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linux-net/Documentation/devicetree/bindings/interrupt-controller/arm,gic-v3.yaml
Douglas Anderson 43cd3ddbff dt-bindings: interrupt-controller: arm,gic-v3: Add quirk for Mediatek SoCs w/ broken FW
When trying to turn on the "pseudo NMI" kernel feature in Linux, it
was discovered that all Mediatek-based Chromebooks that ever shipped
(at least ones with GICv3) had a firmware bug where they wouldn't save
certain GIC "GICR" registers properly. If a processor ever entered a
suspend/idle mode where the GICR registers lost state then they'd be
reset to their default state.

As a result of the bug, if you try to enable "pseudo NMIs" on the
affected devices then certain interrupts will unexpectedly get
promoted to be "pseudo NMIs" and cause crashes / freezes / general
mayhem.

ChromeOS is looking to start turning on "pseudo NMIs" in production to
make crash reports more actionable. To do so, we will release firmware
updates for at least some of the affected Mediatek Chromebooks.
However, even when we update the firmware of a Chromebook it's always
possible that a user will end up booting with old firmware. We need to
be able to detect when we're running with firmware that will crash and
burn if pseudo NMIs are enabled.

The current plan is:
* Update the device trees of all affected Chromebooks to include the
  'mediatek,broken-save-restore-fw' property. The kernel can use this
  to know not to enable certain features like "pseudo NMI". NOTE:
  device trees for Chromebooks are never baked into the firmware but
  are bundled with the kernel. A kernel will never be configured to
  use "pseudo NMIs" and be bundled with an old device tree.
* When we get a fixed firmware for one of these Chromebooks, it will
  patch the device tree to remove this property.

For some details, you can also see the public bug
<https://issuetracker.google.com/281831288>

Reviewed-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230515131353.v2.1.Iabe67a827e206496efec6beb5616d5a3b99c1e65@changeid
2023-05-16 10:42:57 +01:00

305 lines
8.4 KiB
YAML

# SPDX-License-Identifier: GPL-2.0
%YAML 1.2
---
$id: http://devicetree.org/schemas/interrupt-controller/arm,gic-v3.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: ARM Generic Interrupt Controller, version 3
maintainers:
- Marc Zyngier <maz@kernel.org>
description: |
AArch64 SMP cores are often associated with a GICv3, providing Private
Peripheral Interrupts (PPI), Shared Peripheral Interrupts (SPI),
Software Generated Interrupts (SGI), and Locality-specific Peripheral
Interrupts (LPI).
allOf:
- $ref: /schemas/interrupt-controller.yaml#
properties:
compatible:
oneOf:
- items:
- enum:
- qcom,msm8996-gic-v3
- const: arm,gic-v3
- const: arm,gic-v3
interrupt-controller: true
"#address-cells":
enum: [ 0, 1, 2 ]
"#size-cells":
enum: [ 1, 2 ]
ranges: true
"#interrupt-cells":
description: |
Specifies the number of cells needed to encode an interrupt source.
Must be a single cell with a value of at least 3.
If the system requires describing PPI affinity, then the value must
be at least 4.
The 1st cell is the interrupt type; 0 for SPI interrupts, 1 for PPI
interrupts, 2 for interrupts in the Extended SPI range, 3 for the
Extended PPI range. Other values are reserved for future use.
The 2nd cell contains the interrupt number for the interrupt type.
SPI interrupts are in the range [0-987]. PPI interrupts are in the
range [0-15]. Extented SPI interrupts are in the range [0-1023].
Extended PPI interrupts are in the range [0-127].
The 3rd cell is the flags, encoded as follows:
bits[3:0] trigger type and level flags.
1 = edge triggered
4 = level triggered
The 4th cell is a phandle to a node describing a set of CPUs this
interrupt is affine to. The interrupt must be a PPI, and the node
pointed must be a subnode of the "ppi-partitions" subnode. For
interrupt types other than PPI or PPIs that are not partitionned,
this cell must be zero. See the "ppi-partitions" node description
below.
Cells 5 and beyond are reserved for future use and must have a value
of 0 if present.
enum: [ 3, 4 ]
reg:
description: |
Specifies base physical address(s) and size of the GIC
registers, in the following order:
- GIC Distributor interface (GICD)
- GIC Redistributors (GICR), one range per redistributor region
- GIC CPU interface (GICC)
- GIC Hypervisor interface (GICH)
- GIC Virtual CPU interface (GICV)
GICC, GICH and GICV are optional, but must be described if the CPUs
support them. Examples of such CPUs are ARM's implementations of the
ARMv8.0 architecture such as Cortex-A32, A34, A35, A53, A57, A72 and
A73 (this list is not exhaustive).
minItems: 2
maxItems: 4096 # Should be enough?
interrupts:
description:
Interrupt source of the VGIC maintenance interrupt.
maxItems: 1
redistributor-stride:
description:
If using padding pages, specifies the stride of consecutive
redistributors. Must be a multiple of 64kB.
$ref: /schemas/types.yaml#/definitions/uint64
multipleOf: 0x10000
exclusiveMinimum: 0
"#redistributor-regions":
description:
The number of independent contiguous regions occupied by the
redistributors. Required if more than one such region is present.
$ref: /schemas/types.yaml#/definitions/uint32
maximum: 4096
msi-controller:
description:
Only present if the Message Based Interrupt functionality is
being exposed by the HW, and the mbi-ranges property present.
mbi-ranges:
description:
A list of pairs <intid span>, where "intid" is the first SPI of a range
that can be used an MBI, and "span" the size of that range. Multiple
ranges can be provided.
$ref: /schemas/types.yaml#/definitions/uint32-matrix
items:
minItems: 2
maxItems: 2
mbi-alias:
description:
Address property. Base address of an alias of the GICD region containing
only the {SET,CLR}SPI registers to be used if isolation is required,
and if supported by the HW.
$ref: /schemas/types.yaml#/definitions/uint32-array
items:
minItems: 1
maxItems: 2
ppi-partitions:
type: object
additionalProperties: false
description:
PPI affinity can be expressed as a single "ppi-partitions" node,
containing a set of sub-nodes.
patternProperties:
"^interrupt-partition-[0-9]+$":
type: object
additionalProperties: false
properties:
affinity:
$ref: /schemas/types.yaml#/definitions/phandle-array
items:
maxItems: 1
description:
Should be a list of phandles to CPU nodes (as described in
Documentation/devicetree/bindings/arm/cpus.yaml).
required:
- affinity
clocks:
maxItems: 1
clock-names:
items:
- const: aclk
power-domains:
maxItems: 1
resets:
maxItems: 1
mediatek,broken-save-restore-fw:
type: boolean
description:
Asserts that the firmware on this device has issues saving and restoring
GICR registers when the GIC redistributors are powered off.
dependencies:
mbi-ranges: [ msi-controller ]
msi-controller: [ mbi-ranges ]
required:
- compatible
- reg
patternProperties:
"^gic-its@": false
"^interrupt-controller@[0-9a-f]+$": false
# msi-controller is preferred, but allow other names
"^(msi-controller|gic-its|interrupt-controller)@[0-9a-f]+$":
type: object
description:
GICv3 has one or more Interrupt Translation Services (ITS) that are
used to route Message Signalled Interrupts (MSI) to the CPUs.
properties:
compatible:
const: arm,gic-v3-its
msi-controller: true
"#msi-cells":
description:
The single msi-cell is the DeviceID of the device which will generate
the MSI.
const: 1
reg:
description:
Specifies the base physical address and size of the ITS registers.
maxItems: 1
socionext,synquacer-pre-its:
description:
(u32, u32) tuple describing the untranslated
address and size of the pre-ITS window.
$ref: /schemas/types.yaml#/definitions/uint32-array
items:
minItems: 2
maxItems: 2
required:
- compatible
- msi-controller
- "#msi-cells"
- reg
additionalProperties: false
additionalProperties: false
examples:
- |
gic: interrupt-controller@2cf00000 {
compatible = "arm,gic-v3";
#interrupt-cells = <3>;
#address-cells = <1>;
#size-cells = <1>;
ranges;
interrupt-controller;
reg = <0x2f000000 0x10000>, // GICD
<0x2f100000 0x200000>, // GICR
<0x2c000000 0x2000>, // GICC
<0x2c010000 0x2000>, // GICH
<0x2c020000 0x2000>; // GICV
interrupts = <1 9 4>;
msi-controller;
mbi-ranges = <256 128>;
msi-controller@2c200000 {
compatible = "arm,gic-v3-its";
msi-controller;
#msi-cells = <1>;
reg = <0x2c200000 0x20000>;
};
};
- |
interrupt-controller@2c010000 {
compatible = "arm,gic-v3";
#interrupt-cells = <4>;
#address-cells = <1>;
#size-cells = <1>;
ranges;
interrupt-controller;
redistributor-stride = <0x0 0x40000>; // 256kB stride
#redistributor-regions = <2>;
reg = <0x2c010000 0x10000>, // GICD
<0x2d000000 0x800000>, // GICR 1: CPUs 0-31
<0x2e000000 0x800000>, // GICR 2: CPUs 32-63
<0x2c040000 0x2000>, // GICC
<0x2c060000 0x2000>, // GICH
<0x2c080000 0x2000>; // GICV
interrupts = <1 9 4 0>;
msi-controller@2c200000 {
compatible = "arm,gic-v3-its";
msi-controller;
#msi-cells = <1>;
reg = <0x2c200000 0x20000>;
};
msi-controller@2c400000 {
compatible = "arm,gic-v3-its";
msi-controller;
#msi-cells = <1>;
reg = <0x2c400000 0x20000>;
};
ppi-partitions {
part0: interrupt-partition-0 {
affinity = <&cpu0>, <&cpu2>;
};
part1: interrupt-partition-1 {
affinity = <&cpu1>, <&cpu3>;
};
};
};
device@0 {
reg = <0 4>;
interrupts = <1 1 4 &part0>;
};
...