parser simplicity
=================
Many systems that parse DT at runtime already implement an function that
can check for the presence of a string in an array of string, as it is
similar to the process for parsing a list of compatible strings, so a
bunch of new, custom, DT parsing should not be needed.
Getting rid of "riscv,isa" parsing would be a nice simplification, but
unfortunately for backwards compatibility with old dtbs, existing
parsers may not be removable - which may greatly simplify
dt parsing code. In Linux, for example, checking for whether a hart
supports an extension becomes as simple as:
of_property_match_string(node, "riscv,isa-extensions", "zicbom")
vendor extensions
=================
Compared to riscv,isa, this proposed scheme promotes vendor extensions,
oft touted as the strength of RISC-V, to first-class citizens.
At present, extensions are defined as meaning what the RISC-V ISA
specifications say they do. There is no realistic way of using that
interface to provide cross-platform definitions for what vendor
extensions mean. Vendor extensions may also have even less consistency
than RVI do in terms of versioning, or no care about backwards
compatibility.
The new property allows us to assign explicit meanings on a per vendor
extension basis, backed up by a description of their meanings.
fin
===
Create a new file to store the extension meanings and a new
riscv,isa-base property to replace the aspect of riscv,isa that is
not represented by the new property - the base ISA implemented by a hart.
As a starting point, add properties for extensions currently used in
Linux.
Finally, mark riscv,isa as deprecated, as removing support for it in
existing programs would be an ABI break.
CC: Palmer Dabbelt <palmer@xxxxxxxxxxx>
CC: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
CC: Rob Herring <robh+dt@xxxxxxxxxx>
CC: Krzysztof Kozlowski <krzysztof.kozlowski+dt@xxxxxxxxxx>
CC: Alistair Francis <alistair.francis@xxxxxxx>
CC: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
CC: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
CC: Atish Patra <atishp@xxxxxxxxxxxxxx>
CC: Jessica Clarke <jrtc27@xxxxxxxxxx>
CC: Rick Chen <rick@xxxxxxxxxxxxx>
CC: Leo <ycliang@xxxxxxxxxxxxx>
CC: Oleksii <oleksii.kurochko@xxxxxxxxx>
CC: linux-riscv@xxxxxxxxxxxxxxxxxxx
CC: qemu-riscv@xxxxxxxxxx
CC: u-boot@xxxxxxxxxxxxx
CC: devicetree@xxxxxxxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx
Reviewed-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Acked-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
---
Changes in v3:
- Per Rob's suggestion, switch to an array of strings. Cuts down on the
size, compared to booleans. It has a standard mechanism for parsing
(you need to parse arrays of strings for compatibles). It still allows
for having a limited set of explicitly defined properties - so the
advantages over a free-form string still apply.
- Pick up Palmer's Ack and Review (although I expect that he will be the
one to apply this).
---
.../devicetree/bindings/riscv/cpus.yaml | 43 ++-
.../devicetree/bindings/riscv/extensions.yaml | 245 ++++++++++++++++++
2 files changed, 265 insertions(+), 23 deletions(-)
create mode 100644 Documentation/devicetree/bindings/riscv/extensions.yaml
diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml
index 67bd239ead0b..74bc92591086 100644
--- a/Documentation/devicetree/bindings/riscv/cpus.yaml
+++ b/Documentation/devicetree/bindings/riscv/cpus.yaml
@@ -25,6 +25,7 @@ description: |
allOf:
- $ref: /schemas/cpu.yaml#
+ - $ref: extensions.yaml
properties:
compatible:
@@ -82,25 +83,6 @@ properties:
description:
The blocksize in bytes for the Zicboz cache operations.
- riscv,isa:
- description:
- Identifies the specific RISC-V instruction set architecture
- supported by the hart. These are documented in the RISC-V
- User-Level ISA document, available from
- https://riscv.org/specifications/
-
- Due to revisions of the ISA specification, some deviations
- have arisen over time.
- Notably, riscv,isa was defined prior to the creation of the
- Zicntr, Zicsr, Zifencei and Zihpm extensions and thus "i"
- implies "zicntr_zicsr_zifencei_zihpm".
-
- While the isa strings in ISA specification are case
- insensitive, letters in the riscv,isa string must be all
- lowercase.
- $ref: /schemas/types.yaml#/definitions/string
- pattern: ^rv(?:64|32)imaf?d?q?c?b?k?j?p?v?h?(?:[hsxz](?:[a-z])+)?(?:_[hsxz](?:[a-z])+)*$
-
# RISC-V has multiple properties for cache op block sizes as the sizes
# differ between individual CBO extensions
cache-op-block-size: false
@@ -139,8 +121,17 @@ properties:
DMIPS/MHz, relative to highest capacity-dmips-mhz
in the system.
+oneOf:
+ - required:
+ - riscv,isa
+ - required:
+ - riscv,isa-base
+
+dependencies:
+ riscv,isa-base: [ "riscv,isa-extensions" ]
+ riscv,isa-extensions: [ "riscv,isa-base" ]
+
required:
- - riscv,isa
- interrupt-controller
unevaluatedProperties: false
@@ -160,7 +151,9 @@ examples:
i-cache-sets = <128>;
i-cache-size = <16384>;
reg = <0>;
- riscv,isa = "rv64imac";
+ riscv,isa-base = "rv64i";
+ riscv,isa-extensions = "i", "m", "a", "c";
+
cpu_intc0: interrupt-controller {
#interrupt-cells = <1>;
compatible = "riscv,cpu-intc";
@@ -183,8 +176,10 @@ examples:
i-tlb-size = <32>;
mmu-type = "riscv,sv39";
reg = <1>;
- riscv,isa = "rv64imafdc";
tlb-split;
+ riscv,isa-base = "rv64i";
+ riscv,isa-extensions = "i", "m", "a", "f", "d", "c";
+
cpu_intc1: interrupt-controller {
#interrupt-cells = <1>;
compatible = "riscv,cpu-intc";
@@ -202,8 +197,10 @@ examples:
device_type = "cpu";
reg = <0>;
compatible = "riscv";
- riscv,isa = "rv64imafdc";
mmu-type = "riscv,sv48";
+ riscv,isa-base = "rv64i";
+ riscv,isa-extensions = "i", "m", "a", "f", "d", "c";
+
interrupt-controller {
#interrupt-cells = <1>;
interrupt-controller;
diff --git a/Documentation/devicetree/bindings/riscv/extensions.yaml b/Documentation/devicetree/bindings/riscv/extensions.yaml
new file mode 100644
index 000000000000..af98307f2c2c
--- /dev/null
+++ b/Documentation/devicetree/bindings/riscv/extensions.yaml
@@ -0,0 +1,245 @@
+# SPDX-License-Identifier: (GPL-2.0 OR MIT)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/riscv/extensions.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: RISC-V ISA extensions
+
+maintainers:
+ - Paul Walmsley <paul.walmsley@xxxxxxxxxx>
+ - Palmer Dabbelt <palmer@xxxxxxxxxx>
+ - Conor Dooley <conor@xxxxxxxxxx>
+
+description: |
+ RISC-V has a large number of extensions, some of which are "standard"
+ extensions, meaning they are ratified by RISC-V International, and others
+ are "vendor" extensions.
+ This document defines properties that indicate whether a hart supports a
+ given extension.
+
+ Once a standard extension has been ratified, no changes in behaviour can be
+ made without the creation of a new extension.
+ The properties for standard extensions therefore map to their originally
+ ratified states, with the exception of the I, Zicntr & Zihpm extensions.
+ See the "i" property for more information.
+
+select:
+ properties:
+ compatible:
+ contains:
+ const: riscv
+
+properties:
+ riscv,isa:
+ description:
+ Identifies the specific RISC-V instruction set architecture
+ supported by the hart. These are documented in the RISC-V
+ User-Level ISA document, available from
+ https://riscv.org/specifications/
+
+ Due to revisions of the ISA specification, some deviations
+ have arisen over time.
+ Notably, riscv,isa was defined prior to the creation of the
+ Zicntr, Zicsr, Zifencei and Zihpm extensions and thus "i"
+ implies "zicntr_zicsr_zifencei_zihpm".
+
+ While the isa strings in ISA specification are case
+ insensitive, letters in the riscv,isa string must be all
+ lowercase.
+ $ref: /schemas/types.yaml#/definitions/string
+ pattern: ^rv(?:64|32)imaf?d?q?c?b?k?j?p?v?h?(?:[hsxz](?:[a-z])+)?(?:_[hsxz](?:[a-z])+)*$
+ deprecated: true
+
+ riscv,isa-base:
+ description:
+ The base ISA implemented by this hart, as described by the 20191213
+ version of the unprivileged ISA specification.
+ enum:
+ - rv32i
+ - rv64i
+
+ riscv,isa-extensions:
+ $ref: /schemas/types.yaml#/definitions/string-array
+ minItems: 1
+ description: Extensions supported by the hart.
+ items:
+ anyOf:
+ # single letter extensions, in canonical order
+ - const: i
+ description: |
+ The base integer instruction set, as ratified in the 20191213
+ version of the unprivileged ISA specification, with the exception of
+ counter access.
+ Counter access was removed after the ratification of the 20191213
+ version of the unprivileged specification and shunted into the
+ Zicntr and Zihpm extensions.
+
+ - const: m
+ description:
+ The standard M extension for integer multiplication and division, as
+ ratified in the 20191213 version of the unprivileged ISA
+ specification.
+
+ - const: a
+ description:
+ The standard A extension for atomic instructions, as ratified in the
+ 20191213 version of the unprivileged ISA specification.
+
+ - const: f
+ description:
+ The standard F extension for single-precision floating point, as
+ ratified in the 20191213 version of the unprivileged ISA
+ specification.
+
+ - const: d
+ description:
+ The standard D extension for double-precision floating-point, as
+ ratified in the 20191213 version of the unprivileged ISA
+ specification.
+
+ - const: q
+ description:
+ The standard Q extension for quad-precision floating-point, as
+ ratified in the 20191213 version of the unprivileged ISA
+ specification.
+
+ - const: c
+ description:
+ The standard C extension for compressed instructions, as ratified in
+ the 20191213 version of the unprivileged ISA specification.
+
+ - const: v
+ description:
+ The standard V extension for vector operations, as ratified
+ in-and-around commit 7a6c8ae ("Fix text that describes vfmv.v.f
+ encoding") of the riscv-v-spec.
+
+ - const: h
+ description:
+ The standard H extension for hypervisors as ratified in the 20191213
+ version of the privileged ISA specification.
+
+ # multi-letter extensions, sorted alphanumerically
+ - const: smaia
+ description: |
+ The standard Smaia supervisor-level extension for the advanced
+ interrupt architecture for machine-mode-visible csr and behavioural
+ changes to interrupts as frozen at commit ccbddab ("Merge pull
+ request #42 from riscv/jhauser-2023-RC4") of riscv-aia.
+
+ - const: ssaia
+ description: |
+ The standard Ssaia supervisor-level extension for the advanced
+ interrupt architecture for supervisor-mode-visible csr and
+ behavioural changes to interrupts as frozen at commit ccbddab
+ ("Merge pull request #42 from riscv/jhauser-2023-RC4") of riscv-aia.
+
+ - const: sscofpmf
+ description: |
+ The standard Sscofpmf supervisor-level extension for count overflow
+ and mode-based filtering as ratified at commit 01d1df0 ("Add ability
+ to manually trigger workflow. (#2)") of riscv-count-overflow.
+
+ - const: sstc
+ description: |
+ The standard Sstc supervisor-level extension for time compare as
+ ratified at commit 3f9ed34 ("Add ability to manually trigger
+ workflow. (#2)") of riscv-time-compare.
+
+ - const: svinval
+ description:
+ The standard Svinval supervisor-level extension for fine-grained
+ address-translation cache invalidation as ratified in the 20191213
+ version of the privileged ISA specification.
+
+ - const: svnapot
+ description:
+ The standard Svnapot supervisor-level extensions for napot
+ translation contiguity as ratified in the 20191213 version of the
+ privileged ISA specification.
+
+ - const: svpbmt
+ description:
+ The standard Svpbmt supervisor-level extensions for page-based
+ memory types as ratified in the 20191213 version of the privileged
+ ISA specification.
+
+ - const: zba
+ description: |
+ The standard Zba bit-manipulation extension for address generation
+ acceleration instructions as ratified at commit 6d33919 ("Merge pull
+ request #158 from hirooih/clmul-fix-loop-end-condition") of
+ riscv-bitmanip.
+
+ - const: zbb
+ description: |
+ The standard Zbb bit-manipulation extension for basic bit-manipulation
+ as ratified at commit 6d33919 ("Merge pull request #158 from
+ hirooih/clmul-fix-loop-end-condition") of riscv-bitmanip.
+
+ - const: zbc
+ description: |
+ The standard Zbc bit-manipulation extension for carry-less
+ multiplication as ratified at commit 6d33919 ("Merge pull request
+ #158 from hirooih/clmul-fix-loop-end-condition") of riscv-bitmanip.
+
+ - const: zbs
+ description: |
+ The standard Zbs bit-manipulation extension for single-bit
+ instructions as ratified at commit 6d33919 ("Merge pull request #158
+ from hirooih/clmul-fix-loop-end-condition") of riscv-bitmanip.
+
+ - const: zicbom
+ description:
+ The standard Zicbom extension for base cache management operations as
+ ratified in commit 3dd606f ("Create cmobase-v1.0.pdf") of riscv-CMOs.
+
+ - const: zicbop
+ description:
+ The standard Zicbop extension for cache-block prefetch instructions
+ as ratified in commit 3dd606f ("Create cmobase-v1.0.pdf") of
+ riscv-CMOs.
+
+ - const: zicboz
+ description:
+ The standard Zicboz extension for cache-block zeroing as ratified
+ in commit 3dd606f ("Create cmobase-v1.0.pdf") of riscv-CMOs.
+
+ - const: zicntr
+ description:
+ The standard Zicntr extension for base counters and timers, as
+ ratified in the 20191213 version of the unprivileged ISA
+ specification.
+
+ - const: zicsr
+ description:
+ The standard Zicsr extension for control and status register
+ instructions, as ratified in the 20191213 version of the
+ unprivileged ISA specification.
+
+ - const: zifencei
+ description:
+ The standard Zifencei extension for instruction-fetch fence, as
+ ratified in the 20191213 version of the unprivileged ISA
+ specification.
+
+ - const: zihintpause
+ description:
+ The standard Zihintpause extension for pause hints, as ratified in
+ commit d8ab5c7 ("Zihintpause is ratified") of the riscv-isa-manual.
+
+ - const: zihpm
+ description:
+ The standard Zihpm extension for hardware performance counters, as
+ ratified in the 20191213 version of the unprivileged ISA
+ specification.
+
+ - const: ztso
+ description:
+ The standard Ztso extension for total store ordering, as ratified
+ in commit 2e5236 ("Ztso is now ratified.") of the
+ riscv-isa-manual.
+
+additionalProperties: true
+...
--
2.40.1
