drivers/perf: hisi: Add description for HNS3 PMU driver

HNS3 PMU End Point device is supported on HiSilicon HIP09 platform, so
add document hns3-pmu.rst to provide guidance on how to use it.
Signed-off-by: NGuangbin Huang <huangguangbin2@huawei.com>
Reviewed-by: NJohn Garry <john.garry@huawei.com>
Reviewed-by: NShaokun Zhang <zhangshaokun@hisilicon.com>
Link: https://lore.kernel.org/r/20220628063419.38514-2-huangguangbin2@huawei.comSigned-off-by: NWill Deacon <will@kernel.org>

Documentation/admin-guide/perf/hns3-pmu.rst

+======================================
+HNS3 Performance Monitoring Unit (PMU)
+======================================
+
+HNS3(HiSilicon network system 3) Performance Monitoring Unit (PMU) is an
+End Point device to collect performance statistics of HiSilicon SoC NIC.
+On Hip09, each SICL(Super I/O cluster) has one PMU device.
+
+HNS3 PMU supports collection of performance statistics such as bandwidth,
+latency, packet rate and interrupt rate.
+
+Each HNS3 PMU supports 8 hardware events.
+
+HNS3 PMU driver
+===============
+
+The HNS3 PMU driver registers a perf PMU with the name of its sicl id.::
+
+  /sys/devices/hns3_pmu_sicl_<sicl_id>
+
+PMU driver provides description of available events, filter modes, format,
+identifier and cpumask in sysfs.
+
+The "events" directory describes the event code of all supported events
+shown in perf list.
+
+The "filtermode" directory describes the supported filter modes of each
+event.
+
+The "format" directory describes all formats of the config (events) and
+config1 (filter options) fields of the perf_event_attr structure.
+
+The "identifier" file shows version of PMU hardware device.
+
+The "bdf_min" and "bdf_max" files show the supported bdf range of each
+pmu device.
+
+The "hw_clk_freq" file shows the hardware clock frequency of each pmu
+device.
+
+Example usage of checking event code and subevent code::
+
+  $# cat /sys/devices/hns3_pmu_sicl_0/events/dly_tx_normal_to_mac_time
+  config=0x00204
+  $# cat /sys/devices/hns3_pmu_sicl_0/events/dly_tx_normal_to_mac_packet_num
+  config=0x10204
+
+Each performance statistic has a pair of events to get two values to
+calculate real performance data in userspace.
+
+The bits 0~15 of config (here 0x0204) are the true hardware event code. If
+two events have same value of bits 0~15 of config, that means they are
+event pair. And the bit 16 of config indicates getting counter 0 or
+counter 1 of hardware event.
+
+After getting two values of event pair in usersapce, the formula of
+computation to calculate real performance data is:::
+
+  counter 0 / counter 1
+
+Example usage of checking supported filter mode::
+
+  $# cat /sys/devices/hns3_pmu_sicl_0/filtermode/bw_ssu_rpu_byte_num
+  filter mode supported: global/port/port-tc/func/func-queue/
+
+Example usage of perf::
+
+  $# perf list
+  hns3_pmu_sicl_0/bw_ssu_rpu_byte_num/ [kernel PMU event]
+  hns3_pmu_sicl_0/bw_ssu_rpu_time/     [kernel PMU event]
+  ------------------------------------------
+
+  $# perf stat -g -e hns3_pmu_sicl_0/bw_ssu_rpu_byte_num,global=1/ -e hns3_pmu_sicl_0/bw_ssu_rpu_time,global=1/ -I 1000
+  or
+  $# perf stat -g -e hns3_pmu_sicl_0/config=0x00002,global=1/ -e hns3_pmu_sicl_0/config=0x10002,global=1/ -I 1000
+
+
+Filter modes
+--------------
+
+1. global mode
+PMU collect performance statistics for all HNS3 PCIe functions of IO DIE.
+Set the "global" filter option to 1 will enable this mode.
+Example usage of perf::
+
+  $# perf stat -a -e hns3_pmu_sicl_0/config=0x1020F,global=1/ -I 1000
+
+2. port mode
+PMU collect performance statistic of one whole physical port. The port id
+is same as mac id. The "tc" filter option must be set to 0xF in this mode,
+here tc stands for traffic class.
+
+Example usage of perf::
+
+  $# perf stat -a -e hns3_pmu_sicl_0/config=0x1020F,port=0,tc=0xF/ -I 1000
+
+3. port-tc mode
+PMU collect performance statistic of one tc of physical port. The port id
+is same as mac id. The "tc" filter option must be set to 0 ~ 7 in this
+mode.
+Example usage of perf::
+
+  $# perf stat -a -e hns3_pmu_sicl_0/config=0x1020F,port=0,tc=0/ -I 1000
+
+4. func mode
+PMU collect performance statistic of one PF/VF. The function id is BDF of
+PF/VF, its conversion formula::
+
+  func = (bus << 8) + (device << 3) + (function)
+
+for example:
+  BDF         func
+  35:00.0    0x3500
+  35:00.1    0x3501
+  35:01.0    0x3508
+
+In this mode, the "queue" filter option must be set to 0xFFFF.
+Example usage of perf::
+
+  $# perf stat -a -e hns3_pmu_sicl_0/config=0x1020F,bdf=0x3500,queue=0xFFFF/ -I 1000
+
+5. func-queue mode
+PMU collect performance statistic of one queue of PF/VF. The function id
+is BDF of PF/VF, the "queue" filter option must be set to the exact queue
+id of function.
+Example usage of perf::
+
+  $# perf stat -a -e hns3_pmu_sicl_0/config=0x1020F,bdf=0x3500,queue=0/ -I 1000
+
+6. func-intr mode
+PMU collect performance statistic of one interrupt of PF/VF. The function
+id is BDF of PF/VF, the "intr" filter option must be set to the exact
+interrupt id of function.
+Example usage of perf::
+
+  $# perf stat -a -e hns3_pmu_sicl_0/config=0x00301,bdf=0x3500,intr=0/ -I 1000