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-m0"
 161                             "arm,cortex-m0+"
 162                             "arm,cortex-m1"
 163                             "arm,cortex-m3"
 164                             "arm,cortex-m4"
 165                             "arm,cortex-r4"
 166                             "arm,cortex-r5"
 167                             "arm,cortex-r7"
 168                             "brcm,brahma-b15"
 169                             "cavium,thunder"
 170                             "faraday,fa526"
 171                             "intel,sa110"
 172                             "intel,sa1100"
 173                             "marvell,feroceon"
 174                             "marvell,mohawk"
 175                             "marvell,pj4a"
 176                             "marvell,pj4b"
 177                             "marvell,sheeva-v5"
 178                             "qcom,krait"
 179                             "qcom,scorpion"
 180         - enable-method
 181                 Value type: <stringlist>
 182                 Usage and definition depend on ARM architecture version.
 183                         # On ARM v8 64-bit this property is required and must
 184                           be one of:
 185                              "psci"
 186                              "spin-table"
 187                         # On ARM 32-bit systems this property is optional and
 188                           can be one of:
 189                             "allwinner,sun6i-a31"
 190                             "arm,psci"
 191                             "brcm,brahma-b15"
 192                             "marvell,armada-375-smp"
 193                             "marvell,armada-380-smp"
 194                             "marvell,armada-xp-smp"
 195                             "qcom,gcc-msm8660"
 196                             "qcom,kpss-acc-v1"
 197                             "qcom,kpss-acc-v2"
 198                             "rockchip,rk3066-smp"
 199
 200         - cpu-release-addr
 201                 Usage: required for systems that have an "enable-method"
 202                        property value of "spin-table".
 203                 Value type: <prop-encoded-array>
 204                 Definition:
 205                         # On ARM v8 64-bit systems must be a two cell
 206                           property identifying a 64-bit zero-initialised
 207                           memory location.
 208
 209         - qcom,saw
 210                 Usage: required for systems that have an "enable-method"
 211                        property value of "qcom,kpss-acc-v1" or
 212                        "qcom,kpss-acc-v2"
 213                 Value type: <phandle>
 214                 Definition: Specifies the SAW[1] node associated with this CPU.
 215
 216         - qcom,acc
 217                 Usage: required for systems that have an "enable-method"
 218                        property value of "qcom,kpss-acc-v1" or
 219                        "qcom,kpss-acc-v2"
 220                 Value type: <phandle>
 221                 Definition: Specifies the ACC[2] node associated with this CPU.
 222
 223         - cpu-idle-states
 224                 Usage: Optional
 225                 Value type: <prop-encoded-array>
 226                 Definition:
 227                         # List of phandles to idle state nodes supported
 228                           by this cpu [3].
 229
 230 Example 1 (dual-cluster big.LITTLE system 32-bit):
 231
 232         cpus {
 233                 #size-cells = <0>;
 234                 #address-cells = <1>;
 235
 236                 cpu@0 {
 237                         device_type = "cpu";
 238                         compatible = "arm,cortex-a15";
 239                         reg = <0x0>;
 240                 };
 241
 242                 cpu@1 {
 243                         device_type = "cpu";
 244                         compatible = "arm,cortex-a15";
 245                         reg = <0x1>;
 246                 };
 247
 248                 cpu@100 {
 249                         device_type = "cpu";
 250                         compatible = "arm,cortex-a7";
 251                         reg = <0x100>;
 252                 };
 253
 254                 cpu@101 {
 255                         device_type = "cpu";
 256                         compatible = "arm,cortex-a7";
 257                         reg = <0x101>;
 258                 };
 259         };
 260
 261 Example 2 (Cortex-A8 uniprocessor 32-bit system):
 262
 263         cpus {
 264                 #size-cells = <0>;
 265                 #address-cells = <1>;
 266
 267                 cpu@0 {
 268                         device_type = "cpu";
 269                         compatible = "arm,cortex-a8";
 270                         reg = <0x0>;
 271                 };
 272         };
 273
 274 Example 3 (ARM 926EJ-S uniprocessor 32-bit system):
 275
 276         cpus {
 277                 #size-cells = <0>;
 278                 #address-cells = <1>;
 279
 280                 cpu@0 {
 281                         device_type = "cpu";
 282                         compatible = "arm,arm926ej-s";
 283                         reg = <0x0>;
 284                 };
 285         };
 286
 287 Example 4 (ARM Cortex-A57 64-bit system):
 288
 289 cpus {
 290         #size-cells = <0>;
 291         #address-cells = <2>;
 292
 293         cpu@0 {
 294                 device_type = "cpu";
 295                 compatible = "arm,cortex-a57";
 296                 reg = <0x0 0x0>;
 297                 enable-method = "spin-table";
 298                 cpu-release-addr = <0 0x20000000>;
 299         };
 300
 301         cpu@1 {
 302                 device_type = "cpu";
 303                 compatible = "arm,cortex-a57";
 304                 reg = <0x0 0x1>;
 305                 enable-method = "spin-table";
 306                 cpu-release-addr = <0 0x20000000>;
 307         };
 308
 309         cpu@100 {
 310                 device_type = "cpu";
 311                 compatible = "arm,cortex-a57";
 312                 reg = <0x0 0x100>;
 313                 enable-method = "spin-table";
 314                 cpu-release-addr = <0 0x20000000>;
 315         };
 316
 317         cpu@101 {
 318                 device_type = "cpu";
 319                 compatible = "arm,cortex-a57";
 320                 reg = <0x0 0x101>;
 321                 enable-method = "spin-table";
 322                 cpu-release-addr = <0 0x20000000>;
 323         };
 324
 325         cpu@10000 {
 326                 device_type = "cpu";
 327                 compatible = "arm,cortex-a57";
 328                 reg = <0x0 0x10000>;
 329                 enable-method = "spin-table";
 330                 cpu-release-addr = <0 0x20000000>;
 331         };
 332
 333         cpu@10001 {
 334                 device_type = "cpu";
 335                 compatible = "arm,cortex-a57";
 336                 reg = <0x0 0x10001>;
 337                 enable-method = "spin-table";
 338                 cpu-release-addr = <0 0x20000000>;
 339         };
 340
 341         cpu@10100 {
 342                 device_type = "cpu";
 343                 compatible = "arm,cortex-a57";
 344                 reg = <0x0 0x10100>;
 345                 enable-method = "spin-table";
 346                 cpu-release-addr = <0 0x20000000>;
 347         };
 348
 349         cpu@10101 {
 350                 device_type = "cpu";
 351                 compatible = "arm,cortex-a57";
 352                 reg = <0x0 0x10101>;
 353                 enable-method = "spin-table";
 354                 cpu-release-addr = <0 0x20000000>;
 355         };
 356
 357         cpu@100000000 {
 358                 device_type = "cpu";
 359                 compatible = "arm,cortex-a57";
 360                 reg = <0x1 0x0>;
 361                 enable-method = "spin-table";
 362                 cpu-release-addr = <0 0x20000000>;
 363         };
 364
 365         cpu@100000001 {
 366                 device_type = "cpu";
 367                 compatible = "arm,cortex-a57";
 368                 reg = <0x1 0x1>;
 369                 enable-method = "spin-table";
 370                 cpu-release-addr = <0 0x20000000>;
 371         };
 372
 373         cpu@100000100 {
 374                 device_type = "cpu";
 375                 compatible = "arm,cortex-a57";
 376                 reg = <0x1 0x100>;
 377                 enable-method = "spin-table";
 378                 cpu-release-addr = <0 0x20000000>;
 379         };
 380
 381         cpu@100000101 {
 382                 device_type = "cpu";
 383                 compatible = "arm,cortex-a57";
 384                 reg = <0x1 0x101>;
 385                 enable-method = "spin-table";
 386                 cpu-release-addr = <0 0x20000000>;
 387         };
 388
 389         cpu@100010000 {
 390                 device_type = "cpu";
 391                 compatible = "arm,cortex-a57";
 392                 reg = <0x1 0x10000>;
 393                 enable-method = "spin-table";
 394                 cpu-release-addr = <0 0x20000000>;
 395         };
 396
 397         cpu@100010001 {
 398                 device_type = "cpu";
 399                 compatible = "arm,cortex-a57";
 400                 reg = <0x1 0x10001>;
 401                 enable-method = "spin-table";
 402                 cpu-release-addr = <0 0x20000000>;
 403         };
 404
 405         cpu@100010100 {
 406                 device_type = "cpu";
 407                 compatible = "arm,cortex-a57";
 408                 reg = <0x1 0x10100>;
 409                 enable-method = "spin-table";
 410                 cpu-release-addr = <0 0x20000000>;
 411         };
 412
 413         cpu@100010101 {
 414                 device_type = "cpu";
 415                 compatible = "arm,cortex-a57";
 416                 reg = <0x1 0x10101>;
 417                 enable-method = "spin-table";
 418                 cpu-release-addr = <0 0x20000000>;
 419         };
 420 };
 421
 422 --
 423 [1] arm/msm/qcom,saw2.txt
 424 [2] arm/msm/qcom,kpss-acc.txt
 425 [3] ARM Linux kernel documentation - idle states bindings
 426     Documentation/devicetree/bindings/arm/idle-states.txt