6 Currently the ALPS touchpad driver supports five protocol versions in use by
7 ALPS touchpads, called versions 1, 2, 3, 4 and 5.
9 Since roughly mid-2010 several new ALPS touchpads have been released and
10 integrated into a variety of laptops and netbooks. These new touchpads
11 have enough behavior differences that the alps_model_data definition
12 table, describing the properties of the different versions, is no longer
13 adequate. The design choices were to re-define the alps_model_data
14 table, with the risk of regression testing existing devices, or isolate
15 the new devices outside of the alps_model_data table. The latter design
16 choice was made. The new touchpad signatures are named: "Rushmore",
17 "Pinnacle", and "Dolphin", which you will see in the alps.c code.
18 For the purposes of this document, this group of ALPS touchpads will
19 generically be called "new ALPS touchpads".
21 We experimented with probing the ACPI interface _HID (Hardware ID)/_CID
22 (Compatibility ID) definition as a way to uniquely identify the
23 different ALPS variants but there did not appear to be a 1:1 mapping.
24 In fact, it appeared to be an m:n mapping between the _HID and actual
30 All ALPS touchpads should respond to the "E6 report" command sequence:
31 E8-E6-E6-E6-E9. An ALPS touchpad should respond with either 00-00-0A or
32 00-00-64 if no buttons are pressed. The bits 0-2 of the first byte will be 1s
33 if some buttons are pressed.
35 If the E6 report is successful, the touchpad model is identified using the "E7
36 report" sequence: E8-E7-E7-E7-E9. The response is the model signature and is
37 matched against known models in the alps_model_data_array.
39 For older touchpads supporting protocol versions 3 and 4, the E7 report
40 model signature is always 73-02-64. To differentiate between these
41 versions, the response from the "Enter Command Mode" sequence must be
42 inspected as described below.
44 The new ALPS touchpads have an E7 signature of 73-03-50 or 73-03-0A but
45 seem to be better differentiated by the EC Command Mode response.
50 Protocol versions 3 and 4 have a command mode that is used to read and write
51 one-byte device registers in a 16-bit address space. The command sequence
52 EC-EC-EC-E9 places the device in command mode, and the device will respond
53 with 88-07 followed by a third byte. This third byte can be used to determine
54 whether the devices uses the version 3 or 4 protocol.
56 To exit command mode, PSMOUSE_CMD_SETSTREAM (EA) is sent to the touchpad.
58 While in command mode, register addresses can be set by first sending a
59 specific command, either EC for v3 devices or F5 for v4 devices. Then the
60 address is sent one nibble at a time, where each nibble is encoded as a
61 command with optional data. This enoding differs slightly between the v3 and
64 Once an address has been set, the addressed register can be read by sending
65 PSMOUSE_CMD_GETINFO (E9). The first two bytes of the response contains the
66 address of the register being read, and the third contains the value of the
67 register. Registers are written by writing the value one nibble at a time
68 using the same encoding used for addresses.
70 For the new ALPS touchpads, the EC command is used to enter command
71 mode. The response in the new ALPS touchpads is significantly different,
72 and more important in determining the behavior. This code has been
73 separated from the original alps_model_data table and put in the
74 alps_identify function. For example, there seem to be two hardware init
75 sequences for the "Dolphin" touchpads as determined by the second byte
81 In the following tables, the following notation is used.
83 CAPITALS = stick, miniscules = touchpad
85 ?'s can have different meanings on different models, such as wheel rotation,
86 extra buttons, stick buttons on a dualpoint, etc.
91 byte 0: 0 0 YSGN XSGN 1 M R L
92 byte 1: X7 X6 X5 X4 X3 X2 X1 X0
93 byte 2: Y7 Y6 Y5 Y4 Y3 Y2 Y1 Y0
95 Note that the device never signals overflow condition.
97 ALPS Absolute Mode - Protocol Verion 1
98 --------------------------------------
100 byte 0: 1 0 0 0 1 x9 x8 x7
101 byte 1: 0 x6 x5 x4 x3 x2 x1 x0
102 byte 2: 0 ? ? l r ? fin ges
103 byte 3: 0 ? ? ? ? y9 y8 y7
104 byte 4: 0 y6 y5 y4 y3 y2 y1 y0
105 byte 5: 0 z6 z5 z4 z3 z2 z1 z0
107 ALPS Absolute Mode - Protocol Version 2
108 ---------------------------------------
110 byte 0: 1 ? ? ? 1 ? ? ?
111 byte 1: 0 x6 x5 x4 x3 x2 x1 x0
112 byte 2: 0 x10 x9 x8 x7 ? fin ges
113 byte 3: 0 y9 y8 y7 1 M R L
114 byte 4: 0 y6 y5 y4 y3 y2 y1 y0
115 byte 5: 0 z6 z5 z4 z3 z2 z1 z0
117 Dualpoint device -- interleaved packet format
118 ---------------------------------------------
120 byte 0: 1 1 0 0 1 1 1 1
121 byte 1: 0 x6 x5 x4 x3 x2 x1 x0
122 byte 2: 0 x10 x9 x8 x7 0 fin ges
123 byte 3: 0 0 YSGN XSGN 1 1 1 1
124 byte 4: X7 X6 X5 X4 X3 X2 X1 X0
125 byte 5: Y7 Y6 Y5 Y4 Y3 Y2 Y1 Y0
126 byte 6: 0 y9 y8 y7 1 m r l
127 byte 7: 0 y6 y5 y4 y3 y2 y1 y0
128 byte 8: 0 z6 z5 z4 z3 z2 z1 z0
130 ALPS Absolute Mode - Protocol Version 3
131 ---------------------------------------
133 ALPS protocol version 3 has three different packet formats. The first two are
134 associated with touchpad events, and the third is associatd with trackstick
137 The first type is the touchpad position packet.
139 byte 0: 1 ? x1 x0 1 1 1 1
140 byte 1: 0 x10 x9 x8 x7 x6 x5 x4
141 byte 2: 0 y10 y9 y8 y7 y6 y5 y4
142 byte 3: 0 M R L 1 m r l
143 byte 4: 0 mt x3 x2 y3 y2 y1 y0
144 byte 5: 0 z6 z5 z4 z3 z2 z1 z0
146 Note that for some devices the trackstick buttons are reported in this packet,
147 and on others it is reported in the trackstick packets.
149 The second packet type contains bitmaps representing the x and y axes. In the
150 bitmaps a given bit is set if there is a finger covering that position on the
151 given axis. Thus the bitmap packet can be used for low-resolution multi-touch
152 data, although finger tracking is not possible. This packet also encodes the
153 number of contacts (f1 and f0 in the table below).
155 byte 0: 1 1 x1 x0 1 1 1 1
156 byte 1: 0 x8 x7 x6 x5 x4 x3 x2
157 byte 2: 0 y7 y6 y5 y4 y3 y2 y1
158 byte 3: 0 y10 y9 y8 1 1 1 1
159 byte 4: 0 x14 x13 x12 x11 x10 x9 y0
160 byte 5: 0 1 ? ? ? ? f1 f0
162 This packet only appears after a position packet with the mt bit set, and
163 usually only appears when there are two or more contacts (although
164 occasionally it's seen with only a single contact).
166 The final v3 packet type is the trackstick packet.
168 byte 0: 1 1 x7 y7 1 1 1 1
169 byte 1: 0 x6 x5 x4 x3 x2 x1 x0
170 byte 2: 0 y6 y5 y4 y3 y2 y1 y0
171 byte 3: 0 1 0 0 1 0 0 0
172 byte 4: 0 z4 z3 z2 z1 z0 ? ?
173 byte 5: 0 0 1 1 1 1 1 1
175 ALPS Absolute Mode - Protocol Version 4
176 ---------------------------------------
178 Protocol version 4 has an 8-byte packet format.
180 byte 0: 1 ? x1 x0 1 1 1 1
181 byte 1: 0 x10 x9 x8 x7 x6 x5 x4
182 byte 2: 0 y10 y9 y8 y7 y6 y5 y4
183 byte 3: 0 1 x3 x2 y3 y2 y1 y0
184 byte 4: 0 ? ? ? 1 ? r l
185 byte 5: 0 z6 z5 z4 z3 z2 z1 z0
186 byte 6: bitmap data (described below)
187 byte 7: bitmap data (described below)
189 The last two bytes represent a partial bitmap packet, with 3 full packets
190 required to construct a complete bitmap packet. Once assembled, the 6-byte
191 bitmap packet has the following format:
193 byte 0: 0 1 x7 x6 x5 x4 x3 x2
194 byte 1: 0 x1 x0 y4 y3 y2 y1 y0
195 byte 2: 0 0 ? x14 x13 x12 x11 x10
196 byte 3: 0 x9 x8 y9 y8 y7 y6 y5
197 byte 4: 0 0 0 0 0 0 0 0
198 byte 5: 0 0 0 0 0 0 0 y10
200 There are several things worth noting here.
202 1) In the bitmap data, bit 6 of byte 0 serves as a sync byte to
203 identify the first fragment of a bitmap packet.
205 2) The bitmaps represent the same data as in the v3 bitmap packets, although
206 the packet layout is different.
208 3) There doesn't seem to be a count of the contact points anywhere in the v4
209 protocol packets. Deriving a count of contact points must be done by
210 analyzing the bitmaps.
212 4) There is a 3 to 1 ratio of position packets to bitmap packets. Therefore
213 MT position can only be updated for every third ST position update, and
214 the count of contact points can only be updated every third packet as
217 So far no v4 devices with tracksticks have been encountered.
219 ALPS Absolute Mode - Protocol Version 5
220 ---------------------------------------
221 This is basically Protocol Version 3 but with different logic for packet
222 decode. It uses the same alps_process_touchpad_packet_v3 call with a
223 specialized decode_fields function pointer to correctly interpret the
224 packets. This appears to only be used by the Dolphin devices.
226 For single-touch, the 6-byte packet format is:
228 byte 0: 1 1 0 0 1 0 0 0
229 byte 1: 0 x6 x5 x4 x3 x2 x1 x0
230 byte 2: 0 y6 y5 y4 y3 y2 y1 y0
231 byte 3: 0 M R L 1 m r l
232 byte 4: y10 y9 y8 y7 x10 x9 x8 x7
233 byte 5: 0 z6 z5 z4 z3 z2 z1 z0
235 For mt, the format is:
237 byte 0: 1 1 1 n3 1 n2 n1 x24
238 byte 1: 1 y7 y6 y5 y4 y3 y2 y1
239 byte 2: ? x2 x1 y12 y11 y10 y9 y8
240 byte 3: 0 x23 x22 x21 x20 x19 x18 x17
241 byte 4: 0 x9 x8 x7 x6 x5 x4 x3
242 byte 5: 0 x16 x15 x14 x13 x12 x11 x10
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