NTB: Add tool test client

This is a simple debugging driver that enables the doorbell and
scratch pad registers to be read and written from the debugfs.  This
tool enables more complicated debugging to be scripted from user space.
This driver may be used to test that your ntb hardware and drivers are
functioning at a basic level.

Signed-off-by: Allen Hubbe <Allen.Hubbe@emc.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

1 files changed, 32 insertions, 0 deletions

diff --git a/Documentation/ntb.txt b/Documentation/ntb.txt
index e5d1591478ca..b48249a7b607 100644
--- a/Documentation/ntb.txt
+++ b/Documentation/ntb.txt
@@ -64,6 +64,38 @@ Module Parameters:
 * dyndbg - It is suggested to specify dyndbg=+p when loading this module, and
         then to observe debugging output on the console.
 
+### NTB Tool Test Client (ntb\_tool)
+
+The Tool test client serves for debugging, primarily, ntb hardware and drivers.
+The Tool provides access through debugfs for reading, setting, and clearing the
+NTB doorbell, and reading and writing scratchpads.
+
+The Tool does not currently have any module parameters.
+
+Debugfs Files:
+
+* *debugfs*/ntb\_tool/*hw*/ - A directory in debugfs will be created for each
+        NTB device probed by the tool.  This directory is shortened to *hw*
+        below.
+* *hw*/db - This file is used to read, set, and clear the local doorbell.  Not
+        all operations may be supported by all hardware.  To read the doorbell,
+        read the file.  To set the doorbell, write `s` followed by the bits to
+        set (eg: `echo 's 0x0101' > db`).  To clear the doorbell, write `c`
+        followed by the bits to clear.
+* *hw*/mask - This file is used to read, set, and clear the local doorbell mask.
+        See *db* for details.
+* *hw*/peer\_db - This file is used to read, set, and clear the peer doorbell.
+        See *db* for details.
+* *hw*/peer\_mask - This file is used to read, set, and clear the peer doorbell
+        mask.  See *db* for details.
+* *hw*/spad - This file is used to read and write local scratchpads.  To read
+        the values of all scratchpads, read the file.  To write values, write a
+        series of pairs of scratchpad number and value
+        (eg: `echo '4 0x123 7 0xabc' > spad`
+        # to set scratchpads `4` and `7` to `0x123` and `0xabc`, respectively).
+* *hw*/peer\_spad - This file is used to read and write peer scratchpads.  See
+        *spad* for details.
+
 ## NTB Hardware Drivers
 
 NTB hardware drivers should register devices with the NTB core driver.  After