[PATCH 5/5] selftests/thermel/intel: Add test to read power floor status

[Srinivas Pandruvada]

Some SoCs have firmware support to notify, if the system can't lower
power limit to a value requested from user space via RAPL constraints.

This test program waits for notification of power floor and prints. This
program can be used to test this feature and also allows other user space
programs to use as a reference.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
---
 tools/testing/selftests/Makefile              |   1 +
 .../thermal/intel/power_floor/Makefile        |  12 ++
 .../intel/power_floor/power_floor_test.c      | 108 ++++++++++++++++++
 3 files changed, 121 insertions(+)
 create mode 100644 tools/testing/selftests/thermal/intel/power_floor/Makefile
 create mode 100644 tools/testing/selftests/thermal/intel/power_floor/power_floor_test.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 725ce59e4637..c99de76fb20d 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -85,6 +85,7 @@ TARGETS += syscall_user_dispatch
 TARGETS += sysctl
 TARGETS += tc-testing
 TARGETS += tdx
+TARGETS += thermal/intel/power_floor
 TARGETS += thermal/intel/workload_hint
 TARGETS += timens
 ifneq (1, $(quicktest))
diff --git a/tools/testing/selftests/thermal/intel/power_floor/Makefile b/tools/testing/selftests/thermal/intel/power_floor/Makefile
new file mode 100644
index 000000000000..9b88e57dbba5
--- /dev/null
+++ b/tools/testing/selftests/thermal/intel/power_floor/Makefile
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0
+ifndef CROSS_COMPILE
+uname_M := $(shell uname -m 2>/dev/null || echo not)
+ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/)
+
+ifeq ($(ARCH),x86)
+TEST_GEN_PROGS := power_floor_test
+
+include ../../../lib.mk
+
+endif
+endif
diff --git a/tools/testing/selftests/thermal/intel/power_floor/power_floor_test.c b/tools/testing/selftests/thermal/intel/power_floor/power_floor_test.c
new file mode 100644
index 000000000000..0326b39a11b9
--- /dev/null
+++ b/tools/testing/selftests/thermal/intel/power_floor/power_floor_test.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <signal.h>
+
+#define POWER_FLOOR_ENABLE_ATTRIBUTE "/sys/bus/pci/devices/0000:00:04.0/power_limits/power_floor_enable"
+#define POWER_FLOOR_STATUS_ATTRIBUTE  "/sys/bus/pci/devices/0000:00:04.0/power_limits/power_floor_status"
+
+void power_floor_exit(int signum)
+{
+	int fd;
+
+	/* Disable feature via sysfs knob */
+
+	fd = open(POWER_FLOOR_ENABLE_ATTRIBUTE, O_RDWR);
+	if (fd < 0) {
+		perror("Unable to open power floor enable file\n");
+		exit(1);
+	}
+
+	if (write(fd, "0\n", 2) < 0) {
+		perror("Can' disable power floor notifications\n");
+		exit(1);
+	}
+
+	printf("Disabled power floor notifications\n");
+
+	close(fd);
+}
+
+int main(int argc, char **argv)
+{
+	struct pollfd ufd;
+	char status_str[3];
+	int fd, ret;
+
+	if (signal(SIGINT, power_floor_exit) == SIG_IGN)
+		signal(SIGINT, SIG_IGN);
+	if (signal(SIGHUP, power_floor_exit) == SIG_IGN)
+		signal(SIGHUP, SIG_IGN);
+	if (signal(SIGTERM, power_floor_exit) == SIG_IGN)
+		signal(SIGTERM, SIG_IGN);
+
+	/* Enable feature via sysfs knob */
+	fd = open(POWER_FLOOR_ENABLE_ATTRIBUTE, O_RDWR);
+	if (fd < 0) {
+		perror("Unable to open power floor enable file\n");
+		exit(1);
+	}
+
+	if (write(fd, "1\n", 2) < 0) {
+		perror("Can' enable power floor notifications\n");
+		exit(1);
+	}
+
+	close(fd);
+
+	printf("Enabled power floor notifications\n");
+
+	while (1) {
+		fd = open(POWER_FLOOR_STATUS_ATTRIBUTE, O_RDONLY);
+		if (fd < 0) {
+			perror("Unable to power floor status file\n");
+			exit(1);
+		}
+
+		if ((lseek(fd, 0L, SEEK_SET)) < 0) {
+			fprintf(stderr, "Failed to set pointer to beginning\n");
+			exit(1);
+		}
+
+		if (read(fd, status_str, sizeof(status_str)) < 0) {
+			fprintf(stderr, "Failed to read from:%s\n",
+			POWER_FLOOR_STATUS_ATTRIBUTE);
+			exit(1);
+		}
+
+		ufd.fd = fd;
+		ufd.events = POLLPRI;
+
+		ret = poll(&ufd, 1, -1);
+		if (ret < 0) {
+			perror("poll error");
+			exit(1);
+		} else if (ret == 0) {
+			printf("Poll Timeout\n");
+		} else {
+			if ((lseek(fd, 0L, SEEK_SET)) < 0) {
+				fprintf(stderr, "Failed to set pointer to beginning\n");
+				exit(1);
+			}
+
+			if (read(fd, status_str, sizeof(status_str)) < 0)
+				exit(0);
+
+			printf("power floor status: %s\n", status_str);
+		}
+
+		close(fd);
+	}
+}
-- 
2.41.0