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                             "rockchip,rk3036-smp"
 224                             "rockchip,rk3066-smp"
 225                             "ste,dbx500-smp"
 226
 227         - cpu-release-addr
 228                 Usage: required for systems that have an "enable-method"
 229                        property value of "spin-table".
 230                 Value type: <prop-encoded-array>
 231                 Definition:
 232                         # On ARM v8 64-bit systems must be a two cell
 233                           property identifying a 64-bit zero-initialised
 234                           memory location.
 235
 236         - qcom,saw
 237                 Usage: required for systems that have an "enable-method"
 238                        property value of "qcom,kpss-acc-v1" or
 239                        "qcom,kpss-acc-v2"
 240                 Value type: <phandle>
 241                 Definition: Specifies the SAW[1] node associated with this CPU.
 242
 243         - qcom,acc
 244                 Usage: required for systems that have an "enable-method"
 245                        property value of "qcom,kpss-acc-v1" or
 246                        "qcom,kpss-acc-v2"
 247                 Value type: <phandle>
 248                 Definition: Specifies the ACC[2] node associated with this CPU.
 249
 250         - cpu-idle-states
 251                 Usage: Optional
 252                 Value type: <prop-encoded-array>
 253                 Definition:
 254                         # List of phandles to idle state nodes supported
 255                           by this cpu [3].
 256
 257         - capacity-dmips-mhz
 258                 Usage: Optional
 259                 Value type: <u32>
 260                 Definition:
 261                         # u32 value representing CPU capacity [4] in
 262                           DMIPS/MHz, relative to highest capacity-dmips-mhz
 263                           in the system.
 264
 265         - rockchip,pmu
 266                 Usage: optional for systems that have an "enable-method"
 267                        property value of "rockchip,rk3066-smp"
 268                        While optional, it is the preferred way to get access to
 269                        the cpu-core power-domains.
 270                 Value type: <phandle>
 271                 Definition: Specifies the syscon node controlling the cpu core
 272                             power domains.
 273
 274         - dynamic-power-coefficient
 275                 Usage: optional
 276                 Value type: <prop-encoded-array>
 277                 Definition: A u32 value that represents the running time dynamic
 278                             power coefficient in units of mW/MHz/uV^2. The
 279                             coefficient can either be calculated from power
 280                             measurements or derived by analysis.
 281
 282                             The dynamic power consumption of the CPU  is
 283                             proportional to the square of the Voltage (V) and
 284                             the clock frequency (f). The coefficient is used to
 285                             calculate the dynamic power as below -
 286
 287                             Pdyn = dynamic-power-coefficient * V^2 * f
 288
 289                             where voltage is in uV, frequency is in MHz.
 290
 291 Example 1 (dual-cluster big.LITTLE system 32-bit):
 292
 293         cpus {
 294                 #size-cells = <0>;
 295                 #address-cells = <1>;
 296
 297                 cpu@0 {
 298                         device_type = "cpu";
 299                         compatible = "arm,cortex-a15";
 300                         reg = <0x0>;
 301                 };
 302
 303                 cpu@1 {
 304                         device_type = "cpu";
 305                         compatible = "arm,cortex-a15";
 306                         reg = <0x1>;
 307                 };
 308
 309                 cpu@100 {
 310                         device_type = "cpu";
 311                         compatible = "arm,cortex-a7";
 312                         reg = <0x100>;
 313                 };
 314
 315                 cpu@101 {
 316                         device_type = "cpu";
 317                         compatible = "arm,cortex-a7";
 318                         reg = <0x101>;
 319                 };
 320         };
 321
 322 Example 2 (Cortex-A8 uniprocessor 32-bit system):
 323
 324         cpus {
 325                 #size-cells = <0>;
 326                 #address-cells = <1>;
 327
 328                 cpu@0 {
 329                         device_type = "cpu";
 330                         compatible = "arm,cortex-a8";
 331                         reg = <0x0>;
 332                 };
 333         };
 334
 335 Example 3 (ARM 926EJ-S uniprocessor 32-bit system):
 336
 337         cpus {
 338                 #size-cells = <0>;
 339                 #address-cells = <1>;
 340
 341                 cpu@0 {
 342                         device_type = "cpu";
 343                         compatible = "arm,arm926ej-s";
 344                         reg = <0x0>;
 345                 };
 346         };
 347
 348 Example 4 (ARM Cortex-A57 64-bit system):
 349
 350 cpus {
 351         #size-cells = <0>;
 352         #address-cells = <2>;
 353
 354         cpu@0 {
 355                 device_type = "cpu";
 356                 compatible = "arm,cortex-a57";
 357                 reg = <0x0 0x0>;
 358                 enable-method = "spin-table";
 359                 cpu-release-addr = <0 0x20000000>;
 360         };
 361
 362         cpu@1 {
 363                 device_type = "cpu";
 364                 compatible = "arm,cortex-a57";
 365                 reg = <0x0 0x1>;
 366                 enable-method = "spin-table";
 367                 cpu-release-addr = <0 0x20000000>;
 368         };
 369
 370         cpu@100 {
 371                 device_type = "cpu";
 372                 compatible = "arm,cortex-a57";
 373                 reg = <0x0 0x100>;
 374                 enable-method = "spin-table";
 375                 cpu-release-addr = <0 0x20000000>;
 376         };
 377
 378         cpu@101 {
 379                 device_type = "cpu";
 380                 compatible = "arm,cortex-a57";
 381                 reg = <0x0 0x101>;
 382                 enable-method = "spin-table";
 383                 cpu-release-addr = <0 0x20000000>;
 384         };
 385
 386         cpu@10000 {
 387                 device_type = "cpu";
 388                 compatible = "arm,cortex-a57";
 389                 reg = <0x0 0x10000>;
 390                 enable-method = "spin-table";
 391                 cpu-release-addr = <0 0x20000000>;
 392         };
 393
 394         cpu@10001 {
 395                 device_type = "cpu";
 396                 compatible = "arm,cortex-a57";
 397                 reg = <0x0 0x10001>;
 398                 enable-method = "spin-table";
 399                 cpu-release-addr = <0 0x20000000>;
 400         };
 401
 402         cpu@10100 {
 403                 device_type = "cpu";
 404                 compatible = "arm,cortex-a57";
 405                 reg = <0x0 0x10100>;
 406                 enable-method = "spin-table";
 407                 cpu-release-addr = <0 0x20000000>;
 408         };
 409
 410         cpu@10101 {
 411                 device_type = "cpu";
 412                 compatible = "arm,cortex-a57";
 413                 reg = <0x0 0x10101>;
 414                 enable-method = "spin-table";
 415                 cpu-release-addr = <0 0x20000000>;
 416         };
 417
 418         cpu@100000000 {
 419                 device_type = "cpu";
 420                 compatible = "arm,cortex-a57";
 421                 reg = <0x1 0x0>;
 422                 enable-method = "spin-table";
 423                 cpu-release-addr = <0 0x20000000>;
 424         };
 425
 426         cpu@100000001 {
 427                 device_type = "cpu";
 428                 compatible = "arm,cortex-a57";
 429                 reg = <0x1 0x1>;
 430                 enable-method = "spin-table";
 431                 cpu-release-addr = <0 0x20000000>;
 432         };
 433
 434         cpu@100000100 {
 435                 device_type = "cpu";
 436                 compatible = "arm,cortex-a57";
 437                 reg = <0x1 0x100>;
 438                 enable-method = "spin-table";
 439                 cpu-release-addr = <0 0x20000000>;
 440         };
 441
 442         cpu@100000101 {
 443                 device_type = "cpu";
 444                 compatible = "arm,cortex-a57";
 445                 reg = <0x1 0x101>;
 446                 enable-method = "spin-table";
 447                 cpu-release-addr = <0 0x20000000>;
 448         };
 449
 450         cpu@100010000 {
 451                 device_type = "cpu";
 452                 compatible = "arm,cortex-a57";
 453                 reg = <0x1 0x10000>;
 454                 enable-method = "spin-table";
 455                 cpu-release-addr = <0 0x20000000>;
 456         };
 457
 458         cpu@100010001 {
 459                 device_type = "cpu";
 460                 compatible = "arm,cortex-a57";
 461                 reg = <0x1 0x10001>;
 462                 enable-method = "spin-table";
 463                 cpu-release-addr = <0 0x20000000>;
 464         };
 465
 466         cpu@100010100 {
 467                 device_type = "cpu";
 468                 compatible = "arm,cortex-a57";
 469                 reg = <0x1 0x10100>;
 470                 enable-method = "spin-table";
 471                 cpu-release-addr = <0 0x20000000>;
 472         };
 473
 474         cpu@100010101 {
 475                 device_type = "cpu";
 476                 compatible = "arm,cortex-a57";
 477                 reg = <0x1 0x10101>;
 478                 enable-method = "spin-table";
 479                 cpu-release-addr = <0 0x20000000>;
 480         };
 481 };
 482
 483 --
 484 [1] arm/msm/qcom,saw2.txt
 485 [2] arm/msm/qcom,kpss-acc.txt
 486 [3] ARM Linux kernel documentation - idle states bindings
 487     Documentation/devicetree/bindings/arm/idle-states.txt
 488 [4] ARM Linux kernel documentation - cpu capacity bindings
 489     Documentation/devicetree/bindings/arm/cpu-capacity.txt