[PATCH i-g-t v2 1/3] lib/igt_perf: Add utils to extract PMU event info

[Riana Tauro]

From: Vinay Belgaumkar <vinay.belgaumkar at intel.com>

Functions to parse event ID and GT bit shift for PMU events.

v2: Review comments (Riana)
v3: Review comments (Lucas)
v4: fix kernel-doc (Kamil)
    remove parameter for end (Umesh)

Reviewed-by: Riana Tauro <riana.tauro at intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
---
 lib/igt_perf.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_perf.h |  2 ++
 2 files changed, 74 insertions(+)

diff --git a/lib/igt_perf.c b/lib/igt_perf.c
index 3866c6d77..c1b8cc629 100644
--- a/lib/igt_perf.c
+++ b/lib/igt_perf.c
@@ -92,6 +92,78 @@ const char *xe_perf_device(int xe, char *buf, int buflen)
 	return buf;
 }
 
+/**
+ * perf_event_format: Returns the shift positions of an event format param
+ * @device: PMU device
+ * @param: parameter to obtain the shiift
+ * @shift: shift bits for the parameter
+ *
+ * Returns: 0 on success or negative error code
+ */
+int perf_event_format(const char *device, const char *param, uint32_t *shift)
+{
+	char buf[NAME_MAX];
+	ssize_t bytes;
+	int ret = 0, fd;
+	uint32_t end;
+
+	snprintf(buf, sizeof(buf),
+		 "/sys/bus/event_source/devices/%s/format/%s",
+		 device, param);
+
+	fd = open(buf, O_RDONLY | O_CLOEXEC);
+	if (fd < 0)
+		return -EINVAL;
+
+	bytes = read(fd, buf, sizeof(buf) - 1);
+	close(fd);
+	if (bytes < 1)
+		return -EINVAL;
+
+	buf[bytes] = '\0';
+	ret = sscanf(buf, "config:%u-%u", shift, &end);
+	if (ret != 2)
+		return -EINVAL;
+
+	return ret;
+}
+
+/**
+ * perf_event_config:
+ * @device: Device string in driver:pci format
+ * @event: The event name
+ * @config: Pointer to the config
+ *
+ * Returns: 0 for success, negative value on error
+ */
+int perf_event_config(const char *device, const char *event, uint64_t *config)
+{
+	char buf[NAME_MAX];
+	ssize_t bytes;
+	int ret = 0, fd;
+
+	snprintf(buf, sizeof(buf),
+		 "/sys/bus/event_source/devices/%s/events/%s",
+		 device,
+		 event);
+
+	fd = open(buf, O_RDONLY);
+	if (fd < 0)
+		return -EINVAL;
+
+	bytes = read(fd, buf, sizeof(buf) - 1);
+	close(fd);
+	if (bytes < 1)
+		return ret;
+
+	buf[bytes] = '\0';
+	ret = sscanf(buf, "event=0x%lx", config);
+	if (ret != 1)
+		return -EINVAL;
+
+	return 0;
+}
+
 uint64_t xe_perf_type_id(int xe)
 {
 	char buf[80];
diff --git a/lib/igt_perf.h b/lib/igt_perf.h
index 3d9ba2917..58d7d47aa 100644
--- a/lib/igt_perf.h
+++ b/lib/igt_perf.h
@@ -71,5 +71,7 @@ int perf_i915_open(int i915, uint64_t config);
 int perf_i915_open_group(int i915, uint64_t config, int group);
 
 int perf_xe_open(int xe, uint64_t config);
+int perf_event_config(const char *device, const char *event, uint64_t *config);
+int perf_event_format(const char *device, const char *param, uint32_t *shift);
 
 #endif /* I915_PERF_H */
-- 
2.47.1