Re: [PATCH v7] dt-bindings: reserved-memory: Document iommu-addresses
On Tue, 05 Jul 2022 15:06:52 +0200, Thierry Reding wrote: > From: Thierry Reding > > This adds the "iommu-addresses" property to reserved-memory nodes, which > allow describing the interaction of memory regions with IOMMUs. Two use- > cases are supported: > > 1. Static mappings can be described by pairing the "iommu-addresses" > property with a "reg" property. This is mostly useful for adopting > firmware-allocated buffers via identity mappings. One common use- > case where this is required is if early firmware or bootloaders > have set up a bootsplash framebuffer that a display controller is > actively scanning out from during the operating system boot > process. > > 2. If an "iommu-addresses" property exists without a "reg" property, > the reserved-memory node describes an IOVA reservation. Such memory > regions are excluded from the IOVA space available to operating > system drivers and can be used for regions that must not be used to > map arbitrary buffers. > > Each mapping or reservation is tied to a specific device via a phandle > to the device's device tree node. This allows a reserved-memory region > to be reused across multiple devices. > > Signed-off-by: Thierry Reding > --- > Changes in v7: > - keep reserved-memory.txt to avoid broken references > > Changes in v6: > - add device phandle to iommu-addresses property in examples > - remove now unused dt-bindings/reserved-memory.h header > --- > .../reserved-memory/reserved-memory.yaml | 62 +++ > 1 file changed, 62 insertions(+) > My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check' on your patch (DT_CHECKER_FLAGS is new in v5.13): yamllint warnings/errors: dtschema/dtc warnings/errors: Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dts:22.7-45: Warning (reg_format): /reserved-memory/framebuffer@9000:reg: property has invalid length (16 bytes) (#address-cells == 2, #size-cells == 1) Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dts:29.7-40: Warning (reg_format): /bus@0/adsp@299:reg: property has invalid length (16 bytes) (#address-cells == 2, #size-cells == 1) Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dts:34.7-42: Warning (reg_format): /bus@0/display@1520:reg: property has invalid length (16 bytes) (#address-cells == 2, #size-cells == 1) Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dts:9.5-12: Warning (ranges_format): /reserved-memory:ranges: empty "ranges" property but its #size-cells (1) differs from / (2) Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dts:27.9-37.5: Warning (unit_address_vs_reg): /bus@0: node has a unit name, but no reg or ranges property Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dtb: Warning (pci_device_reg): Failed prerequisite 'reg_format' Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dtb: Warning (pci_device_bus_num): Failed prerequisite 'reg_format' Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dtb: Warning (simple_bus_reg): Failed prerequisite 'reg_format' Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dtb: Warning (i2c_bus_reg): Failed prerequisite 'reg_format' Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dtb: Warning (spi_bus_reg): Failed prerequisite 'reg_format' Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dts:21.30-24.7: Warning (avoid_default_addr_size): /reserved-memory/framebuffer@9000: Relying on default #address-cells value Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dts:21.30-24.7: Warning (avoid_default_addr_size): /reserved-memory/framebuffer@9000: Relying on default #size-cells value Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dts:28.24-31.7: Warning (avoid_default_addr_size): /bus@0/adsp@299: Relying on default #address-cells value Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dts:28.24-31.7: Warning (avoid_default_addr_size): /bus@0/adsp@299: Relying on default #size-cells value Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dts:33.27-36.7: Warning (avoid_default_addr_size): /bus@0/display@1520: Relying on default #address-cells value Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dts:33.27-36.7: Warning (avoid_default_addr_size): /bus@0/display@1520: Relying on default #size-cells value Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dtb: Warning (unique_unit_address_if_enabled): Failed prerequisite 'avoid_default_addr_size' /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/reserved-memory/reserved-memory.example.dtb: /: bus@0: 'anyOf'
[PATCH v7] dt-bindings: reserved-memory: Document iommu-addresses
From: Thierry Reding
This adds the "iommu-addresses" property to reserved-memory nodes, which
allow describing the interaction of memory regions with IOMMUs. Two use-
cases are supported:
1. Static mappings can be described by pairing the "iommu-addresses"
property with a "reg" property. This is mostly useful for adopting
firmware-allocated buffers via identity mappings. One common use-
case where this is required is if early firmware or bootloaders
have set up a bootsplash framebuffer that a display controller is
actively scanning out from during the operating system boot
process.
2. If an "iommu-addresses" property exists without a "reg" property,
the reserved-memory node describes an IOVA reservation. Such memory
regions are excluded from the IOVA space available to operating
system drivers and can be used for regions that must not be used to
map arbitrary buffers.
Each mapping or reservation is tied to a specific device via a phandle
to the device's device tree node. This allows a reserved-memory region
to be reused across multiple devices.
Signed-off-by: Thierry Reding
---
Changes in v7:
- keep reserved-memory.txt to avoid broken references
Changes in v6:
- add device phandle to iommu-addresses property in examples
- remove now unused dt-bindings/reserved-memory.h header
---
.../reserved-memory/reserved-memory.yaml | 62 +++
1 file changed, 62 insertions(+)
diff --git
a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml
b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml
index 7a0744052ff6..8b885ee82ff4 100644
--- a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml
+++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml
@@ -52,6 +52,30 @@ properties:
Address and Length pairs. Specifies regions of memory that are
acceptable to allocate from.
+ iommu-addresses:
+$ref: /schemas/types.yaml#/definitions/phandle-array
+description: >
+ A list of phandle and specifier pairs that describe static IO virtual
+ address space mappings and carveouts associated with a given reserved
+ memory region. The phandle in the first cell refers to the device for
+ which the mapping or carveout is to be created.
+
+ The specifier consists of an address/size pair and denotes the IO
+ virtual address range of the region for the given device. The exact
+ format depends on the values of the "#address-cells" and "#size-cells"
+ properties of the device referenced via the phandle.
+
+ When used in combination with a "reg" property, an IOVA mapping is to
+ be established for this memory region. One example where this can be
+ useful is to create an identity mapping for physical memory that the
+ firmware has configured some hardware to access (such as a bootsplash
+ framebuffer).
+
+ If no "reg" property is specified, the "iommu-addresses" property
+ defines carveout regions in the IOVA space for the given device. This
+ can be useful if a certain memory region should not be mapped through
+ the IOMMU.
+
no-map:
type: boolean
description: >
@@ -97,4 +121,42 @@ oneOf:
additionalProperties: true
+examples:
+ - |
+/ {
+ #address-cells = <2>;
+ #size-cells = <2>;
+
+ reserved-memory {
+ranges;
+
+adsp_resv: reservation-adsp {
+ /*
+ * Restrict IOVA mappings for ADSP buffers to the 512 MiB region
+ * from 0x4000 - 0x5fff. Anything outside is reserved by
+ * the ADSP for I/O memory and private memory allocations.
+ */
+ iommu-addresses = < 0x0 0x 0x00 0x4000>,
+< 0x0 0x6000 0xff 0xa000>;
+};
+
+fb: framebuffer@9000 {
+ reg = <0x0 0x9000 0x0 0x0080>;
+ iommu-addresses = < 0x0 0x9000 0x0 0x0080>;
+};
+ };
+
+ bus@0 {
+adsp: adsp@299 {
+ reg = <0x0 0x299 0x0 0x2000>;
+ memory-region = <_resv>;
+};
+
+dc0: display@1520 {
+ reg = <0x0 0x1520 0x0 0x1>;
+ memory-region = <>;
+};
+ };
+};
+
...
--
2.36.1
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