soc: hisilicon: kunpeng_hccs: Support low power feature for the specified HCCS type

Add the low power feature for the specified HCCS type by increasing
and decreasing the used lane number of these HCCS ports on platform.

Signed-off-by: Huisong Li <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>
Signed-off-by: Wei Xu <[email protected]>

Author: LiHuiSong1

Documentation/ABI/testing/sysfs-devices-platform-kunpeng_hccs

@@ -87,3 +87,40 @@ Contact:	Huisong Li <[email protected]>
 Description:
 		This interface is used to show all HCCS types used on the
 		platform, like, HCCS-v1, HCCS-v2 and so on.
+
+What:		/sys/devices/platform/HISI04Bx:00/available_inc_dec_lane_types
+What:		/sys/devices/platform/HISI04Bx:00/dec_lane_of_type
+What:		/sys/devices/platform/HISI04Bx:00/inc_lane_of_type
+Date:		August 2024
+KernelVersion:	6.12
+Contact:	Huisong Li <[email protected]>
+Description:
+		These interfaces under /sys/devices/platform/HISI04Bx/ are
+		used to support the low power consumption feature of some
+		HCCS types by changing the number of lanes used. The interfaces
+		changing the number of lanes used are 'dec_lane_of_type' and
+		'inc_lane_of_type' which require root privileges. These
+		interfaces aren't exposed if no HCCS type on platform support
+		this feature. Please note that decreasing lane number is only
+		allowed if all the specified HCCS ports are not busy.
+
+		The low power consumption interfaces are as follows:
+
+		============================= ==== ================================
+		available_inc_dec_lane_types: (RO) available HCCS types (string) to
+						   increase and decrease the number
+						   of lane used, e.g. HCCS-v2.
+		dec_lane_of_type:             (WO) input HCCS type supported
+						   decreasing lane to decrease the
+						   used lane number of all specified
+						   HCCS type ports on platform to
+						   the minimum.
+						   You can query the 'cur_lane_num'
+						   to get the minimum lane number
+						   after executing successfully.
+		inc_lane_of_type:             (WO) input HCCS type supported
+						   increasing lane to increase the
+						   used lane number of all specified
+						   HCCS type ports on platform to
+						   the full lane state.
+		============================= ==== ================================

drivers/soc/hisilicon/Kconfig

@@ -13,9 +13,12 @@ config KUNPENG_HCCS
 	  interconnection bus protocol.
 	  The performance of application may be affected if some HCCS
 	  ports are not in full lane status, have a large number of CRC
-	  errors and so on.
+	  errors and so on. This may support for reducing system power
+	  consumption if there are HCCS ports supported low power feature
+	  on platform.
 
 	  Say M here if you want to include support for querying the
-	  health status and port information of HCCS on Kunpeng SoC.
+	  health status and port information of HCCS, or reducing system
+	  power consumption on Kunpeng SoC.
 
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