+### 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.
+