[Skiboot] [PATCH] doc: Update VPD, ECID documentation

[Vasant Hegde]

Recently we added `ecid`, `wafer-id` and `wafer-location` properties
under xscom node. Lets document these properties. Also update VPD
documentation.

Signed-off-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>
---
 doc/device-tree/vpd.rst     | 10 ++++++----
 doc/xscom-node-bindings.rst | 10 ++++++++++
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/doc/device-tree/vpd.rst b/doc/device-tree/vpd.rst
index 3e70d38..b54c559 100644
--- a/doc/device-tree/vpd.rst
+++ b/doc/device-tree/vpd.rst
@@ -2,10 +2,10 @@ VPD (Vital Product Data)
 ========================
 
 VPD provides the information about the FRUs (Field Replaceable Unit) present in
-the system and each vpd node in the device tree represents a FRU. These node and
-their properties are specific to the FSP-based systems, passed to the skiboot in
-the form of FSP-defined HDAT structures. skiboot parses these structures and
-add respective nodes in the device tree.
+the system and each vpd node in the device tree represents a FRU. These
+properties are passed to skiboot in the form of HDAT structure. Skiboot parses
+these structures and adds respective nodes in the device tree. These properties
+are available in all system except POWER8 BMC based system.
 
 .. code-block:: dts
 
@@ -21,6 +21,8 @@ add respective nodes in the device tree.
      ibm,chip-id   = <0x0>; /* If part is a chip, Processor Id */
      size = "0032768";      /* DIMM size (applicable for DIMM VPD only) */
      ibm,memory-bus-frequency = <0x0 0x0>; /* DIMM frequency (applicable for DIMM VPD only) */
+     vendor = <vendor name> /* Vendor name */
+     build-date = <build date> /* Manufacturing build date (applicate for P9 BMC systems only) */
    };
  };
 
diff --git a/doc/xscom-node-bindings.rst b/doc/xscom-node-bindings.rst
index 0fd5e93..ee2c58d 100644
--- a/doc/xscom-node-bindings.rst
+++ b/doc/xscom-node-bindings.rst
@@ -26,6 +26,16 @@ Each xscom node has the following properties:
  * reg = <base-address[#parent-address-cells] size[#parent-size-cells]>
  * ibm,chip-id = gcid
  * compatible = "ibm,xscom", "ibm,power8-scom" / "ibm,power7-xscom" 
+ * ecid = <Electronic Chip ID, applicable for POWER9 onwards>
+ * wafer-id = <wafer ID, applicable for POWER9 onwards>
+ * wafer-location = <wafer location, applicable for POWER9 onwards>
+
+ECID
+----
+Electronic Chip ID (ECID) is a process by which the wafer number, chip location
+(i.e. X,Y) and other optional data items are electrically encoded directly on
+the chip. wafer-id property represents wafer number and wafer-location property
+represents chip location (both X and Y location).
 
 
 Chiplet endpoints
-- 
2.9.3