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