Date:	Mon, 14 Oct 2013 16:21:52 +0000
From:	"R, Durgadoss" <durgadoss.r@...el.com>
To:	"Zhang, Rui" <rui.zhang@...el.com>
CC:	"eduardo.valentin@...com" <eduardo.valentin@...com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"hongbo.zhang@...escale.com" <hongbo.zhang@...escale.com>,
	"wni@...dia.com" <wni@...dia.com>
Subject: RE: [PATCHv4 2/9] Thermal: Create sensor level APIs

Hi Rui,

> -----Original Message-----
> From: linux-pm-owner@...r.kernel.org [mailto:linux-pm-
> owner@...r.kernel.org] On Behalf Of Zhang Rui
> Sent: Monday, October 14, 2013 2:56 PM
> To: R, Durgadoss
> Cc: eduardo.valentin@...com; linux-pm@...r.kernel.org; linux-
> kernel@...r.kernel.org; hongbo.zhang@...escale.com; wni@...dia.com
> Subject: Re: [PATCHv4 2/9] Thermal: Create sensor level APIs
> 
> On Wed, 2013-10-02 at 00:08 +0530, Durgadoss R wrote:
> > This patch creates sensor level APIs, in the
> > generic thermal framework.
> >
> > A Thermal sensor is a piece of hardware that can report
> > temperature of the spot in which it is placed. A thermal
> > sensor driver reads the temperature from this sensor
> > and reports it out. This kind of driver can be in
> > any subsystem. If the sensor needs to participate
> > in platform thermal management, the corresponding
> > driver can use the APIs introduced in this patch, to
> > register(or unregister) with the thermal framework.
> >
> > Signed-off-by: Durgadoss R <durgadoss.r@...el.com>
> > ---
> >  drivers/thermal/thermal_core.c |  284
> ++++++++++++++++++++++++++++++++++++++++
> >  include/linux/thermal.h        |   29 ++++
> >  2 files changed, 313 insertions(+)
> >
> > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> > index 8c5131d..8c46567 100644
> > --- a/drivers/thermal/thermal_core.c
> > +++ b/drivers/thermal/thermal_core.c
> > @@ -45,13 +45,16 @@ MODULE_LICENSE("GPL v2");
> >
> >  static DEFINE_IDR(thermal_tz_idr);
> >  static DEFINE_IDR(thermal_cdev_idr);
> > +static DEFINE_IDR(thermal_sensor_idr);
> >  static DEFINE_MUTEX(thermal_idr_lock);
> >
> >  static LIST_HEAD(thermal_tz_list);
> > +static LIST_HEAD(thermal_sensor_list);
> >  static LIST_HEAD(thermal_cdev_list);
> >  static LIST_HEAD(thermal_governor_list);
> >
> >  static DEFINE_MUTEX(thermal_list_lock);
> > +static DEFINE_MUTEX(sensor_list_lock);
> >  static DEFINE_MUTEX(thermal_governor_lock);
> >
> >  static struct thermal_governor *__find_governor(const char *name)
> > @@ -463,6 +466,103 @@ static void thermal_zone_device_check(struct
> work_struct *work)
> >  #define to_thermal_zone(_dev) \
> >  	container_of(_dev, struct thermal_zone_device, device)
> >
> > +#define to_thermal_sensor(_dev) \
> > +	container_of(_dev, struct thermal_sensor, device)
> > +
> > +static ssize_t
> > +sensor_name_show(struct device *dev, struct device_attribute *attr, char
> *buf)
> > +{
> > +	struct thermal_sensor *ts = to_thermal_sensor(dev);
> > +
> > +	return sprintf(buf, "%s\n", ts->name);
> > +}
> > +
> > +static ssize_t
> > +sensor_temp_show(struct device *dev, struct device_attribute *attr, char
> *buf)
> > +{
> > +	int ret;
> > +	long val;
> > +	struct thermal_sensor *ts = to_thermal_sensor(dev);
> > +
> > +	ret = ts->ops->get_temp(ts, &val);
> > +
> > +	return ret ? ret : sprintf(buf, "%ld\n", val);
> > +}
> > +
> > +static ssize_t
> > +hyst_show(struct device *dev, struct device_attribute *attr, char *buf)
> > +{
> > +	int indx, ret;
> > +	long val;
> > +	struct thermal_sensor *ts = to_thermal_sensor(dev);
> > +
> > +	if (!sscanf(attr->attr.name, "threshold%d_hyst", &indx))
> > +		return -EINVAL;
> > +
> > +	ret = ts->ops->get_hyst(ts, indx, &val);
> > +
> > +	return ret ? ret : sprintf(buf, "%ld\n", val);
> > +}
> > +
> > +static ssize_t
> > +hyst_store(struct device *dev, struct device_attribute *attr,
> > +				   const char *buf, size_t count)
> > +{
> > +	int indx, ret;
> > +	long val;
> > +	struct thermal_sensor *ts = to_thermal_sensor(dev);
> > +
> > +	if (!ts->ops->set_hyst)
> > +		return -EPERM;
> > +
> > +	if (!sscanf(attr->attr.name, "threshold%d_hyst", &indx))
> > +		return -EINVAL;
> > +
> > +	if (kstrtol(buf, 10, &val))
> > +		return -EINVAL;
> > +
> > +	ret = ts->ops->set_hyst(ts, indx, val);
> > +
> > +	return ret ? ret : count;
> > +}
> > +
> > +static ssize_t
> > +threshold_show(struct device *dev, struct device_attribute *attr, char *buf)
> > +{
> > +	int indx, ret;
> > +	long val;
> > +	struct thermal_sensor *ts = to_thermal_sensor(dev);
> > +
> > +	if (!sscanf(attr->attr.name, "threshold%d", &indx))
> > +		return -EINVAL;
> > +
> > +	ret = ts->ops->get_threshold(ts, indx, &val);
> > +
> > +	return ret ? ret : sprintf(buf, "%ld\n", val);
> > +}
> > +
> > +static ssize_t
> > +threshold_store(struct device *dev, struct device_attribute *attr,
> > +				   const char *buf, size_t count)
> > +{
> > +	int indx, ret;
> > +	long val;
> > +	struct thermal_sensor *ts = to_thermal_sensor(dev);
> > +
> > +	if (!ts->ops->set_threshold)
> > +		return -EPERM;
> > +
> > +	if (!sscanf(attr->attr.name, "threshold%d", &indx))
> > +		return -EINVAL;
> > +
> > +	if (kstrtol(buf, 10, &val))
> > +		return -EINVAL;
> > +
> > +	ret = ts->ops->set_threshold(ts, indx, val);
> > +
> > +	return ret ? ret : count;
> > +}
> > +
> >  static ssize_t
> >  type_show(struct device *dev, struct device_attribute *attr, char *buf)
> >  {
> > @@ -772,6 +872,10 @@ static DEVICE_ATTR(mode, 0644, mode_show,
> mode_store);
> >  static DEVICE_ATTR(passive, S_IRUGO | S_IWUSR, passive_show,
> passive_store);
> >  static DEVICE_ATTR(policy, S_IRUGO | S_IWUSR, policy_show, policy_store);
> >
> > +/* Thermal sensor attributes */
> > +static DEVICE_ATTR(sensor_name, 0444, sensor_name_show, NULL);
> 
> this attribute is under sensorX/ directory, thus I think "name" is clear
> enough.
> what do you think?

Yes. That makes sense. I will give this a try in next version.

> 
> > +static DEVICE_ATTR(temp_input, 0444, sensor_temp_show, NULL);
> > +
> what about "temp"? to be consistent with the current naming.

I think I tried this, but we already had a 'temp' attribute. So, was compelled
to give another name.

I will try this one again and let you know.

> 
> >  /* sys I/F for cooling device */
> >  #define to_cooling_device(_dev)	\
> >  	container_of(_dev, struct thermal_cooling_device, device)
> > @@ -1585,6 +1689,186 @@ static void remove_trip_attrs(struct
> thermal_zone_device *tz)
> >  	kfree(tz->trip_hyst_attrs);
> >  }
> >
> > + /**
> > + * enable_sensor_thresholds - create sysfs nodes for thresholdX
> IMO, this name is confusing. It looks like that you are enabling the
> sensor hardware here.
> so why not "thermal_sensor_sysfs_add", and you can add the "name" and
> "temp" attribute in this function as well.

Okay. Will do.

> 
> > + * @ts:		the thermal sensor
> > + * @count:	Number of thresholds supported by sensor hardware
> > + *
> > + * 'Thresholds' are temperatures programmed into the sensor hardware,
> > + * on crossing which the sensor can generate an interrupt.
> > + */
> > +static int enable_sensor_thresholds(struct thermal_sensor *ts, int count)
> > +{
> > +	int i;
> > +	int size = sizeof(struct thermal_attr) * count;
> > +
> > +	ts->thresh_attrs = devm_kzalloc(&ts->device, size, GFP_KERNEL);
> > +	if (!ts->thresh_attrs)
> > +		return -ENOMEM;
> > +
> > +	if (ts->ops->get_hyst) {
> > +		ts->hyst_attrs = devm_kzalloc(&ts->device, size, GFP_KERNEL);
> > +		if (!ts->hyst_attrs)
> > +			return -ENOMEM;
> > +	}
> > +
> I do not think you can use devm_kzalloc here.

Any specific reason ?
I thought this memory will be freed when we do device_unregister on 'ts'.
Please enlighten me if this is not the case.

> 
> > +	ts->thresholds = count;
> > +
> > +	/* Create threshold attributes */
> > +	for (i = 0; i < count; i++) {
> > +		snprintf(ts->thresh_attrs[i].name, THERMAL_NAME_LENGTH,
> > +						 "threshold%d", i);
> > +
> > +		sysfs_attr_init(&ts->thresh_attrs[i].attr.attr);
> > +		ts->thresh_attrs[i].attr.attr.name = ts->thresh_attrs[i].name;
> > +		ts->thresh_attrs[i].attr.attr.mode = S_IRUGO | S_IWUSR;
> > +		ts->thresh_attrs[i].attr.show = threshold_show;
> > +		ts->thresh_attrs[i].attr.store = threshold_store;
> > +
> > +		device_create_file(&ts->device, &ts->thresh_attrs[i].attr);
> > +
> > +		/* Create threshold_hyst attributes */
> > +		if (!ts->ops->get_hyst)
> > +			continue;
> > +
> > +		snprintf(ts->hyst_attrs[i].name, THERMAL_NAME_LENGTH,
> > +						 "threshold%d_hyst", i);
> > +
> > +		sysfs_attr_init(&ts->hyst_attrs[i].attr.attr);
> > +		ts->hyst_attrs[i].attr.attr.name = ts->hyst_attrs[i].name;
> > +		ts->hyst_attrs[i].attr.attr.mode = S_IRUGO | S_IWUSR;
> > +		ts->hyst_attrs[i].attr.show = hyst_show;
> > +		ts->hyst_attrs[i].attr.store = hyst_store;
> > +
> > +		device_create_file(&ts->device, &ts->hyst_attrs[i].attr);
> > +	}
> > +	return 0;
> > +}
> > +
> > +/**
> > + * thermal_sensor_register - register a new thermal sensor
> > + * @name:	name of the thermal sensor
> > + * @count:	Number of thresholds supported by hardware
> > + * @ops:	standard thermal sensor callbacks
> > + * @devdata:	private device data
> > + *
> > + * On Success returns a thermal sensor reference, otherwise:
> > + * -EINVAL for invalid parameters,
> > + * -ENOMEM for insufficient memory cases,
> > +*/
> > +struct thermal_sensor *thermal_sensor_register(const char *name, int count,
> > +			struct thermal_sensor_ops *ops, void *devdata)
> > +{
> > +	struct thermal_sensor *ts;
> > +	int ret;
> > +
> > +	if (!name || (name && strlen(name) >= THERMAL_NAME_LENGTH))
> > +		return ERR_PTR(-EINVAL);
> > +
> > +	if (!ops || !ops->get_temp)
> > +		return ERR_PTR(-EINVAL);
> > +
> > +	ts = kzalloc(sizeof(*ts), GFP_KERNEL);
> > +	if (!ts)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	idr_init(&ts->idr);
> > +	ret = get_idr(&thermal_sensor_idr, &thermal_idr_lock, &ts->id);
> > +	if (ret)
> > +		goto exit_free;
> > +
> > +	strlcpy(ts->name, name, sizeof(ts->name));
> > +	ts->ops = ops;
> > +	ts->devdata = devdata;
> > +	ts->device.class = &thermal_class;
> > +
> > +	dev_set_name(&ts->device, "sensor%d", ts->id);
> > +	ret = device_register(&ts->device);
> > +	if (ret)
> > +		goto exit_idr;
> > +
> > +	ret = device_create_file(&ts->device, &dev_attr_sensor_name);
> > +	if (ret)
> > +		goto exit_unregister;
> > +
> > +	ret = device_create_file(&ts->device, &dev_attr_temp_input);
> > +	if (ret)
> > +		goto exit_name;
> > +
> > +	if (count > 0 && ts->ops->get_threshold) {
> > +		ret = enable_sensor_thresholds(ts, count);
> > +		if (ret)
> > +			goto exit_temp;
> > +	}
> > +
> > +	/* Add this sensor to the global list of sensors */
> > +	mutex_lock(&sensor_list_lock);
> > +	list_add_tail(&ts->node, &thermal_sensor_list);
> > +	mutex_unlock(&sensor_list_lock);
> > +
> > +	return ts;
> > +
> > +exit_temp:
> > +	device_remove_file(&ts->device, &dev_attr_temp_input);
> > +exit_name:
> > +	device_remove_file(&ts->device, &dev_attr_sensor_name);
> > +exit_unregister:
> > +	device_unregister(&ts->device);
> > +exit_idr:
> > +	release_idr(&thermal_sensor_idr, &thermal_idr_lock, ts->id);
> > +exit_free:
> > +	kfree(ts);
> > +	return ERR_PTR(ret);
> > +}
> > +EXPORT_SYMBOL(thermal_sensor_register);
> > +
> > +/**
> > + * remove_thermal_zone - removes the sysfs nodes for given sensor
> 
> s/remove_thermal_zone/thermal_sensor_unregister
> 
> > + * @ts:	Thermal sensor to be removed.
> > + */
> > +void thermal_sensor_unregister(struct thermal_sensor *ts)
> > +{
> > +	int i;
> > +	struct thermal_sensor *pos, *next;
> > +	bool found = false;
> > +
> > +	if (!ts)
> > +		return;
> > +
> > +	mutex_lock(&sensor_list_lock);
> > +	list_for_each_entry_safe(pos, next, &thermal_sensor_list, node) {
> > +		if (pos == ts) {
> > +			list_del(&ts->node);
> > +			found = true;
> > +			break;
> > +		}
> > +	}
> > +	mutex_unlock(&sensor_list_lock);
> > +
> > +	if (!found)
> > +		return;
> > +
> > +	for (i = 0; i < ts->thresholds; i++) {
> > +		device_remove_file(&ts->device, &ts->thresh_attrs[i].attr);
> > +		if (ts->ops->get_hyst) {
> > +			device_remove_file(&ts->device,
> > +					&ts->hyst_attrs[i].attr);
> > +		}
> > +	}
> > +
> > +	device_remove_file(&ts->device, &dev_attr_sensor_name);
> > +	device_remove_file(&ts->device, &dev_attr_temp_input);
> > +
> hmmm, I'd prefer you to introduce a separate function for the sysfs
> cleanup code.

From the above comment, we can have a similar 
thermal_sensor_sysfs_remove function.

Thanks,
Durga

> 
> thanks,
> rui
> > +	release_idr(&thermal_sensor_idr, &thermal_idr_lock, ts->id);
> > +	idr_destroy(&ts->idr);
> > +
> > +	device_unregister(&ts->device);
> > +
> > +	kfree(ts);
> > +	return;
> > +}
> > +EXPORT_SYMBOL(thermal_sensor_unregister);
> > +
> >  /**
> >   * thermal_zone_device_register() - register a new thermal zone device
> >   * @type:	the thermal zone device type
> > diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> > index a386a1c..25fc562 100644
> > --- a/include/linux/thermal.h
> > +++ b/include/linux/thermal.h
> > @@ -58,6 +58,7 @@
> >  #define DEFAULT_THERMAL_GOVERNOR       "user_space"
> >  #endif
> >
> > +struct thermal_sensor;
> >  struct thermal_zone_device;
> >  struct thermal_cooling_device;
> >
> > @@ -139,6 +140,15 @@ struct thermal_cooling_device_ops {
> >  	int (*set_cur_state) (struct thermal_cooling_device *, unsigned long);
> >  };
> >
> > +struct thermal_sensor_ops {
> > +	int (*get_temp) (struct thermal_sensor *, long *);
> > +	int (*get_trend) (struct thermal_sensor *, int, enum thermal_trend *);
> > +	int (*set_threshold) (struct thermal_sensor *, int, long);
> > +	int (*get_threshold) (struct thermal_sensor *, int, long *);
> > +	int (*set_hyst) (struct thermal_sensor *, int, long);
> > +	int (*get_hyst) (struct thermal_sensor *, int, long *);
> > +};
> > +
> >  struct thermal_cooling_device {
> >  	int id;
> >  	char type[THERMAL_NAME_LENGTH];
> > @@ -156,6 +166,21 @@ struct thermal_attr {
> >  	char name[THERMAL_NAME_LENGTH];
> >  };
> >
> > +struct thermal_sensor {
> > +	char name[THERMAL_NAME_LENGTH];
> > +	int id;
> > +	int temp;
> > +	int prev_temp;
> > +	int thresholds;
> > +	void *devdata;
> > +	struct idr idr;
> > +	struct device device;
> > +	struct list_head node;
> > +	struct thermal_sensor_ops *ops;
> > +	struct thermal_attr *thresh_attrs;
> > +	struct thermal_attr *hyst_attrs;
> > +};
> > +
> >  struct thermal_zone_device {
> >  	int id;
> >  	char type[THERMAL_NAME_LENGTH];
> > @@ -248,6 +273,10 @@ struct thermal_instance *get_thermal_instance(struct
> thermal_zone_device *,
> >  void thermal_cdev_update(struct thermal_cooling_device *);
> >  void thermal_notify_framework(struct thermal_zone_device *, int);
> >
> > +struct thermal_sensor *thermal_sensor_register(const char *, int,
> > +				struct thermal_sensor_ops *, void *);
> > +void thermal_sensor_unregister(struct thermal_sensor *);
> > +
> >  #ifdef CONFIG_NET
> >  extern int thermal_generate_netlink_event(struct thermal_zone_device *tz,
> >  						enum events event);
> 
> 
> --
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