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[68.147.0.187]) by smtp.gmail.com with ESMTPSA id c136-20020a63358e000000b003c14af5063bsm11882556pga.83.2022.05.02.09.49.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 May 2022 09:49:13 -0700 (PDT) Date: Mon, 2 May 2022 10:49:11 -0600 From: Mathieu Poirier To: German Gomez Cc: coresight@lists.linaro.org, suzuki.poulose@arm.com, james.clark@arm.com, leo.yan@linaro.org, mike.leach@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] coresight: etm4x: Expose default timestamp source in sysfs Message-ID: <20220502164911.GB2498226@p14s> References: <20220429123100.268059-1-german.gomez@arm.com> <20220429123100.268059-2-german.gomez@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220429123100.268059-2-german.gomez@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 29, 2022 at 01:30:59PM +0100, German Gomez wrote: > Add a new sysfs interface in /sys/bus/coresight/devices/etm/ts_source > indicating the configured timestamp source when the ETM device driver > was probed. > > The perf tool will use this information to detect if the trace data > timestamp matches the kernel time, enabling correlation of CoreSight > trace with perf events. > > Suggested-by: Suzuki K Poulose > Signed-off-by: German Gomez > --- > arch/arm64/include/asm/sysreg.h | 1 + > .../coresight/coresight-etm4x-sysfs.c | 34 +++++++++++++++++++ > 2 files changed, 35 insertions(+) > > diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h > index 38508e507d73a..263a7bee06f9a 100644 > --- a/arch/arm64/include/asm/sysreg.h > +++ b/arch/arm64/include/asm/sysreg.h > @@ -1146,6 +1146,7 @@ > #define SYS_MPIDR_SAFE_VAL (BIT(31)) > > #define TRFCR_ELx_TS_SHIFT 5 > +#define TRFCR_ELx_TS_MASK ((0x3UL) << TRFCR_ELx_TS_SHIFT) > #define TRFCR_ELx_TS_VIRTUAL ((0x1UL) << TRFCR_ELx_TS_SHIFT) > #define TRFCR_ELx_TS_GUEST_PHYSICAL ((0x2UL) << TRFCR_ELx_TS_SHIFT) > #define TRFCR_ELx_TS_PHYSICAL ((0x3UL) << TRFCR_ELx_TS_SHIFT) > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c > index a0640fa5c55bd..c0c375c0cfde2 100644 > --- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c > +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c > @@ -2264,6 +2264,39 @@ static ssize_t cpu_show(struct device *dev, > } > static DEVICE_ATTR_RO(cpu); > > +static int etmv4_to_ts_source(struct etmv4_drvdata *drvdata) > +{ > + int val; > + > + if (!drvdata->trfcr) > + return -1; > + > + switch (drvdata->trfcr & TRFCR_ELx_TS_MASK) { > + case TRFCR_ELx_TS_VIRTUAL: > + case TRFCR_ELx_TS_GUEST_PHYSICAL: > + case TRFCR_ELx_TS_PHYSICAL: > + val = FIELD_GET(TRFCR_ELx_TS_MASK, drvdata->trfcr); > + break; > + default: > + val = -1; > + break; > + } I don't think the above is big and/or complex enough to mandate a separate function - please move to ts_source_show(). > + > + return val; > +} > + > +static ssize_t ts_source_show(struct device *dev, > + struct device_attribute *attr, > + char *buf) > +{ > + int val; > + struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent); > + > + val = etmv4_to_ts_source(drvdata); > + return sysfs_emit(buf, "%d\n", val); > +} > +static DEVICE_ATTR_RO(ts_source); > + > static struct attribute *coresight_etmv4_attrs[] = { > &dev_attr_nr_pe_cmp.attr, > &dev_attr_nr_addr_cmp.attr, > @@ -2318,6 +2351,7 @@ static struct attribute *coresight_etmv4_attrs[] = { > &dev_attr_vmid_val.attr, > &dev_attr_vmid_masks.attr, > &dev_attr_cpu.attr, > + &dev_attr_ts_source.attr, > NULL, > }; > > -- > 2.25.1 >