char/bsr: add sysfs interface documentation

Descriptions have collected from code comments and by reading through
code.

Signed-off-by: Aishwarya Pant <aishpant@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --git a/Documentation/ABI/testing/sysfs-class-bsr b/Documentation/ABI/testing/sysfs-class-bsr
new file mode 100644 (file)
index 0000000..7bf145d
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-bsr
@@ -0,0 +1,25 @@
+What:          /sys/class/bsr/bsr*/bsr_size
+Date:          Jul, 2008
+KernelVersion: 2.6.27
+Contact:       Arnd Bergmann <arnd@arndb.de>,
+               Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Description:
+               (RO) Size of the barrier-synchronization register (BSR)
+               register in bytes.
+
+What:          /sys/class/bsr/bsr*/bsr_length
+Date:          Jul, 2008
+KernelVersion: 2.6.27
+Contact:       Arnd Bergmann <arnd@arndb.de>,
+               Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Description:
+               (RO) The length of memory region that can be mapped in bytes.
+
+What:          /sys/class/bsr/bsr*/bsr_stride
+Date:          Jul, 2008
+KernelVersion: 2.6.27
+Contact:       Arnd Bergmann <arnd@arndb.de>,
+               Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Description:
+               (RO) The stride or the interval at which the allocated BSR bytes
+               repeat within the mapping.