hwmon: (aquacomputer_d5next) Add support for Aquacomputer Octo

Extend aquacomputer_d5next driver to expose hardware temperature sensors
and fans of the Aquacomputer Octo fan controller, which communicates
through a proprietary USB HID protocol.

Four temperature sensors and eight PWM controllable fans are available.
Additionally, serial number, firmware version and power-on count are
exposed through debugfs.

This driver has been tested on x86_64.
Signed-off-by: Aleksa Savic <savicaleksa83@gmail.com>
Link: https://lore.kernel.org/r/20220404134212.9690-1-savicaleksa83@gmail.com
[groeck: Add missing "select CRC16"]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/aquacomputer_d5next.rst

@@ -7,6 +7,7 @@ Supported devices:
 
 * Aquacomputer D5 Next watercooling pump
 * Aquacomputer Farbwerk 360 RGB controller
+* Aquacomputer Octo fan controller
 
 Author: Aleksa Savic
 
@@ -28,6 +29,9 @@ seems to require sending it a complete configuration. That includes addressable
 RGB LEDs, for which there is no standard sysfs interface. Thus, that task is
 better suited for userspace tools.
 
+The Octo exposes four temperature sensors and eight PWM controllable fans, along
+with their speed (in RPM), power, voltage and current.
+
 The Farbwerk 360 exposes four temperature sensors. Depending on the device,
 not all sysfs and debugfs entries will be available.
 

drivers/hwmon/Kconfig

@@ -256,11 +256,13 @@ config SENSORS_AHT10
 	  will be called aht10.
 
 config SENSORS_AQUACOMPUTER_D5NEXT
-	tristate "Aquacomputer D5 Next watercooling pump"
+	tristate "Aquacomputer D5 Next, Octo and Farbwerk 360"
 	depends on USB_HID
+	select CRC16
 	help
-	  If you say yes here you get support for the Aquacomputer D5 Next
-	  watercooling pump sensors.
+	  If you say yes here you get support for sensors and fans of
+	  the Aquacomputer D5 Next watercooling pump, Octo fan
+	  controller and Farbwerk 360 RGB controller, where available.
 
 	  This driver can also be built as a module. If so, the module
 	  will be called aquacomputer_d5next.