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From:   "Rafael J. Wysocki" <rjw@rjwysocki.net>
To:     Linux ACPI <linux-acpi@vger.kernel.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        Michal Wilczynski <michal.wilczynski@intel.com>,
        Zhang Rui <rui.zhang@intel.com>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Daniel Lezcano <daniel.lezcano@linaro.org>
Subject: [PATCH v2 1/8] thermal: core: Add mechanism for connecting trips with driver data
Date:   Fri, 21 Jul 2023 14:46:38 +0200
Message-ID: <4862397.31r3eYUQgx@kreacher>
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From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Some drivers need to update trip point data (temperature and/or
hysteresis) upon notifications from the platform firmware or they
may need to reprogram hardware when trip point parameters are changed
via sysfs.  For those purposes, they need to connect struct thermal_trip
to a private data set associated with the trip or the other way around
and using a trip point index for that may not always work, because the
core may need to reorder the trips during thermal zone registration (in
particular, they may need to be sorted).

To allow that to be done without using a trip point index, introduce
a new field in struct thermal_trip that can be pointed by the driver
to its own data structure containing a trip pointer to be initialized
by the core during thermal zone registration.  That pointer will then
have to be updated by the core every time the location of the given
trip point object in memory changes.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v1 -> v2: No changes.

---
 drivers/thermal/thermal_core.c |   20 +++++++++++++++++---
 include/linux/thermal.h        |   13 +++++++++++++
 2 files changed, 30 insertions(+), 3 deletions(-)

Index: linux-pm/include/linux/thermal.h
===================================================================
--- linux-pm.orig/include/linux/thermal.h
+++ linux-pm/include/linux/thermal.h
@@ -76,16 +76,29 @@ struct thermal_zone_device_ops {
 	void (*critical)(struct thermal_zone_device *);
 };
 
+struct thermal_trip_ref {
+	struct thermal_trip *trip;
+};
+
 /**
  * struct thermal_trip - representation of a point in temperature domain
  * @temperature: temperature value in miliCelsius
  * @hysteresis: relative hysteresis in miliCelsius
  * @type: trip point type
+ * @driver_ref: driver's reference to this trip point
+ *
+ * If @driver_ref is not NULL, the trip pointer in the object pointed to by it
+ * will be initialized by the core during thermal zone registration and updated
+ * whenever the location of the given trip object changes.  This allows the
+ * driver to access the trip point data without knowing the relative ordering
+ * of trips within the trip table used by the core and, given a trip pointer,
+ * to get back to its private data associated with the given trip.
  */
 struct thermal_trip {
 	int temperature;
 	int hysteresis;
 	enum thermal_trip_type type;
+	struct thermal_trip_ref *driver_ref;
 };
 
 struct thermal_cooling_device_ops {
Index: linux-pm/drivers/thermal/thermal_core.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.c
+++ linux-pm/drivers/thermal/thermal_core.c
@@ -1306,14 +1306,28 @@ thermal_zone_device_register_with_trips(
 	if (result)
 		goto release_device;
 
+	mutex_lock(&tz->lock);
+
 	for (count = 0; count < num_trips; count++) {
-		struct thermal_trip trip;
+		int temperature = 0;
+
+		if (trips) {
+			temperature = trips[count].temperature;
+			if (trips[count].driver_ref)
+				trips[count].driver_ref->trip = &trips[count];
+		} else {
+			struct thermal_trip trip;
 
-		result = thermal_zone_get_trip(tz, count, &trip);
-		if (result || !trip.temperature)
+			result = __thermal_zone_get_trip(tz, count, &trip);
+			if (!result)
+				temperature = trip.temperature;
+		}
+		if (!temperature)
 			set_bit(count, &tz->trips_disabled);
 	}
 
+	mutex_unlock(&tz->lock);
+
 	/* Update 'this' zone's governor information */
 	mutex_lock(&thermal_governor_lock);