[PATCH v2 3/3] powerpc: Document details on H_HTM hcall

[Madhavan Srinivasan <maddy@linux.ibm.com>]

Add documentation to 'papr_hcalls.rst' describing the
input, output and return values of the H_HTM hcall as
per the internal specification.

With patch series applied and booted, list of files in debugfs path

# pwd
/sys/kernel/debug/powerpc/htmdump
# ls
coreindexonchip  htmtype  nodalchipindex  nodeindex  trace

Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
---
Changelog v1:
- Updated commit message to include htmdump folder files 

 Documentation/arch/powerpc/papr_hcalls.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/arch/powerpc/papr_hcalls.rst b/Documentation/arch/powerpc/papr_hcalls.rst
index 80d2c0aadab5..805e1cb9bab9 100644
--- a/Documentation/arch/powerpc/papr_hcalls.rst
+++ b/Documentation/arch/powerpc/papr_hcalls.rst
@@ -289,6 +289,17 @@ to be issued multiple times in order to be completely serviced. The
 subsequent hcalls to the hypervisor until the hcall is completely serviced
 at which point H_SUCCESS or other error is returned by the hypervisor.
 
+**H_HTM**
+
+| Input: flags, target, operation (op), op-param1, op-param2, op-param3
+| Out: *dumphtmbufferdata*
+| Return Value: *H_Success,H_Busy,H_LongBusyOrder,H_Partial,H_Parameter,
+		 H_P2,H_P3,H_P4,H_P5,H_P6,H_State,H_Not_Available,H_Authority*
+
+H_HTM supports setup, configuration, control and dumping of Hardware Trace
+Macro (HTM) function and its data. HTM buffer stores tracing data for functions
+like core instruction, core LLAT and nest.
+
 References
 ==========
 .. [1] "Power Architecture Platform Reference"
-- 
2.45.2