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authorJames Morris <jmorris@namei.org>2009-05-08 17:56:47 +1000
committerJames Morris <jmorris@namei.org>2009-05-08 17:56:47 +1000
commitd254117099d711f215e62427f55dfb8ebd5ad011 (patch)
tree0848ff8dd74314fec14a86497f8d288c86ba7c65 /Documentation/input
parent07ff7a0b187f3951788f64ae1f30e8109bc8e9eb (diff)
parent8c9ed899b44c19e81859fbb0e9d659fe2f8630fc (diff)
Merge branch 'master' into next
Diffstat (limited to 'Documentation/input')
-rw-r--r--Documentation/input/bcm5974.txt65
-rw-r--r--Documentation/input/multi-touch-protocol.txt140
-rw-r--r--Documentation/input/rotary-encoder.txt101
3 files changed, 306 insertions, 0 deletions
diff --git a/Documentation/input/bcm5974.txt b/Documentation/input/bcm5974.txt
new file mode 100644
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+BCM5974 Driver (bcm5974)
+------------------------
+ Copyright (C) 2008-2009 Henrik Rydberg <rydberg@euromail.se>
+
+The USB initialization and package decoding was made by Scott Shawcroft as
+part of the touchd user-space driver project:
+ Copyright (C) 2008 Scott Shawcroft (scott.shawcroft@gmail.com)
+
+The BCM5974 driver is based on the appletouch driver:
+ Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
+ Copyright (C) 2005 Johannes Berg (johannes@sipsolutions.net)
+ Copyright (C) 2005 Stelian Pop (stelian@popies.net)
+ Copyright (C) 2005 Frank Arnold (frank@scirocco-5v-turbo.de)
+ Copyright (C) 2005 Peter Osterlund (petero2@telia.com)
+ Copyright (C) 2005 Michael Hanselmann (linux-kernel@hansmi.ch)
+ Copyright (C) 2006 Nicolas Boichat (nicolas@boichat.ch)
+
+This driver adds support for the multi-touch trackpad on the new Apple
+Macbook Air and Macbook Pro laptops. It replaces the appletouch driver on
+those computers, and integrates well with the synaptics driver of the Xorg
+system.
+
+Known to work on Macbook Air, Macbook Pro Penryn and the new unibody
+Macbook 5 and Macbook Pro 5.
+
+Usage
+-----
+
+The driver loads automatically for the supported usb device ids, and
+becomes available both as an event device (/dev/input/event*) and as a
+mouse via the mousedev driver (/dev/input/mice).
+
+USB Race
+--------
+
+The Apple multi-touch trackpads report both mouse and keyboard events via
+different interfaces of the same usb device. This creates a race condition
+with the HID driver, which, if not told otherwise, will find the standard
+HID mouse and keyboard, and claim the whole device. To remedy, the usb
+product id must be listed in the mouse_ignore list of the hid driver.
+
+Debug output
+------------
+
+To ease the development for new hardware version, verbose packet output can
+be switched on with the debug kernel module parameter. The range [1-9]
+yields different levels of verbosity. Example (as root):
+
+echo -n 9 > /sys/module/bcm5974/parameters/debug
+
+tail -f /var/log/debug
+
+echo -n 0 > /sys/module/bcm5974/parameters/debug
+
+Trivia
+------
+
+The driver was developed at the ubuntu forums in June 2008 [1], and now has
+a more permanent home at bitmath.org [2].
+
+Links
+-----
+
+[1] http://ubuntuforums.org/showthread.php?t=840040
+[2] http://http://bitmath.org/code/
diff --git a/Documentation/input/multi-touch-protocol.txt b/Documentation/input/multi-touch-protocol.txt
new file mode 100644
index 00000000000..9f09557aea3
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+++ b/Documentation/input/multi-touch-protocol.txt
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+Multi-touch (MT) Protocol
+-------------------------
+ Copyright (C) 2009 Henrik Rydberg <rydberg@euromail.se>
+
+
+Introduction
+------------
+
+In order to utilize the full power of the new multi-touch devices, a way to
+report detailed finger data to user space is needed. This document
+describes the multi-touch (MT) protocol which allows kernel drivers to
+report details for an arbitrary number of fingers.
+
+
+Usage
+-----
+
+Anonymous finger details are sent sequentially as separate packets of ABS
+events. Only the ABS_MT events are recognized as part of a finger
+packet. The end of a packet is marked by calling the input_mt_sync()
+function, which generates a SYN_MT_REPORT event. The end of multi-touch
+transfer is marked by calling the usual input_sync() function.
+
+A set of ABS_MT events with the desired properties is defined. The events
+are divided into categories, to allow for partial implementation. The
+minimum set consists of ABS_MT_TOUCH_MAJOR, ABS_MT_POSITION_X and
+ABS_MT_POSITION_Y, which allows for multiple fingers to be tracked. If the
+device supports it, the ABS_MT_WIDTH_MAJOR may be used to provide the size
+of the approaching finger. Anisotropy and direction may be specified with
+ABS_MT_TOUCH_MINOR, ABS_MT_WIDTH_MINOR and ABS_MT_ORIENTATION. Devices with
+more granular information may specify general shapes as blobs, i.e., as a
+sequence of rectangular shapes grouped together by an
+ABS_MT_BLOB_ID. Finally, the ABS_MT_TOOL_TYPE may be used to specify
+whether the touching tool is a finger or a pen or something else.
+
+
+Event Semantics
+---------------
+
+The word "contact" is used to describe a tool which is in direct contact
+with the surface. A finger, a pen or a rubber all classify as contacts.
+
+ABS_MT_TOUCH_MAJOR
+
+The length of the major axis of the contact. The length should be given in
+surface units. If the surface has an X times Y resolution, the largest
+possible value of ABS_MT_TOUCH_MAJOR is sqrt(X^2 + Y^2), the diagonal.
+
+ABS_MT_TOUCH_MINOR
+
+The length, in surface units, of the minor axis of the contact. If the
+contact is circular, this event can be omitted.
+
+ABS_MT_WIDTH_MAJOR
+
+The length, in surface units, of the major axis of the approaching
+tool. This should be understood as the size of the tool itself. The
+orientation of the contact and the approaching tool are assumed to be the
+same.
+
+ABS_MT_WIDTH_MINOR
+
+The length, in surface units, of the minor axis of the approaching
+tool. Omit if circular.
+
+The above four values can be used to derive additional information about
+the contact. The ratio ABS_MT_TOUCH_MAJOR / ABS_MT_WIDTH_MAJOR approximates
+the notion of pressure. The fingers of the hand and the palm all have
+different characteristic widths [1].
+
+ABS_MT_ORIENTATION
+
+The orientation of the ellipse. The value should describe half a revolution
+clockwise around the touch center. The scale of the value is arbitrary, but
+zero should be returned for an ellipse aligned along the Y axis of the
+surface. As an example, an index finger placed straight onto the axis could
+return zero orientation, something negative when twisted to the left, and
+something positive when twisted to the right. This value can be omitted if
+the touching object is circular, or if the information is not available in
+the kernel driver.
+
+ABS_MT_POSITION_X
+
+The surface X coordinate of the center of the touching ellipse.
+
+ABS_MT_POSITION_Y
+
+The surface Y coordinate of the center of the touching ellipse.
+
+ABS_MT_TOOL_TYPE
+
+The type of approaching tool. A lot of kernel drivers cannot distinguish
+between different tool types, such as a finger or a pen. In such cases, the
+event should be omitted. The protocol currently supports MT_TOOL_FINGER and
+MT_TOOL_PEN [2].
+
+ABS_MT_BLOB_ID
+
+The BLOB_ID groups several packets together into one arbitrarily shaped
+contact. This is a low-level anonymous grouping, and should not be confused
+with the high-level contactID, explained below. Most kernel drivers will
+not have this capability, and can safely omit the event.
+
+
+Finger Tracking
+---------------
+
+The kernel driver should generate an arbitrary enumeration of the set of
+anonymous contacts currently on the surface. The order in which the packets
+appear in the event stream is not important.
+
+The process of finger tracking, i.e., to assign a unique contactID to each
+initiated contact on the surface, is left to user space; preferably the
+multi-touch X driver [3]. In that driver, the contactID stays the same and
+unique until the contact vanishes (when the finger leaves the surface). The
+problem of assigning a set of anonymous fingers to a set of identified
+fingers is a euclidian bipartite matching problem at each event update, and
+relies on a sufficiently rapid update rate.
+
+Notes
+-----
+
+In order to stay compatible with existing applications, the data
+reported in a finger packet must not be recognized as single-touch
+events. In addition, all finger data must bypass input filtering,
+since subsequent events of the same type refer to different fingers.
+
+The first kernel driver to utilize the MT protocol is the bcm5974 driver,
+where examples can be found.
+
+[1] With the extension ABS_MT_APPROACH_X and ABS_MT_APPROACH_Y, the
+difference between the contact position and the approaching tool position
+could be used to derive tilt.
+[2] The list can of course be extended.
+[3] The multi-touch X driver is currently in the prototyping stage. At the
+time of writing (April 2009), the MT protocol is not yet merged, and the
+prototype implements finger matching, basic mouse support and two-finger
+scrolling. The project aims at improving the quality of current multi-touch
+functionality available in the synaptics X driver, and in addition
+implement more advanced gestures.
diff --git a/Documentation/input/rotary-encoder.txt b/Documentation/input/rotary-encoder.txt
new file mode 100644
index 00000000000..435102a26d9
--- /dev/null
+++ b/Documentation/input/rotary-encoder.txt
@@ -0,0 +1,101 @@
+rotary-encoder - a generic driver for GPIO connected devices
+Daniel Mack <daniel@caiaq.de>, Feb 2009
+
+0. Function
+-----------
+
+Rotary encoders are devices which are connected to the CPU or other
+peripherals with two wires. The outputs are phase-shifted by 90 degrees
+and by triggering on falling and rising edges, the turn direction can
+be determined.
+
+The phase diagram of these two outputs look like this:
+
+ _____ _____ _____
+ | | | | | |
+ Channel A ____| |_____| |_____| |____
+
+ : : : : : : : : : : : :
+ __ _____ _____ _____
+ | | | | | | |
+ Channel B |_____| |_____| |_____| |__
+
+ : : : : : : : : : : : :
+ Event a b c d a b c d a b c d
+
+ |<-------->|
+ one step
+
+
+For more information, please see
+ http://en.wikipedia.org/wiki/Rotary_encoder
+
+
+1. Events / state machine
+-------------------------
+
+a) Rising edge on channel A, channel B in low state
+ This state is used to recognize a clockwise turn
+
+b) Rising edge on channel B, channel A in high state
+ When entering this state, the encoder is put into 'armed' state,
+ meaning that there it has seen half the way of a one-step transition.
+
+c) Falling edge on channel A, channel B in high state
+ This state is used to recognize a counter-clockwise turn
+
+d) Falling edge on channel B, channel A in low state
+ Parking position. If the encoder enters this state, a full transition
+ should have happend, unless it flipped back on half the way. The
+ 'armed' state tells us about that.
+
+2. Platform requirements
+------------------------
+
+As there is no hardware dependent call in this driver, the platform it is
+used with must support gpiolib. Another requirement is that IRQs must be
+able to fire on both edges.
+
+
+3. Board integration
+--------------------
+
+To use this driver in your system, register a platform_device with the
+name 'rotary-encoder' and associate the IRQs and some specific platform
+data with it.
+
+struct rotary_encoder_platform_data is declared in
+include/linux/rotary-encoder.h and needs to be filled with the number of
+steps the encoder has and can carry information about externally inverted
+signals (because of used invertig buffer or other reasons).
+
+Because GPIO to IRQ mapping is platform specific, this information must
+be given in seperately to the driver. See the example below.
+
+---------<snip>---------
+
+/* board support file example */
+
+#include <linux/input.h>
+#include <linux/rotary_encoder.h>
+
+#define GPIO_ROTARY_A 1
+#define GPIO_ROTARY_B 2
+
+static struct rotary_encoder_platform_data my_rotary_encoder_info = {
+ .steps = 24,
+ .axis = ABS_X,
+ .gpio_a = GPIO_ROTARY_A,
+ .gpio_b = GPIO_ROTARY_B,
+ .inverted_a = 0,
+ .inverted_b = 0,
+};
+
+static struct platform_device rotary_encoder_device = {
+ .name = "rotary-encoder",
+ .id = 0,
+ .dev = {
+ .platform_data = &my_rotary_encoder_info,
+ }
+};
+