On 03/25/2019 09:56 PM, Mathieu Poirier wrote:
Configure timestamps to be emitted at regular intervals in the trace stream to temporally correlate instructions executed on different CPUs.
Signed-off-by: Mathieu Poirier mathieu.poirier@linaro.org
drivers/hwtracing/coresight/coresight-etm4x.c | 115 +++++++++++++++++- 1 file changed, 112 insertions(+), 3 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c index 732ae12fca9b..45c341a5aa0b 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.c +++ b/drivers/hwtracing/coresight/coresight-etm4x.c @@ -138,8 +138,11 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata) drvdata->base + TRCCNTVRn(i)); }
- /* Resource selector pair 0 is always implemented and reserved */
- for (i = 0; i < drvdata->nr_resource * 2; i++)
- /*
* Resource selector pair 0 is always implemented and reserved. As* such start at 2.*/- for (i = 2; i < drvdata->nr_resource * 2; i++) writel_relaxed(config->res_ctrl[i], drvdata->base + TRCRSCTLRn(i));
To be frank, that looks like a separate fix for the existing driver, from this series.
@@ -201,6 +204,97 @@ static void etm4_enable_hw_smp_call(void *info) arg->rc = etm4_enable_hw(arg->drvdata); } +/*
- The goal of function etm4_config_timestamp_event() is to configure a
- counter that will tell the tracer to emit a timestamp packet when it
- reaches zero. This is done in order to get a more fine grained idea
- of when instructions are executed so that they can be correlated
- with execution on other CPUs.
- To do this the counter itself is configured to self reload and
- TRCRSCTLR1 (always true) used to get the counter to decrement. From
- there a resource selector is configured with the counter and the
- timestamp control register to use the resource selector to trigger the
- event that will insert a timestamp packet in the stream.
- */
+static int etm4_config_timestamp_event(struct etmv4_drvdata *drvdata) +{
- int i, ctridx, ret = -EINVAL;
- int counter, rselector;
- u32 val = 0;
- struct etmv4_config *config = &drvdata->config;
- /* No point in trying if we don't have at least one counter */
- if (!drvdata->nr_cntr)
goto out;- /* Find a counter that hasn't been initialised */
- for (i = 0; i < drvdata->nr_cntr; i++)
if (config->cntr_val[i] == 0)break;- /* Remember what counter we used */
- counter = 1 << i;
- ctridx = i;
- /* All the counters have been configured already, bail out */
- if (i == drvdata->nr_cntr) {
pr_err("%s: no available counter found\n", __func__);goto out;- }
Should this be pr_debug ? This could be easily triggered to flood the dmesg. Also, I think the return code could be -ENODEV or -ENOSPC rather than -EINVAL in this case.
- /*
* Initialise original and reload counter value to the smallest* possible value in order to get as much precision as we can.*/- config->cntr_val[ctridx] = 1;
- config->cntrldvr[ctridx] = 1;
We could delay the initialisation until we find the resource selector to avoid clearing them later.
- /* Set the trace counter control register */
- val = 0x1 << 16 | /* Bit 16, reload counter automatically */
0x0 << 7 | /* Select single resource selector */0x1; /* Resource selector 1, i.e always true */- config->cntr_ctrl[ctridx] = val;
- /*
* Searching for an available resource selector to use, starting at* '2' since every implementation has at least 2 resource selector.* ETMIDR4 gives the number of resource selector _pairs_,* hence multiply by 2.*/- for (i = 2; i < drvdata->nr_resource * 2; i++)
if (!config->res_ctrl[i])break;- /* Remember what resource selector we used */
- rselector = i;
- if (i == drvdata->nr_resource * 2) {
pr_err("%s: no available resource selector found\n", __func__);
Same as above. This shouldn't be an error, may be a debug. It is a crunch of resources, a usage error from the user and not kernel.
/* Backout what we did and exit */config->cntr_ctrl[ctridx] = 0;config->cntrldvr[ctridx] = 0;config->cntr_val[ctridx] = 0;goto out;- }
- val = 0x2 << 16 | /* Group 0b0010 - Counter and sequencers */
counter << 0; /* Counter to use */- config->res_ctrl[i] = val;
- val = 0x0 << 7 | /* Select single resource selector */
rselector; /* Resource selector */- config->ts_ctrl = val;
- ret = 0;
+out:
- return ret;
+}
- static int etm4_parse_event_config(struct etmv4_drvdata *drvdata, struct perf_event *event) {
@@ -236,9 +330,24 @@ static int etm4_parse_event_config(struct etmv4_drvdata *drvdata, /* TRM: Must program this for cycacc to work */ config->ccctlr = ETM_CYC_THRESHOLD_DEFAULT; }
- if (attr->config & BIT(ETM_OPT_TS))
- if (attr->config & BIT(ETM_OPT_TS)) {
/** Configure timestamps to be emitted at regular intervals in* order to correlate instructions executed on different CPUs* (CPU-wide trace scenarios).*/ret = etm4_config_timestamp_event(drvdata);/** No need to go further if timestamp intervals can't* be configured.*/if (ret)goto out;- /* bit[11], Global timestamp tracing bit */ config->cfg |= BIT(11);
- }
if (attr->config & BIT(ETM_OPT_CTXTID)) /* bit[6], Context ID tracing bit */
Rest all looks good to me.
Suzuki