fbdev: defio and Metronomefb

Implement support for the E-Ink Metronome controller.  It provides an mmapable
interface to the controller using defio support.  It was tested with a gumstix
pxa255 with Vizplex media using Xfbdev and various X clients such as xeyes,
xpdf, xloadimage.

This patch also fixes the following bug: Defio would cause a hang on write
access to the framebuffer as the page fault would be called ad-infinitum.  It
fixes fb_defio by setting the mapping to be used by page_mkclean.

Signed-off-by: Jaya Kumar <jayakumar.lkml@gmail.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 38 insertions, 0 deletions

diff --git a/Documentation/fb/metronomefb.txt b/Documentation/fb/metronomefb.txt
new file mode 100644
index 000000000000..b9a2e7b7e838
--- /dev/null
+++ b/Documentation/fb/metronomefb.txt
@@ -0,0 +1,38 @@
+                        Metronomefb
+                        -----------
+Maintained by Jaya Kumar <jayakumar.lkml.gmail.com>
+Last revised: Nov 20, 2007
+
+Metronomefb is a driver for the Metronome display controller. The controller
+is from E-Ink Corporation. It is intended to be used to drive the E-Ink
+Vizplex display media. E-Ink hosts some details of this controller and the
+display media here http://www.e-ink.com/products/matrix/metronome.html .
+
+Metronome is interfaced to the host CPU through the AMLCD interface. The
+host CPU generates the control information and the image in a framebuffer
+which is then delivered to the AMLCD interface by a host specific method.
+Currently, that's implemented for the PXA's LCDC controller. The display and
+error status are each pulled through individual GPIOs.
+
+Metronomefb was written for the PXA255/gumstix/lyre combination and
+therefore currently has board set specific code in it. If other boards based on
+other architectures are available, then the host specific code can be separated
+and abstracted out.
+
+Metronomefb requires waveform information which is delivered via the AMLCD
+interface to the metronome controller. The waveform information is expected to
+be delivered from userspace via the firmware class interface. The waveform file
+can be compressed as long as your udev or hotplug script is aware of the need
+to uncompress it before delivering it. metronomefb will ask for waveform.wbf
+which would typically go into /lib/firmware/waveform.wbf depending on your
+udev/hotplug setup. I have only tested with a single waveform file which was
+originally labeled 23P01201_60_WT0107_MTC. I do not know what it stands for.
+Caution should be exercised when manipulating the waveform as there may be
+a possibility that it could have some permanent effects on the display media.
+I neither have access to nor know exactly what the waveform does in terms of
+the physical media.
+
+Metronomefb uses the deferred IO interface so that it can provide a memory
+mappable frame buffer. It has been tested with tinyx (Xfbdev). It is known
+to work at this time with xeyes, xclock, xloadimage, xpdf.
+