selftest/powerpc: Add PAPR sysfs attributes sniff test

Include a testcase to check if the sysfs files for energy and frequency
related have its related attribute files exist and populated

Signed-off-by: Pratik R. Sampat <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

tools/testing/selftests/powerpc/Makefile

···
 	   eeh			\
 	   vphn         \
 	   math		\
+	   papr_attributes	\
 	   ptrace	\
 	   security	\
 	   mce

tools/testing/selftests/powerpc/papr_attributes/.gitignore

···
+# SPDX-License-Identifier: GPL-2.0-only
+attr_test

tools/testing/selftests/powerpc/papr_attributes/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
+TEST_GEN_PROGS := attr_test
+
+top_srcdir = ../../../../..
+include ../../lib.mk
+
+$(TEST_GEN_PROGS): ../harness.c ../utils.c

tools/testing/selftests/powerpc/papr_attributes/attr_test.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * PAPR Energy attributes sniff test
+ * This checks if the papr folders and contents are populated relating to
+ * the energy and frequency attributes
+ *
+ * Copyright 2022, Pratik Rajesh Sampat, IBM Corp.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <dirent.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#include "utils.h"
+
+enum energy_freq_attrs {
+	POWER_PERFORMANCE_MODE = 1,
+	IDLE_POWER_SAVER_STATUS = 2,
+	MIN_FREQ = 3,
+	STAT_FREQ = 4,
+	MAX_FREQ = 6,
+	PROC_FOLDING_STATUS = 8
+};
+
+enum type {
+	INVALID,
+	STR_VAL,
+	NUM_VAL
+};
+
+int value_type(int id)
+{
+	int val_type;
+
+	switch (id) {
+	case POWER_PERFORMANCE_MODE:
+	case IDLE_POWER_SAVER_STATUS:
+		val_type = STR_VAL;
+		break;
+	case MIN_FREQ:
+	case STAT_FREQ:
+	case MAX_FREQ:
+	case PROC_FOLDING_STATUS:
+		val_type = NUM_VAL;
+		break;
+	default:
+		val_type = INVALID;
+	}
+
+	return val_type;
+}
+
+int verify_energy_info(void)
+{
+	const char *path = "/sys/firmware/papr/energy_scale_info";
+	struct dirent *entry;
+	struct stat s;
+	DIR *dirp;
+
+	if (stat(path, &s) || !S_ISDIR(s.st_mode))
+		return -1;
+	dirp = opendir(path);
+
+	while ((entry = readdir(dirp)) != NULL) {
+		char file_name[64];
+		int id, attr_type;
+		FILE *f;
+
+		if (strcmp(entry->d_name, ".") == 0 ||
+		    strcmp(entry->d_name, "..") == 0)
+			continue;
+
+		id = atoi(entry->d_name);
+		attr_type = value_type(id);
+		if (attr_type == INVALID)
+			return -1;
+
+		/* Check if the files exist and have data in them */
+		sprintf(file_name, "%s/%d/desc", path, id);
+		f = fopen(file_name, "r");
+		if (!f || fgetc(f) == EOF)
+			return -1;
+
+		sprintf(file_name, "%s/%d/value", path, id);
+		f = fopen(file_name, "r");
+		if (!f || fgetc(f) == EOF)
+			return -1;
+
+		if (attr_type == STR_VAL) {
+			sprintf(file_name, "%s/%d/value_desc", path, id);
+			f = fopen(file_name, "r");
+			if (!f || fgetc(f) == EOF)
+				return -1;
+		}
+	}
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(verify_energy_info, "papr_attributes");
+}