[PATCH V2 2/3] perf/imx_ddr: Add system PMU identifier for userspace

From: Joakim Zhang
Date: Tue May 19 2020 - 22:59:35 EST


The DDR Perf for i.MX8 is a system PMU whose axi id would different from
SoC to SoC. Need expose system PMU identifier for userspace which refer
to /sys/bus/event_source/devices/<PMU DEVICE>/identifier.

Signed-off-by: Joakim Zhang <qiangqing.zhang@xxxxxxx>
---
drivers/perf/fsl_imx8_ddr_perf.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)

diff --git a/drivers/perf/fsl_imx8_ddr_perf.c b/drivers/perf/fsl_imx8_ddr_perf.c
index 90884d14f95f..ba523a94f4d7 100644
--- a/drivers/perf/fsl_imx8_ddr_perf.c
+++ b/drivers/perf/fsl_imx8_ddr_perf.c
@@ -76,6 +76,7 @@ struct ddr_pmu {
unsigned int cpu;
struct hlist_node node;
struct device *dev;
+ const char *identifier;
struct perf_event *events[NUM_COUNTERS];
int active_events;
enum cpuhp_state cpuhp_state;
@@ -84,6 +85,27 @@ struct ddr_pmu {
int id;
};

+static ssize_t ddr_perf_identifier_show(struct device *dev,
+ struct device_attribute *attr,
+ char *page)
+{
+ struct ddr_pmu *pmu = dev_get_drvdata(dev);
+
+ return sprintf(page, "%s\n", pmu->identifier);
+}
+
+static struct device_attribute ddr_perf_identifier_attr =
+ __ATTR(identifier, 0444, ddr_perf_identifier_show, NULL);
+
+static struct attribute *ddr_perf_identifier_attrs[] = {
+ &ddr_perf_identifier_attr.attr,
+ NULL,
+};
+
+static struct attribute_group ddr_perf_identifier_attr_group = {
+ .attrs = ddr_perf_identifier_attrs,
+};
+
enum ddr_perf_filter_capabilities {
PERF_CAP_AXI_ID_FILTER = 0,
PERF_CAP_AXI_ID_FILTER_ENHANCED,
@@ -237,6 +259,7 @@ static const struct attribute_group *attr_groups[] = {
&ddr_perf_format_attr_group,
&ddr_perf_cpumask_attr_group,
&ddr_perf_filter_cap_attr_group,
+ &ddr_perf_identifier_attr_group,
NULL,
};

@@ -601,6 +624,7 @@ static int ddr_perf_probe(struct platform_device *pdev)
struct ddr_pmu *pmu;
struct device_node *np;
void __iomem *base;
+ const char *identifier = NULL;
char *name;
int num;
int ret;
@@ -620,6 +644,11 @@ static int ddr_perf_probe(struct platform_device *pdev)

platform_set_drvdata(pdev, pmu);

+ ret = of_property_read_string(np, "identifier", &identifier);
+ if (ret < 0)
+ dev_warn(&pdev->dev, "Failed to get identifier\n");
+ pmu->identifier = identifier;
+
name = devm_kasprintf(&pdev->dev, GFP_KERNEL, DDR_PERF_DEV_NAME "%d",
num);
if (!name)
--
2.17.1