[media] media: rc: add sysfs scancode filtering interface

Add and document a generic sysfs based scancode filtering interface for
making use of IR data matching hardware to filter out uninteresting
scancodes. Two filters exist, one for normal operation and one for
filtering scancodes which are permitted to wake the system from suspend.

The following files are added to /sys/class/rc/rc?/:
 - filter: normal scancode filter value
 - filter_mask: normal scancode filter mask
 - wakeup_filter: wakeup scancode filter value
 - wakeup_filter_mask: wakeup scancode filter mask

A new s_filter() driver callback is added which must arrange for the
specified filter to be applied at the right time. Drivers can convert
the scancode filter into a raw IR data filter, which can be applied
immediately or later (for wake up filters).

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Mauro Carvalho Chehab <m.chehab@samsung.com>
Cc: linux-media@vger.kernel.org
Cc: Rob Landley <rob@landley.net>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-rc b/Documentation/ABI/testing/sysfs-class-rc
index 52bc057b5d06..c0e1d14cae6e 100644
--- a/Documentation/ABI/testing/sysfs-class-rc
+++ b/Documentation/ABI/testing/sysfs-class-rc
@@ -32,3 +32,61 @@ Description:
 		Writing "none" will disable all protocols.
 		Write fails with EINVAL if an invalid protocol combination or
 		unknown protocol name is used.
+
+What:		/sys/class/rc/rcN/filter
+Date:		Jan 2014
+KernelVersion:	3.15
+Contact:	Mauro Carvalho Chehab <m.chehab@samsung.com>
+Description:
+		Sets the scancode filter expected value.
+		Use in combination with /sys/class/rc/rcN/filter_mask to set the
+		expected value of the bits set in the filter mask.
+		If the hardware supports it then scancodes which do not match
+		the filter will be ignored. Otherwise the write will fail with
+		an error.
+		This value may be reset to 0 if the current protocol is altered.
+
+What:		/sys/class/rc/rcN/filter_mask
+Date:		Jan 2014
+KernelVersion:	3.15
+Contact:	Mauro Carvalho Chehab <m.chehab@samsung.com>
+Description:
+		Sets the scancode filter mask of bits to compare.
+		Use in combination with /sys/class/rc/rcN/filter to set the bits
+		of the scancode which should be compared against the expected
+		value. A value of 0 disables the filter to allow all valid
+		scancodes to be processed.
+		If the hardware supports it then scancodes which do not match
+		the filter will be ignored. Otherwise the write will fail with
+		an error.
+		This value may be reset to 0 if the current protocol is altered.
+
+What:		/sys/class/rc/rcN/wakeup_filter
+Date:		Jan 2014
+KernelVersion:	3.15
+Contact:	Mauro Carvalho Chehab <m.chehab@samsung.com>
+Description:
+		Sets the scancode wakeup filter expected value.
+		Use in combination with /sys/class/rc/rcN/wakeup_filter_mask to
+		set the expected value of the bits set in the wakeup filter mask
+		to trigger a system wake event.
+		If the hardware supports it and wakeup_filter_mask is not 0 then
+		scancodes which match the filter will wake the system from e.g.
+		suspend to RAM or power off.
+		Otherwise the write will fail with an error.
+		This value may be reset to 0 if the current protocol is altered.
+
+What:		/sys/class/rc/rcN/wakeup_filter_mask
+Date:		Jan 2014
+KernelVersion:	3.15
+Contact:	Mauro Carvalho Chehab <m.chehab@samsung.com>
+Description:
+		Sets the scancode wakeup filter mask of bits to compare.
+		Use in combination with /sys/class/rc/rcN/wakeup_filter to set
+		the bits of the scancode which should be compared against the
+		expected value to trigger a system wake event.
+		If the hardware supports it and wakeup_filter_mask is not 0 then
+		scancodes which match the filter will wake the system from e.g.
+		suspend to RAM or power off.
+		Otherwise the write will fail with an error.
+		This value may be reset to 0 if the current protocol is altered.