Add support for power consumption sensors through opal-sensors sysfs

The OPAL firmware on PowerNV (non-virtualized POWER) may export
certain sensors in the system through sysfs entries.

While arguably we *should* go and support the more standard locations
in sysfs to put power information (which existing powertop code would
pick up without modification), existing systems do have this interface
and the extra code needed to get information from it is minimal.

With this patch, on a powernv system that has a power consumption
sensor (e.g. an IBM S822L), powertop will display current power
usage.

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

4 files changed, 107 insertions, 0 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 87d8469..8357bae 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -67,6 +67,8 @@ powertop_SOURCES = \
 	measurement/measurement.h \
 	measurement/sysfs.cpp \
 	measurement/sysfs.h \
+	measurement/opal-sensors.cpp \
+	measurement/opal-sensors.h \
 	parameters/learn.cpp \
 	parameters/parameters.cpp \
 	parameters/parameters.h \
diff --git a/src/measurement/measurement.cpp b/src/measurement/measurement.cpp
index efbdc1e..68c41fe 100644
--- a/src/measurement/measurement.cpp
+++ b/src/measurement/measurement.cpp
@@ -26,6 +26,7 @@
 #include "acpi.h"
 #include "extech.h"
 #include "sysfs.h"
+#include "opal-sensors.h"
 #include "../parameters/parameters.h"
 #include "../lib.h"
 
@@ -130,9 +131,22 @@ void acpi_power_meters_callback(const char *d_name)
 		power_meters.push_back(meter);
 }
 
+void sysfs_opal_sensors_callback(const char *d_name)
+{
+	class opal_sensors_power_meter *meter;
+
+	if (strncmp(d_name, "power", 5) != 0)
+		return;
+
+	meter = new(std::nothrow) class opal_sensors_power_meter(d_name);
+	if (meter)
+		power_meters.push_back(meter);
+}
+
 void detect_power_meters(void)
 {
 	process_directory("/sys/class/power_supply", sysfs_power_meters_callback);
+	process_directory("/sys/devices/platform/opal-sensor/hwmon/hwmon0", sysfs_opal_sensors_callback);
 	if (power_meters.size() == 0) {
 		process_directory("/proc/acpi/battery", acpi_power_meters_callback);
 	}
diff --git a/src/measurement/opal-sensors.cpp b/src/measurement/opal-sensors.cpp
new file mode 100644
index 0000000..4198b63
--- /dev/null
+++ b/src/measurement/opal-sensors.cpp
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2015 IBM Corp.
+ *
+ * This file is part of PowerTOP
+ *
+ * This program file is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program in a file named COPYING; if not, write to the
+ * Free Software Foundation, Inc,
+ * 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA
+ * or just google for it.
+ *
+ * Authors:
+ *	Stewart Smith <stewart@linux.vnet.ibm.com>
+ */
+#include "measurement.h"
+#include "opal-sensors.h"
+#include "../lib.h"
+#include <string.h>
+#include <stdio.h>
+#include <limits.h>
+
+opal_sensors_power_meter::opal_sensors_power_meter(const char *power_supply_name)
+{
+	strncpy(name, power_supply_name, sizeof(name));
+}
+
+double opal_sensors_power_meter::joules_consumed(void)
+{
+	char filename[PATH_MAX];
+	bool ok;
+	int value;
+	double r = 0;
+
+	snprintf(filename, sizeof(filename), "/sys/devices/platform/opal-sensor/hwmon/hwmon0/%s", name);
+	value = read_sysfs(filename, &ok);
+
+	if(ok)
+		r = value / 1000000.0;
+	return r;
+}
diff --git a/src/measurement/opal-sensors.h b/src/measurement/opal-sensors.h
new file mode 100644
index 0000000..d8aa5e2
--- /dev/null
+++ b/src/measurement/opal-sensors.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2015 IBM Corp.
+ *
+ * This file is part of PowerTOP
+ *
+ * This program file is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program in a file named COPYING; if not, write to the
+ * Free Software Foundation, Inc,
+ * 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA
+ * or just google for it.
+ *
+ * Authors:
+ *	Stewart Smith <stewart@linux.vnet.ibm.com>
+ */
+#ifndef INCLUDE_GUARD_OPAL_SENSORS_H
+#define INCLUDE_GUARD_OPAL_SENSORS_H
+
+#include "measurement.h"
+
+class opal_sensors_power_meter: public power_meter {
+	char name[256];
+public:
+	opal_sensors_power_meter(const char *power_supply_name);
+	virtual void start_measurement(void) {};
+	virtual void end_measurement(void) {};
+
+	virtual double joules_consumed(void);
+	virtual double dev_capacity(void) { return 0.0; }
+};
+
+#endif