[v5,2/2] hwmon: ibmpowernv: Add attributes to enable/disable sensor groups

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 v4:
- As per Mpe's suggestion store device_node instead of phandles and
  clean it after init
- s/sg_data/sgrp_data

 Documentation/hwmon/ibmpowernv |  43 ++++++-
 drivers/hwmon/ibmpowernv.c     | 256 +++++++++++++++++++++++++++++++++++------
 2 files changed, 265 insertions(+), 34 deletions(-)

On 07/14/2018 11:54 PM, Shilpasri G Bhat wrote:
> 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 v4:
> - As per Mpe's suggestion store device_node instead of phandles and
>    clean it after init
> - s/sg_data/sgrp_data
> 
>   Documentation/hwmon/ibmpowernv |  43 ++++++-
>   drivers/hwmon/ibmpowernv.c     | 256 +++++++++++++++++++++++++++++++++++------
>   2 files changed, 265 insertions(+), 34 deletions(-)
> 
> diff --git a/Documentation/hwmon/ibmpowernv b/Documentation/hwmon/ibmpowernv
> index 8826ba2..5646825 100644
> --- a/Documentation/hwmon/ibmpowernv
> +++ b/Documentation/hwmon/ibmpowernv
> @@ -33,9 +33,48 @@ fanX_input		Measured RPM value.
>   fanX_min		Threshold RPM for alert generation.
>   fanX_fault		0: No fail condition
>   			1: Failing fan
> +
>   tempX_input		Measured ambient temperature.
>   tempX_max		Threshold ambient temperature for alert generation.
> -inX_input		Measured power supply voltage
> +tempX_highest		Historical maximum temperature
> +tempX_lowest		Historical minimum temperature
> +tempX_enable		Enable/disable all temperature sensors belonging to the
> +			sub-group. In POWER9, this attribute corresponds to
> +			each OCC. Using this attribute each OCC can be asked to
> +			disable/enable all of its temperature sensors.
> +			1: Enable
> +			0: Disable
> +
> +inX_input		Measured power supply voltage (millivolt)
>   inX_fault		0: No fail condition.
>   			1: Failing power supply.
> -power1_input		System power consumption (microWatt)
> +inX_highest		Historical maximum voltage
> +inX_lowest		Historical minimum voltage
> +inX_enable		Enable/disable all voltage sensors belonging to the
> +			sub-group. In POWER9, this attribute corresponds to
> +			each OCC. Using this attribute each OCC can be asked to
> +			disable/enable all of its voltage sensors.
> +			1: Enable
> +			0: Disable
> +
> +powerX_input		Power consumption (microWatt)
> +powerX_input_highest	Historical maximum power
> +powerX_input_lowest	Historical minimum power
> +powerX_enable		Enable/disable all power sensors belonging to the
> +			sub-group. In POWER9, this attribute corresponds to
> +			each OCC. Using this attribute each OCC can be asked to
> +			disable/enable all of its power sensors.
> +			1: Enable
> +			0: Disable
> +
> +currX_input		Measured current (milliampere)
> +currX_highest		Historical maximum current
> +currX_lowest		Historical minimum current
> +currX_enable		Enable/disable all current sensors belonging to the
> +			sub-group. In POWER9, this attribute corresponds to
> +			each OCC. Using this attribute each OCC can be asked to
> +			disable/enable all of its current sensors.
> +			1: Enable
> +			0: Disable
> +
> +energyX_input		Cumulative energy (microJoule)
> diff --git a/drivers/hwmon/ibmpowernv.c b/drivers/hwmon/ibmpowernv.c
> index f829dad..a509b9b 100644
> --- a/drivers/hwmon/ibmpowernv.c
> +++ b/drivers/hwmon/ibmpowernv.c
> @@ -90,11 +90,23 @@ struct sensor_data {
>   	char label[MAX_LABEL_LEN];
>   	char name[MAX_ATTR_LEN];
>   	struct device_attribute dev_attr;
> +	struct sensor_group_data *sgrp_data;
> +};
> +
> +struct sensor_group_data {
> +	struct mutex mutex;
> +	struct device_node **of_nodes;
> +	u32 gid;
> +	u32 nr_nodes;
> +	enum sensors type;
> +	bool enable;
>   };
>   
>   struct platform_data {
>   	const struct attribute_group *attr_groups[MAX_SENSOR_TYPE + 1];
> +	struct sensor_group_data *sgrp_data;
>   	u32 sensors_count; /* Total count of sensors from each group */
> +	u32 nr_sensor_groups; /* Total number of sensor groups */
>   };
>   
>   static ssize_t show_sensor(struct device *dev, struct device_attribute *devattr,
> @@ -105,6 +117,9 @@ static ssize_t show_sensor(struct device *dev, struct device_attribute *devattr,
>   	ssize_t ret;
>   	u64 x;
>   
> +	if (sdata->sgrp_data && !sdata->sgrp_data->enable)
> +		return -ENODATA;
> +
>   	ret =  opal_get_sensor_data_u64(sdata->id, &x);
>   
>   	if (ret)
> @@ -120,6 +135,46 @@ 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->sgrp_data->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 *sgrp_data = sdata->sgrp_data;
> +	bool data;
> +	int ret;
> +
> +	ret = kstrtobool(buf, &data);
> +	if (ret)
> +		return ret;
> +
> +	ret = mutex_lock_interruptible(&sgrp_data->mutex);
> +	if (ret)
> +		return ret;
> +
> +	if (data != sgrp_data->enable) {
> +		ret =  sensor_group_enable(sgrp_data->gid, data);
> +		if (!ret)
> +			sgrp_data->enable = data;
> +	}
> +
> +	if (!ret)
> +		ret = count;
> +
> +	mutex_unlock(&sgrp_data->mutex);
> +	return ret;
> +}
> +
>   static ssize_t show_label(struct device *dev, struct device_attribute *devattr,
>   			  char *buf)
>   {
> @@ -292,12 +347,129 @@ 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 platform_data *pdata)
> +{
> +	struct sensor_group_data *sgrp_data;
> +	struct device_node *groups, *sgrp;
> +	enum sensors type;
> +	int count = 0, ret = 0;
> +
> +	groups = of_find_node_by_path("/ibm,opal/sensor-groups");
> +	if (!groups)
> +		return ret;
> +
> +	for_each_child_of_node(groups, sgrp) {
> +		type = get_sensor_type(sgrp);
> +		if (type != MAX_SENSOR_TYPE)
> +			pdata->nr_sensor_groups++;
> +	}
> +
> +	if (!pdata->nr_sensor_groups)
> +		goto out;
> +
> +	sgrp_data = devm_kcalloc(&pdev->dev, pdata->nr_sensor_groups,
> +				 sizeof(*sgrp_data), GFP_KERNEL);
> +	if (!sgrp_data) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +
> +	for_each_child_of_node(groups, sgrp) {
> +		const __be32 *phandles;
> +		int len, gid, i, k = 0;
> +
> +		type = get_sensor_type(sgrp);
> +		if (type == MAX_SENSOR_TYPE)
> +			continue;
> +
> +		if (of_property_read_u32(sgrp, "sensor-group-id", &gid))
> +			continue;
> +
> +		phandles = of_get_property(sgrp, "sensors", &len);
> +		if (!phandles)
> +			continue;
> +
> +		len /= sizeof(u32);
> +		if (!len)
> +			continue;
> +
> +		sgrp_data[count].of_nodes = devm_kcalloc(&pdev->dev,
> +						sizeof(struct device_node *),
> +						len, GFP_KERNEL);
> +		if (!sgrp_data[count].of_nodes) {
> +			ret = -ENOMEM;
> +			of_node_put(sgrp);
> +			goto out;
> +		}
> +
> +		for (i = 0; i < len; i++) {
> +			struct device_node *node;
> +
> +			node = of_parse_phandle(sgrp, "sensors", i);
> +			if (!node)
> +				continue;
> +			sgrp_data[count].of_nodes[k++] = node;

I don't immediately see where "node" is used later. As mentioned below,
I'll need to have a much closer look into the code to understand what
is going on here.

> +		}
> +
> +		sensor_groups[type].attr_count++;
> +		sgrp_data[count].gid = gid;
> +		sgrp_data[count].type = type;
> +		sgrp_data[count].nr_nodes = len;
> +		mutex_init(&sgrp_data[count].mutex);
> +		sgrp_data[count++].enable = false;
> +	}
> +	pdata->sgrp_data = sgrp_data;
> +out:
> +	of_node_put(groups);
> +	return ret;
> +}
> +
> +static struct sensor_group_data *get_sensor_group(struct platform_data *pdata,
> +						  struct device_node *node,
> +						  enum sensors type)
> +{
> +	struct sensor_group_data *sgrp_data = pdata->sgrp_data;
> +	int i, j;
> +
> +	for (i = 0; i < pdata->nr_sensor_groups; i++) {
> +		if (type != sgrp_data[i].type)
> +			continue;
> +
> +		for (j = 0; j < sgrp_data[i].nr_nodes; j++)
> +			if (sgrp_data[i].of_nodes[j] == node)
> +				return &sgrp_data[i];
> +	}
> +
> +	return NULL;
> +}
> +
> +static void clean_sensor_group_of_node(struct platform_device *pdev)
> +{
> +	struct platform_data *pdata = platform_get_drvdata(pdev);
> +	struct sensor_group_data *sgrp_data = pdata->sgrp_data;
> +	int i, j;
> +
> +	for (i = 0; i < pdata->nr_sensor_groups; i++) {
> +		for (j = 0; j < sgrp_data[i].nr_nodes; j++)
> +			of_node_put(sgrp_data[i].of_nodes[j]);
> +
> +		devm_kfree(&pdev->dev, sgrp_data[i].of_nodes);

The whole point of calling devm_kzalloc() is that calling devm_kfree()
is not necessary. Any call to devm_kfree() is a strong indication
that something is wrong.

> +		sgrp_data[i].of_nodes = NULL;
> +	}
> +}
> +

Ok, this will require a detailed review. I don't understand what this
function is about. It seems that sgrp_data[].of_nodes is only allocated
to be  freed at the end of create_dev_attrs(), suggesting that the cleared
data isn't needed for runtime and thus should not be stored in an
array in the first place. I'll have to understand this much better
than I do right now before approving it.

Guenter

>   static int populate_attr_groups(struct platform_device *pdev)
>   {
>   	struct platform_data *pdata = platform_get_drvdata(pdev);
>   	const struct attribute_group **pgroups = pdata->attr_groups;
>   	struct device_node *opal, *np;
>   	enum sensors type;
> +	int ret;
> +
> +	ret = init_sensor_group_data(pdev, pdata);
> +	if (ret)
> +		return ret;
>   
>   	opal = of_find_node_by_path("/ibm,opal/sensors");
>   	for_each_child_of_node(opal, np) {
> @@ -344,7 +516,10 @@ 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 +527,33 @@ 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 *sgrp_data,
>   			    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->sgrp_data = sgrp_data;
>   }
>   
>   static char *get_max_attr(enum sensors type)
> @@ -403,24 +588,23 @@ static int create_device_attrs(struct platform_device *pdev)
>   	const struct attribute_group **pgroups = pdata->attr_groups;
>   	struct device_node *opal, *np;
>   	struct sensor_data *sdata;
> -	u32 sensor_id;
> -	enum sensors type;
>   	u32 count = 0;
> -	int err = 0;
> +	u32 group_attr_id[MAX_SENSOR_TYPE] = {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 *sgrp_data;
>   		const char *attr_name;
> -		u32 opal_index;
> +		u32 opal_index, hw_id;
> +		u32 sensor_id;
>   		const char *label;
> +		enum sensors type;
>   
>   		if (np->name == NULL)
>   			continue;
> @@ -456,14 +640,12 @@ 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);
> -
> -		create_hwmon_attr(&sdata[count], attr_name, show_sensor);
> -
> -		pgroups[type]->attrs[sensor_groups[type].attr_count++] =
> -				&sdata[count++].dev_attr.attr;
> +		hw_id = get_sensor_hwmon_index(&sdata[count], sdata, count);
> +		sgrp_data = get_sensor_group(pdata, np, type);
> +		populate_sensor(&sdata[count], opal_index, hw_id, sensor_id,
> +				attr_name, type, pgroups[type], sgrp_data,
> +				show_sensor, NULL);
> +		count++;
>   
>   		if (!of_property_read_string(np, "label", &label)) {
>   			/*
> @@ -474,35 +656,44 @@ 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);
> +					NULL, show_label, 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,
> -					sdata[count - 1].hwmon_index,
> +			populate_sensor(&sdata[count], opal_index, hw_id,
>   					sensor_id, attr_name, type,
> -					pgroups[type], show_sensor);
> +					pgroups[type], sgrp_data, 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,
> -					sdata[count - 1].hwmon_index,
> +			populate_sensor(&sdata[count], opal_index, hw_id,
>   					sensor_id, attr_name, type,
> -					pgroups[type], show_sensor);
> +					pgroups[type], sgrp_data, show_sensor,
> +					NULL);
> +			count++;
> +		}
> +
> +		if (sgrp_data && !sgrp_data->enable) {
> +			sgrp_data->enable = true;
> +			hw_id = ++group_attr_id[type];
> +			populate_sensor(&sdata[count], opal_index, hw_id,
> +					sgrp_data->gid, "enable", type,
> +					pgroups[type], sgrp_data, show_enable,
> +					store_enable);
>   			count++;
>   		}
>   	}
>   
> -exit_put_node:
>   	of_node_put(opal);
> -	return err;
> +	clean_sensor_group_of_node(pdev);
> +	return 0;
>   }
>   
>   static int ibmpowernv_probe(struct platform_device *pdev)
> @@ -517,6 +708,7 @@ static int ibmpowernv_probe(struct platform_device *pdev)
>   
>   	platform_set_drvdata(pdev, pdata);
>   	pdata->sensors_count = 0;
> +	pdata->nr_sensor_groups = 0;
>   	err = populate_attr_groups(pdev);
>   	if (err)
>   		return err;
>

Hi,

On 07/17/2018 07:17 PM, Guenter Roeck wrote:
> On 07/14/2018 11:54 PM, Shilpasri G Bhat wrote:
>> 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 v4:
>> - As per Mpe's suggestion store device_node instead of phandles and
>>    clean it after init
>> - s/sg_data/sgrp_data
>>
>>   Documentation/hwmon/ibmpowernv |  43 ++++++-
>>   drivers/hwmon/ibmpowernv.c     | 256 +++++++++++++++++++++++++++++++++++------
>>   2 files changed, 265 insertions(+), 34 deletions(-)
>>
>> diff --git a/Documentation/hwmon/ibmpowernv b/Documentation/hwmon/ibmpowernv
>> index 8826ba2..5646825 100644
>> --- a/Documentation/hwmon/ibmpowernv
>> +++ b/Documentation/hwmon/ibmpowernv
>> @@ -33,9 +33,48 @@ fanX_input        Measured RPM value.
>>   fanX_min        Threshold RPM for alert generation.
>>   fanX_fault        0: No fail condition
>>               1: Failing fan
>> +
>>   tempX_input        Measured ambient temperature.
>>   tempX_max        Threshold ambient temperature for alert generation.
>> -inX_input        Measured power supply voltage
>> +tempX_highest        Historical maximum temperature
>> +tempX_lowest        Historical minimum temperature
>> +tempX_enable        Enable/disable all temperature sensors belonging to the
>> +            sub-group. In POWER9, this attribute corresponds to
>> +            each OCC. Using this attribute each OCC can be asked to
>> +            disable/enable all of its temperature sensors.
>> +            1: Enable
>> +            0: Disable
>> +
>> +inX_input        Measured power supply voltage (millivolt)
>>   inX_fault        0: No fail condition.
>>               1: Failing power supply.
>> -power1_input        System power consumption (microWatt)
>> +inX_highest        Historical maximum voltage
>> +inX_lowest        Historical minimum voltage
>> +inX_enable        Enable/disable all voltage sensors belonging to the
>> +            sub-group. In POWER9, this attribute corresponds to
>> +            each OCC. Using this attribute each OCC can be asked to
>> +            disable/enable all of its voltage sensors.
>> +            1: Enable
>> +            0: Disable
>> +
>> +powerX_input        Power consumption (microWatt)
>> +powerX_input_highest    Historical maximum power
>> +powerX_input_lowest    Historical minimum power
>> +powerX_enable        Enable/disable all power sensors belonging to the
>> +            sub-group. In POWER9, this attribute corresponds to
>> +            each OCC. Using this attribute each OCC can be asked to
>> +            disable/enable all of its power sensors.
>> +            1: Enable
>> +            0: Disable
>> +
>> +currX_input        Measured current (milliampere)
>> +currX_highest        Historical maximum current
>> +currX_lowest        Historical minimum current
>> +currX_enable        Enable/disable all current sensors belonging to the
>> +            sub-group. In POWER9, this attribute corresponds to
>> +            each OCC. Using this attribute each OCC can be asked to
>> +            disable/enable all of its current sensors.
>> +            1: Enable
>> +            0: Disable
>> +
>> +energyX_input        Cumulative energy (microJoule)
>> diff --git a/drivers/hwmon/ibmpowernv.c b/drivers/hwmon/ibmpowernv.c
>> index f829dad..a509b9b 100644
>> --- a/drivers/hwmon/ibmpowernv.c
>> +++ b/drivers/hwmon/ibmpowernv.c
>> @@ -90,11 +90,23 @@ struct sensor_data {
>>       char label[MAX_LABEL_LEN];
>>       char name[MAX_ATTR_LEN];
>>       struct device_attribute dev_attr;
>> +    struct sensor_group_data *sgrp_data;
>> +};
>> +
>> +struct sensor_group_data {
>> +    struct mutex mutex;
>> +    struct device_node **of_nodes;
>> +    u32 gid;
>> +    u32 nr_nodes;
>> +    enum sensors type;
>> +    bool enable;
>>   };
>>     struct platform_data {
>>       const struct attribute_group *attr_groups[MAX_SENSOR_TYPE + 1];
>> +    struct sensor_group_data *sgrp_data;
>>       u32 sensors_count; /* Total count of sensors from each group */
>> +    u32 nr_sensor_groups; /* Total number of sensor groups */
>>   };
>>     static ssize_t show_sensor(struct device *dev, struct device_attribute
>> *devattr,
>> @@ -105,6 +117,9 @@ static ssize_t show_sensor(struct device *dev, struct
>> device_attribute *devattr,
>>       ssize_t ret;
>>       u64 x;
>>   +    if (sdata->sgrp_data && !sdata->sgrp_data->enable)
>> +        return -ENODATA;
>> +
>>       ret =  opal_get_sensor_data_u64(sdata->id, &x);
>>         if (ret)
>> @@ -120,6 +135,46 @@ 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->sgrp_data->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 *sgrp_data = sdata->sgrp_data;
>> +    bool data;
>> +    int ret;
>> +
>> +    ret = kstrtobool(buf, &data);
>> +    if (ret)
>> +        return ret;
>> +
>> +    ret = mutex_lock_interruptible(&sgrp_data->mutex);
>> +    if (ret)
>> +        return ret;
>> +
>> +    if (data != sgrp_data->enable) {
>> +        ret =  sensor_group_enable(sgrp_data->gid, data);
>> +        if (!ret)
>> +            sgrp_data->enable = data;
>> +    }
>> +
>> +    if (!ret)
>> +        ret = count;
>> +
>> +    mutex_unlock(&sgrp_data->mutex);
>> +    return ret;
>> +}
>> +
>>   static ssize_t show_label(struct device *dev, struct device_attribute *devattr,
>>                 char *buf)
>>   {
>> @@ -292,12 +347,129 @@ 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 platform_data *pdata)
>> +{
>> +    struct sensor_group_data *sgrp_data;
>> +    struct device_node *groups, *sgrp;
>> +    enum sensors type;
>> +    int count = 0, ret = 0;
>> +
>> +    groups = of_find_node_by_path("/ibm,opal/sensor-groups");
>> +    if (!groups)
>> +        return ret;
>> +
>> +    for_each_child_of_node(groups, sgrp) {
>> +        type = get_sensor_type(sgrp);
>> +        if (type != MAX_SENSOR_TYPE)
>> +            pdata->nr_sensor_groups++;
>> +    }
>> +
>> +    if (!pdata->nr_sensor_groups)
>> +        goto out;
>> +
>> +    sgrp_data = devm_kcalloc(&pdev->dev, pdata->nr_sensor_groups,
>> +                 sizeof(*sgrp_data), GFP_KERNEL);
>> +    if (!sgrp_data) {
>> +        ret = -ENOMEM;
>> +        goto out;
>> +    }
>> +
>> +    for_each_child_of_node(groups, sgrp) {
>> +        const __be32 *phandles;
>> +        int len, gid, i, k = 0;
>> +
>> +        type = get_sensor_type(sgrp);
>> +        if (type == MAX_SENSOR_TYPE)
>> +            continue;
>> +
>> +        if (of_property_read_u32(sgrp, "sensor-group-id", &gid))
>> +            continue;
>> +
>> +        phandles = of_get_property(sgrp, "sensors", &len);
>> +        if (!phandles)
>> +            continue;
>> +
>> +        len /= sizeof(u32);
>> +        if (!len)
>> +            continue;
>> +
>> +        sgrp_data[count].of_nodes = devm_kcalloc(&pdev->dev,
>> +                        sizeof(struct device_node *),
>> +                        len, GFP_KERNEL);
>> +        if (!sgrp_data[count].of_nodes) {
>> +            ret = -ENOMEM;
>> +            of_node_put(sgrp);
>> +            goto out;
>> +        }
>> +
>> +        for (i = 0; i < len; i++) {
>> +            struct device_node *node;
>> +
>> +            node = of_parse_phandle(sgrp, "sensors", i);
>> +            if (!node)
>> +                continue;
>> +            sgrp_data[count].of_nodes[k++] = node;
> 
> I don't immediately see where "node" is used later. As mentioned below,
> I'll need to have a much closer look into the code to understand what
> is going on here.

sgrp_data[count].of_nodes is used to store the pointers to sensor nodes
belonging to sensor-group 'sgrp_data[count]' . This is being used later in
to find the sensor-group of each sensor in create_device_attrs()

> 
>> +        }
>> +
>> +        sensor_groups[type].attr_count++;
>> +        sgrp_data[count].gid = gid;
>> +        sgrp_data[count].type = type;
>> +        sgrp_data[count].nr_nodes = len;
>> +        mutex_init(&sgrp_data[count].mutex);
>> +        sgrp_data[count++].enable = false;
>> +    }
>> +    pdata->sgrp_data = sgrp_data;
>> +out:
>> +    of_node_put(groups);
>> +    return ret;
>> +}
>> +
>> +static struct sensor_group_data *get_sensor_group(struct platform_data *pdata,
>> +                          struct device_node *node,
>> +                          enum sensors type)
>> +{
>> +    struct sensor_group_data *sgrp_data = pdata->sgrp_data;
>> +    int i, j;
>> +
>> +    for (i = 0; i < pdata->nr_sensor_groups; i++) {
>> +        if (type != sgrp_data[i].type)
>> +            continue;
>> +
>> +        for (j = 0; j < sgrp_data[i].nr_nodes; j++)
>> +            if (sgrp_data[i].of_nodes[j] == node)
>> +                return &sgrp_data[i];
>> +    }
>> +
>> +    return NULL;
>> +}
>> +
>> +static void clean_sensor_group_of_node(struct platform_device *pdev)
>> +{
>> +    struct platform_data *pdata = platform_get_drvdata(pdev);
>> +    struct sensor_group_data *sgrp_data = pdata->sgrp_data;
>> +    int i, j;
>> +
>> +    for (i = 0; i < pdata->nr_sensor_groups; i++) {
>> +        for (j = 0; j < sgrp_data[i].nr_nodes; j++)
>> +            of_node_put(sgrp_data[i].of_nodes[j]);
>> +
>> +        devm_kfree(&pdev->dev, sgrp_data[i].of_nodes);
> 
> The whole point of calling devm_kzalloc() is that calling devm_kfree()
> is not necessary. Any call to devm_kfree() is a strong indication
> that something is wrong.
> 
>> +        sgrp_data[i].of_nodes = NULL;
>> +    }
>> +}
>> +
> 
> Ok, this will require a detailed review. I don't understand what this
> function is about. It seems that sgrp_data[].of_nodes is only allocated
> to be  freed at the end of create_dev_attrs(), suggesting that the cleared
> data isn't needed for runtime and thus should not be stored in an
> array in the first place. I'll have to understand this much better
> than I do right now before approving it.
> 

Yeah sgrp_data[].of_nodes is not required at runtime. This can be defined locally.


Thanks and Regards,
Shilpa

> Guenter
> 
>>   static int populate_attr_groups(struct platform_device *pdev)
>>   {
>>       struct platform_data *pdata = platform_get_drvdata(pdev);
>>       const struct attribute_group **pgroups = pdata->attr_groups;
>>       struct device_node *opal, *np;
>>       enum sensors type;
>> +    int ret;
>> +
>> +    ret = init_sensor_group_data(pdev, pdata);
>> +    if (ret)
>> +        return ret;
>>         opal = of_find_node_by_path("/ibm,opal/sensors");
>>       for_each_child_of_node(opal, np) {
>> @@ -344,7 +516,10 @@ 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 +527,33 @@ 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 *sgrp_data,
>>                   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->sgrp_data = sgrp_data;
>>   }
>>     static char *get_max_attr(enum sensors type)
>> @@ -403,24 +588,23 @@ static int create_device_attrs(struct platform_device
>> *pdev)
>>       const struct attribute_group **pgroups = pdata->attr_groups;
>>       struct device_node *opal, *np;
>>       struct sensor_data *sdata;
>> -    u32 sensor_id;
>> -    enum sensors type;
>>       u32 count = 0;
>> -    int err = 0;
>> +    u32 group_attr_id[MAX_SENSOR_TYPE] = {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 *sgrp_data;
>>           const char *attr_name;
>> -        u32 opal_index;
>> +        u32 opal_index, hw_id;
>> +        u32 sensor_id;
>>           const char *label;
>> +        enum sensors type;
>>             if (np->name == NULL)
>>               continue;
>> @@ -456,14 +640,12 @@ 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);
>> -
>> -        create_hwmon_attr(&sdata[count], attr_name, show_sensor);
>> -
>> -        pgroups[type]->attrs[sensor_groups[type].attr_count++] =
>> -                &sdata[count++].dev_attr.attr;
>> +        hw_id = get_sensor_hwmon_index(&sdata[count], sdata, count);
>> +        sgrp_data = get_sensor_group(pdata, np, type);
>> +        populate_sensor(&sdata[count], opal_index, hw_id, sensor_id,
>> +                attr_name, type, pgroups[type], sgrp_data,
>> +                show_sensor, NULL);
>> +        count++;
>>             if (!of_property_read_string(np, "label", &label)) {
>>               /*
>> @@ -474,35 +656,44 @@ 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);
>> +                    NULL, show_label, 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,
>> -                    sdata[count - 1].hwmon_index,
>> +            populate_sensor(&sdata[count], opal_index, hw_id,
>>                       sensor_id, attr_name, type,
>> -                    pgroups[type], show_sensor);
>> +                    pgroups[type], sgrp_data, 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,
>> -                    sdata[count - 1].hwmon_index,
>> +            populate_sensor(&sdata[count], opal_index, hw_id,
>>                       sensor_id, attr_name, type,
>> -                    pgroups[type], show_sensor);
>> +                    pgroups[type], sgrp_data, show_sensor,
>> +                    NULL);
>> +            count++;
>> +        }
>> +
>> +        if (sgrp_data && !sgrp_data->enable) {
>> +            sgrp_data->enable = true;
>> +            hw_id = ++group_attr_id[type];
>> +            populate_sensor(&sdata[count], opal_index, hw_id,
>> +                    sgrp_data->gid, "enable", type,
>> +                    pgroups[type], sgrp_data, show_enable,
>> +                    store_enable);
>>               count++;
>>           }
>>       }
>>   -exit_put_node:
>>       of_node_put(opal);
>> -    return err;
>> +    clean_sensor_group_of_node(pdev);
>> +    return 0;
>>   }
>>     static int ibmpowernv_probe(struct platform_device *pdev)
>> @@ -517,6 +708,7 @@ static int ibmpowernv_probe(struct platform_device *pdev)
>>         platform_set_drvdata(pdev, pdata);
>>       pdata->sensors_count = 0;
>> +    pdata->nr_sensor_groups = 0;
>>       err = populate_attr_groups(pdev);
>>       if (err)
>>           return err;
>>
>