diff mbox

[v2,1/2] Documentation: devicetree: arm: cpus/cpu nodes bindings updates

Message ID 1379330464-27917-2-git-send-email-lorenzo.pieralisi@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Lorenzo Pieralisi Sept. 16, 2013, 11:21 a.m. UTC 
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

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
 Documentation/devicetree/bindings/arm/cpus.txt | 391 ++++++++++++++++++++++---
 1 file changed, 344 insertions(+), 47 deletions(-)

Comments

Jason Cooper Sept. 16, 2013, 1:32 p.m. UTC | #1 
On Mon, Sep 16, 2013 at 12:21:03PM +0100, Lorenzo Pieralisi wrote:
> 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
> 
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> ---
>  Documentation/devicetree/bindings/arm/cpus.txt | 391 ++++++++++++++++++++++---
>  1 file changed, 344 insertions(+), 47 deletions(-)

For the Marvell bits:

Acked-by: Jason Cooper <jason@lakedaemon.net>

thx,

Jason.
Gregory CLEMENT Sept. 16, 2013, 7:28 p.m. UTC | #2 
On 16/09/2013 13:21, Lorenzo Pieralisi wrote:
> 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
> 

For the Marvell (EBU) related part

Acked-by:Gregory CLEMENT <gregory.clement@free-electrons.com>

I would like to point that pj4b could be split in two flavors:
pj4b (currently used by Armada 370) and pj4b-mp (currently used
by Armada XP). The motivation for a such split would be for the errata
fix which can be different between pj4b and pj4b_mp. As we can
detect them at runtime, we don't need it from the device tree.
So we can live with a single pj4b binding.

Regards,
Mark Rutland Sept. 25, 2013, 4:12 p.m. UTC | #3 
Hi Lorenzo,

This looks good, but I have a couple comments.

On Mon, Sep 16, 2013 at 12:21:03PM +0100, Lorenzo Pieralisi wrote:
> 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
> 
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

[...]

> +=====================================
> +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 1, to enable a simple enumeration
> +			  scheme for processors that do not have a HW CPU
> +			  identification register.
> +			# 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.

Under some situations (where mpidr_el1[63:32] == 0), #address-cells =
<1> needs to be supported for 64-bit hardware, to maintain compatibility
with kvmtool. Will had a commit specifically to allow this (72aea393a2:
"arm64: smp: honour #address-size when parsing CPU reg property"), which
mentions the kvmtool compatibility issue.

I think we need to state that it _should_ be 2. If all the identifiying
bits in the upper half of the register (currently Aff3) are zero, then 1
cell is permitted, and the cell refers to mpidr_el1[31:0].

It's possible that bits which are currently RES0 may become identifying
bits in future, so for the moment we could state that we only allow one
cell when all of mpidr_el1[63:32] is zero, and if mpidr_el1[40:42,23:0]
becomes insufficient to uniquely identify a CPU we need to update the
binding document.

> +
> +	- #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 required and must be set to 0.
> +
> +			# 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.

These all look fine to me.

> +
> +			# 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.

This probably needs to be reworded to cover the #address-cells = <1>
case mentioned above.

[...]

> +	- 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 systems 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.
> +

Later, we should probably split these into individual bindings docs to
better describe platform requirements. We don't need to do that now.

Otherwise this looks good. Thanks for all the hard work putting this
together, sorry for the last-minute change request.

With the #address-cells = <1> fixups:

Acked-by: Mark Rutland <mark.rutland@arm.com>

Thanks,
Mark.
diff mbox

Patch

diff --git a/Documentation/devicetree/bindings/arm/cpus.txt b/Documentation/devicetree/bindings/arm/cpus.txt
index f32494d..e534110 100644
--- a/Documentation/devicetree/bindings/arm/cpus.txt
+++ b/Documentation/devicetree/bindings/arm/cpus.txt
@@ -1,77 +1,374 @@ 
-* 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 1, to enable a simple enumeration
+			  scheme for processors that do not have a HW CPU
+			  identification register.
+			# 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 required and must be set to 0.
+
+			# 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,pj4a"
+			    "marvell,pj4b"
+			    "marvell,sheeva-v5"
+			    "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 systems 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@0 {
+		cpu@0 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a15";
 			reg = <0x0>;
 		};
 
-		CPU1: cpu@1 {
+		cpu@1 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a15";
 			reg = <0x1>;
 		};
 
-		CPU2: cpu@100 {
+		cpu@100 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a7";
 			reg = <0x100>;
 		};
 
-		CPU3: cpu@101 {
+		cpu@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@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 = <1>;
+
+		cpu@0 {
+			device_type = "cpu";
+			compatible = "arm,arm926ej-s";
+			reg = <0x0>;
+		};
+	};
+
+Example 4 (ARM Cortex-A57 64-bit system):
+
+cpus {
+	#size-cells = <0>;
+	#address-cells = <2>;
+
+	cpu@0 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x0 0x0>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@1 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x0 0x1>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@100 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x0 0x100>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@101 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x0 0x101>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@10000 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x0 0x10000>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@10001 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x0 0x10001>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@10100 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x0 0x10100>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@10101 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x0 0x10101>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@100000000 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x1 0x0>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@100000001 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x1 0x1>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@100000100 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x1 0x100>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@100000101 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x1 0x101>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@100010000 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x1 0x10000>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@100010001 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x1 0x10001>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@100010100 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x1 0x10100>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+
+	cpu@100010101 {
+		device_type = "cpu";
+		compatible = "arm,cortex-a57";
+		reg = <0x1 0x10101>;
+		enable-method = "spin-table";
+		cpu-release-addr = <0 0x20000000>;
+	};
+};