3 files changed, 94 insertions, 5 deletions

diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
index 4c105934c599..2ba4c9bb790a 100644
--- a/Documentation/thermal/sysfs-api.txt
+++ b/Documentation/thermal/sysfs-api.txt
@@ -121,6 +121,7 @@ Thermal zone device sys I/F, created once it's registered:
     |---mode:                   Working mode of the thermal zone
     |---trip_point_[0-*]_temp:  Trip point temperature
     |---trip_point_[0-*]_type:  Trip point type
+    |---trip_point_[0-*]_hyst:  Hysteresis value for this trip point
 
 Thermal cooling device sys I/F, created once it's registered:
 /sys/class/thermal/cooling_device[0-*]:
@@ -190,6 +191,11 @@ trip_point_[0-*]_type
         thermal zone.
         RO, Optional
 
+trip_point_[0-*]_hyst
+        The hysteresis value for a trip point, represented as an integer
+        Unit: Celsius
+        RW, Optional
+
 cdev[0-*]
         Sysfs link to the thermal cooling device node where the sys I/F
         for cooling device throttling control represents.
diff --git a/drivers/thermal/thermal_sys.c b/drivers/thermal/thermal_sys.c
index 5feb3353213f..2d7a9fe8f365 100644
--- a/drivers/thermal/thermal_sys.c
+++ b/drivers/thermal/thermal_sys.c
@@ -240,6 +240,52 @@ trip_point_temp_show(struct device *dev, struct device_attribute *attr,
 }
 
 static ssize_t
+trip_point_hyst_store(struct device *dev, struct device_attribute *attr,
+                        const char *buf, size_t count)
+{
+        struct thermal_zone_device *tz = to_thermal_zone(dev);
+        int trip, ret;
+        unsigned long temperature;
+
+        if (!tz->ops->set_trip_hyst)
+                return -EPERM;
+
+        if (!sscanf(attr->attr.name, "trip_point_%d_hyst", &trip))
+                return -EINVAL;
+
+        if (kstrtoul(buf, 10, &temperature))
+                return -EINVAL;
+
+        /*
+         * We are not doing any check on the 'temperature' value
+         * here. The driver implementing 'set_trip_hyst' has to
+         * take care of this.
+         */
+        ret = tz->ops->set_trip_hyst(tz, trip, temperature);
+
+        return ret ? ret : count;
+}
+
+static ssize_t
+trip_point_hyst_show(struct device *dev, struct device_attribute *attr,
+                        char *buf)
+{
+        struct thermal_zone_device *tz = to_thermal_zone(dev);
+        int trip, ret;
+        unsigned long temperature;
+
+        if (!tz->ops->get_trip_hyst)
+                return -EPERM;
+
+        if (!sscanf(attr->attr.name, "trip_point_%d_hyst", &trip))
+                return -EINVAL;
+
+        ret = tz->ops->get_trip_hyst(tz, trip, &temperature);
+
+        return ret ? ret : sprintf(buf, "%ld\n", temperature);
+}
+
+static ssize_t
 passive_store(struct device *dev, struct device_attribute *attr,
                     const char *buf, size_t count)
 {
@@ -1091,21 +1137,29 @@ EXPORT_SYMBOL(thermal_zone_device_update);
 static int create_trip_attrs(struct thermal_zone_device *tz, int mask)
 {
         int indx;
+        int size = sizeof(struct thermal_attr) * tz->trips;
 
-        tz->trip_type_attrs =
-                kzalloc(sizeof(struct thermal_attr) * tz->trips, GFP_KERNEL);
+        tz->trip_type_attrs = kzalloc(size, GFP_KERNEL);
         if (!tz->trip_type_attrs)
                 return -ENOMEM;
 
-        tz->trip_temp_attrs =
-                kzalloc(sizeof(struct thermal_attr) * tz->trips, GFP_KERNEL);
+        tz->trip_temp_attrs = kzalloc(size, GFP_KERNEL);
         if (!tz->trip_temp_attrs) {
                 kfree(tz->trip_type_attrs);
                 return -ENOMEM;
         }
 
-        for (indx = 0; indx < tz->trips; indx++) {
+        if (tz->ops->get_trip_hyst) {
+                tz->trip_hyst_attrs = kzalloc(size, GFP_KERNEL);
+                if (!tz->trip_hyst_attrs) {
+                        kfree(tz->trip_type_attrs);
+                        kfree(tz->trip_temp_attrs);
+                        return -ENOMEM;
+                }
+        }
 
+
+        for (indx = 0; indx < tz->trips; indx++) {
                 /* create trip type attribute */
                 snprintf(tz->trip_type_attrs[indx].name, THERMAL_NAME_LENGTH,
                          "trip_point_%d_type", indx);
@@ -1136,6 +1190,26 @@ static int create_trip_attrs(struct thermal_zone_device *tz, int mask)
 
                 device_create_file(&tz->device,
                                    &tz->trip_temp_attrs[indx].attr);
+
+                /* create Optional trip hyst attribute */
+                if (!tz->ops->get_trip_hyst)
+                        continue;
+                snprintf(tz->trip_hyst_attrs[indx].name, THERMAL_NAME_LENGTH,
+                         "trip_point_%d_hyst", indx);
+
+                sysfs_attr_init(&tz->trip_hyst_attrs[indx].attr.attr);
+                tz->trip_hyst_attrs[indx].attr.attr.name =
+                                        tz->trip_hyst_attrs[indx].name;
+                tz->trip_hyst_attrs[indx].attr.attr.mode = S_IRUGO;
+                tz->trip_hyst_attrs[indx].attr.show = trip_point_hyst_show;
+                if (tz->ops->set_trip_hyst) {
+                        tz->trip_hyst_attrs[indx].attr.attr.mode |= S_IWUSR;
+                        tz->trip_hyst_attrs[indx].attr.store =
+                                        trip_point_hyst_store;
+                }
+
+                device_create_file(&tz->device,
+                                   &tz->trip_hyst_attrs[indx].attr);
         }
         return 0;
 }
@@ -1149,9 +1223,13 @@ static void remove_trip_attrs(struct thermal_zone_device *tz)
                                    &tz->trip_type_attrs[indx].attr);
                 device_remove_file(&tz->device,
                                    &tz->trip_temp_attrs[indx].attr);
+                if (tz->ops->get_trip_hyst)
+                        device_remove_file(&tz->device,
+                                  &tz->trip_hyst_attrs[indx].attr);
         }
         kfree(tz->trip_type_attrs);
         kfree(tz->trip_temp_attrs);
+        kfree(tz->trip_hyst_attrs);
 }
 
 /**
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index 6eaf9146c847..cfc8d908892e 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -60,6 +60,10 @@ struct thermal_zone_device_ops {
                               unsigned long *);
         int (*set_trip_temp) (struct thermal_zone_device *, int,
                               unsigned long);
+        int (*get_trip_hyst) (struct thermal_zone_device *, int,
+                              unsigned long *);
+        int (*set_trip_hyst) (struct thermal_zone_device *, int,
+                              unsigned long);
         int (*get_crit_temp) (struct thermal_zone_device *, unsigned long *);
         int (*notify) (struct thermal_zone_device *, int,
                        enum thermal_trip_type);
@@ -98,6 +102,7 @@ struct thermal_zone_device {
         struct device device;
         struct thermal_attr *trip_temp_attrs;
         struct thermal_attr *trip_type_attrs;
+        struct thermal_attr *trip_hyst_attrs;
         void *devdata;
         int trips;
         int tc1;