ARM DT cpus/cpu and topology bindings
cover ARM DT cpus/cpu and topology bindings
Hi,
this patch resumes DT topology/cpu bindings discussions for ARM that were started here:
https://lists.ozlabs.org/pipermail/devicetree-discuss/2013-April/031725.html
https://lists.ozlabs.org/pipermail/devicetree-discuss/2013-April/032450.html
They have been partially reviewed but following the new DT bindings approval guidelines are still to be debated and updated accordingly.
Given the dependency on booting protocol in-kernel docs for ARM v8, I left on purpose the method "spin-table" in the cpu node "enable-method" property to kickstart a proper discussion on the subject before taking a definite action on it.
Comments very welcome.
Lorenzo
Lorenzo Pieralisi (2):
Documentation: devicetree: arm: cpus/cpu nodes bindings updates
Documentation: DT: arm: define CPU topology bindings
Documentation/devicetree/bindings/arm/cpus.txt | 424 ++++++++++++++++-- Documentation/devicetree/bindings/arm/topology.txt | 492 +++++++++++++++++++++ 2 files changed, 869 insertions(+), 47 deletions(-) create mode 100644 Documentation/devicetree/bindings/arm/topology.txt
Signature · 1 line
1.8.2.2
PATCH 1/2 Documentation: devicetree: arm: cpus/cpu nodes bindings updates
In order to extend the current cpu nodes bindings to newer CPUs inclusive of AArch64 and to update support for older ARM CPUs this patch updates device tree documentation for the cpu nodes bindings.
Main changes:
- adds 64-bit bindings
- define usage of #address-cells
- defines behaviour on pre and post v7 uniprocessor systems
- adds ARM 11MPcore specific reg property definition
--- Documentation/devicetree/bindings/arm/cpus.txt | 424 ++++++++++++++++++++++--- 1 file changed, 377 insertions(+), 47 deletions(-)
Documentation/devicetree/bindings/arm/cpus.txt +377 -47
@@ -1,77 +1,407 @@ -* ARM CPUs binding description +================= +ARM CPUs bindings +================= The device tree allows to describe the layout of CPUs in a system through the "cpus" node, which in turn contains a number of subnodes (ie "cpu") defining properties for every cpu. -Bindings for CPU nodes follow the ePAPR standard, available from: - -http://devicetree.org - -For the ARM architecture every CPU node must contain the following properties: - -- device_type: must be "cpu" -- reg: property matching the CPU MPIDR[23:0] register bits - reg[31:24] bits must be set to 0 -- compatible: should be one of: - "arm,arm1020" - "arm,arm1020e" - "arm,arm1022" - "arm,arm1026" - "arm,arm720" - "arm,arm740" - "arm,arm7tdmi" - "arm,arm920" - "arm,arm922" - "arm,arm925" - "arm,arm926" - "arm,arm940" - "arm,arm946" - "arm,arm9tdmi" - "arm,cortex-a5" - "arm,cortex-a7" - "arm,cortex-a8" - "arm,cortex-a9" - "arm,cortex-a15" - "arm,arm1136" - "arm,arm1156" - "arm,arm1176" - "arm,arm11mpcore" - "faraday,fa526" - "intel,sa110" - "intel,sa1100" - "marvell,feroceon" - "marvell,mohawk" - "marvell,xsc3" - "marvell,xscale" - -Example: +Bindings for CPU nodes follow the ePAPR v1.1 standard, available from: + +https://www.power.org/documentation/epapr-version-1-1/ + +with updates for 32-bit and 64-bit ARM systems provided in this document. + +================================ +Convention used in this document +================================ + +This document follows the conventions described in the ePAPR v1.1, with +the addition: + +- square brackets define bitfields, eg reg[7:0] value of the bitfield in + the reg property contained in bits 7 down to 0 + +===================================== +cpus and cpu node bindings definition +===================================== + +The ARM architecture, in accordance with the ePAPR, requires the cpus and cpu +nodes to be present and contain the properties described below. + +- cpus node + + Description: Container of cpu nodes + + The node name must be "cpus". + + A cpus node must define the following properties: + + - #address-cells + Usage: required + Value type: <u32> + + Definition depends on ARM architecture version and + configuration: + + # On uniprocessor ARM architectures previous to v7 + value must be 0, since they have no register + providing CPU identification. + # On 32-bit ARM 11 MPcore, ARM v7 or later systems + value must be 1, that corresponds to CPUID/MPIDR + registers sizes. + # On ARM v8 64-bit systems value must be set to 2, + that corresponds to the MPIDR_EL1 register size. + + - #size-cells + Usage: required + Value type: <u32> + Definition: must be set to 0 + +- cpu node + + Description: Describes a CPU in an ARM based system + + PROPERTIES + + - device_type + Usage: required + Value type: <string> + Definition: must be "cpu" + - reg + Usage and definition depend on ARM architecture version and + configuration: + + # On uniprocessor ARM architectures previous to v7 + this property is optional since they do not define + any register that provides a CPU identifier. + Any value set in the reg property for these CPUs + should be ignored. + + # On ARM 11 MPcore based systems this property is + required and matches the CPUID[11:0] register bits. + + Bits [11:0] in the reg cell must be set to + bits [11:0] in CPU ID register. + + All other bits in the reg cell must be set to 0. + + # On 32-bit ARM v7 or later systems this property is + required and matches the CPU MPIDR[23:0] register + bits. + + Bits [23:0] in the reg cell must be set to + bits [23:0] in MPIDR. + + All other bits in the reg cell must be set to 0. + + # On ARM v8 64-bit systems this property is required + and matches the MPIDR_EL1 register affinity bits: + + The first reg cell bits [7:0] must be set to + bits [39:32] of MPIDR_EL1. + + The second reg cell bits [23:0] must be set to + bits [23:0] of MPIDR_EL1. + + All other bits in the reg cells must be set to 0. + + - compatible: + Usage: required + Value type: <string> + Definition: should be one of: + "arm,arm710t" + "arm,arm720t" + "arm,arm740t" + "arm,arm7ej-s" + "arm,arm7tdmi" + "arm,arm7tdmi-s" + "arm,arm9es" + "arm,arm9ej-s" + "arm,arm920t" + "arm,arm922t" + "arm,arm925" + "arm,arm926e-s" + "arm,arm926ej-s" + "arm,arm940t" + "arm,arm946e-s" + "arm,arm966e-s" + "arm,arm968e-s" + "arm,arm9tdmi" + "arm,arm1020e" + "arm,arm1020t" + "arm,arm1022e" + "arm,arm1026ej-s" + "arm,arm1136j-s" + "arm,arm1136jf-s" + "arm,arm1156t2-s" + "arm,arm1156t2f-s" + "arm,arm1176jzf" + "arm,arm1176jz-s" + "arm,arm1176jzf-s" + "arm,arm11mpcore" + "arm,cortex-a5" + "arm,cortex-a7" + "arm,cortex-a8" + "arm,cortex-a9" + "arm,cortex-a15" + "arm,cortex-a53" + "arm,cortex-a57" + "arm,cortex-m0" + "arm,cortex-m0+" + "arm,cortex-m1" + "arm,cortex-m3" + "arm,cortex-m4" + "arm,cortex-r4" + "arm,cortex-r5" + "arm,cortex-r7" + "faraday,fa526" + "intel,sa110" + "intel,sa1100" + "marvell,feroceon" + "marvell,mohawk" + "marvell,pj4" + "marvell,sheeva-v7" + "marvell,xsc3" + "marvell,xscale" + "qcom,krait" + "qcom,scorpion" + - enable-method + Value type: <stringlist> + Usage and definition depend on ARM architecture version. + # On ARM v8 64-bit this property is required and must + be one of: + "spin-table" + "psci" + # On ARM 32-bit system this property is optional. + + - cpu-release-addr + Usage: required for systems that have an "enable-method" + property value of "spin-table". + Value type: <prop-encoded-array> + Definition: + # On ARM v8 64-bit systems must be a two cell + property identifying a 64-bit zero-initialised + memory location. + +Example 1 (dual-cluster big.LITTLE system 32-bit): cpus { #size-cells = <0>; #address-cells = <1>; - CPU0: cpu at 0 { + cpu at 0 { device_type = "cpu"; compatible = "arm,cortex-a15"; reg = <0x0>; }; - CPU1: cpu at 1 { + cpu at 1 { device_type = "cpu"; compatible = "arm,cortex-a15"; reg = <0x1>; }; - CPU2: cpu at 100 { + cpu at 100 { device_type = "cpu"; compatible = "arm,cortex-a7"; reg = <0x100>; }; - CPU3: cpu at 101 { + cpu at 101 { device_type = "cpu"; compatible = "arm,cortex-a7"; reg = <0x101>; }; }; + +Example 2 (Cortex-A8 uniprocessor 32-bit system): + + cpus { + #size-cells = <0>; + #address-cells = <1>; + + cpu at 0 { + device_type = "cpu"; + compatible = "arm,cortex-a8"; + reg = <0x0>; + }; + }; + +Example 3 (ARM 926EJ-S uniprocessor 32-bit system): + + cpus { + #size-cells = <0>; + #address-cells = <0>; + + cpu { + device_type = "cpu"; + compatible = "arm,arm926ej-s"; + }; + }; + +Example 4 (ARM Cortex-A57 64-bit system running OS in AArch64): + +cpus { + #size-cells = <0>; + #address-cells = <2>; + + cpu at 0 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x0>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 1 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x1>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x100>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x101>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 10000 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x10000>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 10001 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x10001>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 10100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x10100>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 10101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x10101>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 100000000 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x0>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 100000001 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x1>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 100000100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x100>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 100000101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x101>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 100010000 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x10000>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 100010001 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x10001>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 100010100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x10100>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + cpu at 100010101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x10101>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; +}; + +Example 5 (ARM Cortex-A57 64-bit system running OS in AArch32): + +cpus { + #size-cells = <0>; + #address-cells = <2>; + + cpu at 0 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x0>; + }; + + cpu at 1 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x1>; + }; + + cpu at 100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x100>; + }; + + cpu at 101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x101>; + }; +};
Signature · 1 line
1.8.2.2
PATCH 1/2 Documentation: devicetree: arm: cpus/cpu nodes bindings updates
Quoted 10 lines · Lorenzo Pieralisi
In order to extend the current cpu nodes bindings to newer CPUs inclusive of AArch64 and to update support for older ARM CPUs this patch updates device tree documentation for the cpu nodes bindings.
Main changes:
- adds 64-bit bindings
- define usage of #address-cells
- defines behaviour on pre and post v7 uniprocessor systems
- adds ARM 11MPcore specific reg property definition
Quoted 5 lines
Signed-off-by Lorenzo Pieralisi <[email protected]>--- Documentation/devicetree/bindings/arm/cpus.txt | 424 ++++++++++++++++++++++--- 1 file changed, 377 insertions(+), 47 deletions(-)
The binding looks mostly fine to me.
[snip]
Documentation/devicetree/bindings/arm/cpus.txt line 166
Quoted 9 lines
Documentation/devicetree/bindings/arm/cpus.txt +9
-0+ "faraday,fa526" + "intel,sa110" + "intel,sa1100" + "marvell,feroceon" + "marvell,mohawk" + "marvell,pj4" + "marvell,sheeva-v7" + "marvell,xsc3" + "marvell,xscale"
Better make sure the Marvell folks are happy with these. We don't need another rename here. I'm too annoyed with all the renames to pay attention.
Documentation/devicetree/bindings/arm/cpus.txt line 244
Quoted 3 lines
Documentation/devicetree/bindings/arm/cpus.txt +3
-0+ +Example 4 (ARM Cortex-A57 64-bit system running OS in AArch64): +
Going back to my comments that the dtb can't be dependent on the OS, these 2 examples don't make sense.
Documentation/devicetree/bindings/arm/cpus.txt line 378
Quoted 2 lines
Documentation/devicetree/bindings/arm/cpus.txt +2
-0+ +Example 5 (ARM Cortex-A57 64-bit system running OS in AArch32):
This example should be removed.
Rob
Quoted 30 lines
Documentation/devicetree/bindings/arm/cpus.txt +29
-0+ +cpus { + #size-cells = <0>; + #address-cells = <2>; + + cpu at 0 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x0>; + }; + + cpu at 1 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x1>; + }; + + cpu at 100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x100>; + }; + + cpu at 101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x101>; + }; +};
PATCH 1/2 Documentation: devicetree: arm: cpus/cpu nodes bindings updates
[adding Andrew, Gregory and Thomas to check the Marvell compatible names]
Quoted 21 lines · Rob Herring
Quoted 10 lines · Lorenzo Pieralisi
In order to extend the current cpu nodes bindings to newer CPUs inclusive of AArch64 and to update support for older ARM CPUs this patch updates device tree documentation for the cpu nodes bindings.
Main changes:
- adds 64-bit bindings
- define usage of #address-cells
- defines behaviour on pre and post v7 uniprocessor systems
- adds ARM 11MPcore specific reg property definitionQuoted 5 lines
Signed-off-by Lorenzo Pieralisi <[email protected]>--- Documentation/devicetree/bindings/arm/cpus.txt | 424 ++++++++++++++++++++++--- 1 file changed, 377 insertions(+), 47 deletions(-)The binding looks mostly fine to me.
[snip]
Quoted 12 lines
Documentation/devicetree/bindings/arm/cpus.txt line 166
Quoted 9 lines
Documentation/devicetree/bindings/arm/cpus.txt +9
-0+ "faraday,fa526" + "intel,sa110" + "intel,sa1100" + "marvell,feroceon" + "marvell,mohawk" + "marvell,pj4" + "marvell,sheeva-v7" + "marvell,xsc3" + "marvell,xscale"Better make sure the Marvell folks are happy with these. We don't need another rename here. I'm too annoyed with all the renames to pay attention.
Ok, I will verify that, I copied maintainers in.
On a side note I have just noticed that last cycle some dts were merged in the kernel with cpu nodes that are not compliant (not picking on anyone, eg am4372.dtsi).
Please prevent this from happening from now onwards, really please.
Quoted 6 lines
Documentation/devicetree/bindings/arm/cpus.txt line 244
Quoted 3 lines
Documentation/devicetree/bindings/arm/cpus.txt +3
-0+ +Example 4 (ARM Cortex-A57 64-bit system running OS in AArch64): +Going back to my comments that the dtb can't be dependent on the OS, these 2 examples don't make sense.
Gah, my bad sorry, I missed the examples while removing dependency on the OS from the bindings.
Quoted 4 lines
Documentation/devicetree/bindings/arm/cpus.txt line 378
Quoted 2 lines
Documentation/devicetree/bindings/arm/cpus.txt +2
-0+ +Example 5 (ARM Cortex-A57 64-bit system running OS in AArch32):This example should be removed.
Yes, consider it done, see above.
Thanks,
Lorenzo
PATCH 1/2 Documentation: devicetree: arm: cpus/cpu nodes bindings updates
Hi Lorenzo,
Quoted 4 lines · Lorenzo Pieralisi
On a side note I have just noticed that last cycle some dts were merged in the kernel with cpu nodes that are not compliant (not picking on anyone,
eg
am4372.dtsi).
mea culpa
am4372.dtsi was posted early in last cycle and started it's journey towards mainline after quite sometime. iirc, am4372 was posted around the time cpu node update was on the lists.
The relevant silicon is in pre-silicon stage, I was going back & forth on whether patches to fix it should go in -rc's or the coming merge window, finally settled for next merge window as am43x won't boot on mainline with last Kernel version.
The patches to fix cpu nodes in am4372 has been posted, acked by Mark Rutland, hopefully would make into mainline this merge window.
Regards
Afzal
PATCH 1/2 Documentation: devicetree: arm: cpus/cpu nodes bindings updates
In reply to Lorenzo PieralisiHi Rob, all,
Quoted 21 lines · Lorenzo Pieralisi
[adding Andrew, Gregory and Thomas to check the Marvell compatible names]
Quoted 18 lines · Rob Herring
Quoted 10 lines · Lorenzo Pieralisi
In order to extend the current cpu nodes bindings to newer CPUs inclusive of AArch64 and to update support for older ARM CPUs this patch updates device tree documentation for the cpu nodes bindings.
Main changes:
- adds 64-bit bindings
- define usage of #address-cells
- defines behaviour on pre and post v7 uniprocessor systems
- adds ARM 11MPcore specific reg property definitionQuoted 5 lines
Signed-off-by Lorenzo Pieralisi <[email protected]>--- Documentation/devicetree/bindings/arm/cpus.txt | 424 ++++++++++++++++++++++--- 1 file changed, 377 insertions(+), 47 deletions(-)The binding looks mostly fine to me.
These bindings have still not received an ACK, and need review by Marvell guys in copy for the new compatible strings below.
Most importantly, we need to make a decision on the pre v7 uniprocessor systems, where MPIDR/CPUID are non-existent and the reg property is a pure SW enumeration. Current bindings (ie this patch) define
#address-cells = <0>;
for those processors (and there are a number of dts in the kernel with that set-up); Grant and Benjamin had a strong feeling against this choice, I have to make a decision on how to proceed, please let me know.
Comments welcome.
Lorenzo
Quoted 48 lines
Quoted 15 lines
[snip]
Documentation/devicetree/bindings/arm/cpus.txt line 166
Quoted 9 lines
Documentation/devicetree/bindings/arm/cpus.txt +9
-0+ "faraday,fa526" + "intel,sa110" + "intel,sa1100" + "marvell,feroceon" + "marvell,mohawk" + "marvell,pj4" + "marvell,sheeva-v7" + "marvell,xsc3" + "marvell,xscale"Better make sure the Marvell folks are happy with these. We don't need another rename here. I'm too annoyed with all the renames to pay attention.
Ok, I will verify that, I copied maintainers in.
On a side note I have just noticed that last cycle some dts were merged in the kernel with cpu nodes that are not compliant (not picking on anyone, eg
am4372.dtsi).
Please prevent this from happening from now onwards, really please.Quoted 6 lines
Documentation/devicetree/bindings/arm/cpus.txt line 244
Quoted 3 lines
Documentation/devicetree/bindings/arm/cpus.txt +3
-0+ +Example 4 (ARM Cortex-A57 64-bit system running OS in AArch64): +Going back to my comments that the dtb can't be dependent on the OS, these 2 examples don't make sense.
Gah, my bad sorry, I missed the examples while removing dependency on the OS from the bindings.
Quoted 4 lines
Documentation/devicetree/bindings/arm/cpus.txt line 378
Quoted 2 lines
Documentation/devicetree/bindings/arm/cpus.txt +2
-0+ +Example 5 (ARM Cortex-A57 64-bit system running OS in AArch32):This example should be removed.
Yes, consider it done, see above.
Thanks,
Lorenzo--
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PATCH 1/2 Documentation: devicetree: arm: cpus/cpu nodes bindings updates
Quoted 23 lines · Lorenzo Pieralisi
Hi Rob, all,
Quoted 20 lines · Lorenzo Pieralisi
[adding Andrew, Gregory and Thomas to check the Marvell compatible names]
Quoted 17 lines · Rob Herring
Quoted 15 lines · Lorenzo Pieralisi
In order to extend the current cpu nodes bindings to newer CPUs inclusive of AArch64 and to update support for older ARM CPUs this patch updates device tree documentation for the cpu nodes bindings.
Main changes:
- adds 64-bit bindings
- define usage of #address-cells
- defines behaviour on pre and post v7 uniprocessor systems
- adds ARM 11MPcore specific reg property definitionSigned-off-by Lorenzo Pieralisi <[email protected]>--- Documentation/devicetree/bindings/arm/cpus.txt | 424 ++++++++++++++++++++++--- 1 file changed, 377 insertions(+), 47 deletions(-)
Quoted 4 lines
Quoted 1 line
Quoted 1 line
The binding looks mostly fine to me.
These bindings have still not received an ACK, and need review by Marvell guys in copy for the new compatible strings below.
If you can't get comment, then leave them out if they are not used already. If they are used, then tough shit when they want to change.
Quoted 10 lines
Most importantly, we need to make a decision on the pre v7 uniprocessor systems, where MPIDR/CPUID are non-existent and the reg property is a pure SW enumeration. Current bindings (ie this patch) define
#address-cells = <0>;
for those processors (and there are a number of dts in the kernel with that set-up); Grant and Benjamin had a strong feeling against this choice, I have to make a decision on how to proceed, please let me know.
I agree that we should define #address-cells to 1 and reg will be simply 0,1,2,etc. in this case.
This change and fixing the example as I pointed out are what I was waiting to see.
Rob
Quoted 54 lines
Comments welcome.
Lorenzo
Quoted 48 lines
Quoted 15 lines
[snip]
Documentation/devicetree/bindings/arm/cpus.txt line 166
Quoted 9 lines
Documentation/devicetree/bindings/arm/cpus.txt +9
-0+ "faraday,fa526" + "intel,sa110" + "intel,sa1100" + "marvell,feroceon" + "marvell,mohawk" + "marvell,pj4" + "marvell,sheeva-v7" + "marvell,xsc3" + "marvell,xscale"Better make sure the Marvell folks are happy with these. We don't need another rename here. I'm too annoyed with all the renames to pay attention.
Ok, I will verify that, I copied maintainers in.
On a side note I have just noticed that last cycle some dts were merged in the kernel with cpu nodes that are not compliant (not picking on anyone, eg
am4372.dtsi).
Please prevent this from happening from now onwards, really please.Quoted 6 lines
Documentation/devicetree/bindings/arm/cpus.txt line 244
Quoted 3 lines
Documentation/devicetree/bindings/arm/cpus.txt +3
-0+ +Example 4 (ARM Cortex-A57 64-bit system running OS in AArch64): +Going back to my comments that the dtb can't be dependent on the OS, these 2 examples don't make sense.
Gah, my bad sorry, I missed the examples while removing dependency on the OS from the bindings.
Quoted 4 lines
Documentation/devicetree/bindings/arm/cpus.txt line 378
Quoted 2 lines
Documentation/devicetree/bindings/arm/cpus.txt +2
-0+ +Example 5 (ARM Cortex-A57 64-bit system running OS in AArch32):This example should be removed.
Yes, consider it done, see above.
Thanks,
Lorenzo--
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PATCH 1/2 Documentation: devicetree: arm: cpus/cpu nodes bindings updates
Quoted 24 lines · Rob Herring
Quoted 23 lines · Lorenzo Pieralisi
Hi Rob, all,
Quoted 20 lines · Lorenzo Pieralisi
[adding Andrew, Gregory and Thomas to check the Marvell compatible names]
Quoted 17 lines · Rob Herring
Quoted 15 lines · Lorenzo Pieralisi
In order to extend the current cpu nodes bindings to newer CPUs inclusive of AArch64 and to update support for older ARM CPUs this patch updates device tree documentation for the cpu nodes bindings.
Main changes:
- adds 64-bit bindings
- define usage of #address-cells
- defines behaviour on pre and post v7 uniprocessor systems
- adds ARM 11MPcore specific reg property definitionSigned-off-by Lorenzo Pieralisi <[email protected]>--- Documentation/devicetree/bindings/arm/cpus.txt | 424 ++++++++++++++++++++++--- 1 file changed, 377 insertions(+), 47 deletions(-)
Quoted 7 lines
Quoted 4 lines
Quoted 1 line
Quoted 1 line
The binding looks mostly fine to me.
These bindings have still not received an ACK, and need review by Marvell guys in copy for the new compatible strings below.
If you can't get comment, then leave them out if they are not used already. If they are used, then tough shit when they want to change.
Hi Rob
We are working on it. Hope to be able to comment soon.
Andrew
PATCH 1/2 Documentation: devicetree: arm: cpus/cpu nodes bindings updates
In reply to Rob HerringQuoted 37 lines · Rob Herring
Quoted 23 lines · Lorenzo Pieralisi
Hi Rob, all,
Quoted 20 lines · Lorenzo Pieralisi
[adding Andrew, Gregory and Thomas to check the Marvell compatible names]
Quoted 17 lines · Rob Herring
Quoted 15 lines · Lorenzo Pieralisi
In order to extend the current cpu nodes bindings to newer CPUs inclusive of AArch64 and to update support for older ARM CPUs this patch updates device tree documentation for the cpu nodes bindings.
Main changes:
- adds 64-bit bindings
- define usage of #address-cells
- defines behaviour on pre and post v7 uniprocessor systems
- adds ARM 11MPcore specific reg property definitionSigned-off-by Lorenzo Pieralisi <[email protected]>--- Documentation/devicetree/bindings/arm/cpus.txt | 424 ++++++++++++++++++++++--- 1 file changed, 377 insertions(+), 47 deletions(-)Quoted 4 lines
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The binding looks mostly fine to me.
These bindings have still not received an ACK, and need review by Marvell guys in copy for the new compatible strings below.
If you can't get comment, then leave them out if they are not used already. If they are used, then tough shit when they want to change.
Quoted 5 lines
Most importantly, we need to make a decision on the pre v7 uniprocessor systems, where MPIDR/CPUID are non-existent and the reg property is a pure SW enumeration. Current bindings (ie this patch) define
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#address-cells = <0>;
for those processors (and there are a number of dts in the kernel with that set-up); Grant and Benjamin had a strong feeling against this choice, I have to make a decision on how to proceed, please let me know.
I agree that we should define #address-cells to 1 and reg will be simply 0,1,2,etc. in this case.
Ok, so this means that when these bindings are finally acked and queued for merging, there will be a slew of dts in the kernel that will need patching (again) and this is likely to ruffle feathers. Honestly I would leave this task to platform maintainers, if we all agree.
Quoted 2 lines
This change and fixing the example as I pointed out are what I was waiting to see.
Perfect, given that I got feedback from Andrew, I will be posting a final version very soon.
Lorenzo
PATCH 1/2 Documentation: devicetree: arm: cpus/cpu nodes bindings updates
In reply to Lorenzo PieralisiQuoted 13 lines
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Documentation/devicetree/bindings/arm/cpus.txt line 166
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Documentation/devicetree/bindings/arm/cpus.txt +9
-0+ "faraday,fa526" + "intel,sa110" + "intel,sa1100" + "marvell,feroceon" + "marvell,mohawk" + "marvell,pj4" + "marvell,sheeva-v7" + "marvell,xsc3" + "marvell,xscale"Better make sure the Marvell folks are happy with these. We don't need another rename here. I'm too annoyed with all the renames to pay attention.
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Ok, I will verify that, I copied maintainers in.
Hi Lorenzo
Here are the compatibility strings we would like, and a comment about which SoCs will/do use them.
"marvell,feroceon" - Orion5x
"marvell,sheeva-v5" - Mv78xx0, Kirkwood
"marvell,pj4a" - Dove "marvell,pj4b" - Armada XP, Armada 370, Armada 1500 "marvell,mohawk" - Armada 100
"marvell,xscale" & "marvell,xsc3" should be removed.
The compatibility strings are not correct, or present in all the current <soc>.dtsi files.
orion5x cpus needs adding.
mv78xx0 needs adding.kirkwood.dtsi needs changing.armada-370-xp.dtsi need changing.
armada-xp-mv*.dtsi needs changing.
We will deal with these in the next cycle.
Thanks
Andrew
PATCH 1/2 Documentation: devicetree: arm: cpus/cpu nodes bindings updates
Quoted 31 lines · Andrew Lunn
Quoted 13 lines
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Documentation/devicetree/bindings/arm/cpus.txt line 166
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Documentation/devicetree/bindings/arm/cpus.txt +9
-0+ "faraday,fa526" + "intel,sa110" + "intel,sa1100" + "marvell,feroceon" + "marvell,mohawk" + "marvell,pj4" + "marvell,sheeva-v7" + "marvell,xsc3" + "marvell,xscale"Better make sure the Marvell folks are happy with these. We don't need another rename here. I'm too annoyed with all the renames to pay attention.
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Ok, I will verify that, I copied maintainers in.
Hi Lorenzo
Here are the compatibility strings we would like, and a comment about which SoCs will/do use them.
"marvell,feroceon" - Orion5x
"marvell,sheeva-v5" - Mv78xx0, Kirkwood"marvell,pj4a" - Dove "marvell,pj4b" - Armada XP, Armada 370, Armada 1500 "marvell,mohawk" - Armada 100"marvell,xscale" & "marvell,xsc3" should be removed.
The compatibility strings are not correct, or present in all the current <soc>.dtsi files.
Quoted 7 lines
orion5x cpus needs adding.
mv78xx0 needs adding.kirkwood.dtsineeds changing.armada-370-xp.dtsineed changing.
armada-xp-mv*.dtsi needs changing.We will deal with these in the next cycle.
Thank you very much Andrew, appreciated. I will update the document accordingly and should be able to post a final version very soon.
Lorenzo
PATCH 1/2 Documentation: devicetree: arm: cpus/cpu nodes bindings updates
In reply to Lorenzo PieralisiQuoted 3 lines · Lorenzo Pieralisi
In order to extend the current cpu nodes bindings to newer CPUs inclusive of AArch64 and to update support for older ARM CPUs this patch updates device tree documentation for the cpu nodes bindings.
At a brief glance, I have no particular issues with this binding. However, it'd be best if one of the DT bindings reviewers who worked for ARM gave the ack.
PATCH 1/2 Documentation: devicetree: arm: cpus/cpu nodes bindings updates
In reply to Lorenzo PieralisiQuoted 15 lines · Lorenzo Pieralisi
+=====================================
Documentation/devicetree/bindings/arm/cpus.txt +14
-0+cpus and cpu node bindings definition +===================================== + +The ARM architecture, in accordance with the ePAPR, requires the cpus and cpu +nodes to be present and contain the properties described below. + +- cpus node + + Description: Container of cpu nodes + + The node name must be "cpus". + + A cpus node must define the following properties: +
Documentation/devicetree/bindings/arm/cpus.txt line 49
Quoted 10 lines
Documentation/devicetree/bindings/arm/cpus.txt +10
-0+ - #address-cells + Usage: required + Value type: <u32> + + Definition depends on ARM architecture version and + configuration: + + # On uniprocessor ARM architectures previous to v7 + value must be 0, since they have no register + providing CPU identification.
Just clued into this point from the other thread; Don't do this. Uniprocessor should follow the same rules as 32bit or 64bit for the value of #address-cells, and cpu nodes should have a reg property, even if it is merely set to '0'.
g.
PATCH 2/2 Documentation: DT: arm: define CPU topology bindings
In reply to Lorenzo PieralisiThe advent of multi-cluster ARM systems requires a mechanism to describe how in hierarchical terms CPUs are connected in ARM SoCs so that the kernel can initialize and map resources like IRQs and memory space to specific group(s) of CPUs.
The CPU topology is made up of multiple hierarchy levels whose bottom layers (aka leaf nodes in device tree syntax) contain links to the HW CPUs in the system.
The topology bindings are generic for both 32-bit and 64-bit systems and lay the groundwork on top of which affinity schemes can be built.
This patch provides the documentation in the kernel required to define the device tree bindings describing the CPU topology for ARM 32-bit and 64-bit systems.
--- Documentation/devicetree/bindings/arm/topology.txt | 492 +++++++++++++++++++++ 1 file changed, 492 insertions(+) create mode 100644 Documentation/devicetree/bindings/arm/topology.txt
Documentation/devicetree/bindings/arm/topology.txt new file +492 -0
@@ -0,0 +1,492 @@ +=========================================== +ARM topology binding description +=========================================== + +=========================================== +1 - Introduction +=========================================== + +In an ARM system, the hierarchy of CPUs is defined through three entities that +are used to describe the layout of physical CPUs in the system: + +- cluster +- core +- thread + +The cpu nodes (bindings defined in [1]) represent the devices that +correspond to physical CPUs and are to be mapped to the hierarchy levels. + +The bottom hierarchy level sits at core or thread level depending on whether +symmetric multi-threading (SMT) is supported or not. + +For instance in a system where CPUs support SMT, "cpu" nodes represent all +threads existing in the system and map to the hierarchy level "thread" above. +In systems where SMT is not supported "cpu" nodes represent all cores present +in the system and map to the hierarchy level "core" above. + +ARM topology bindings allow one to associate cpu nodes with hierarchical groups +corresponding to the system hierarchy; syntactically they are defined as device +tree nodes. + +The remainder of this document provides the topology bindings for ARM, based +on the ePAPR standard, available from: + +http://www.power.org/documentation/epapr-version-1-1/ + +If not stated otherwise, whenever a reference to a cpu node phandle is made its +value must point to a cpu node compliant with the cpu node bindings as +documented in [1]. +A topology description containing phandles to cpu nodes that are not compliant +with bindings standardized in [1] is therefore considered invalid. + +=========================================== +2 - cpu-map node +=========================================== + +The ARM CPU topology is defined within the cpu-map node, which is a direct +child of the cpus node and provides a container where the actual topology +nodes are listed. + +- cpu-map node + + Usage: Optional - Provide ARM CPU topology to the OS + + Description: The cpu-map node is just a container node where its + subnodes describe the CPU topology + + Node name must be "cpu-map". + + The cpu-map node's parent node must be the cpus node. + + The cpu-map node's child nodes can be: + + - one or more cluster nodes + + Any other configuration is considered invalid. + +The cpu-map node can only contain three types of child nodes: + +- cluster node +- core node +- thread node + +whose bindings are described in paragraph 3. + +The nodes describing the CPU topology (cluster/core/thread) can only be +defined within the cpu-map node. +Any other configuration is consider invalid and therefore must be ignored. + +=========================================== +2.1 - cpu-map child nodes naming convention +=========================================== + +cpu-map child nodes must follow a naming convention where the node name +must be "clusterN", "coreN", "threadN" depending on the node type (ie +cluster/core/thread) (where N = {0, 1, ...} is the node number; nodes which +are siblings within a single common parent node must be given a unique and +sequential N value, starting from 0). +cpu-map child nodes which do not share a common parent node can have the same +name (ie same number N as other cpu-map child nodes at different device tree +levels) since name uniqueness will be guaranteed by the device tree hierarchy. + +=========================================== +3 - cluster/core/thread node bindings +=========================================== + +Bindings for cluster/cpu/thread nodes are defined as follows: + +- cluster node + + Description: must be declared within a cpu-map node, one node + per cluster. A system can contain several layers of + clustering and cluster nodes can be contained in parent + cluster nodes. + + The cluster node name must be "clusterN" as described in 2.1 above. + A cluster node can not be a leaf node. + + A cluster node's child nodes must be: + + - one or more cluster nodes; or + - one or more core nodes + + Any other configuration is considered invalid. + +- core node + + Description: must be declared in a cluster node, one node per core in + the cluster. If the system does not support SMT, core + nodes are leaf nodes, otherwise they become containers of + thread nodes. + + The core node name must be "coreN" as described in 2.1 above. + + A core node must be a leaf node if SMT is not supported. + + Properties for core nodes that are leaf nodes: + + - cpu + Usage: required + Value type: <phandle> + Definition: a phandle to the cpu node that corresponds to the + core node. + + If a core node is not a leaf node (CPUs supporting SMT) a core node's + child nodes can be: + + - one or more thread nodes + + Any other configuration is considered invalid. + +- thread node + + Description: must be declared in a core node, one node per thread + in the core if the system supports SMT. Thread nodes are + always leaf nodes in the device tree. + + The thread node name must be "threadN" as described in 2.1 above. + + A thread node must be a leaf node. + + A thread node must contain the following property: + + - cpu + Usage: required + Value type: <phandle> + Definition: a phandle to the cpu node that corresponds to + the thread node. + +=========================================== +4 - Example dts +=========================================== + +Example 1 (ARM 64-bit, 16-cpu system, two clusters of clusters): + +cpus { + #size-cells = <0>; + #address-cells = <2>; + + cpu-map { + cluster0 { + cluster0 { + core0 { + thread0 { + cpu = <&CPU0>; + }; + thread1 { + cpu = <&CPU1>; + }; + }; + + core1 { + thread0 { + cpu = <&CPU2>; + }; + thread1 { + cpu = <&CPU3>; + }; + }; + }; + + cluster1 { + core0 { + thread0 { + cpu = <&CPU4>; + }; + thread1 { + cpu = <&CPU5>; + }; + }; + + core1 { + thread0 { + cpu = <&CPU6>; + }; + thread1 { + cpu = <&CPU7>; + }; + }; + }; + }; + + cluster1 { + cluster0 { + core0 { + thread0 { + cpu = <&CPU8>; + }; + thread1 { + cpu = <&CPU9>; + }; + }; + core1 { + thread0 { + cpu = <&CPU10>; + }; + thread1 { + cpu = <&CPU11>; + }; + }; + }; + + cluster1 { + core0 { + thread0 { + cpu = <&CPU12>; + }; + thread1 { + cpu = <&CPU13>; + }; + }; + core1 { + thread0 { + cpu = <&CPU14>; + }; + thread1 { + cpu = <&CPU15>; + }; + }; + }; + }; + }; + + CPU0: cpu at 0 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x0>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU1: cpu at 1 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x1>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU2: cpu at 100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x100>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU3: cpu at 101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x101>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU4: cpu at 10000 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x10000>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU5: cpu at 10001 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x10001>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU6: cpu at 10100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x10100>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU7: cpu at 10101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x10101>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU8: cpu at 100000000 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x0>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU9: cpu at 100000001 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x1>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU10: cpu at 100000100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x100>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU11: cpu at 100000101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x101>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU12: cpu at 100010000 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x10000>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU13: cpu at 100010001 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x10001>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU14: cpu at 100010100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x10100>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU15: cpu at 100010101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x10101>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; +}; + +Example 2 (ARM 32-bit, dual-cluster, 8-cpu system, no SMT): + +cpus { + #size-cells = <0>; + #address-cells = <1>; + + cpu-map { + cluster0 { + core0 { + cpu = <&CPU0>; + }; + core1 { + cpu = <&CPU1>; + }; + core2 { + cpu = <&CPU2>; + }; + core3 { + cpu = <&CPU3>; + }; + }; + + cluster1 { + core0 { + cpu = <&CPU4>; + }; + core1 { + cpu = <&CPU5>; + }; + core2 { + cpu = <&CPU6>; + }; + core3 { + cpu = <&CPU7>; + }; + }; + }; + + CPU0: cpu at 0 { + device_type = "cpu"; + compatible = "arm,cortex-a15"; + reg = <0x0>; + }; + + CPU1: cpu at 1 { + device_type = "cpu"; + compatible = "arm,cortex-a15"; + reg = <0x1>; + }; + + CPU2: cpu at 2 { + device_type = "cpu"; + compatible = "arm,cortex-a15"; + reg = <0x2>; + }; + + CPU3: cpu at 3 { + device_type = "cpu"; + compatible = "arm,cortex-a15"; + reg = <0x3>; + }; + + CPU4: cpu at 100 { + device_type = "cpu"; + compatible = "arm,cortex-a7"; + reg = <0x100>; + }; + + CPU5: cpu at 101 { + device_type = "cpu"; + compatible = "arm,cortex-a7"; + reg = <0x101>; + }; + + CPU6: cpu at 102 { + device_type = "cpu"; + compatible = "arm,cortex-a7"; + reg = <0x102>; + }; + + CPU7: cpu at 103 { + device_type = "cpu"; + compatible = "arm,cortex-a7"; + reg = <0x103>; + }; +}; + +Example 3 (ARM 32-bit, cortex-a8 single core): + +cpus { + #size-cells = <0>; + #address-cells = <1>; + + cpu-map { + cluster0 { + core0 { + cpu = <&CPU0>; + }; + }; + }; + + CPU0: cpu at 0 { + device_type = "cpu"; + compatible = "arm,cortex-a8"; + reg = <0x0>; + }; +}; + +=============================================================================== +[1] ARM Linux kernel documentation + Documentation/devicetree/bindings/arm/cpus.txt
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1.8.2.2
PATCH 2/2 Documentation: DT: arm: define CPU topology bindings
[replying to self]
Bindings defined in this patch have been hanging in the balance for quite a while, I would ask DT maintainers (and everyone else) please to have a look and provide an ACK/NACK as they deem fit, thank you very much.
Comments welcome.
Thanks,
Lorenzo
Quoted 523 lines · Lorenzo Pieralisi
The advent of multi-cluster ARM systems requires a mechanism to describe how in hierarchical terms CPUs are connected in ARM SoCs so that the kernel can initialize and map resources like IRQs and memory space to specific group(s) of CPUs.
The CPU topology is made up of multiple hierarchy levels whose bottom layers (aka leaf nodes in device tree syntax) contain links to the HW CPUs in the system.
The topology bindings are generic for both 32-bit and 64-bit systems and lay the groundwork on top of which affinity schemes can be built.
This patch provides the documentation in the kernel required to define the device tree bindings describing the CPU topology for ARM 32-bit and 64-bit systems.
Signed-off-by Lorenzo Pieralisi <[email protected]>--- Documentation/devicetree/bindings/arm/topology.txt | 492 +++++++++++++++++++++ 1 file changed, 492 insertions(+) create mode 100644 Documentation/devicetree/bindings/arm/topology.txtDocumentation/devicetree/bindings/arm/topology.txt new file +492
-1@@ -0,0 +1,492 @@ +=========================================== +ARM topology binding description +=========================================== + +=========================================== +1 - Introduction +=========================================== + +In an ARM system, the hierarchy of CPUs is defined through three entities that +are used to describe the layout of physical CPUs in the system: + +- cluster +- core +- thread + +The cpu nodes (bindings defined in [1]) represent the devices that +correspond to physical CPUs and are to be mapped to the hierarchy levels. + +The bottom hierarchy level sits at core or thread level depending on whether +symmetric multi-threading (SMT) is supported or not. + +For instance in a system where CPUs support SMT, "cpu" nodes represent all +threads existing in the system and map to the hierarchy level "thread" above. +In systems where SMT is not supported "cpu" nodes represent all cores present +in the system and map to the hierarchy level "core" above. + +ARM topology bindings allow one to associate cpu nodes with hierarchical groups +corresponding to the system hierarchy; syntactically they are defined as device +tree nodes. + +The remainder of this document provides the topology bindings for ARM, based +on the ePAPR standard, available from: + +http://www.power.org/documentation/epapr-version-1-1/ + +If not stated otherwise, whenever a reference to a cpu node phandle is made its +value must point to a cpu node compliant with the cpu node bindings as +documented in [1]. +A topology description containing phandles to cpu nodes that are not compliant +with bindings standardized in [1] is therefore considered invalid. + +=========================================== +2 - cpu-map node +=========================================== + +The ARM CPU topology is defined within the cpu-map node, which is a direct +child of the cpus node and provides a container where the actual topology +nodes are listed. + +- cpu-map node + + Usage: Optional - Provide ARM CPU topology to the OS + + Description: The cpu-map node is just a container node where its + subnodes describe the CPU topology + + Node name must be "cpu-map". + + The cpu-map node's parent node must be the cpus node. + + The cpu-map node's child nodes can be: + + - one or more cluster nodes + + Any other configuration is considered invalid. + +The cpu-map node can only contain three types of child nodes: + +- cluster node +- core node +- thread node + +whose bindings are described in paragraph 3. + +The nodes describing the CPU topology (cluster/core/thread) can only be +defined within the cpu-map node. +Any other configuration is consider invalid and therefore must be ignored. + +=========================================== +2.1 - cpu-map child nodes naming convention +=========================================== + +cpu-map child nodes must follow a naming convention where the node name +must be "clusterN", "coreN", "threadN" depending on the node type (ie +cluster/core/thread) (where N = {0, 1, ...} is the node number; nodes which +are siblings within a single common parent node must be given a unique and +sequential N value, starting from 0). +cpu-map child nodes which do not share a common parent node can have the same +name (ie same number N as other cpu-map child nodes at different device tree +levels) since name uniqueness will be guaranteed by the device tree hierarchy. + +=========================================== +3 - cluster/core/thread node bindings +=========================================== + +Bindings for cluster/cpu/thread nodes are defined as follows: + +- cluster node + + Description: must be declared within a cpu-map node, one node + per cluster. A system can contain several layers of + clustering and cluster nodes can be contained in parent + cluster nodes. + + The cluster node name must be "clusterN" as described in 2.1 above. + A cluster node can not be a leaf node. + + A cluster node's child nodes must be: + + - one or more cluster nodes; or + - one or more core nodes + + Any other configuration is considered invalid. + +- core node + + Description: must be declared in a cluster node, one node per core in + the cluster. If the system does not support SMT, core + nodes are leaf nodes, otherwise they become containers of + thread nodes. + + The core node name must be "coreN" as described in 2.1 above. + + A core node must be a leaf node if SMT is not supported. + + Properties for core nodes that are leaf nodes: + + - cpu + Usage: required + Value type: <phandle> + Definition: a phandle to the cpu node that corresponds to the + core node. + + If a core node is not a leaf node (CPUs supporting SMT) a core node's + child nodes can be: + + - one or more thread nodes + + Any other configuration is considered invalid. + +- thread node + + Description: must be declared in a core node, one node per thread + in the core if the system supports SMT. Thread nodes are + always leaf nodes in the device tree. + + The thread node name must be "threadN" as described in 2.1 above. + + A thread node must be a leaf node. + + A thread node must contain the following property: + + - cpu + Usage: required + Value type: <phandle> + Definition: a phandle to the cpu node that corresponds to + the thread node. + +=========================================== +4 - Example dts +=========================================== + +Example 1 (ARM 64-bit, 16-cpu system, two clusters of clusters): + +cpus { + #size-cells = <0>; + #address-cells = <2>; + + cpu-map { + cluster0 { + cluster0 { + core0 { + thread0 { + cpu = <&CPU0>; + }; + thread1 { + cpu = <&CPU1>; + }; + }; + + core1 { + thread0 { + cpu = <&CPU2>; + }; + thread1 { + cpu = <&CPU3>; + }; + }; + }; + + cluster1 { + core0 { + thread0 { + cpu = <&CPU4>; + }; + thread1 { + cpu = <&CPU5>; + }; + }; + + core1 { + thread0 { + cpu = <&CPU6>; + }; + thread1 { + cpu = <&CPU7>; + }; + }; + }; + }; + + cluster1 { + cluster0 { + core0 { + thread0 { + cpu = <&CPU8>; + }; + thread1 { + cpu = <&CPU9>; + }; + }; + core1 { + thread0 { + cpu = <&CPU10>; + }; + thread1 { + cpu = <&CPU11>; + }; + }; + }; + + cluster1 { + core0 { + thread0 { + cpu = <&CPU12>; + }; + thread1 { + cpu = <&CPU13>; + }; + }; + core1 { + thread0 { + cpu = <&CPU14>; + }; + thread1 { + cpu = <&CPU15>; + }; + }; + }; + }; + }; + + CPU0: cpu at 0 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x0>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU1: cpu at 1 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x1>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU2: cpu at 100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x100>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU3: cpu at 101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x101>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU4: cpu at 10000 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x10000>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU5: cpu at 10001 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x10001>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU6: cpu at 10100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x10100>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU7: cpu at 10101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x0 0x10101>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU8: cpu at 100000000 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x0>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU9: cpu at 100000001 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x1>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU10: cpu at 100000100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x100>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU11: cpu at 100000101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x101>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU12: cpu at 100010000 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x10000>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU13: cpu at 100010001 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x10001>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU14: cpu at 100010100 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x10100>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; + + CPU15: cpu at 100010101 { + device_type = "cpu"; + compatible = "arm,cortex-a57"; + reg = <0x1 0x10101>; + enable-method = "spin-table"; + cpu-release-addr = <0 0x20000000>; + }; +}; + +Example 2 (ARM 32-bit, dual-cluster, 8-cpu system, no SMT): + +cpus { + #size-cells = <0>; + #address-cells = <1>; + + cpu-map { + cluster0 { + core0 { + cpu = <&CPU0>; + }; + core1 { + cpu = <&CPU1>; + }; + core2 { + cpu = <&CPU2>; + }; + core3 { + cpu = <&CPU3>; + }; + }; + + cluster1 { + core0 { + cpu = <&CPU4>; + }; + core1 { + cpu = <&CPU5>; + }; + core2 { + cpu = <&CPU6>; + }; + core3 { + cpu = <&CPU7>; + }; + }; + }; + + CPU0: cpu at 0 { + device_type = "cpu"; + compatible = "arm,cortex-a15"; + reg = <0x0>; + }; + + CPU1: cpu at 1 { + device_type = "cpu"; + compatible = "arm,cortex-a15"; + reg = <0x1>; + }; + + CPU2: cpu at 2 { + device_type = "cpu"; + compatible = "arm,cortex-a15"; + reg = <0x2>; + }; + + CPU3: cpu at 3 { + device_type = "cpu"; + compatible = "arm,cortex-a15"; + reg = <0x3>; + }; + + CPU4: cpu at 100 { + device_type = "cpu"; + compatible = "arm,cortex-a7"; + reg = <0x100>; + }; + + CPU5: cpu at 101 { + device_type = "cpu"; + compatible = "arm,cortex-a7"; + reg = <0x101>; + }; + + CPU6: cpu at 102 { + device_type = "cpu"; + compatible = "arm,cortex-a7"; + reg = <0x102>; + }; + + CPU7: cpu at 103 { + device_type = "cpu"; + compatible = "arm,cortex-a7"; + reg = <0x103>; + }; +}; + +Example 3 (ARM 32-bit, cortex-a8 single core): + +cpus { + #size-cells = <0>; + #address-cells = <1>; + + cpu-map { + cluster0 { + core0 { + cpu = <&CPU0>; + }; + }; + }; + + CPU0: cpu at 0 { + device_type = "cpu"; + compatible = "arm,cortex-a8"; + reg = <0x0>; + }; +}; + +=============================================================================== +[1] ARM Linux kernel documentation + Documentation/devicetree/bindings/arm/cpus.txt --1.8.2.2
PATCH 2/2 Documentation: DT: arm: define CPU topology bindings
In reply to Lorenzo PieralisiQuoted 11 lines · Lorenzo Pieralisi
The advent of multi-cluster ARM systems requires a mechanism to describe how in hierarchical terms CPUs are connected in ARM SoCs so that the kernel can initialize and map resources like IRQs and memory space to specific group(s) of CPUs.
The CPU topology is made up of multiple hierarchy levels whose bottom layers (aka leaf nodes in device tree syntax) contain links to the HW CPUs in the system.
The topology bindings are generic for both 32-bit and 64-bit systems and lay the groundwork on top of which affinity schemes can be built.
By affinity schemes, you mean further bindings? Do we need this binding until that point?
As is, I don't have much comment.
[snip]
Documentation/devicetree/bindings/arm/topology.txt line 481
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Documentation/devicetree/bindings/arm/topology.txt new file +13
-0+Example 3 (ARM 32-bit, cortex-a8 single core): + +cpus { + #size-cells = <0>; + #address-cells = <1>; + + cpu-map { + cluster0 { + core0 { + cpu = <&CPU0>; + }; + }; + };
This example seems utterly pointless. I think we should be specific that single core does not contain a cpu-map. I suppose we could have a threaded, single core case, but let's address that if we ever do.
Rob
Quoted 12 lines
Documentation/devicetree/bindings/arm/topology.txt new file +11
-0+ + CPU0: cpu at 0 { + device_type = "cpu"; + compatible = "arm,cortex-a8"; + reg = <0x0>; + }; +}; + +=============================================================================== +[1] ARM Linux kernel documentation + Documentation/devicetree/bindings/arm/cpus.txt
PATCH 2/2 Documentation: DT: arm: define CPU topology bindings
Quoted 10 lines · Rob Herring
Quoted 9 lines · Lorenzo Pieralisi
The advent of multi-cluster ARM systems requires a mechanism to describe how in hierarchical terms CPUs are connected in ARM SoCs so that the kernel can initialize and map resources like IRQs and memory space to specific group(s) of CPUs.
The CPU topology is made up of multiple hierarchy levels whose bottom layers (aka leaf nodes in device tree syntax) contain links to the HW CPUs in the system.
Quoted 5 lines
Quoted 2 lines
The topology bindings are generic for both 32-bit and 64-bit systems and lay the groundwork on top of which affinity schemes can be built.
By affinity schemes, you mean further bindings? Do we need this binding until that point?
Well, further bindings (for HW like perf counters) will rely on these topology bindings to build IRQ affinity masks for instance.
I think we should go on and publish these bindings asap so that we can rely on them to properly describe topologies for ARM from the beginning.
Current reliance on MPIDR is a leap of faith.
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As is, I don't have much comment.
I take this as positive feedback, or put it another way, that you think bindings are sound.
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[snip]
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Documentation/devicetree/bindings/arm/topology.txt new file +9
-0+Example 3 (ARM 32-bit, cortex-a8 single core): + +cpus { + #size-cells = <0>; + #address-cells = <1>; + + cpu-map { + cluster0 { + core0 {
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Documentation/devicetree/bindings/arm/topology.txt line 179
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Documentation/devicetree/bindings/arm/topology.txt new file +4
-0+ cpu = <&CPU0>; + }; + }; + };This example seems utterly pointless. I think we should be specific that single core does not contain a cpu-map. I suppose we could have a threaded, single core case, but let's address that if we ever do.
Ok right. We can have a multi cluster system where one cluster is made up of a single CPU, then a binding like the one above makes sense. I will rule cpu-map out for uniprocessor systems.
Lorenzo
Quoted 17 lines
Rob
Quoted 12 lines
Documentation/devicetree/bindings/arm/topology.txt new file +11
-0+ + CPU0: cpu at 0 { + device_type = "cpu"; + compatible = "arm,cortex-a8"; + reg = <0x0>; + }; +}; + +=============================================================================== +[1] ARM Linux kernel documentation + Documentation/devicetree/bindings/arm/cpus.txt