Commit e6e238c3 authored by Amit Daniel Kachhap's avatar Amit Daniel Kachhap Committed by Zhang Rui

thermal: sysfs: Add a new sysfs node emul_temp for thermal emulation

This patch adds support to set the emulated temperature method in
thermal zone (sensor). After setting this feature thermal zone may
report this temperature and not the actual temperature. The emulation
implementation may be based on sensor capability through platform
specific handler or pure software emulation if no platform handler defined.

This is useful in debugging different temperature threshold and its
associated cooling action. Critical threshold's cannot be emulated.
Writing 0 on this node should disable emulation.
Signed-off-by: default avatarAmit Daniel Kachhap <>
Acked-by: default avatarKukjin Kim <>
Signed-off-by: default avatarZhang Rui <>
parent c8165dc0
......@@ -55,6 +55,8 @@ temperature) and throttle appropriate devices.
.get_trip_type: get the type of certain trip point.
.get_trip_temp: get the temperature above which the certain trip point
will be fired.
.set_emul_temp: set the emulation temperature which helps in debugging
different threshold temperature points.
1.1.2 void thermal_zone_device_unregister(struct thermal_zone_device *tz)
......@@ -153,6 +155,7 @@ Thermal zone device sys I/F, created once it's registered:
|---trip_point_[0-*]_temp: Trip point temperature
|---trip_point_[0-*]_type: Trip point type
|---trip_point_[0-*]_hyst: Hysteresis value for this trip point
|---emul_temp: Emulated temperature set node
Thermal cooling device sys I/F, created once it's registered:
......@@ -252,6 +255,16 @@ passive
Valid values: 0 (disabled) or greater than 1000
RW, Optional
Interface to set the emulated temperature method in thermal zone
(sensor). After setting this temperature, the thermal zone may pass
this temperature to platform emulation function if registered or
cache it locally. This is useful in debugging different temperature
threshold and its associated cooling action. This is write only node
and writing 0 on this node should disable emulation.
Unit: millidegree Celsius
WO, Optional
* Cooling device attributes *
......@@ -78,6 +78,14 @@ config CPU_THERMAL
and not the ACPI interface.
If you want this support, you should say Y here.
bool "Thermal emulation mode support"
Enable this option to make a emul_temp sysfs node in thermal zone
directory to support temperature emulation. With emulation sysfs node,
user can manually input temperature and test the different trip
threshold behaviour for simulation purpose.
bool "SPEAr thermal sensor driver"
depends on PLAT_SPEAR
......@@ -378,24 +378,54 @@ static void handle_thermal_trip(struct thermal_zone_device *tz, int trip)
static int thermal_zone_get_temp(struct thermal_zone_device *tz,
unsigned long *temp)
int ret = 0, count;
unsigned long crit_temp = -1UL;
enum thermal_trip_type type;
ret = tz->ops->get_temp(tz, temp);
if (!tz->emul_temperature)
goto skip_emul;
for (count = 0; count < tz->trips; count++) {
ret = tz->ops->get_trip_type(tz, count, &type);
if (!ret && type == THERMAL_TRIP_CRITICAL) {
ret = tz->ops->get_trip_temp(tz, count, &crit_temp);
if (ret)
goto skip_emul;
if (*temp < crit_temp)
*temp = tz->emul_temperature;
return ret;
static void update_temperature(struct thermal_zone_device *tz)
long temp;
int ret;
ret = tz->ops->get_temp(tz, &temp);
ret = thermal_zone_get_temp(tz, &temp);
if (ret) {
dev_warn(&tz->device, "failed to read out thermal zone %d\n",
goto exit;
tz->last_temperature = tz->temperature;
tz->temperature = temp;
......@@ -438,10 +468,7 @@ temp_show(struct device *dev, struct device_attribute *attr, char *buf)
long temperature;
int ret;
if (!tz->ops->get_temp)
return -EPERM;
ret = tz->ops->get_temp(tz, &temperature);
ret = thermal_zone_get_temp(tz, &temperature);
if (ret)
return ret;
......@@ -701,6 +728,31 @@ policy_show(struct device *dev, struct device_attribute *devattr, char *buf)
return sprintf(buf, "%s\n", tz->governor->name);
static ssize_t
emul_temp_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
struct thermal_zone_device *tz = to_thermal_zone(dev);
int ret = 0;
unsigned long temperature;
if (kstrtoul(buf, 10, &temperature))
return -EINVAL;
if (!tz->ops->set_emul_temp) {
tz->emul_temperature = temperature;
} else {
ret = tz->ops->set_emul_temp(tz, temperature);
return ret ? ret : count;
static DEVICE_ATTR(emul_temp, S_IWUSR, NULL, emul_temp_store);
static DEVICE_ATTR(type, 0444, type_show, NULL);
static DEVICE_ATTR(temp, 0444, temp_show, NULL);
static DEVICE_ATTR(mode, 0644, mode_show, mode_store);
......@@ -843,7 +895,7 @@ temp_input_show(struct device *dev, struct device_attribute *attr, char *buf)
struct thermal_zone_device *tz = temp->tz;
ret = tz->ops->get_temp(tz, &temperature);
ret = thermal_zone_get_temp(tz, &temperature);
if (ret)
return ret;
......@@ -1596,6 +1648,11 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
goto unregister;
result = device_create_file(&tz->device, &dev_attr_emul_temp);
if (result)
goto unregister;
/* Create policy attribute */
result = device_create_file(&tz->device, &dev_attr_policy);
if (result)
......@@ -123,6 +123,7 @@ struct thermal_zone_device_ops {
int (*set_trip_hyst) (struct thermal_zone_device *, int,
unsigned long);
int (*get_crit_temp) (struct thermal_zone_device *, unsigned long *);
int (*set_emul_temp) (struct thermal_zone_device *, unsigned long);
int (*get_trend) (struct thermal_zone_device *, int,
enum thermal_trend *);
int (*notify) (struct thermal_zone_device *, int,
......@@ -165,6 +166,7 @@ struct thermal_zone_device {
int polling_delay;
int temperature;
int last_temperature;
int emul_temperature;
int passive;
unsigned int forced_passive;
const struct thermal_zone_device_ops *ops;
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