Documentation/devicetree/bindings/arm/cpus.txt

   1 =================
   2 ARM CPUs bindings
   3 =================
   4
   5 The device tree allows to describe the layout of CPUs in a system through
   6 the "cpus" node, which in turn contains a number of subnodes (ie "cpu")
   7 defining properties for every cpu.
   8
   9 Bindings for CPU nodes follow the Devicetree Specification, available from:
  10
  11 https://www.devicetree.org/specifications/
  12
  13 with updates for 32-bit and 64-bit ARM systems provided in this document.
  14
  15 ================================
  16 Convention used in this document
  17 ================================
  18
  19 This document follows the conventions described in the Devicetree
  20 Specification, with the addition:
  21
  22 - square brackets define bitfields, eg reg[7:0] value of the bitfield in
  23   the reg property contained in bits 7 down to 0
  24
  25 =====================================
  26 cpus and cpu node bindings definition
  27 =====================================
  28
  29 The ARM architecture, in accordance with the Devicetree Specification,
  30 requires the cpus and cpu nodes to be present and contain the properties
  31 described below.
  32
  33 - cpus node
  34
  35         Description: Container of cpu nodes
  36
  37         The node name must be "cpus".
  38
  39         A cpus node must define the following properties:
  40
  41         - #address-cells
  42                 Usage: required
  43                 Value type: <u32>
  44
  45                 Definition depends on ARM architecture version and
  46                 configuration:
  47
  48                         # On uniprocessor ARM architectures previous to v7
  49                           value must be 1, to enable a simple enumeration
  50                           scheme for processors that do not have a HW CPU
  51                           identification register.
  52                         # On 32-bit ARM 11 MPcore, ARM v7 or later systems
  53                           value must be 1, that corresponds to CPUID/MPIDR
  54                           registers sizes.
  55                         # On ARM v8 64-bit systems value should be set to 2,
  56                           that corresponds to the MPIDR_EL1 register size.
  57                           If MPIDR_EL1[63:32] value is equal to 0 on all CPUs
  58                           in the system, #address-cells can be set to 1, since
  59                           MPIDR_EL1[63:32] bits are not used for CPUs
  60                           identification.
  61         - #size-cells
  62                 Usage: required
  63                 Value type: <u32>
  64                 Definition: must be set to 0
  65
  66 - cpu node
  67
  68         Description: Describes a CPU in an ARM based system
  69
  70         PROPERTIES
  71
  72         - device_type
  73                 Usage: required
  74                 Value type: <string>
  75                 Definition: must be "cpu"
  76         - reg
  77                 Usage and definition depend on ARM architecture version and
  78                 configuration:
  79
  80                         # On uniprocessor ARM architectures previous to v7
  81                           this property is required and must be set to 0.
  82
  83                         # On ARM 11 MPcore based systems this property is
  84                           required and matches the CPUID[11:0] register bits.
  85
  86                           Bits [11:0] in the reg cell must be set to
  87                           bits [11:0] in CPU ID register.
  88
  89                           All other bits in the reg cell must be set to 0.
  90
  91                         # On 32-bit ARM v7 or later systems this property is
  92                           required and matches the CPU MPIDR[23:0] register
  93                           bits.
  94
  95                           Bits [23:0] in the reg cell must be set to
  96                           bits [23:0] in MPIDR.
  97
  98                           All other bits in the reg cell must be set to 0.
  99
 100                         # On ARM v8 64-bit systems this property is required
 101                           and matches the MPIDR_EL1 register affinity bits.
 102
 103                           * If cpus node's #address-cells property is set to 2
 104
 105                             The first reg cell bits [7:0] must be set to
 106                             bits [39:32] of MPIDR_EL1.
 107
 108                             The second reg cell bits [23:0] must be set to
 109                             bits [23:0] of MPIDR_EL1.
 110
 111                           * If cpus node's #address-cells property is set to 1
 112
 113                             The reg cell bits [23:0] must be set to bits [23:0]
 114                             of MPIDR_EL1.
 115
 116                           All other bits in the reg cells must be set to 0.
 117
 118         - compatible:
 119                 Usage: required
 120                 Value type: <string>
 121                 Definition: should be one of:
 122                             "arm,arm710t"
 123                             "arm,arm720t"
 124                             "arm,arm740t"
 125                             "arm,arm7ej-s"
 126                             "arm,arm7tdmi"
 127                             "arm,arm7tdmi-s"
 128                             "arm,arm9es"
 129                             "arm,arm9ej-s"
 130                             "arm,arm920t"
 131                             "arm,arm922t"
 132                             "arm,arm925"
 133                             "arm,arm926e-s"
 134                             "arm,arm926ej-s"
 135                             "arm,arm940t"
 136                             "arm,arm946e-s"
 137                             "arm,arm966e-s"
 138                             "arm,arm968e-s"
 139                             "arm,arm9tdmi"
 140                             "arm,arm1020e"
 141                             "arm,arm1020t"
 142                             "arm,arm1022e"
 143                             "arm,arm1026ej-s"
 144                             "arm,arm1136j-s"
 145                             "arm,arm1136jf-s"
 146                             "arm,arm1156t2-s"
 147                             "arm,arm1156t2f-s"
 148                             "arm,arm1176jzf"
 149                             "arm,arm1176jz-s"
 150                             "arm,arm1176jzf-s"
 151                             "arm,arm11mpcore"
 152                             "arm,cortex-a5"
 153                             "arm,cortex-a7"
 154                             "arm,cortex-a8"
 155                             "arm,cortex-a9"
 156                             "arm,cortex-a12"
 157                             "arm,cortex-a15"
 158                             "arm,cortex-a17"
 159                             "arm,cortex-a53"
 160                             "arm,cortex-a57"
 161                             "arm,cortex-a72"
 162                             "arm,cortex-a73"
 163                             "arm,cortex-m0"
 164                             "arm,cortex-m0+"
 165                             "arm,cortex-m1"
 166                             "arm,cortex-m3"
 167                             "arm,cortex-m4"
 168                             "arm,cortex-r4"
 169                             "arm,cortex-r5"
 170                             "arm,cortex-r7"
 171                             "brcm,brahma-b15"
 172                             "brcm,brahma-b53"
 173                             "brcm,vulcan"
 174                             "cavium,thunder"
 175                             "cavium,thunder2"
 176                             "faraday,fa526"
 177                             "intel,sa110"
 178                             "intel,sa1100"
 179                             "marvell,feroceon"
 180                             "marvell,mohawk"
 181                             "marvell,pj4a"
 182                             "marvell,pj4b"
 183                             "marvell,sheeva-v5"
 184                             "nvidia,tegra132-denver"
 185                             "nvidia,tegra186-denver"
 186                             "nvidia,tegra194-carmel"
 187                             "qcom,krait"
 188                             "qcom,kryo"
 189                             "qcom,kryo385"
 190                             "qcom,scorpion"
 191         - enable-method
 192                 Value type: <stringlist>
 193                 Usage and definition depend on ARM architecture version.
 194                         # On ARM v8 64-bit this property is required and must
 195                           be one of:
 196                              "psci"
 197                              "spin-table"
 198                         # On ARM 32-bit systems this property is optional and
 199                           can be one of:
 200                             "actions,s500-smp"
 201                             "allwinner,sun6i-a31"
 202                             "allwinner,sun8i-a23"
 203                             "allwinner,sun9i-a80-smp"
 204                             "amlogic,meson8-smp"
 205                             "amlogic,meson8b-smp"
 206                             "arm,realview-smp"
 207                             "brcm,bcm11351-cpu-method"
 208                             "brcm,bcm23550"
 209                             "brcm,bcm2836-smp"
 210                             "brcm,bcm-nsp-smp"
 211                             "brcm,brahma-b15"
 212                             "marvell,armada-375-smp"
 213                             "marvell,armada-380-smp"
 214                             "marvell,armada-390-smp"
 215                             "marvell,armada-xp-smp"
 216                             "marvell,98dx3236-smp"
 217                             "mediatek,mt6589-smp"
 218                             "mediatek,mt81xx-tz-smp"
 219                             "qcom,gcc-msm8660"
 220                             "qcom,kpss-acc-v1"
 221                             "qcom,kpss-acc-v2"
 222                             "renesas,apmu"
 223                             "renesas,r9a06g032-smp"
 224                             "rockchip,rk3036-smp"
 225                             "rockchip,rk3066-smp"
 226                             "ste,dbx500-smp"
 227
 228         - cpu-release-addr
 229                 Usage: required for systems that have an "enable-method"
 230                        property value of "spin-table".
 231                 Value type: <prop-encoded-array>
 232                 Definition:
 233                         # On ARM v8 64-bit systems must be a two cell
 234                           property identifying a 64-bit zero-initialised
 235                           memory location.
 236
 237         - qcom,saw
 238                 Usage: required for systems that have an "enable-method"
 239                        property value of "qcom,kpss-acc-v1" or
 240                        "qcom,kpss-acc-v2"
 241                 Value type: <phandle>
 242                 Definition: Specifies the SAW[1] node associated with this CPU.
 243
 244         - qcom,acc
 245                 Usage: required for systems that have an "enable-method"
 246                        property value of "qcom,kpss-acc-v1" or
 247                        "qcom,kpss-acc-v2"
 248                 Value type: <phandle>
 249                 Definition: Specifies the ACC[2] node associated with this CPU.
 250
 251         - cpu-idle-states
 252                 Usage: Optional
 253                 Value type: <prop-encoded-array>
 254                 Definition:
 255                         # List of phandles to idle state nodes supported
 256                           by this cpu [3].
 257
 258         - capacity-dmips-mhz
 259                 Usage: Optional
 260                 Value type: <u32>
 261                 Definition:
 262                         # u32 value representing CPU capacity [4] in
 263                           DMIPS/MHz, relative to highest capacity-dmips-mhz
 264                           in the system.
 265
 266         - rockchip,pmu
 267                 Usage: optional for systems that have an "enable-method"
 268                        property value of "rockchip,rk3066-smp"
 269                        While optional, it is the preferred way to get access to
 270                        the cpu-core power-domains.
 271                 Value type: <phandle>
 272                 Definition: Specifies the syscon node controlling the cpu core
 273                             power domains.
 274
 275         - dynamic-power-coefficient
 276                 Usage: optional
 277                 Value type: <prop-encoded-array>
 278                 Definition: A u32 value that represents the running time dynamic
 279                             power coefficient in units of uW/MHz/V^2. The
 280                             coefficient can either be calculated from power
 281                             measurements or derived by analysis.
 282
 283                             The dynamic power consumption of the CPU  is
 284                             proportional to the square of the Voltage (V) and
 285                             the clock frequency (f). The coefficient is used to
 286                             calculate the dynamic power as below -
 287
 288                             Pdyn = dynamic-power-coefficient * V^2 * f
 289
 290                             where voltage is in V, frequency is in MHz.
 291
 292 Example 1 (dual-cluster big.LITTLE system 32-bit):
 293
 294         cpus {
 295                 #size-cells = <0>;
 296                 #address-cells = <1>;
 297
 298                 cpu@0 {
 299                         device_type = "cpu";
 300                         compatible = "arm,cortex-a15";
 301                         reg = <0x0>;
 302                 };
 303
 304                 cpu@1 {
 305                         device_type = "cpu";
 306                         compatible = "arm,cortex-a15";
 307                         reg = <0x1>;
 308                 };
 309
 310                 cpu@100 {
 311                         device_type = "cpu";
 312                         compatible = "arm,cortex-a7";
 313                         reg = <0x100>;
 314                 };
 315
 316                 cpu@101 {
 317                         device_type = "cpu";
 318                         compatible = "arm,cortex-a7";
 319                         reg = <0x101>;
 320                 };
 321         };
 322
 323 Example 2 (Cortex-A8 uniprocessor 32-bit system):
 324
 325         cpus {
 326                 #size-cells = <0>;
 327                 #address-cells = <1>;
 328
 329                 cpu@0 {
 330                         device_type = "cpu";
 331                         compatible = "arm,cortex-a8";
 332                         reg = <0x0>;
 333                 };
 334         };
 335
 336 Example 3 (ARM 926EJ-S uniprocessor 32-bit system):
 337
 338         cpus {
 339                 #size-cells = <0>;
 340                 #address-cells = <1>;
 341
 342                 cpu@0 {
 343                         device_type = "cpu";
 344                         compatible = "arm,arm926ej-s";
 345                         reg = <0x0>;
 346                 };
 347         };
 348
 349 Example 4 (ARM Cortex-A57 64-bit system):
 350
 351 cpus {
 352         #size-cells = <0>;
 353         #address-cells = <2>;
 354
 355         cpu@0 {
 356                 device_type = "cpu";
 357                 compatible = "arm,cortex-a57";
 358                 reg = <0x0 0x0>;
 359                 enable-method = "spin-table";
 360                 cpu-release-addr = <0 0x20000000>;
 361         };
 362
 363         cpu@1 {
 364                 device_type = "cpu";
 365                 compatible = "arm,cortex-a57";
 366                 reg = <0x0 0x1>;
 367                 enable-method = "spin-table";
 368                 cpu-release-addr = <0 0x20000000>;
 369         };
 370
 371         cpu@100 {
 372                 device_type = "cpu";
 373                 compatible = "arm,cortex-a57";
 374                 reg = <0x0 0x100>;
 375                 enable-method = "spin-table";
 376                 cpu-release-addr = <0 0x20000000>;
 377         };
 378
 379         cpu@101 {
 380                 device_type = "cpu";
 381                 compatible = "arm,cortex-a57";
 382                 reg = <0x0 0x101>;
 383                 enable-method = "spin-table";
 384                 cpu-release-addr = <0 0x20000000>;
 385         };
 386
 387         cpu@10000 {
 388                 device_type = "cpu";
 389                 compatible = "arm,cortex-a57";
 390                 reg = <0x0 0x10000>;
 391                 enable-method = "spin-table";
 392                 cpu-release-addr = <0 0x20000000>;
 393         };
 394
 395         cpu@10001 {
 396                 device_type = "cpu";
 397                 compatible = "arm,cortex-a57";
 398                 reg = <0x0 0x10001>;
 399                 enable-method = "spin-table";
 400                 cpu-release-addr = <0 0x20000000>;
 401         };
 402
 403         cpu@10100 {
 404                 device_type = "cpu";
 405                 compatible = "arm,cortex-a57";
 406                 reg = <0x0 0x10100>;
 407                 enable-method = "spin-table";
 408                 cpu-release-addr = <0 0x20000000>;
 409         };
 410
 411         cpu@10101 {
 412                 device_type = "cpu";
 413                 compatible = "arm,cortex-a57";
 414                 reg = <0x0 0x10101>;
 415                 enable-method = "spin-table";
 416                 cpu-release-addr = <0 0x20000000>;
 417         };
 418
 419         cpu@100000000 {
 420                 device_type = "cpu";
 421                 compatible = "arm,cortex-a57";
 422                 reg = <0x1 0x0>;
 423                 enable-method = "spin-table";
 424                 cpu-release-addr = <0 0x20000000>;
 425         };
 426
 427         cpu@100000001 {
 428                 device_type = "cpu";
 429                 compatible = "arm,cortex-a57";
 430                 reg = <0x1 0x1>;
 431                 enable-method = "spin-table";
 432                 cpu-release-addr = <0 0x20000000>;
 433         };
 434
 435         cpu@100000100 {
 436                 device_type = "cpu";
 437                 compatible = "arm,cortex-a57";
 438                 reg = <0x1 0x100>;
 439                 enable-method = "spin-table";
 440                 cpu-release-addr = <0 0x20000000>;
 441         };
 442
 443         cpu@100000101 {
 444                 device_type = "cpu";
 445                 compatible = "arm,cortex-a57";
 446                 reg = <0x1 0x101>;
 447                 enable-method = "spin-table";
 448                 cpu-release-addr = <0 0x20000000>;
 449         };
 450
 451         cpu@100010000 {
 452                 device_type = "cpu";
 453                 compatible = "arm,cortex-a57";
 454                 reg = <0x1 0x10000>;
 455                 enable-method = "spin-table";
 456                 cpu-release-addr = <0 0x20000000>;
 457         };
 458
 459         cpu@100010001 {
 460                 device_type = "cpu";
 461                 compatible = "arm,cortex-a57";
 462                 reg = <0x1 0x10001>;
 463                 enable-method = "spin-table";
 464                 cpu-release-addr = <0 0x20000000>;
 465         };
 466
 467         cpu@100010100 {
 468                 device_type = "cpu";
 469                 compatible = "arm,cortex-a57";
 470                 reg = <0x1 0x10100>;
 471                 enable-method = "spin-table";
 472                 cpu-release-addr = <0 0x20000000>;
 473         };
 474
 475         cpu@100010101 {
 476                 device_type = "cpu";
 477                 compatible = "arm,cortex-a57";
 478                 reg = <0x1 0x10101>;
 479                 enable-method = "spin-table";
 480                 cpu-release-addr = <0 0x20000000>;
 481         };
 482 };
 483
 484 --
 485 [1] arm/msm/qcom,saw2.txt
 486 [2] arm/msm/qcom,kpss-acc.txt
 487 [3] ARM Linux kernel documentation - idle states bindings
 488     Documentation/devicetree/bindings/arm/idle-states.txt
 489 [4] ARM Linux kernel documentation - cpu capacity bindings
 490     Documentation/devicetree/bindings/arm/cpu-capacity.txt