[PATCH linux v5 18/18] Documenation: Add basic FSI text file

[christopher.lee.bostic@gmail.com]

From: Chris Bostic <cbostic@us.ibm.com>

Add documentation explaining the basics of FSI and how to find
more information.

Signed-off-by: Chris Bostic <cbostic@us.ibm.com>
---
 Documentation/fsi.txt | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 Documentation/fsi.txt

diff --git a/Documentation/fsi.txt b/Documentation/fsi.txt
new file mode 100644
index 0000000..b8c94a0
--- /dev/null
+++ b/Documentation/fsi.txt
@@ -0,0 +1,36 @@
+The Flexible Support Interface (FSI) is a two wire bus consisting of
+a serial data line and a clock capable of running at up to 166 MHz.
+FSI features strong data integrity with CRC protection and is capable
+of very high fan out.
+
+The complete hardware specification[1] for FSI is publicly available on
+the OpenPower Foundation website:
+
+[1] http://openpowerfoundation.org/wp-content/uploads/resources/OpenFSI-spec/content/ch_preface.html
+
+Common FSI terminology:
+
+* Master
+    Controller of the FSI bus.  Only the master is allowed to control the
+    clock line and is the initiator of all transactions on a bus.
+
+* Slave
+    The receiver or target of a master initiated transaction.  The slave
+    cannot initiate communications on a bus and must respond to any
+    master requests for data.
+
+* CFAM
+    Stands for Common Field replaceable unit Access Macro.  A CFAM is an
+    ASIC residing in any device requiring FSI communications. CFAMs
+    consist of an array of hardware 'engines' used for various purposes.
+    I2C masters, UARTs, General Purpose IO hardware are common types of
+    these engines.
+
+* Configuration Space / Configuration Table
+    A table contained at the beginning of each CFAM address space.
+    This table lists information such as the CFAM's ID, which engine types
+    and versions it contains, as well as its addressing range.
+
+* FSI Client driver
+    A device driver that registers with the FSI core so that it can access
+    devices it owns on an FSI bus.
-- 
1.8.2.2