linux/Documentation/devicetree/bindings/powerpc/fsl/guts.txt
Timur Tabi 0408753fae powerpc/85xx: describe the PAMU topology in the device tree
The PAMU caches use the LIODNs to determine which cache lines hold the
entries for the corresponding LIODs.  The LIODNs must therefore be
carefully assigned to avoid cache thrashing -- two active LIODs with
LIODNs that put them in the same cache line.

Currently, LIODNs are statically assigned by U-Boot, but this has
limitations.  LIODNs are assigned even for devices that may be disabled
or unused by the kernel.  Static assignments also do not allow for device
drivers which may know which LIODs can be used simultaneously.  In
other words, we really should assign LIODNs dynamically in Linux.

To do that, we need to describe the PAMU device and cache topologies in
the device trees.

Signed-off-by: Timur Tabi <timur@freescale.com>
Acked-by: Stuart Yoder <stuart.yoder@freescale.com>
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
2013-02-13 07:49:02 -06:00

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* Global Utilities Block
The global utilities block controls power management, I/O device
enabling, power-on-reset configuration monitoring, general-purpose
I/O signal configuration, alternate function selection for multiplexed
signals, and clock control.
Required properties:
- compatible : Should define the compatible device type for
global-utilities.
- reg : Offset and length of the register set for the device.
Recommended properties:
- fsl,has-rstcr : Indicates that the global utilities register set
contains a functioning "reset control register" (i.e. the board
is wired to reset upon setting the HRESET_REQ bit in this register).
- fsl,liodn-bits : Indicates the number of defined bits in the LIODN
registers, for those SOCs that have a PAMU device.
Examples:
global-utilities@e0000 { /* global utilities block */
compatible = "fsl,mpc8548-guts";
reg = <e0000 1000>;
fsl,has-rstcr;
};
guts: global-utilities@e0000 {
compatible = "fsl,qoriq-device-config-1.0";
reg = <0xe0000 0xe00>;
fsl,has-rstcr;
#sleep-cells = <1>;
fsl,liodn-bits = <12>;
};