diff options
Diffstat (limited to 'Documentation/devicetree/bindings/arm/topology.txt')
| -rw-r--r-- | Documentation/devicetree/bindings/arm/topology.txt | 474 |
1 files changed, 474 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/arm/topology.txt b/Documentation/devicetree/bindings/arm/topology.txt new file mode 100644 index 000000000000..4aa20e7a424e --- /dev/null +++ b/Documentation/devicetree/bindings/arm/topology.txt | |||
| @@ -0,0 +1,474 @@ | |||
| 1 | =========================================== | ||
| 2 | ARM topology binding description | ||
| 3 | =========================================== | ||
| 4 | |||
| 5 | =========================================== | ||
| 6 | 1 - Introduction | ||
| 7 | =========================================== | ||
| 8 | |||
| 9 | In an ARM system, the hierarchy of CPUs is defined through three entities that | ||
| 10 | are used to describe the layout of physical CPUs in the system: | ||
| 11 | |||
| 12 | - cluster | ||
| 13 | - core | ||
| 14 | - thread | ||
| 15 | |||
| 16 | The cpu nodes (bindings defined in [1]) represent the devices that | ||
| 17 | correspond to physical CPUs and are to be mapped to the hierarchy levels. | ||
| 18 | |||
| 19 | The bottom hierarchy level sits at core or thread level depending on whether | ||
| 20 | symmetric multi-threading (SMT) is supported or not. | ||
| 21 | |||
| 22 | For instance in a system where CPUs support SMT, "cpu" nodes represent all | ||
| 23 | threads existing in the system and map to the hierarchy level "thread" above. | ||
| 24 | In systems where SMT is not supported "cpu" nodes represent all cores present | ||
| 25 | in the system and map to the hierarchy level "core" above. | ||
| 26 | |||
| 27 | ARM topology bindings allow one to associate cpu nodes with hierarchical groups | ||
| 28 | corresponding to the system hierarchy; syntactically they are defined as device | ||
| 29 | tree nodes. | ||
| 30 | |||
| 31 | The remainder of this document provides the topology bindings for ARM, based | ||
| 32 | on the ePAPR standard, available from: | ||
| 33 | |||
| 34 | http://www.power.org/documentation/epapr-version-1-1/ | ||
| 35 | |||
| 36 | If not stated otherwise, whenever a reference to a cpu node phandle is made its | ||
| 37 | value must point to a cpu node compliant with the cpu node bindings as | ||
| 38 | documented in [1]. | ||
| 39 | A topology description containing phandles to cpu nodes that are not compliant | ||
| 40 | with bindings standardized in [1] is therefore considered invalid. | ||
| 41 | |||
| 42 | =========================================== | ||
| 43 | 2 - cpu-map node | ||
| 44 | =========================================== | ||
| 45 | |||
| 46 | The ARM CPU topology is defined within the cpu-map node, which is a direct | ||
| 47 | child of the cpus node and provides a container where the actual topology | ||
| 48 | nodes are listed. | ||
| 49 | |||
| 50 | - cpu-map node | ||
| 51 | |||
| 52 | Usage: Optional - On ARM SMP systems provide CPUs topology to the OS. | ||
| 53 | ARM uniprocessor systems do not require a topology | ||
| 54 | description and therefore should not define a | ||
| 55 | cpu-map node. | ||
| 56 | |||
| 57 | Description: The cpu-map node is just a container node where its | ||
| 58 | subnodes describe the CPU topology. | ||
| 59 | |||
| 60 | Node name must be "cpu-map". | ||
| 61 | |||
| 62 | The cpu-map node's parent node must be the cpus node. | ||
| 63 | |||
| 64 | The cpu-map node's child nodes can be: | ||
| 65 | |||
| 66 | - one or more cluster nodes | ||
| 67 | |||
| 68 | Any other configuration is considered invalid. | ||
| 69 | |||
| 70 | The cpu-map node can only contain three types of child nodes: | ||
| 71 | |||
| 72 | - cluster node | ||
| 73 | - core node | ||
| 74 | - thread node | ||
| 75 | |||
| 76 | whose bindings are described in paragraph 3. | ||
| 77 | |||
| 78 | The nodes describing the CPU topology (cluster/core/thread) can only be | ||
| 79 | defined within the cpu-map node. | ||
| 80 | Any other configuration is consider invalid and therefore must be ignored. | ||
| 81 | |||
| 82 | =========================================== | ||
| 83 | 2.1 - cpu-map child nodes naming convention | ||
| 84 | =========================================== | ||
| 85 | |||
| 86 | cpu-map child nodes must follow a naming convention where the node name | ||
| 87 | must be "clusterN", "coreN", "threadN" depending on the node type (ie | ||
| 88 | cluster/core/thread) (where N = {0, 1, ...} is the node number; nodes which | ||
| 89 | are siblings within a single common parent node must be given a unique and | ||
| 90 | sequential N value, starting from 0). | ||
| 91 | cpu-map child nodes which do not share a common parent node can have the same | ||
| 92 | name (ie same number N as other cpu-map child nodes at different device tree | ||
| 93 | levels) since name uniqueness will be guaranteed by the device tree hierarchy. | ||
| 94 | |||
| 95 | =========================================== | ||
| 96 | 3 - cluster/core/thread node bindings | ||
| 97 | =========================================== | ||
| 98 | |||
| 99 | Bindings for cluster/cpu/thread nodes are defined as follows: | ||
| 100 | |||
| 101 | - cluster node | ||
| 102 | |||
| 103 | Description: must be declared within a cpu-map node, one node | ||
| 104 | per cluster. A system can contain several layers of | ||
| 105 | clustering and cluster nodes can be contained in parent | ||
| 106 | cluster nodes. | ||
| 107 | |||
| 108 | The cluster node name must be "clusterN" as described in 2.1 above. | ||
| 109 | A cluster node can not be a leaf node. | ||
| 110 | |||
| 111 | A cluster node's child nodes must be: | ||
| 112 | |||
| 113 | - one or more cluster nodes; or | ||
| 114 | - one or more core nodes | ||
| 115 | |||
| 116 | Any other configuration is considered invalid. | ||
| 117 | |||
| 118 | - core node | ||
| 119 | |||
| 120 | Description: must be declared in a cluster node, one node per core in | ||
| 121 | the cluster. If the system does not support SMT, core | ||
| 122 | nodes are leaf nodes, otherwise they become containers of | ||
| 123 | thread nodes. | ||
| 124 | |||
| 125 | The core node name must be "coreN" as described in 2.1 above. | ||
| 126 | |||
| 127 | A core node must be a leaf node if SMT is not supported. | ||
| 128 | |||
| 129 | Properties for core nodes that are leaf nodes: | ||
| 130 | |||
| 131 | - cpu | ||
| 132 | Usage: required | ||
| 133 | Value type: <phandle> | ||
| 134 | Definition: a phandle to the cpu node that corresponds to the | ||
| 135 | core node. | ||
| 136 | |||
| 137 | If a core node is not a leaf node (CPUs supporting SMT) a core node's | ||
| 138 | child nodes can be: | ||
| 139 | |||
| 140 | - one or more thread nodes | ||
| 141 | |||
| 142 | Any other configuration is considered invalid. | ||
| 143 | |||
| 144 | - thread node | ||
| 145 | |||
| 146 | Description: must be declared in a core node, one node per thread | ||
| 147 | in the core if the system supports SMT. Thread nodes are | ||
| 148 | always leaf nodes in the device tree. | ||
| 149 | |||
| 150 | The thread node name must be "threadN" as described in 2.1 above. | ||
| 151 | |||
| 152 | A thread node must be a leaf node. | ||
| 153 | |||
| 154 | A thread node must contain the following property: | ||
| 155 | |||
| 156 | - cpu | ||
| 157 | Usage: required | ||
| 158 | Value type: <phandle> | ||
| 159 | Definition: a phandle to the cpu node that corresponds to | ||
| 160 | the thread node. | ||
| 161 | |||
| 162 | =========================================== | ||
| 163 | 4 - Example dts | ||
| 164 | =========================================== | ||
| 165 | |||
| 166 | Example 1 (ARM 64-bit, 16-cpu system, two clusters of clusters): | ||
| 167 | |||
| 168 | cpus { | ||
| 169 | #size-cells = <0>; | ||
| 170 | #address-cells = <2>; | ||
| 171 | |||
| 172 | cpu-map { | ||
| 173 | cluster0 { | ||
| 174 | cluster0 { | ||
| 175 | core0 { | ||
| 176 | thread0 { | ||
| 177 | cpu = <&CPU0>; | ||
| 178 | }; | ||
| 179 | thread1 { | ||
| 180 | cpu = <&CPU1>; | ||
| 181 | }; | ||
| 182 | }; | ||
| 183 | |||
| 184 | core1 { | ||
| 185 | thread0 { | ||
| 186 | cpu = <&CPU2>; | ||
| 187 | }; | ||
| 188 | thread1 { | ||
| 189 | cpu = <&CPU3>; | ||
| 190 | }; | ||
| 191 | }; | ||
| 192 | }; | ||
| 193 | |||
| 194 | cluster1 { | ||
| 195 | core0 { | ||
| 196 | thread0 { | ||
| 197 | cpu = <&CPU4>; | ||
| 198 | }; | ||
| 199 | thread1 { | ||
| 200 | cpu = <&CPU5>; | ||
| 201 | }; | ||
| 202 | }; | ||
| 203 | |||
| 204 | core1 { | ||
| 205 | thread0 { | ||
| 206 | cpu = <&CPU6>; | ||
| 207 | }; | ||
| 208 | thread1 { | ||
| 209 | cpu = <&CPU7>; | ||
| 210 | }; | ||
| 211 | }; | ||
| 212 | }; | ||
| 213 | }; | ||
| 214 | |||
| 215 | cluster1 { | ||
| 216 | cluster0 { | ||
| 217 | core0 { | ||
| 218 | thread0 { | ||
| 219 | cpu = <&CPU8>; | ||
| 220 | }; | ||
| 221 | thread1 { | ||
| 222 | cpu = <&CPU9>; | ||
| 223 | }; | ||
| 224 | }; | ||
| 225 | core1 { | ||
| 226 | thread0 { | ||
| 227 | cpu = <&CPU10>; | ||
| 228 | }; | ||
| 229 | thread1 { | ||
| 230 | cpu = <&CPU11>; | ||
| 231 | }; | ||
| 232 | }; | ||
| 233 | }; | ||
| 234 | |||
| 235 | cluster1 { | ||
| 236 | core0 { | ||
| 237 | thread0 { | ||
| 238 | cpu = <&CPU12>; | ||
| 239 | }; | ||
| 240 | thread1 { | ||
| 241 | cpu = <&CPU13>; | ||
| 242 | }; | ||
| 243 | }; | ||
| 244 | core1 { | ||
| 245 | thread0 { | ||
| 246 | cpu = <&CPU14>; | ||
| 247 | }; | ||
| 248 | thread1 { | ||
| 249 | cpu = <&CPU15>; | ||
| 250 | }; | ||
| 251 | }; | ||
| 252 | }; | ||
| 253 | }; | ||
| 254 | }; | ||
| 255 | |||
| 256 | CPU0: cpu@0 { | ||
| 257 | device_type = "cpu"; | ||
| 258 | compatible = "arm,cortex-a57"; | ||
| 259 | reg = <0x0 0x0>; | ||
| 260 | enable-method = "spin-table"; | ||
| 261 | cpu-release-addr = <0 0x20000000>; | ||
| 262 | }; | ||
| 263 | |||
| 264 | CPU1: cpu@1 { | ||
| 265 | device_type = "cpu"; | ||
| 266 | compatible = "arm,cortex-a57"; | ||
| 267 | reg = <0x0 0x1>; | ||
| 268 | enable-method = "spin-table"; | ||
| 269 | cpu-release-addr = <0 0x20000000>; | ||
| 270 | }; | ||
| 271 | |||
| 272 | CPU2: cpu@100 { | ||
| 273 | device_type = "cpu"; | ||
| 274 | compatible = "arm,cortex-a57"; | ||
| 275 | reg = <0x0 0x100>; | ||
| 276 | enable-method = "spin-table"; | ||
| 277 | cpu-release-addr = <0 0x20000000>; | ||
| 278 | }; | ||
| 279 | |||
| 280 | CPU3: cpu@101 { | ||
| 281 | device_type = "cpu"; | ||
| 282 | compatible = "arm,cortex-a57"; | ||
| 283 | reg = <0x0 0x101>; | ||
| 284 | enable-method = "spin-table"; | ||
| 285 | cpu-release-addr = <0 0x20000000>; | ||
| 286 | }; | ||
| 287 | |||
| 288 | CPU4: cpu@10000 { | ||
| 289 | device_type = "cpu"; | ||
| 290 | compatible = "arm,cortex-a57"; | ||
| 291 | reg = <0x0 0x10000>; | ||
| 292 | enable-method = "spin-table"; | ||
| 293 | cpu-release-addr = <0 0x20000000>; | ||
| 294 | }; | ||
| 295 | |||
| 296 | CPU5: cpu@10001 { | ||
| 297 | device_type = "cpu"; | ||
| 298 | compatible = "arm,cortex-a57"; | ||
| 299 | reg = <0x0 0x10001>; | ||
| 300 | enable-method = "spin-table"; | ||
| 301 | cpu-release-addr = <0 0x20000000>; | ||
| 302 | }; | ||
| 303 | |||
| 304 | CPU6: cpu@10100 { | ||
| 305 | device_type = "cpu"; | ||
| 306 | compatible = "arm,cortex-a57"; | ||
| 307 | reg = <0x0 0x10100>; | ||
| 308 | enable-method = "spin-table"; | ||
| 309 | cpu-release-addr = <0 0x20000000>; | ||
| 310 | }; | ||
| 311 | |||
| 312 | CPU7: cpu@10101 { | ||
| 313 | device_type = "cpu"; | ||
| 314 | compatible = "arm,cortex-a57"; | ||
| 315 | reg = <0x0 0x10101>; | ||
| 316 | enable-method = "spin-table"; | ||
| 317 | cpu-release-addr = <0 0x20000000>; | ||
| 318 | }; | ||
| 319 | |||
| 320 | CPU8: cpu@100000000 { | ||
| 321 | device_type = "cpu"; | ||
| 322 | compatible = "arm,cortex-a57"; | ||
| 323 | reg = <0x1 0x0>; | ||
| 324 | enable-method = "spin-table"; | ||
| 325 | cpu-release-addr = <0 0x20000000>; | ||
| 326 | }; | ||
| 327 | |||
| 328 | CPU9: cpu@100000001 { | ||
| 329 | device_type = "cpu"; | ||
| 330 | compatible = "arm,cortex-a57"; | ||
| 331 | reg = <0x1 0x1>; | ||
| 332 | enable-method = "spin-table"; | ||
| 333 | cpu-release-addr = <0 0x20000000>; | ||
| 334 | }; | ||
| 335 | |||
| 336 | CPU10: cpu@100000100 { | ||
| 337 | device_type = "cpu"; | ||
| 338 | compatible = "arm,cortex-a57"; | ||
| 339 | reg = <0x1 0x100>; | ||
| 340 | enable-method = "spin-table"; | ||
| 341 | cpu-release-addr = <0 0x20000000>; | ||
| 342 | }; | ||
| 343 | |||
| 344 | CPU11: cpu@100000101 { | ||
| 345 | device_type = "cpu"; | ||
| 346 | compatible = "arm,cortex-a57"; | ||
| 347 | reg = <0x1 0x101>; | ||
| 348 | enable-method = "spin-table"; | ||
| 349 | cpu-release-addr = <0 0x20000000>; | ||
| 350 | }; | ||
| 351 | |||
| 352 | CPU12: cpu@100010000 { | ||
| 353 | device_type = "cpu"; | ||
| 354 | compatible = "arm,cortex-a57"; | ||
| 355 | reg = <0x1 0x10000>; | ||
| 356 | enable-method = "spin-table"; | ||
| 357 | cpu-release-addr = <0 0x20000000>; | ||
| 358 | }; | ||
| 359 | |||
| 360 | CPU13: cpu@100010001 { | ||
| 361 | device_type = "cpu"; | ||
| 362 | compatible = "arm,cortex-a57"; | ||
| 363 | reg = <0x1 0x10001>; | ||
| 364 | enable-method = "spin-table"; | ||
| 365 | cpu-release-addr = <0 0x20000000>; | ||
| 366 | }; | ||
| 367 | |||
| 368 | CPU14: cpu@100010100 { | ||
| 369 | device_type = "cpu"; | ||
| 370 | compatible = "arm,cortex-a57"; | ||
| 371 | reg = <0x1 0x10100>; | ||
| 372 | enable-method = "spin-table"; | ||
| 373 | cpu-release-addr = <0 0x20000000>; | ||
| 374 | }; | ||
| 375 | |||
| 376 | CPU15: cpu@100010101 { | ||
| 377 | device_type = "cpu"; | ||
| 378 | compatible = "arm,cortex-a57"; | ||
| 379 | reg = <0x1 0x10101>; | ||
| 380 | enable-method = "spin-table"; | ||
| 381 | cpu-release-addr = <0 0x20000000>; | ||
| 382 | }; | ||
| 383 | }; | ||
| 384 | |||
| 385 | Example 2 (ARM 32-bit, dual-cluster, 8-cpu system, no SMT): | ||
| 386 | |||
| 387 | cpus { | ||
| 388 | #size-cells = <0>; | ||
| 389 | #address-cells = <1>; | ||
| 390 | |||
| 391 | cpu-map { | ||
| 392 | cluster0 { | ||
| 393 | core0 { | ||
| 394 | cpu = <&CPU0>; | ||
| 395 | }; | ||
| 396 | core1 { | ||
| 397 | cpu = <&CPU1>; | ||
| 398 | }; | ||
| 399 | core2 { | ||
| 400 | cpu = <&CPU2>; | ||
| 401 | }; | ||
| 402 | core3 { | ||
| 403 | cpu = <&CPU3>; | ||
| 404 | }; | ||
| 405 | }; | ||
| 406 | |||
| 407 | cluster1 { | ||
| 408 | core0 { | ||
| 409 | cpu = <&CPU4>; | ||
| 410 | }; | ||
| 411 | core1 { | ||
| 412 | cpu = <&CPU5>; | ||
| 413 | }; | ||
| 414 | core2 { | ||
| 415 | cpu = <&CPU6>; | ||
| 416 | }; | ||
| 417 | core3 { | ||
| 418 | cpu = <&CPU7>; | ||
| 419 | }; | ||
| 420 | }; | ||
| 421 | }; | ||
| 422 | |||
| 423 | CPU0: cpu@0 { | ||
| 424 | device_type = "cpu"; | ||
| 425 | compatible = "arm,cortex-a15"; | ||
| 426 | reg = <0x0>; | ||
| 427 | }; | ||
| 428 | |||
| 429 | CPU1: cpu@1 { | ||
| 430 | device_type = "cpu"; | ||
| 431 | compatible = "arm,cortex-a15"; | ||
| 432 | reg = <0x1>; | ||
| 433 | }; | ||
| 434 | |||
| 435 | CPU2: cpu@2 { | ||
| 436 | device_type = "cpu"; | ||
| 437 | compatible = "arm,cortex-a15"; | ||
| 438 | reg = <0x2>; | ||
| 439 | }; | ||
| 440 | |||
| 441 | CPU3: cpu@3 { | ||
| 442 | device_type = "cpu"; | ||
| 443 | compatible = "arm,cortex-a15"; | ||
| 444 | reg = <0x3>; | ||
| 445 | }; | ||
| 446 | |||
| 447 | CPU4: cpu@100 { | ||
| 448 | device_type = "cpu"; | ||
| 449 | compatible = "arm,cortex-a7"; | ||
| 450 | reg = <0x100>; | ||
| 451 | }; | ||
| 452 | |||
| 453 | CPU5: cpu@101 { | ||
| 454 | device_type = "cpu"; | ||
| 455 | compatible = "arm,cortex-a7"; | ||
| 456 | reg = <0x101>; | ||
| 457 | }; | ||
| 458 | |||
| 459 | CPU6: cpu@102 { | ||
| 460 | device_type = "cpu"; | ||
| 461 | compatible = "arm,cortex-a7"; | ||
| 462 | reg = <0x102>; | ||
| 463 | }; | ||
| 464 | |||
| 465 | CPU7: cpu@103 { | ||
| 466 | device_type = "cpu"; | ||
| 467 | compatible = "arm,cortex-a7"; | ||
| 468 | reg = <0x103>; | ||
| 469 | }; | ||
| 470 | }; | ||
| 471 | |||
| 472 | =============================================================================== | ||
| 473 | [1] ARM Linux kernel documentation | ||
| 474 | Documentation/devicetree/bindings/arm/cpus.txt | ||
