[PATCH i-g-t] tests/intel/intel_hwmon: Warn on zero-valued numeric attributes

[Karthik Poosa <karthik.poosa@intel.com>]

Add a check for numeric hwmon attribute values and emit a warning when a
valid numeric attribute reports 0.
This acts as a sanity check for valid telemetry data reported via hwmon.

Exclude *_label attributes from this validation to avoid false warnings on
non-numeric label entries.

Also include the necessary headers required for numeric parsing helpers.

Signed-off-by: Karthik Poosa <karthik.poosa@intel.com>
Assisted-by: GitHub-Copilot:GPT-5.3-Codex
---
 tests/intel/intel_hwmon.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/tests/intel/intel_hwmon.c b/tests/intel/intel_hwmon.c
index f185c1ca3..6fe57a334 100644
--- a/tests/intel/intel_hwmon.c
+++ b/tests/intel/intel_hwmon.c
@@ -4,6 +4,8 @@
  */
 
 #include <dirent.h>
+#include <errno.h>
+#include <stdlib.h>
 #include <sys/stat.h>
 #include "igt.h"
 #include "igt_hwmon.h"
@@ -26,6 +28,31 @@
 
 IGT_TEST_DESCRIPTION("Tests for intel hwmon");
 
+static bool value_is_numeric_zero(const char *val)
+{
+	char *end;
+	long long num;
+
+	errno = 0;
+	num = strtoll(val, &end, 10);
+	if (errno || *val == '\0' || *end != '\0')
+		return false;
+
+	return num == 0;
+}
+
+static bool is_hmwon_label(const char *name)
+{
+	const char *suffix = "_label";
+	size_t name_len = strlen(name);
+	size_t suffix_len = strlen(suffix);
+
+	if (name_len < suffix_len)
+		return false;
+
+	return !strcmp(name + name_len - suffix_len, suffix);
+}
+
 static void check_if_temp_valid(int hwm, char *sysfs_name)
 {
 	int32_t cur_temp = 0, limit = 0;
@@ -64,9 +91,11 @@ static void hwmon_read(int hwm)
 		igt_assert(igt_sysfs_scanf(hwm, de->d_name, "%127s", val) == 1);
 		igt_debug("'%s': %s\n", de->d_name, val);
 
+		if (!is_hmwon_label(de->d_name) && value_is_numeric_zero(val))
+			igt_warn("hwmon sysfs entry '%s' has zero value\n", de->d_name);
+
 		if (!strncmp(de->d_name, "temp", 4))
 			check_if_temp_valid(hwm, de->d_name);
-
 	}
 	closedir(dir);
 }
-- 
2.25.1