thermal: intel: intel_soc_dts_iosf: Rework critical trip setup

Critical trip points appear in the DTS thermal zones only after those
thermal zones have been registered via intel_soc_dts_iosf_init().
Moreover, they are "created" by changing the type of an existing trip
point from THERMAL_TRIP_PASSIVE to THERMAL_TRIP_CRITICAL via
intel_soc_dts_iosf_add_read_only_critical_trip(), the caller of which
has to be careful enough to pass at least 1 as the number of read-only
trip points to intel_soc_dts_iosf_init() beforehand.

This is questionable, because user space may have started to use the
trips at the time when intel_soc_dts_iosf_add_read_only_critical_trip()
runs and there is no synchronization between it and sys_set_trip_temp().

To address it, use the observation that nonzero number of read-only
trip points is only passed to intel_soc_dts_iosf_init() when critical
trip points are going to be used, so in fact that function may get all
of the information regarding the critical trip points upfront and it
can configure them before registering the corresponding thermal zones.

Accordingly, replace the read_only_trip_count argument of
intel_soc_dts_iosf_init() with a pair of new arguments related to
critical trip points: a bool one indicating whether or not critical
trip points are to be used at all and an int one representing the
critical trip point temperature offset relative to Tj_max. Use these
arguments to configure the critical trip points before the registration
of the thermal zones and to compute the number of writeable trip points
in add_dts_thermal_zone().

Modify both callers of intel_soc_dts_iosf_init() to take these changes
into account and drop the intel_soc_dts_iosf_add_read_only_critical_trip()
call, that is not necessary any more, from intel_soc_thermal_init(),
which also allows it to return success right after requesting the IRQ.

Finally, drop intel_soc_dts_iosf_add_read_only_critical_trip()
altogether, because it does not have any more users.

Signed-off-by: Rafael J. Wysocki <[e-mail]>
Reviewed-by: Srinivas Pandruvada <[e-mail]>

drivers/thermal/intel/int340x_thermal/processor_thermal_device_pci_legacy.c

···
 		 * ACPI/MSR. So we don't want to fail for auxiliary DTSs.
 		 */
 		proc_priv->soc_dts = intel_soc_dts_iosf_init(
-					INTEL_SOC_DTS_INTERRUPT_MSI, 0);
+					INTEL_SOC_DTS_INTERRUPT_MSI, false, 0);
 
 		if (!IS_ERR(proc_priv->soc_dts) && pdev->irq) {
 			ret = pci_enable_msi(pdev);

drivers/thermal/intel/intel_soc_dts_iosf.c

···
 }
 
 static int add_dts_thermal_zone(int id, struct intel_soc_dts_sensor_entry *dts,
-				int read_only_trip_cnt)
+				bool critical_trip)
 {
+	int writable_trip_cnt = SOC_MAX_DTS_TRIPS;
 	char name[10];
 	unsigned long trip;
-	int writable_trip_cnt;
 	int trip_mask;
 	unsigned long ptps;
 	u32 store_ptps;
···
 
 	dts->id = id;
 
-	writable_trip_cnt = SOC_MAX_DTS_TRIPS - read_only_trip_cnt;
+	if (critical_trip)
+		writable_trip_cnt--;
+
 	trip_mask = GENMASK(writable_trip_cnt - 1, 0);
 
 	/* Check if the writable trip we provide is not used by BIOS */
···
 err_ret:
 	return ret;
 }
-
-int intel_soc_dts_iosf_add_read_only_critical_trip(
-	struct intel_soc_dts_sensors *sensors, int critical_offset)
-{
-	int i, j;
-
-	for (i = 0; i < SOC_MAX_DTS_SENSORS; ++i) {
-		struct intel_soc_dts_sensor_entry *entry = &sensors->soc_dts[i];
-		int temp = sensors->tj_max - critical_offset;
-		unsigned long mask = entry->trip_mask;
-
-		j = find_first_zero_bit(&mask, SOC_MAX_DTS_TRIPS);
-		if (j < SOC_MAX_DTS_TRIPS)
-			return configure_trip(entry, j, THERMAL_TRIP_CRITICAL, temp);
-	}
-
-	return -EINVAL;
-}
-EXPORT_SYMBOL_GPL(intel_soc_dts_iosf_add_read_only_critical_trip);
 
 void intel_soc_dts_iosf_interrupt_handler(struct intel_soc_dts_sensors *sensors)
 {
···
 	configure_trip(&sensors->soc_dts[dts_index], 1, 0, 0);
 }
 
-struct intel_soc_dts_sensors *intel_soc_dts_iosf_init(
-	enum intel_soc_dts_interrupt_type intr_type, int read_only_trip_count)
+struct intel_soc_dts_sensors *
+intel_soc_dts_iosf_init(enum intel_soc_dts_interrupt_type intr_type,
+			bool critical_trip, int crit_offset)
 {
 	struct intel_soc_dts_sensors *sensors;
 	int tj_max;
···
 
 	if (!iosf_mbi_available())
 		return ERR_PTR(-ENODEV);
-
-	if (read_only_trip_count > SOC_MAX_DTS_TRIPS)
-		return ERR_PTR(-EINVAL);
 
 	tj_max = intel_tcc_get_tjmax(-1);
 	if (tj_max < 0)
···
 	sensors->tj_max = tj_max * 1000;
 
 	for (i = 0; i < SOC_MAX_DTS_SENSORS; ++i) {
+		enum thermal_trip_type trip_type;
+		int temp;
+
 		sensors->soc_dts[i].sensors = sensors;
 
 		ret = configure_trip(&sensors->soc_dts[i], 0,
···
 		if (ret)
 			goto err_reset_trips;
 
-		ret = configure_trip(&sensors->soc_dts[i], 1,
-				     THERMAL_TRIP_PASSIVE, 0);
+		if (critical_trip) {
+			trip_type = THERMAL_TRIP_CRITICAL;
+			temp = sensors->tj_max - crit_offset;
+		} else {
+			trip_type = THERMAL_TRIP_PASSIVE;
+			temp = 0;
+		}
+		ret = configure_trip(&sensors->soc_dts[i], 1, trip_type, temp);
 		if (ret)
 			goto err_reset_trips;
 	}
 
 	for (i = 0; i < SOC_MAX_DTS_SENSORS; ++i) {
-		ret = add_dts_thermal_zone(i, &sensors->soc_dts[i],
-					   read_only_trip_count);
+		ret = add_dts_thermal_zone(i, &sensors->soc_dts[i], critical_trip);
 		if (ret)
 			goto err_remove_zone;
 	}

drivers/thermal/intel/intel_soc_dts_iosf.h

···
 	struct intel_soc_dts_sensor_entry soc_dts[SOC_MAX_DTS_SENSORS];
 };
 
-struct intel_soc_dts_sensors *intel_soc_dts_iosf_init(
-	enum intel_soc_dts_interrupt_type intr_type, int read_only_trip_count);
+
+struct intel_soc_dts_sensors *
+intel_soc_dts_iosf_init(enum intel_soc_dts_interrupt_type intr_type,
+			bool critical_trip, int crit_offset);
 void intel_soc_dts_iosf_exit(struct intel_soc_dts_sensors *sensors);
 void intel_soc_dts_iosf_interrupt_handler(
 				struct intel_soc_dts_sensors *sensors);
-int intel_soc_dts_iosf_add_read_only_critical_trip(
-	struct intel_soc_dts_sensors *sensors, int critical_offset);
 #endif

drivers/thermal/intel/intel_soc_dts_thermal.c

···
 		return -ENODEV;
 
 	/* Create a zone with 2 trips with marked as read only */
-	soc_dts = intel_soc_dts_iosf_init(INTEL_SOC_DTS_INTERRUPT_APIC, 1);
+	soc_dts = intel_soc_dts_iosf_init(INTEL_SOC_DTS_INTERRUPT_APIC, true,
+					  crit_offset);
 	if (IS_ERR(soc_dts)) {
 		err = PTR_ERR(soc_dts);
 		return err;
···
 		}
 	}
 
-	err = intel_soc_dts_iosf_add_read_only_critical_trip(soc_dts,
-							     crit_offset);
-	if (err)
-		goto error_trips;
-
 	return 0;
-
-error_trips:
-	if (soc_dts_thres_irq) {
-		free_irq(soc_dts_thres_irq, soc_dts);
-		acpi_unregister_gsi(soc_dts_thres_gsi);
-	}
-	intel_soc_dts_iosf_exit(soc_dts);
-
-	return err;
 }
 
 static void __exit intel_soc_thermal_exit(void)