[PATCH v8 1/5] powerpc: Document details on H_SCM_HEALTH hcall

[Vaibhav Jain <vaibhav@linux.ibm.com>]

Add documentation to 'papr_hcalls.rst' describing the bitmap flags
that are returned from H_SCM_HEALTH hcall as per the PAPR-SCM
specification.

Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
---
Changelog:
v7..v8:
* Added a clarification on bit-ordering of Health Bitmap

Resend:
* None

v6..v7:
* None

v5..v6:
* New patch in the series
---
 Documentation/powerpc/papr_hcalls.rst | 45 ++++++++++++++++++++++++---
 1 file changed, 41 insertions(+), 4 deletions(-)

diff --git a/Documentation/powerpc/papr_hcalls.rst b/Documentation/powerpc/papr_hcalls.rst
index 3493631a60f8..45063f305813 100644
--- a/Documentation/powerpc/papr_hcalls.rst
+++ b/Documentation/powerpc/papr_hcalls.rst
@@ -220,13 +220,50 @@ from the LPAR memory.
 **H_SCM_HEALTH**
 
 | Input: drcIndex
-| Out: *health-bitmap, health-bit-valid-bitmap*
+| Out: *health-bitmap (r4), health-bit-valid-bitmap (r5)*
 | Return Value: *H_Success, H_Parameter, H_Hardware*
 
 Given a DRC Index return the info on predictive failure and overall health of
-the NVDIMM. The asserted bits in the health-bitmap indicate a single predictive
-failure and health-bit-valid-bitmap indicate which bits in health-bitmap are
-valid.
+the NVDIMM. The asserted bits in the health-bitmap indicate one or more states
+(described in table below) of the NVDIMM and health-bit-valid-bitmap indicate
+which bits in health-bitmap are valid. The bits are reported in
+reverse bit ordering for example a value of 0xC400000000000000
+indicates bits 0, 1, and 5 are valid.
+
+Health Bitmap Flags:
+
++------+-----------------------------------------------------------------------+
+|  Bit |               Definition                                              |
++======+=======================================================================+
+|  00  | SCM device is unable to persist memory contents.                      |
+|      | If the system is powered down, nothing will be saved.                 |
++------+-----------------------------------------------------------------------+
+|  01  | SCM device failed to persist memory contents. Either contents were not|
+|      | saved successfully on power down or were not restored properly on     |
+|      | power up.                                                             |
++------+-----------------------------------------------------------------------+
+|  02  | SCM device contents are persisted from previous IPL. The data from    |
+|      | the last boot were successfully restored.                             |
++------+-----------------------------------------------------------------------+
+|  03  | SCM device contents are not persisted from previous IPL. There was no |
+|      | data to restore from the last boot.                                   |
++------+-----------------------------------------------------------------------+
+|  04  | SCM device memory life remaining is critically low                    |
++------+-----------------------------------------------------------------------+
+|  05  | SCM device will be garded off next IPL due to failure                 |
++------+-----------------------------------------------------------------------+
+|  06  | SCM contents cannot persist due to current platform health status. A  |
+|      | hardware failure may prevent data from being saved or restored.       |
++------+-----------------------------------------------------------------------+
+|  07  | SCM device is unable to persist memory contents in certain conditions |
++------+-----------------------------------------------------------------------+
+|  08  | SCM device is encrypted                                               |
++------+-----------------------------------------------------------------------+
+|  09  | SCM device has successfully completed a requested erase or secure     |
+|      | erase procedure.                                                      |
++------+-----------------------------------------------------------------------+
+|10:63 | Reserved / Unused                                                     |
++------+-----------------------------------------------------------------------+
 
 **H_SCM_PERFORMANCE_STATS**
 
-- 
2.26.2
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