[PATCH v4 4/7] ARM: kernel: add device tree init map function

Lorenzo Pieralisi lorenzo.pieralisi at arm.com
Mon Nov 19 09:07:07 EST 2012


On Mon, Nov 19, 2012 at 01:54:18PM +0000, Mark Rutland wrote:
> On Mon, Nov 19, 2012 at 12:45:03PM +0000, Lorenzo Pieralisi wrote:
> > When booting through a device tree, the kernel cpu logical id map can be
> > initialized using device tree data passed by FW or through an embedded blob.
> > 
> > This patch adds a function that parses device tree "cpu" nodes and
> > retrieves the corresponding CPUs hardware identifiers (MPIDR).
> > It sets the possible cpus and the cpu logical map values according to
> > the number of CPUs defined in the device tree and respective properties.
> > 
> > The device tree HW identifiers are considered valid if all CPU nodes contain
> > a "reg" property, there are no duplicate "reg" entries and the DT defines a
> > CPU node whose "reg" property matches the MPIDR[23:0] of the boot CPU.
> > 
> > The primary CPU is assigned cpu logical number 0 to keep the current convention
> > valid.
> > 
> > Current bindings documentation is included in the patch:
> > 
> > Documentation/devicetree/bindings/arm/cpus.txt
> > 
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> > Acked-by: Nicolas Pitre <nico at linaro.org>
> > ---
> >  Documentation/devicetree/bindings/arm/cpus.txt |  77 +++++++++++++++++++
> >  arch/arm/include/asm/prom.h                    |   2 +
> >  arch/arm/kernel/devtree.c                      | 100 +++++++++++++++++++++++++
> >  3 files changed, 179 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/arm/cpus.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/arm/cpus.txt b/Documentation/devicetree/bindings/arm/cpus.txt
> > new file mode 100644
> > index 0000000..46c3589
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/arm/cpus.txt
> > @@ -0,0 +1,77 @@
> > +* ARM CPUs binding description
> > +
> > +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:
> > +
> > +	cpus {
> > +		#size-cells = <0>;
> > +		#address-cells = <1>;
> > +
> > +		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 100 {
> > +			device_type = "cpu";
> > +			compatible = "arm, cortex-a7";
> > +			reg = <0x100>;
> > +		};
> > +
> > +		CPU3: cpu at 101 {
> > +			device_type = "cpu";
> > +			compatible = "arm, cortex-a7";
> > +			reg = <0x101>;
> > +		};
> > +	};
> 
> Those spaces in the compatible strings shouldn't be there.

Thanks for your patience, I missed that, now fixed.

Thanks !
Lorenzo




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