moves the motor to the position.

Add 'degrees' sysfs attribute:
  *read*: how many degrees the motor can move

Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com>
---
v2:
* Added ABI in testing
v3:
* No changes

 .../ABI/testing/sysfs-driver-servo-pwm        | 20 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 21 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-servo-pwm

diff --git a/Documentation/ABI/testing/sysfs-driver-servo-pwm b/Documentation/ABI/testing/sysfs-driver-servo-pwm
new file mode 100644
index 000000000000..9c4d897073fa
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-servo-pwm
@@ -0,0 +1,20 @@
+What:		/sys/devices/platform/servo*/angle
+Date:		Feb 2023
+Contact:	Angelo Compagnucci <angelo@amarulasolutions.com>
+Description:
+		(RW) read or write servo motor position angle.
+		Servo motor can move between 0 and max degrees angle.
+		As soon the vale is written, the motor will move to the selected
+		angle. Reading the value gives the motor position.
+Users:		any user space application which wants to move the servo
+		motor position.
+
+What:		/sys/devices/platform/servo*/degrees
+Date:		Feb 2023
+Contact:	Angelo Compagnucci <angelo@amarulasolutions.com>
+Description:
+		(RO) read the servo motor movement degrees.
+		Servo motor can move between 0 and max degrees angle.
+		Reading the value gives the motor max degrees angle supported.
+Users:		any user space application which wants to know the max degrees
+		angle motor supports.
diff --git a/MAINTAINERS b/MAINTAINERS
index 8f4af64deb1b..356daea0861d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8741,6 +8741,7 @@ GENERIC PWM SERVO DRIVER
 M:	"Angelo Compagnucci" <angelo@amarulasolutions.com>
 L:	linux-pwm@vger.kernel.org
 S:	Maintained
+F:	Documentation/ABI/testing/sysfs-driver-servo-pwm
 F:	drivers/misc/servo-pwm.c
 
 GENERIC RESISTIVE TOUCHSCREEN ADC DRIVER
-- 
2.34.1