/[linux-patches]/genpatches-2.6/tags/3.0-30/2625_Input-ALPS-Add-documentation-for-protocol-versions-3.patch
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Contents of /genpatches-2.6/tags/3.0-30/2625_Input-ALPS-Add-documentation-for-protocol-versions-3.patch

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Revision 2206 - (show annotations) (download)
Mon Sep 17 18:58:14 2012 UTC (23 months ago) by mpagano
File size: 8030 byte(s)
3.0-30 release
1 From fe497d37d0548dc51716214b026310a800a0fed8 Mon Sep 17 00:00:00 2001
2 From: Seth Forshee <seth.forshee@canonical.com>
3 Date: Wed, 14 Sep 2011 11:40:38 -0500
4 Subject: [PATCH 7/8] Input: ALPS - Add documentation for protocol versions 3 and 4
5
6 Also converts from using "old" and "new" to describe the already-known
7 protocols to using "version 1" and "version 2" to match the code.
8
9 Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
10 ---
11 Documentation/input/alps.txt | 136 ++++++++++++++++++++++++++++++++++++++----
12 1 files changed, 125 insertions(+), 11 deletions(-)
13
14 diff --git a/Documentation/input/alps.txt b/Documentation/input/alps.txt
15 index e88c921..ac2dd9c 100644
16 --- a/Documentation/input/alps.txt
17 +++ b/Documentation/input/alps.txt
18 @@ -4,12 +4,9 @@ ALPS Touchpad Protocol
19 Introduction
20 ------------
21
22 -Currently the ALPS touchpad driver supports two protocol versions in use by
23 -ALPS touchpads, the "old" and "new" protocol versions. Fundamentally these
24 -differ only in the format of their event packets (in reality many features may
25 -be found on new protocol devices that aren't found on the old protocol
26 -devices, but these are handled transparently as feature differences rather
27 -than protocol differences).
28 +Currently the ALPS touchpad driver supports four protocol versions in use by
29 +ALPS touchpads, called versions 1, 2, 3, and 4. Information about the various
30 +protocol versions is contained in the following sections.
31
32 Detection
33 ---------
34 @@ -22,10 +19,38 @@ If the E6 report is successful, the touchpad model is identified using the "E7
35 report" sequence: E8-E7-E7-E7-E9. The response is the model signature and is
36 matched against known models in the alps_model_data_array.
37
38 +With protocol versions 3 and 4, the E7 report model signature is always
39 +73-02-64. To differentiate between these versions, the response from the
40 +"Enter Command Mode" sequence must be inspected as described below.
41 +
42 +Command Mode
43 +------------
44 +
45 +Protocol versions 3 and 4 have a command mode that is used to read and write
46 +one-byte device registers in a 16-bit address space. The command sequence
47 +EC-EC-EC-E9 places the device in command mode, and the device will respond
48 +with 88-07 followed by a third byte. This third byte can be used to determine
49 +whether the devices uses the version
50 +3 or 4 protocol.
51 +
52 +To exit command mode, PSMOUSE_CMD_SETSTREAM (EA) is sent to the touchpad.
53 +
54 +While in command mode, register addresses can be set by first sending a
55 +specific command, either EC for v3 devices or F5 for v4 devices. Then the
56 +address is sent one nibble at a time, where each nibble is encoded as a
57 +command with optional data. This enoding differs slightly between the v3 and
58 +v4 protocols.
59 +
60 +Once an address has been set, the addressed register can be read by sending
61 +PSMOUSE_CMD_GETINFO (E9). The first two bytes of the response contains the
62 +address of the register being read, and the third contains the value of the
63 +register. Registers are written by writing the value one nibble at a time
64 +using the same encoding used for addresses.
65 +
66 Packet Format
67 -------------
68
69 -In the following tables, the following notation us used.
70 +In the following tables, the following notation is used.
71
72 CAPITALS = stick, miniscules = touchpad
73
74 @@ -41,8 +66,8 @@ PS/2 packet format
75
76 Note that the device never signals overflow condition.
77
78 -ALPS Absolute Mode - Old Format
79 --------------------------------
80 +ALPS Absolute Mode - Protocol Verion 1
81 +--------------------------------------
82
83 byte 0: 1 0 0 0 1 x9 x8 x7
84 byte 1: 0 x6 x5 x4 x3 x2 x1 x0
85 @@ -51,8 +76,8 @@ ALPS Absolute Mode - Old Format
86 byte 4: 0 y6 y5 y4 y3 y2 y1 y0
87 byte 5: 0 z6 z5 z4 z3 z2 z1 z0
88
89 -ALPS Absolute Mode - New Format
90 --------------------------------
91 +ALPS Absolute Mode - Protocol Version 2
92 +---------------------------------------
93
94 byte 0: 1 ? ? ? 1 ? ? ?
95 byte 1: 0 x6 x5 x4 x3 x2 x1 x0
96 @@ -73,3 +98,92 @@ Dualpoint device -- interleaved packet format
97 byte 6: 0 y9 y8 y7 1 m r l
98 byte 7: 0 y6 y5 y4 y3 y2 y1 y0
99 byte 8: 0 z6 z5 z4 z3 z2 z1 z0
100 +
101 +ALPS Absolute Mode - Protocol Version 3
102 +---------------------------------------
103 +
104 +ALPS protocol version 3 has three different packet formats. The first two are
105 +associated with touchpad events, and the third is associatd with trackstick
106 +events.
107 +
108 +The first type is the touchpad position packet.
109 +
110 + byte 0: 1 ? x1 x0 1 1 1 1
111 + byte 1: 0 x10 x9 x8 x7 x6 x5 x4
112 + byte 2: 0 y10 y9 y8 y7 y6 y5 y4
113 + byte 3: 0 M R L 1 m r l
114 + byte 4: 0 mt x3 x2 y3 y2 y1 y0
115 + byte 5: 0 z6 z5 z4 z3 z2 z1 z0
116 +
117 +Note that for some devices the trackstick buttons are reported in this packet,
118 +and on others it is reported in the trackstick packets.
119 +
120 +The second packet type contains bitmaps representing the x and y axes. In the
121 +bitmaps a given bit is set if there is a finger covering that position on the
122 +given axis. Thus the bitmap packet can be used for low-resolution multi-touch
123 +data, although finger tracking is not possible. This packet also encodes the
124 +number of contacts (f1 and f0 in the table below).
125 +
126 + byte 0: 1 1 x1 x0 1 1 1 1
127 + byte 1: 0 x8 x7 x6 x5 x4 x3 x2
128 + byte 2: 0 y7 y6 y5 y4 y3 y2 y1
129 + byte 3: 0 y10 y9 y8 1 1 1 1
130 + byte 4: 0 x14 x13 x12 x11 x10 x9 y0
131 + byte 5: 0 1 ? ? ? ? f1 f0
132 +
133 +This packet only appears after a position packet with the mt bit set, and
134 +ususally only appears when there are two or more contacts (although
135 +ocassionally it's seen with only a single contact).
136 +
137 +The final v3 packet type is the trackstick packet.
138 +
139 + byte 0: 1 1 x7 y7 1 1 1 1
140 + byte 1: 0 x6 x5 x4 x3 x2 x1 x0
141 + byte 2: 0 y6 y5 y4 y3 y2 y1 y0
142 + byte 3: 0 1 0 0 1 0 0 0
143 + byte 4: 0 z4 z3 z2 z1 z0 ? ?
144 + byte 5: 0 0 1 1 1 1 1 1
145 +
146 +ALPS Absolute Mode - Protocol Version 4
147 +---------------------------------------
148 +
149 +Protocol version 4 has an 8-byte packet format.
150 +
151 + byte 0: 1 ? x1 x0 1 1 1 1
152 + byte 1: 0 x10 x9 x8 x7 x6 x5 x4
153 + byte 2: 0 y10 y9 y8 y7 y6 y5 y4
154 + byte 3: 0 1 x3 x2 y3 y2 y1 y0
155 + byte 4: 0 ? ? ? 1 ? r l
156 + byte 5: 0 z6 z5 z4 z3 z2 z1 z0
157 + byte 6: bitmap data (described below)
158 + byte 7: bitmap data (described below)
159 +
160 +The last two bytes represent a partial bitmap packet, with 3 full packets
161 +required to construct a complete bitmap packet. Once assembled, the 6-byte
162 +bitmap packet has the following format:
163 +
164 + byte 0: 0 1 x7 x6 x5 x4 x3 x2
165 + byte 1: 0 x1 x0 y4 y3 y2 y1 y0
166 + byte 2: 0 ? ? x14 x13 x12 x11 x10
167 + byte 3: 0 x9 x8 y9 y8 y7 y6 y5
168 + byte 4: 0 0 0 0 0 0 0 0
169 + byte 5: 0 0 0 0 0 0 0 y10
170 +
171 +There are several things worth noting here.
172 +
173 + 1) In the bitmap data, bit 6 of byte 0 serves as a sync byte to
174 + identify the first fragment of a bitmap packet.
175 +
176 + 2) The bitmaps represent the same data as in the v3 bitmap packets, although
177 + the packet layout is different.
178 +
179 + 3) There doesn't seem to be a count of the contact points anywhere in the v4
180 + protocol packets. Deriving a count of contact points must be done by
181 + analyzing the bitmaps.
182 +
183 + 4) There is a 3 to 1 ratio of position packets to bitmap packets. Therefore
184 + MT position can only be updated for every third ST position update, and
185 + the count of contact points can only be updated every third packet as
186 + well.
187 +
188 +So far no v4 devices with tracksticks have been encountered.
189 --
190 1.7.4.1

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