1ALPS Touchpad Protocol 2---------------------- 3 4Introduction 5------------ 6Currently the ALPS touchpad driver supports seven protocol versions in use by 7ALPS touchpads, called versions 1, 2, 3, 4, 5, 6 and 7. 8 9Since roughly mid-2010 several new ALPS touchpads have been released and 10integrated into a variety of laptops and netbooks. These new touchpads 11have enough behavior differences that the alps_model_data definition 12table, describing the properties of the different versions, is no longer 13adequate. The design choices were to re-define the alps_model_data 14table, with the risk of regression testing existing devices, or isolate 15the new devices outside of the alps_model_data table. The latter design 16choice was made. The new touchpad signatures are named: "Rushmore", 17"Pinnacle", and "Dolphin", which you will see in the alps.c code. 18For the purposes of this document, this group of ALPS touchpads will 19generically be called "new ALPS touchpads". 20 21We experimented with probing the ACPI interface _HID (Hardware ID)/_CID 22(Compatibility ID) definition as a way to uniquely identify the 23different ALPS variants but there did not appear to be a 1:1 mapping. 24In fact, it appeared to be an m:n mapping between the _HID and actual 25hardware type. 26 27Detection 28--------- 29 30All ALPS touchpads should respond to the "E6 report" command sequence: 31E8-E6-E6-E6-E9. An ALPS touchpad should respond with either 00-00-0A or 3200-00-64 if no buttons are pressed. The bits 0-2 of the first byte will be 1s 33if some buttons are pressed. 34 35If the E6 report is successful, the touchpad model is identified using the "E7 36report" sequence: E8-E7-E7-E7-E9. The response is the model signature and is 37matched against known models in the alps_model_data_array. 38 39For older touchpads supporting protocol versions 3 and 4, the E7 report 40model signature is always 73-02-64. To differentiate between these 41versions, the response from the "Enter Command Mode" sequence must be 42inspected as described below. 43 44The new ALPS touchpads have an E7 signature of 73-03-50 or 73-03-0A but 45seem to be better differentiated by the EC Command Mode response. 46 47Command Mode 48------------ 49 50Protocol versions 3 and 4 have a command mode that is used to read and write 51one-byte device registers in a 16-bit address space. The command sequence 52EC-EC-EC-E9 places the device in command mode, and the device will respond 53with 88-07 followed by a third byte. This third byte can be used to determine 54whether the devices uses the version 3 or 4 protocol. 55 56To exit command mode, PSMOUSE_CMD_SETSTREAM (EA) is sent to the touchpad. 57 58While in command mode, register addresses can be set by first sending a 59specific command, either EC for v3 devices or F5 for v4 devices. Then the 60address is sent one nibble at a time, where each nibble is encoded as a 61command with optional data. This encoding differs slightly between the v3 and 62v4 protocols. 63 64Once an address has been set, the addressed register can be read by sending 65PSMOUSE_CMD_GETINFO (E9). The first two bytes of the response contains the 66address of the register being read, and the third contains the value of the 67register. Registers are written by writing the value one nibble at a time 68using the same encoding used for addresses. 69 70For the new ALPS touchpads, the EC command is used to enter command 71mode. The response in the new ALPS touchpads is significantly different, 72and more important in determining the behavior. This code has been 73separated from the original alps_model_data table and put in the 74alps_identify function. For example, there seem to be two hardware init 75sequences for the "Dolphin" touchpads as determined by the second byte 76of the EC response. 77 78Packet Format 79------------- 80 81In the following tables, the following notation is used. 82 83 CAPITALS = stick, miniscules = touchpad 84 85?'s can have different meanings on different models, such as wheel rotation, 86extra buttons, stick buttons on a dualpoint, etc. 87 88PS/2 packet format 89------------------ 90 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 94 95Note that the device never signals overflow condition. 96 97For protocol version 2 devices when the trackpoint is used, and no fingers 98are on the touchpad, the M R L bits signal the combined status of both the 99pointingstick and touchpad buttons. 100 101ALPS Absolute Mode - Protocol Version 1 102-------------------------------------- 103 104 byte 0: 1 0 0 0 1 x9 x8 x7 105 byte 1: 0 x6 x5 x4 x3 x2 x1 x0 106 byte 2: 0 ? ? l r ? fin ges 107 byte 3: 0 ? ? ? ? y9 y8 y7 108 byte 4: 0 y6 y5 y4 y3 y2 y1 y0 109 byte 5: 0 z6 z5 z4 z3 z2 z1 z0 110 111ALPS Absolute Mode - Protocol Version 2 112--------------------------------------- 113 114 byte 0: 1 ? ? ? 1 PSM PSR PSL 115 byte 1: 0 x6 x5 x4 x3 x2 x1 x0 116 byte 2: 0 x10 x9 x8 x7 ? fin ges 117 byte 3: 0 y9 y8 y7 1 M R L 118 byte 4: 0 y6 y5 y4 y3 y2 y1 y0 119 byte 5: 0 z6 z5 z4 z3 z2 z1 z0 120 121Protocol Version 2 DualPoint devices send standard PS/2 mouse packets for 122the DualPoint Stick. The M, R and L bits signal the combined status of both 123the pointingstick and touchpad buttons, except for Dell dualpoint devices 124where the pointingstick buttons get reported separately in the PSM, PSR 125and PSL bits. 126 127Dualpoint device -- interleaved packet format 128--------------------------------------------- 129 130 byte 0: 1 1 0 0 1 1 1 1 131 byte 1: 0 x6 x5 x4 x3 x2 x1 x0 132 byte 2: 0 x10 x9 x8 x7 0 fin ges 133 byte 3: 0 0 YSGN XSGN 1 1 1 1 134 byte 4: X7 X6 X5 X4 X3 X2 X1 X0 135 byte 5: Y7 Y6 Y5 Y4 Y3 Y2 Y1 Y0 136 byte 6: 0 y9 y8 y7 1 m r l 137 byte 7: 0 y6 y5 y4 y3 y2 y1 y0 138 byte 8: 0 z6 z5 z4 z3 z2 z1 z0 139 140Devices which use the interleaving format normally send standard PS/2 mouse 141packets for the DualPoint Stick + ALPS Absolute Mode packets for the 142touchpad, switching to the interleaved packet format when both the stick and 143the touchpad are used at the same time. 144 145ALPS Absolute Mode - Protocol Version 3 146--------------------------------------- 147 148ALPS protocol version 3 has three different packet formats. The first two are 149associated with touchpad events, and the third is associated with trackstick 150events. 151 152The first type is the touchpad position packet. 153 154 byte 0: 1 ? x1 x0 1 1 1 1 155 byte 1: 0 x10 x9 x8 x7 x6 x5 x4 156 byte 2: 0 y10 y9 y8 y7 y6 y5 y4 157 byte 3: 0 M R L 1 m r l 158 byte 4: 0 mt x3 x2 y3 y2 y1 y0 159 byte 5: 0 z6 z5 z4 z3 z2 z1 z0 160 161Note that for some devices the trackstick buttons are reported in this packet, 162and on others it is reported in the trackstick packets. 163 164The second packet type contains bitmaps representing the x and y axes. In the 165bitmaps a given bit is set if there is a finger covering that position on the 166given axis. Thus the bitmap packet can be used for low-resolution multi-touch 167data, although finger tracking is not possible. This packet also encodes the 168number of contacts (f1 and f0 in the table below). 169 170 byte 0: 1 1 x1 x0 1 1 1 1 171 byte 1: 0 x8 x7 x6 x5 x4 x3 x2 172 byte 2: 0 y7 y6 y5 y4 y3 y2 y1 173 byte 3: 0 y10 y9 y8 1 1 1 1 174 byte 4: 0 x14 x13 x12 x11 x10 x9 y0 175 byte 5: 0 1 ? ? ? ? f1 f0 176 177This packet only appears after a position packet with the mt bit set, and 178usually only appears when there are two or more contacts (although 179occasionally it's seen with only a single contact). 180 181The final v3 packet type is the trackstick packet. 182 183 byte 0: 1 1 x7 y7 1 1 1 1 184 byte 1: 0 x6 x5 x4 x3 x2 x1 x0 185 byte 2: 0 y6 y5 y4 y3 y2 y1 y0 186 byte 3: 0 1 0 0 1 0 0 0 187 byte 4: 0 z4 z3 z2 z1 z0 ? ? 188 byte 5: 0 0 1 1 1 1 1 1 189 190ALPS Absolute Mode - Protocol Version 4 191--------------------------------------- 192 193Protocol version 4 has an 8-byte packet format. 194 195 byte 0: 1 ? x1 x0 1 1 1 1 196 byte 1: 0 x10 x9 x8 x7 x6 x5 x4 197 byte 2: 0 y10 y9 y8 y7 y6 y5 y4 198 byte 3: 0 1 x3 x2 y3 y2 y1 y0 199 byte 4: 0 ? ? ? 1 ? r l 200 byte 5: 0 z6 z5 z4 z3 z2 z1 z0 201 byte 6: bitmap data (described below) 202 byte 7: bitmap data (described below) 203 204The last two bytes represent a partial bitmap packet, with 3 full packets 205required to construct a complete bitmap packet. Once assembled, the 6-byte 206bitmap packet has the following format: 207 208 byte 0: 0 1 x7 x6 x5 x4 x3 x2 209 byte 1: 0 x1 x0 y4 y3 y2 y1 y0 210 byte 2: 0 0 ? x14 x13 x12 x11 x10 211 byte 3: 0 x9 x8 y9 y8 y7 y6 y5 212 byte 4: 0 0 0 0 0 0 0 0 213 byte 5: 0 0 0 0 0 0 0 y10 214 215There are several things worth noting here. 216 217 1) In the bitmap data, bit 6 of byte 0 serves as a sync byte to 218 identify the first fragment of a bitmap packet. 219 220 2) The bitmaps represent the same data as in the v3 bitmap packets, although 221 the packet layout is different. 222 223 3) There doesn't seem to be a count of the contact points anywhere in the v4 224 protocol packets. Deriving a count of contact points must be done by 225 analyzing the bitmaps. 226 227 4) There is a 3 to 1 ratio of position packets to bitmap packets. Therefore 228 MT position can only be updated for every third ST position update, and 229 the count of contact points can only be updated every third packet as 230 well. 231 232So far no v4 devices with tracksticks have been encountered. 233 234ALPS Absolute Mode - Protocol Version 5 235--------------------------------------- 236This is basically Protocol Version 3 but with different logic for packet 237decode. It uses the same alps_process_touchpad_packet_v3 call with a 238specialized decode_fields function pointer to correctly interpret the 239packets. This appears to only be used by the Dolphin devices. 240 241For single-touch, the 6-byte packet format is: 242 243 byte 0: 1 1 0 0 1 0 0 0 244 byte 1: 0 x6 x5 x4 x3 x2 x1 x0 245 byte 2: 0 y6 y5 y4 y3 y2 y1 y0 246 byte 3: 0 M R L 1 m r l 247 byte 4: y10 y9 y8 y7 x10 x9 x8 x7 248 byte 5: 0 z6 z5 z4 z3 z2 z1 z0 249 250For mt, the format is: 251 252 byte 0: 1 1 1 n3 1 n2 n1 x24 253 byte 1: 1 y7 y6 y5 y4 y3 y2 y1 254 byte 2: ? x2 x1 y12 y11 y10 y9 y8 255 byte 3: 0 x23 x22 x21 x20 x19 x18 x17 256 byte 4: 0 x9 x8 x7 x6 x5 x4 x3 257 byte 5: 0 x16 x15 x14 x13 x12 x11 x10 258 259ALPS Absolute Mode - Protocol Version 6 260--------------------------------------- 261 262For trackstick packet, the format is: 263 264 byte 0: 1 1 1 1 1 1 1 1 265 byte 1: 0 X6 X5 X4 X3 X2 X1 X0 266 byte 2: 0 Y6 Y5 Y4 Y3 Y2 Y1 Y0 267 byte 3: ? Y7 X7 ? ? M R L 268 byte 4: Z7 Z6 Z5 Z4 Z3 Z2 Z1 Z0 269 byte 5: 0 1 1 1 1 1 1 1 270 271For touchpad packet, the format is: 272 273 byte 0: 1 1 1 1 1 1 1 1 274 byte 1: 0 0 0 0 x3 x2 x1 x0 275 byte 2: 0 0 0 0 y3 y2 y1 y0 276 byte 3: ? x7 x6 x5 x4 ? r l 277 byte 4: ? y7 y6 y5 y4 ? ? ? 278 byte 5: z7 z6 z5 z4 z3 z2 z1 z0 279 280(v6 touchpad does not have middle button) 281 282ALPS Absolute Mode - Protocol Version 7 283--------------------------------------- 284 285For trackstick packet, the format is: 286 287 byte 0: 0 1 0 0 1 0 0 0 288 byte 1: 1 1 * * 1 M R L 289 byte 2: X7 1 X5 X4 X3 X2 X1 X0 290 byte 3: Z6 1 Y6 X6 1 Y2 Y1 Y0 291 byte 4: Y7 0 Y5 Y4 Y3 1 1 0 292 byte 5: T&P 0 Z5 Z4 Z3 Z2 Z1 Z0 293 294For touchpad packet, the format is: 295 296 packet-fmt b7 b6 b5 b4 b3 b2 b1 b0 297 byte 0: TWO & MULTI L 1 R M 1 Y0-2 Y0-1 Y0-0 298 byte 0: NEW L 1 X1-5 1 1 Y0-2 Y0-1 Y0-0 299 byte 1: Y0-10 Y0-9 Y0-8 Y0-7 Y0-6 Y0-5 Y0-4 Y0-3 300 byte 2: X0-11 1 X0-10 X0-9 X0-8 X0-7 X0-6 X0-5 301 byte 3: X1-11 1 X0-4 X0-3 1 X0-2 X0-1 X0-0 302 byte 4: TWO X1-10 TWO X1-9 X1-8 X1-7 X1-6 X1-5 X1-4 303 byte 4: MULTI X1-10 TWO X1-9 X1-8 X1-7 X1-6 Y1-5 1 304 byte 4: NEW X1-10 TWO X1-9 X1-8 X1-7 X1-6 0 0 305 byte 5: TWO & NEW Y1-10 0 Y1-9 Y1-8 Y1-7 Y1-6 Y1-5 Y1-4 306 byte 5: MULTI Y1-10 0 Y1-9 Y1-8 Y1-7 Y1-6 F-1 F-0 307 308 L: Left button 309 R / M: Non-clickpads: Right / Middle button 310 Clickpads: When > 2 fingers are down, and some fingers 311 are in the button area, then the 2 coordinates reported 312 are for fingers outside the button area and these report 313 extra fingers being present in the right / left button 314 area. Note these fingers are not added to the F field! 315 so if a TWO packet is received and R = 1 then there are 316 3 fingers down, etc. 317 TWO: 1: Two touches present, byte 0/4/5 are in TWO fmt 318 0: If byte 4 bit 0 is 1, then byte 0/4/5 are in MULTI fmt 319 otherwise byte 0 bit 4 must be set and byte 0/4/5 are 320 in NEW fmt 321 F: Number of fingers - 3, 0 means 3 fingers, 1 means 4 ... 322