doc: soc: hisilicon: Add Kunpeng HCCS driver documentation

Document the sysfs attributes description provided by HCCS driver on
Kunpeng SoC.
Signed-off-by: Huisong Li <lihuisong@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>

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

+What:		/sys/devices/platform/HISI04Bx:00/chipX/all_linked
+What:		/sys/devices/platform/HISI04Bx:00/chipX/linked_full_lane
+What:		/sys/devices/platform/HISI04Bx:00/chipX/crc_err_cnt
+Date:		November 2023
+KernelVersion:	6.6
+Contact:	Huisong Li <lihuisong@huawei.org>
+Description:
+		The /sys/devices/platform/HISI04Bx:00/chipX/ directory
+		contains read-only attributes exposing some summarization
+		information of all HCCS ports under a specified chip.
+		The X in 'chipX' indicates the Xth chip on platform.
+
+		There are following attributes in this directory:
+
+		================= ==== =========================================
+		all_linked:       (RO) if all enabled ports on this chip are
+				       linked (bool).
+		linked_full_lane: (RO) if all linked ports on this chip are full
+				       lane (bool).
+		crc_err_cnt:      (RO) total CRC err count for all ports on this
+				       chip.
+		================= ==== =========================================
+
+What:		/sys/devices/platform/HISI04Bx:00/chipX/dieY/all_linked
+What:		/sys/devices/platform/HISI04Bx:00/chipX/dieY/linked_full_lane
+What:		/sys/devices/platform/HISI04Bx:00/chipX/dieY/crc_err_cnt
+Date:		November 2023
+KernelVersion:	6.6
+Contact:	Huisong Li <lihuisong@huawei.org>
+Description:
+		The /sys/devices/platform/HISI04Bx:00/chipX/dieY/ directory
+		contains read-only attributes exposing some summarization
+		information of all HCCS ports under a specified die.
+		The Y in 'dieY' indicates the hardware id of the die on chip who
+		has chip id X.
+
+		There are following attributes in this directory:
+
+		================= ==== =========================================
+		all_linked:       (RO) if all enabled ports on this die are
+				       linked (bool).
+		linked_full_lane: (RO) if all linked ports on this die are full
+				       lane (bool).
+		crc_err_cnt:      (RO) total CRC err count for all ports on this
+				       die.
+		================= ==== =========================================
+
+What:		/sys/devices/platform/HISI04Bx:00/chipX/dieY/hccsN/type
+What:		/sys/devices/platform/HISI04Bx:00/chipX/dieY/hccsN/lane_mode
+What:		/sys/devices/platform/HISI04Bx:00/chipX/dieY/hccsN/enable
+What:		/sys/devices/platform/HISI04Bx:00/chipX/dieY/hccsN/cur_lane_num
+What:		/sys/devices/platform/HISI04Bx:00/chipX/dieY/hccsN/link_fsm
+What:		/sys/devices/platform/HISI04Bx:00/chipX/dieY/hccsN/lane_mask
+What:		/sys/devices/platform/HISI04Bx:00/chipX/dieY/hccsN/crc_err_cnt
+Date:		November 2023
+KernelVersion:	6.6
+Contact:	Huisong Li <lihuisong@huawei.org>
+Description:
+		The /sys/devices/platform/HISI04Bx/chipX/dieX/hccsN/ directory
+		contains read-only attributes exposing information about
+		a HCCS port. The N value in 'hccsN' indicates this port id.
+		The X in 'chipX' indicates the ID of the chip to which the
+		HCCS port belongs. For example, X ranges from to 'n - 1' if the
+		chip number on platform is n.
+		The Y in 'dieY' indicates the hardware id of the die to which
+		the hccs port belongs.
+		Note: type, lane_mode and enable are fixed attributes on running
+		platform.
+
+		The HCCS port have the following attributes:
+
+		============= ==== =============================================
+		type:         (RO) port type (string), e.g. HCCS-v1 -> H32
+		lane_mode:    (RO) the lane mode of this port (string), e.g. x8
+		enable:       (RO) indicate if this port is enabled (bool).
+		cur_lane_num: (RO) current lane number of this port.
+		link_fsm:     (RO) link finite state machine of this port.
+		lane_mask:    (RO) current lane mask of this port, every bit
+			           indicates a lane.
+		crc_err_cnt:  (RO) CRC err count on this port.
+		============= ==== =============================================

MAINTAINERS

@@ -9310,6 +9310,7 @@ F:	drivers/i2c/busses/i2c-hisi.c
 HISILICON KUNPENG SOC HCCS DRIVER
 M:	Huisong Li <lihuisong@huawei.com>
 S:	Maintained
+F:	Documentation/ABI/testing/sysfs-devices-platform-kunpeng_hccs
 F:	drivers/soc/hisilicon/kunpeng_hccs.c
 F:	drivers/soc/hisilicon/kunpeng_hccs.h