1 // SPDX-License-Identifier: GPL-2.0-only
3 * fair_share.c - A simple weight based Thermal governor
5 * Copyright (C) 2012 Intel Corp
6 * Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
8 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
10 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
13 #include <linux/thermal.h>
14 #include "thermal_trace.h"
16 #include "thermal_core.h"
18 static int get_trip_level(struct thermal_zone_device
*tz
)
20 const struct thermal_trip_desc
*level_td
= NULL
;
21 const struct thermal_trip_desc
*td
;
24 for_each_trip_desc(tz
, td
) {
25 if (td
->threshold
> tz
->temperature
)
30 if (!level_td
|| td
->threshold
> level_td
->threshold
)
34 /* Bail out if the temperature is not greater than any trips. */
38 trace_thermal_zone_trip(tz
, thermal_zone_trip_id(tz
, &level_td
->trip
),
45 * fair_share_throttle - throttles devices associated with the given zone
46 * @tz: thermal_zone_device
47 * @td: trip point descriptor
48 * @trip_level: number of trips crossed by the zone temperature
50 * Throttling Logic: This uses three parameters to calculate the new
51 * throttle state of the cooling devices associated with the given zone.
53 * Parameters used for Throttling:
54 * P1. max_state: Maximum throttle state exposed by the cooling device.
55 * P2. weight[i]/total_weight:
56 * How 'effective' the 'i'th device is, in cooling the given zone.
57 * P3. trip_level/max_no_of_trips:
58 * This describes the extent to which the devices should be throttled.
59 * We do not want to throttle too much when we trip a lower temperature,
60 * whereas the throttling is at full swing if we trip critical levels.
61 * new_state of cooling device = P3 * P2 * P1
63 static void fair_share_throttle(struct thermal_zone_device
*tz
,
64 const struct thermal_trip_desc
*td
,
67 struct thermal_instance
*instance
;
71 list_for_each_entry(instance
, &td
->thermal_instances
, trip_node
) {
72 total_weight
+= instance
->weight
;
76 list_for_each_entry(instance
, &td
->thermal_instances
, trip_node
) {
77 struct thermal_cooling_device
*cdev
= instance
->cdev
;
81 dividend
= trip_level
;
82 dividend
*= cdev
->max_state
;
83 divisor
= tz
->num_trips
;
85 dividend
*= instance
->weight
;
86 divisor
*= total_weight
;
88 divisor
*= nr_instances
;
90 instance
->target
= div_u64(dividend
, divisor
);
92 thermal_cdev_update_nocheck(cdev
);
96 static void fair_share_manage(struct thermal_zone_device
*tz
)
98 int trip_level
= get_trip_level(tz
);
99 const struct thermal_trip_desc
*td
;
101 lockdep_assert_held(&tz
->lock
);
103 for_each_trip_desc(tz
, td
) {
104 const struct thermal_trip
*trip
= &td
->trip
;
106 if (trip
->temperature
== THERMAL_TEMP_INVALID
||
107 trip
->type
== THERMAL_TRIP_CRITICAL
||
108 trip
->type
== THERMAL_TRIP_HOT
)
111 fair_share_throttle(tz
, td
, trip_level
);
115 static struct thermal_governor thermal_gov_fair_share
= {
116 .name
= "fair_share",
117 .manage
= fair_share_manage
,
119 THERMAL_GOVERNOR_DECLARE(thermal_gov_fair_share
);