docs: octeontx2: Add Documentation for NPA health reporters

Add Documentation for devlink health reporters for NPA block.
Signed-off-by: NGeorge Cherian <george.cherian@marvell.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Documentation/networking/device_drivers/ethernet/marvell/octeontx2.rst

@@ -12,6 +12,7 @@ Contents
 - `Overview`_
 - `Drivers`_
 - `Basic packet flow`_
+- `Devlink health reporters`_
 
 Overview
 ========
@@ -157,3 +158,52 @@ Egress
 3. The SQ descriptor ring is maintained in buffers allocated from SQ mapped pool of NPA block LF.
 4. NIX block transmits the pkt on the designated channel.
 5. NPC MCAM entries can be installed to divert pkt onto a different channel.
+
+Devlink health reporters
+========================
+
+NPA Reporters
+-------------
+The NPA reporters are responsible for reporting and recovering the following group of errors
+1. GENERAL events
+   - Error due to operation of unmapped PF.
+   - Error due to disabled alloc/free for other HW blocks (NIX, SSO, TIM, DPI and AURA).
+2. ERROR events
+   - Fault due to NPA_AQ_INST_S read or NPA_AQ_RES_S write.
+   - AQ Doorbell Error.
+3. RAS events
+   - RAS Error Reporting for NPA_AQ_INST_S/NPA_AQ_RES_S.
+4. RVU events
+   - Error due to unmapped slot.
+
+Sample Output
+-------------
+~# devlink health
+pci/0002:01:00.0:
+  reporter hw_npa_intr
+      state healthy error 2872 recover 2872 last_dump_date 2020-12-10 last_dump_time 09:39:09 grace_period 0 auto_recover true auto_dump true
+  reporter hw_npa_gen
+      state healthy error 2872 recover 2872 last_dump_date 2020-12-11 last_dump_time 04:43:04 grace_period 0 auto_recover true auto_dump true
+  reporter hw_npa_err
+      state healthy error 2871 recover 2871 last_dump_date 2020-12-10 last_dump_time 09:39:17 grace_period 0 auto_recover true auto_dump true
+   reporter hw_npa_ras
+      state healthy error 0 recover 0 last_dump_date 2020-12-10 last_dump_time 09:32:40 grace_period 0 auto_recover true auto_dump true
+
+Each reporter dumps the
+ - Error Type
+ - Error Register value
+ - Reason in words
+
+For eg:
+~# devlink health dump show  pci/0002:01:00.0 reporter hw_npa_gen
+ NPA_AF_GENERAL:
+         NPA General Interrupt Reg : 1
+         NIX0: free disabled RX
+~# devlink health dump show  pci/0002:01:00.0 reporter hw_npa_intr
+ NPA_AF_RVU:
+         NPA RVU Interrupt Reg : 1
+         Unmap Slot Error
+~# devlink health dump show  pci/0002:01:00.0 reporter hw_npa_err
+ NPA_AF_ERR:
+        NPA Error Interrupt Reg : 4096
+        AQ Doorbell Error