[PATCH v2 2/2] hwmon: ibmpowernv: Add attributes to enable/disable sensor groups

[Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>]

On-Chip-Controller(OCC) is an embedded micro-processor in POWER9 chip
which measures various system and chip level sensors. These sensors
comprises of environmental sensors (like power, temperature, current
and voltage) and performance sensors (like utilization, frequency).
All these sensors are copied to main memory at a regular interval of
100ms. OCC provides a way to select a group of sensors that is copied
to the main memory to increase the update frequency of selected sensor
groups. When a sensor-group is disabled, OCC will not copy it to main
memory and those sensors read 0 values.

This patch provides support for enabling/disabling the sensor groups
like power, temperature, current and voltage. This patch adds new
per-senor sysfs attribute to disable and enable them.

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
---
Changes from v1:
- Add per-sensor 'enable' attribute
- Return -ENODATA when sensor is disabled

 Documentation/hwmon/sysfs-interface |  22 +++
 drivers/hwmon/ibmpowernv.c          | 281 +++++++++++++++++++++++++++++++-----
 2 files changed, 264 insertions(+), 39 deletions(-)

diff --git a/Documentation/hwmon/sysfs-interface b/Documentation/hwmon/sysfs-interface
index fc337c3..38ab05c 100644
--- a/Documentation/hwmon/sysfs-interface
+++ b/Documentation/hwmon/sysfs-interface
@@ -184,6 +184,11 @@ vrm		Voltage Regulator Module version number.
 		Affects the way the driver calculates the CPU core reference
 		voltage from the vid pins.
 
+in[0-*]_enable	Enable or disable the sensor
+		1 : Enable
+		0 : Disable
+		RW
+
 Also see the Alarms section for status flags associated with voltages.
 
 
@@ -409,6 +414,12 @@ temp_reset_history
 		Reset temp_lowest and temp_highest for all sensors
 		WO
 
+temp[1-*]_enable
+		Enable or disable the sensor
+		1 : Enable
+		0 : Disable
+		RW
+
 Some chips measure temperature using external thermistors and an ADC, and
 report the temperature measurement as a voltage. Converting this voltage
 back to a temperature (or the other way around for limits) requires
@@ -468,6 +479,12 @@ curr_reset_history
 		Reset currX_lowest and currX_highest for all sensors
 		WO
 
+curr[1-*]_enable
+		Enable or disable the sensor
+		1 : Enable
+		0 : Disable
+		RW
+
 Also see the Alarms section for status flags associated with currents.
 
 *********
@@ -566,6 +583,11 @@ power[1-*]_crit			Critical maximum power.
 				Unit: microWatt
 				RW
 
+power[1-*]_enable		Enable or disable the sensor
+				1 : Enable
+				0 : Disable
+				RW
+
 Also see the Alarms section for status flags associated with power readings.
 
 **********
diff --git a/drivers/hwmon/ibmpowernv.c b/drivers/hwmon/ibmpowernv.c
index f829dad..61e04cf 100644
--- a/drivers/hwmon/ibmpowernv.c
+++ b/drivers/hwmon/ibmpowernv.c
@@ -90,8 +90,28 @@ struct sensor_data {
 	char label[MAX_LABEL_LEN];
 	char name[MAX_ATTR_LEN];
 	struct device_attribute dev_attr;
+	struct sensor_group_data *sgdata;
+	struct sensor_data *sdata[3];
+	bool enable;
 };
 
+static struct sensor_group_data {
+	u32 gid;
+	u32 nr_phandle;
+	u32 nr_sensor;
+	enum sensors type;
+	const __be32 *phandles;
+	struct sensor_data **sensors;
+	bool enable;
+} *sg_data;
+
+/*
+ * To synchronise writes to struct sensor_data.enable and
+ * struct sensor_group_data.enable
+ */
+DEFINE_MUTEX(sensor_groups_mutex);
+static int nr_sensor_groups;
+
 struct platform_data {
 	const struct attribute_group *attr_groups[MAX_SENSOR_TYPE + 1];
 	u32 sensors_count; /* Total count of sensors from each group */
@@ -105,6 +125,9 @@ static ssize_t show_sensor(struct device *dev, struct device_attribute *devattr,
 	ssize_t ret;
 	u64 x;
 
+	if (sdata->sgdata && !sdata->enable)
+		return -ENODATA;
+
 	ret =  opal_get_sensor_data_u64(sdata->id, &x);
 
 	if (ret)
@@ -120,6 +143,74 @@ static ssize_t show_sensor(struct device *dev, struct device_attribute *devattr,
 	return sprintf(buf, "%llu\n", x);
 }
 
+static ssize_t show_enable(struct device *dev,
+			   struct device_attribute *devattr, char *buf)
+{
+	struct sensor_data *sdata = container_of(devattr, struct sensor_data,
+						 dev_attr);
+
+	return sprintf(buf, "%u\n", sdata->enable);
+}
+
+static ssize_t store_enable(struct device *dev,
+			    struct device_attribute *devattr,
+			    const char *buf, size_t count)
+{
+	struct sensor_data *sdata = container_of(devattr, struct sensor_data,
+						 dev_attr);
+	struct sensor_group_data *sg = sdata->sgdata;
+	u32 data;
+	int ret, i;
+	bool send_command;
+
+	ret = kstrtoint(buf, 0, &data);
+	if (ret)
+		return ret;
+
+	if (data != 0 && data != 1)
+		return -EIO;
+
+	ret = mutex_lock_interruptible(&sensor_groups_mutex);
+	if (ret)
+		return ret;
+
+	sdata->enable = data;
+	if ((data && sg->enable) || (!data && !sg->enable)) {
+		send_command = false;
+	} else if (data && !sg->enable) {
+		/* Enable if first sensor in the group */
+		send_command = true;
+	} else if (!data && sg->enable) {
+		/* Disable if last sensor in the group */
+		send_command = true;
+		for (i = 0; i < sg->nr_sensor; i++) {
+			struct sensor_data *sd = sg->sensors[i];
+
+			if (sd->enable) {
+				send_command = false;
+				break;
+			}
+		}
+	}
+
+	if (send_command) {
+		ret =  sensor_group_enable(sg->gid, data);
+		if (!ret)
+			sg->enable = data;
+	}
+
+	if (!ret) {
+		for (i = 0; i < ARRAY_SIZE(sdata->sdata); i++)
+			sdata->sdata[i]->enable = data;
+		ret = count;
+	} else {
+		ret = -EIO;
+	}
+
+	mutex_unlock(&sensor_groups_mutex);
+	return ret;
+}
+
 static ssize_t show_label(struct device *dev, struct device_attribute *devattr,
 			  char *buf)
 {
@@ -292,6 +383,90 @@ static u32 get_sensor_hwmon_index(struct sensor_data *sdata,
 	return ++sensor_groups[sdata->type].hwmon_index;
 }
 
+static int init_sensor_group_data(struct platform_device *pdev)
+{
+	struct device_node *sensor_groups, *sg;
+	enum sensors type;
+	int count = 0, ret = 0;
+
+	sensor_groups = of_find_node_by_path("/ibm,opal/sensor-groups");
+	if (!sensor_groups)
+		return ret;
+
+	for_each_child_of_node(sensor_groups, sg) {
+		type = get_sensor_type(sg);
+		if (type != MAX_SENSOR_TYPE)
+			nr_sensor_groups++;
+	}
+
+	if (!nr_sensor_groups)
+		goto out;
+
+	sg_data = devm_kzalloc(&pdev->dev, nr_sensor_groups * sizeof(*sg_data),
+			       GFP_KERNEL);
+	if (!sg_data) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	for_each_child_of_node(sensor_groups, sg) {
+		const __be32 *phandles;
+		int len, gid;
+
+		type = get_sensor_type(sg);
+		if (type == MAX_SENSOR_TYPE)
+			continue;
+
+		if (of_property_read_u32(sg, "sensor-group-id", &gid))
+			continue;
+
+		phandles = of_get_property(sg, "sensors", &len);
+		if (!phandles)
+			continue;
+
+		len /= sizeof(u32);
+		if (!len)
+			continue;
+
+		sg_data[count].sensors = devm_kzalloc(&pdev->dev,
+					    len * sizeof(struct sensor_data *),
+					    GFP_KERNEL);
+		if (!sg_data[count].sensors) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		sg_data[count].nr_sensor = 0;
+		sg_data[count].gid = gid;
+		sg_data[count].type = type;
+		sg_data[count].nr_phandle = len;
+		sg_data[count].phandles = phandles;
+		sg_data[count++].enable = true;
+	}
+out:
+	of_node_put(sensor_groups);
+	return ret;
+}
+
+static struct sensor_group_data *get_sensor_group(struct device_node *np,
+						  enum sensors type)
+{
+	int i, j;
+
+	for (i = 0; i < nr_sensor_groups; i++) {
+		const __be32 *phandles = sg_data[i].phandles;
+
+		if (type != sg_data[i].type)
+			continue;
+
+		for (j = 0; j < sg_data[i].nr_phandle; j++)
+			if (be32_to_cpu(phandles[j]) == np->phandle)
+				return &sg_data[i];
+	}
+
+	return NULL;
+}
+
 static int populate_attr_groups(struct platform_device *pdev)
 {
 	struct platform_data *pdata = platform_get_drvdata(pdev);
@@ -299,6 +474,9 @@ static int populate_attr_groups(struct platform_device *pdev)
 	struct device_node *opal, *np;
 	enum sensors type;
 
+	if (init_sensor_group_data(pdev))
+		return -ENOMEM;
+
 	opal = of_find_node_by_path("/ibm,opal/sensors");
 	for_each_child_of_node(opal, np) {
 		const char *label;
@@ -313,7 +491,7 @@ static int populate_attr_groups(struct platform_device *pdev)
 		sensor_groups[type].attr_count++;
 
 		/*
-		 * add attributes for labels, min and max
+		 * add attributes for labels, min, max and enable
 		 */
 		if (!of_property_read_string(np, "label", &label))
 			sensor_groups[type].attr_count++;
@@ -321,6 +499,8 @@ static int populate_attr_groups(struct platform_device *pdev)
 			sensor_groups[type].attr_count++;
 		if (of_find_property(np, "sensor-data-max", NULL))
 			sensor_groups[type].attr_count++;
+		if (get_sensor_group(np, type))
+			sensor_groups[type].attr_count++;
 	}
 
 	of_node_put(opal);
@@ -344,7 +524,10 @@ static int populate_attr_groups(struct platform_device *pdev)
 static void create_hwmon_attr(struct sensor_data *sdata, const char *attr_name,
 			      ssize_t (*show)(struct device *dev,
 					      struct device_attribute *attr,
-					      char *buf))
+					      char *buf),
+			    ssize_t (*store)(struct device *dev,
+					     struct device_attribute *attr,
+					     const char *buf, size_t count))
 {
 	snprintf(sdata->name, MAX_ATTR_LEN, "%s%d_%s",
 		 sensor_groups[sdata->type].name, sdata->hwmon_index,
@@ -352,23 +535,34 @@ static void create_hwmon_attr(struct sensor_data *sdata, const char *attr_name,
 
 	sysfs_attr_init(&sdata->dev_attr.attr);
 	sdata->dev_attr.attr.name = sdata->name;
-	sdata->dev_attr.attr.mode = S_IRUGO;
 	sdata->dev_attr.show = show;
+	if (store) {
+		sdata->dev_attr.store = store;
+		sdata->dev_attr.attr.mode = 0664;
+	} else {
+		sdata->dev_attr.attr.mode = 0444;
+	}
 }
 
 static void populate_sensor(struct sensor_data *sdata, int od, int hd, int sid,
 			    const char *attr_name, enum sensors type,
 			    const struct attribute_group *pgroup,
+			    struct sensor_group_data *sgdata,
 			    ssize_t (*show)(struct device *dev,
 					    struct device_attribute *attr,
-					    char *buf))
+					    char *buf),
+			    ssize_t (*store)(struct device *dev,
+					     struct device_attribute *attr,
+					     const char *buf, size_t count))
 {
 	sdata->id = sid;
 	sdata->type = type;
 	sdata->opal_index = od;
 	sdata->hwmon_index = hd;
-	create_hwmon_attr(sdata, attr_name, show);
+	create_hwmon_attr(sdata, attr_name, show, store);
 	pgroup->attrs[sensor_groups[type].attr_count++] = &sdata->dev_attr.attr;
+	sdata->enable = true;
+	sdata->sgdata = sgdata;
 }
 
 static char *get_max_attr(enum sensors type)
@@ -408,18 +602,17 @@ static int create_device_attrs(struct platform_device *pdev)
 	u32 count = 0;
 	int err = 0;
 
-	opal = of_find_node_by_path("/ibm,opal/sensors");
 	sdata = devm_kcalloc(&pdev->dev,
 			     pdata->sensors_count, sizeof(*sdata),
 			     GFP_KERNEL);
-	if (!sdata) {
-		err = -ENOMEM;
-		goto exit_put_node;
-	}
+	if (!sdata)
+		return -ENOMEM;
 
+	opal = of_find_node_by_path("/ibm,opal/sensors");
 	for_each_child_of_node(opal, np) {
+		struct sensor_group_data *sgdata;
 		const char *attr_name;
-		u32 opal_index;
+		u32 opal_index, hw_id;
 		const char *label;
 
 		if (np->name == NULL)
@@ -456,14 +649,43 @@ static int create_device_attrs(struct platform_device *pdev)
 			opal_index = INVALID_INDEX;
 		}
 
-		sdata[count].opal_index = opal_index;
-		sdata[count].hwmon_index =
-			get_sensor_hwmon_index(&sdata[count], sdata, count);
+		hw_id = get_sensor_hwmon_index(&sdata[count], sdata, count);
+		sgdata = get_sensor_group(np, type);
+		populate_sensor(&sdata[count], opal_index, hw_id, sensor_id,
+				attr_name, type, pgroups[type], sgdata,
+				show_sensor, NULL);
+		count++;
+
+		if (!of_property_read_u32(np, "sensor-data-max", &sensor_id)) {
+			attr_name = get_max_attr(type);
+			populate_sensor(&sdata[count], opal_index, hw_id,
+					sensor_id, attr_name, type,
+					pgroups[type], sgdata, show_sensor,
+					NULL);
+			count++;
+		}
+
+		if (!of_property_read_u32(np, "sensor-data-min", &sensor_id)) {
+			attr_name = get_min_attr(type);
+			populate_sensor(&sdata[count], opal_index, hw_id,
+					sensor_id, attr_name, type,
+					pgroups[type], sgdata, show_sensor,
+					NULL);
+			count++;
+		}
 
-		create_hwmon_attr(&sdata[count], attr_name, show_sensor);
+		if (sgdata) {
+			int i;
 
-		pgroups[type]->attrs[sensor_groups[type].attr_count++] =
-				&sdata[count++].dev_attr.attr;
+			sgdata->sensors[sgdata->nr_sensor++] = &sdata[count];
+			populate_sensor(&sdata[count], opal_index, hw_id,
+					sgdata->gid, "enable", type,
+					pgroups[type], sgdata, show_enable,
+					store_enable);
+			for (i = 0; i < ARRAY_SIZE(sdata[count].sdata); i++)
+				sdata[count].sdata[i] = &sdata[count - i - 1];
+			count++;
+		}
 
 		if (!of_property_read_string(np, "label", &label)) {
 			/*
@@ -474,34 +696,15 @@ static int create_device_attrs(struct platform_device *pdev)
 			 */
 
 			make_sensor_label(np, &sdata[count], label);
-			populate_sensor(&sdata[count], opal_index,
-					sdata[count - 1].hwmon_index,
+			populate_sensor(&sdata[count], opal_index, hw_id,
 					sensor_id, "label", type, pgroups[type],
-					show_label);
-			count++;
-		}
-
-		if (!of_property_read_u32(np, "sensor-data-max", &sensor_id)) {
-			attr_name = get_max_attr(type);
-			populate_sensor(&sdata[count], opal_index,
-					sdata[count - 1].hwmon_index,
-					sensor_id, attr_name, type,
-					pgroups[type], show_sensor);
-			count++;
-		}
-
-		if (!of_property_read_u32(np, "sensor-data-min", &sensor_id)) {
-			attr_name = get_min_attr(type);
-			populate_sensor(&sdata[count], opal_index,
-					sdata[count - 1].hwmon_index,
-					sensor_id, attr_name, type,
-					pgroups[type], show_sensor);
+					NULL, show_label, NULL);
 			count++;
 		}
 	}
 
-exit_put_node:
 	of_node_put(opal);
+
 	return err;
 }
 
-- 
1.8.3.1