On Mon, Jan 09, 2023 at 10:17:41AM +0000, Conor Dooley wrote: > On Mon, Jan 09, 2023 at 10:27:15AM +0100, Andrew Jones wrote: > > On Sun, Jan 08, 2023 at 09:50:48PM +0000, Conor Dooley wrote: > > > From: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> > > > > > > The SBI PMU extension requires a firmware to be aware of the event to > > > counter/mhpmevent mappings supported by the hardware. OpenSBI may use > > > DeviceTree to describe the PMU mappings. This binding is currently > > > described in markdown in OpenSBI (since v1.0 in Dec 2021) & used by QEMU > > > since v7.2.0. > > > > > > Import the binding for use while validating dtb dumps from QEMU and > > > upcoming hardware (eg JH7110 SoC) that will make use of the event > > > mapping. > > > > > > Link: https://github.com/riscv-software-src/opensbi/blob/master/docs/pmu_support.md > > > Link: https://github.com/riscv-non-isa/riscv-sbi-doc/blob/master/riscv-sbi.adoc # Performance Monitoring Unit Extension > > > Co-developed-by: Atish Patra <atishp@xxxxxxxxxxxx> > > > Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx> > > > Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> > > > --- > > > Changes in v4: > > > - A bunch of minor description/comment changes suggested by Drew > > > > > > Changes in v3: > > > - align descriptions to SBI spec (and fix a misinterpretation of mine) > > > - switch to a nested items description, since the descriptions are for > > > the elements of each entry, not the entries themselves > > > > > > Changes in v2: > > > - use the schema mechanism for dependancies between properties > > > - +CC perf maintainers... > > > - move the matrix element descriptions into regular item descriptions > > > rather than doing so freeform in the property description > > > - drop some description text that no longer applies since changes were > > > made to the SBI spec > > > - drop mention of the "generic platform" which is OpenSBI specific > > > - drop the min/max items from the matrices, they don't appear to be > > > needed? > > > > > > Note: > > > OpenSBI is BSD-2-Clause licensed so I am unsure as to whether I can > > > submit it with a dual license. > > > --- > > > .../devicetree/bindings/perf/riscv,pmu.yaml | 160 ++++++++++++++++++ > > > 1 file changed, 160 insertions(+) > > > create mode 100644 Documentation/devicetree/bindings/perf/riscv,pmu.yaml > > > > > > diff --git a/Documentation/devicetree/bindings/perf/riscv,pmu.yaml b/Documentation/devicetree/bindings/perf/riscv,pmu.yaml > > > new file mode 100644 > > > index 000000000000..5e7a54e3d91b > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/perf/riscv,pmu.yaml > > > @@ -0,0 +1,160 @@ > > > +# SPDX-License-Identifier: BSD-2-Clause > > > +%YAML 1.2 > > > +--- > > > +$id: http://devicetree.org/schemas/perf/riscv,pmu.yaml# > > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > > + > > > +title: RISC-V SBI PMU events > > > + > > > +maintainers: > > > + - Atish Patra <atishp@xxxxxxxxxxxx> > > > + > > > +description: | > > > + The SBI PMU extension allows supervisor software to configure, start and > > > + stop any performance counter at anytime. Thus, a user can leverage all > > > + capabilities of performance analysis tools, such as perf, if the SBI PMU > > > + extension is enabled. The following constraints apply: > > > + > > > + The platform must provide information about PMU event to counter mappings > > > + via device tree or platform specific hooks. Otherwise, the SBI PMU > > > + extension will not be enabled. > > > + > > > + Platforms should provide information about the PMU event selector values > > > + that should be encoded in the expected value of MHPMEVENTx while configuring > > > + MHPMCOUNTERx for that specific event. This can be done via a device tree or > > > + platform specific hooks. The exact value to be written to MHPMEVENTx is > > > + completely dependent on the platform. > > > > The previous two paragraphs reference 'platform specific hooks'. I don't > > think this DT-specific description, as opposed to the more general OpenSBI > > description it's derived from, should reference the hooks, as "hooks" > > aren't defined in this context. > > Do you have any suggestion about how it should be worded? It is > apparently valid to have only a compatible string in the dt-binding and > rely on using platform hooks to communicate the mapping. In that case, > the dt-binding only communicates the presence of SBI PMU support. > IMO, if we don't mention that that is a valid way, the fact that we only > require a compatible for a DT to be valid looks like a mistake in the > binding. Maybe just replace 'platform specific hooks' with 'in a platform specific way'? I'm mostly just hung up on "hooks" (pun definitely intended), as this document lives in the Linux repo and there aren't any hooks. Thanks, drew > > Thanks, > Conor. > > > > + For information on the SBI specification see the section "Performance > > > + Monitoring Unit Extension" of: > > > + https://github.com/riscv-non-isa/riscv-sbi-doc/blob/master/riscv-sbi.adoc > > > + > > > +properties: > > > + compatible: > > > + const: riscv,pmu > > > + > > > + riscv,event-to-mhpmevent: > > > + $ref: /schemas/types.yaml#/definitions/uint32-matrix > > > + description: > > > + Represents an ONE-to-ONE mapping between a PMU event and the event > > > + selector value that the platform expects to be written to the MHPMEVENTx > > > + CSR for that event. > > > + The mapping is encoded in an matrix format where each element represents > > > + an event. > > > + This property shouldn't encode any raw hardware event. > > > + items: > > > + items: > > > + - description: event_idx, a 20-bit wide encoding of the event type and > > > + code. Refer to the SBI specification for a complete description of > > > + the event types and codes. > > > + - description: upper 32 bits of the event selector value for MHPMEVENTx > > > + - description: lower 32 bits of the event selector value for MHPMEVENTx > > > + > > > + riscv,event-to-mhpmcounters: > > > + $ref: /schemas/types.yaml#/definitions/uint32-matrix > > > + description: > > > + Represents a MANY-to-MANY mapping between a range of events and all the > > > + MHPMCOUNTERx in a bitmap format that can be used to monitor these range > > > + of events. The information is encoded in an matrix format where each > > > + element represents a certain range of events and corresponding counters. > > > + This property shouldn't encode any raw event. > > > + items: > > > + items: > > > + - description: first event_idx of the range of events > > > + - description: last event_idx of the range of events > > > + - description: bitmap of MHPMCOUNTERx for this event > > > + > > > + riscv,raw-event-to-mhpmcounters: > > > + $ref: /schemas/types.yaml#/definitions/uint32-matrix > > > + description: > > > + Represents an ONE-to-MANY or MANY-to-MANY mapping between the rawevent(s) > > > + and all the MHPMCOUNTERx in a bitmap format that can be used to monitor > > > + that raw event. > > > + The encoding of the raw events are platform specific. The information is > > > + encoded in a matrix format where each element represents the specific raw > > > + event(s). > > > + If a platform directly encodes each raw PMU event as a unique ID, the > > > + value of variant must be 0xffffffff_ffffffff. > > > + items: > > > + items: > > > + - description: > > > + upper 32 invariant bits for the range of events > > > + - description: > > > + lower 32 invariant bits for the range of events > > > + - description: > > > + upper 32 bits of the variant bit mask for the range of events > > > + - description: > > > + lower 32 bits of the variant bit mask for the range of events > > > + - description: > > > + bitmap of all MHPMCOUNTERx that can monitor the range of events > > > + > > > +dependencies: > > > + "riscv,event-to-mhpmevent": [ "riscv,event-to-mhpmcounters" ] > > > + "riscv,event-to-mhpmcounters": [ "riscv,event-to-mhpmevent" ] > > > + > > > +required: > > > + - compatible > > > + > > > +additionalProperties: false > > > + > > > +examples: > > > + - | > > > + pmu { > > > + compatible = "riscv,pmu"; > > > + riscv,event-to-mhpmevent = <0x0000B 0x0000 0x0001>; > > > + riscv,event-to-mhpmcounters = <0x00001 0x00001 0x00000001>, > > > + <0x00002 0x00002 0x00000004>, > > > + <0x00003 0x0000A 0x00000ff8>, > > > + <0x10000 0x10033 0x000ff000>; > > > + riscv,raw-event-to-mhpmcounters = > > > + /* For event ID 0x0002 */ > > > + <0x0000 0x0002 0xffffffff 0xffffffff 0x00000f8>, > > > + /* For event ID 0-4 */ > > > + <0x0 0x0 0xffffffff 0xfffffff0 0x00000ff0>, > > > + /* For event ID 0xffffffff0000000f - 0xffffffff000000ff */ > > > + <0xffffffff 0x0 0xffffffff 0xffffff0f 0x00000ff0>; > > > + }; > > > + > > > + - | > > > + /* > > > + * For HiFive Unmatched board the encodings can be found here > > > + * https://sifive.cdn.prismic.io/sifive/1a82e600-1f93-4f41-b2d8-86ed8b16acba_fu740-c000-manual-v1p6.pdf > > > + * > > > + * This example also binds standard SBI PMU hardware IDs to U74 PMU event > > > + * codes, U74 uses a bitfield for events encoding, so several U74 events > > > + * can be bound to a single perf ID. > > > + * See SBI PMU hardware IDs in arch/riscv/include/asm/sbi.h > > > + */ > > > + pmu { > > > + compatible = "riscv,pmu"; > > > + riscv,event-to-mhpmevent = > > > + /* SBI_PMU_HW_CACHE_REFERENCES -> Instruction or Data cache/ITIM busy */ > > > + <0x00003 0x00000000 0x1801>, > > > + /* SBI_PMU_HW_CACHE_MISSES -> Instruction or Data cache miss or MMIO access */ > > > + <0x00004 0x00000000 0x0302>, > > > + /* SBI_PMU_HW_BRANCH_INSTRUCTIONS -> Conditional branch retired */ > > > + <0x00005 0x00000000 0x4000>, > > > + /* SBI_PMU_HW_BRANCH_MISSES -> Branch or jump misprediction */ > > > + <0x00006 0x00000000 0x6001>, > > > + /* L1D_READ_MISS -> Data cache miss or MMIO access */ > > > + <0x10001 0x00000000 0x0202>, > > > + /* L1D_WRITE_ACCESS -> Data cache write-back */ > > > + <0x10002 0x00000000 0x0402>, > > > + /* L1I_READ_ACCESS -> Instruction cache miss */ > > > + <0x10009 0x00000000 0x0102>, > > > + /* LL_READ_MISS -> UTLB miss */ > > > + <0x10011 0x00000000 0x2002>, > > > + /* DTLB_READ_MISS -> Data TLB miss */ > > > + <0x10019 0x00000000 0x1002>, > > > + /* ITLB_READ_MISS-> Instruction TLB miss */ > > > + <0x10021 0x00000000 0x0802>; > > > + riscv,event-to-mhpmcounters = <0x00003 0x00006 0x18>, > > > + <0x10001 0x10002 0x18>, > > > + <0x10009 0x10009 0x18>, > > > + <0x10011 0x10011 0x18>, > > > + <0x10019 0x10019 0x18>, > > > + <0x10021 0x10021 0x18>; > > > + riscv,raw-event-to-mhpmcounters = <0x0 0x0 0xffffffff 0xfc0000ff 0x18>, > > > + <0x0 0x1 0xffffffff 0xfff800ff 0x18>, > > > + <0x0 0x2 0xffffffff 0xffffe0ff 0x18>; > > > + }; > > > -- > > > 2.39.0 > > > > > > > Besides the comment above, > > > > Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx> > > > > Thanks, > > drew > > > > _______________________________________________ > > linux-riscv mailing list > > linux-riscv@xxxxxxxxxxxxxxxxxxx > > http://lists.infradead.org/mailman/listinfo/linux-riscv
