thermal: ACPI: Move the ACPI thermal library to drivers/acpi/

The ACPI thermal library contains functions that can be used to
retrieve trip point temperature values through the platform firmware
for various types of trip points.  Each of these functions basically
evaluates a specific ACPI object, checks if the value produced by it
is reasonable and returns it (or THERMAL_TEMP_INVALID if anything
fails).

It made sense to hold it in drivers/thermal/ so long as it was only used
by the code in that directory, but since it is also going to be used by
the ACPI thermal driver located in drivers/acpi/, move it to the latter
in order to keep the code related to evaluating ACPI objects defined in
the specification proper together.

No intentional functional impact.

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

3 files changed, 122 insertions, 0 deletions

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index f819e760ff195..6f2bfcf7645ce 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -61,6 +61,10 @@ config ACPI_CCA_REQUIRED
 config ACPI_TABLE_LIB
 	bool
 
+config ACPI_THERMAL_LIB
+       depends on THERMAL
+       bool
+
 config ACPI_DEBUGGER
 	bool "AML debugger interface"
 	select ACPI_DEBUG
@@ -327,6 +331,7 @@ config ACPI_THERMAL
 	tristate "Thermal Zone"
 	depends on ACPI_PROCESSOR
 	select THERMAL
+	select ACPI_THERMAL_LIB
 	default y
 	help
 	  This driver supports ACPI thermal zones.  Most mobile and
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index eaa09bf52f176..2a52083704e6a 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -89,6 +89,7 @@ obj-$(CONFIG_ACPI_TAD)		+= acpi_tad.o
 obj-$(CONFIG_ACPI_PCI_SLOT)	+= pci_slot.o
 obj-$(CONFIG_ACPI_PROCESSOR)	+= processor.o
 obj-$(CONFIG_ACPI)		+= container.o
+obj-$(CONFIG_ACPI_THERMAL_LIB)	+= thermal_lib.o
 obj-$(CONFIG_ACPI_THERMAL)	+= thermal.o
 obj-$(CONFIG_ACPI_PLATFORM_PROFILE) 	+= platform_profile.o
 obj-$(CONFIG_ACPI_NFIT)		+= nfit/
diff --git a/drivers/acpi/thermal_lib.c b/drivers/acpi/thermal_lib.c
new file mode 100644
index 0000000000000..43eaf0f2ff49b
--- /dev/null
+++ b/drivers/acpi/thermal_lib.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2023 Linaro Limited
+ * Copyright 2023 Intel Corporation
+ *
+ * Library routines for populating a generic thermal trip point structure
+ * with data obtained by evaluating a specific object in the ACPI Namespace.
+ */
+#include <linux/acpi.h>
+#include <linux/units.h>
+#include <linux/thermal.h>
+
+/*
+ * Minimum temperature for full military grade is 218°K (-55°C) and
+ * max temperature is 448°K (175°C). We can consider those values as
+ * the boundaries for the [trips] temperature returned by the
+ * firmware. Any values out of these boundaries may be considered
+ * bogus and we can assume the firmware has no data to provide.
+ */
+#define TEMP_MIN_DECIK	2180
+#define TEMP_MAX_DECIK	4480
+
+static int thermal_acpi_trip_temp(struct acpi_device *adev, char *obj_name,
+				  int *ret_temp)
+{
+	unsigned long long temp;
+	acpi_status status;
+
+	status = acpi_evaluate_integer(adev->handle, obj_name, NULL, &temp);
+	if (ACPI_FAILURE(status)) {
+		acpi_handle_debug(adev->handle, "%s evaluation failed\n", obj_name);
+		return -ENODATA;
+	}
+
+	if (temp >= TEMP_MIN_DECIK && temp <= TEMP_MAX_DECIK) {
+		*ret_temp = deci_kelvin_to_millicelsius(temp);
+	} else {
+		acpi_handle_debug(adev->handle, "%s result %llu out of range\n",
+				  obj_name, temp);
+		*ret_temp = THERMAL_TEMP_INVALID;
+	}
+
+	return 0;
+}
+
+/**
+ * thermal_acpi_active_trip_temp - Retrieve active trip point temperature
+ * @adev: Target thermal zone ACPI device object.
+ * @id: Active cooling level (0 - 9).
+ * @ret_temp: Address to store the retrieved temperature value on success.
+ *
+ * Evaluate the _ACx object for the thermal zone represented by @adev to obtain
+ * the temperature of the active cooling trip point corresponding to the active
+ * cooling level given by @id.
+ *
+ * Return 0 on success or a negative error value on failure.
+ */
+int thermal_acpi_active_trip_temp(struct acpi_device *adev, int id, int *ret_temp)
+{
+	char obj_name[] = {'_', 'A', 'C', '0' + id, '\0'};
+
+	if (id < 0 || id > 9)
+		return -EINVAL;
+
+	return thermal_acpi_trip_temp(adev, obj_name, ret_temp);
+}
+EXPORT_SYMBOL_GPL(thermal_acpi_active_trip_temp);
+
+/**
+ * thermal_acpi_passive_trip_temp - Retrieve passive trip point temperature
+ * @adev: Target thermal zone ACPI device object.
+ * @ret_temp: Address to store the retrieved temperature value on success.
+ *
+ * Evaluate the _PSV object for the thermal zone represented by @adev to obtain
+ * the temperature of the passive cooling trip point.
+ *
+ * Return 0 on success or -ENODATA on failure.
+ */
+int thermal_acpi_passive_trip_temp(struct acpi_device *adev, int *ret_temp)
+{
+	return thermal_acpi_trip_temp(adev, "_PSV", ret_temp);
+}
+EXPORT_SYMBOL_GPL(thermal_acpi_passive_trip_temp);
+
+/**
+ * thermal_acpi_hot_trip_temp - Retrieve hot trip point temperature
+ * @adev: Target thermal zone ACPI device object.
+ * @ret_temp: Address to store the retrieved temperature value on success.
+ *
+ * Evaluate the _HOT object for the thermal zone represented by @adev to obtain
+ * the temperature of the trip point at which the system is expected to be put
+ * into the S4 sleep state.
+ *
+ * Return 0 on success or -ENODATA on failure.
+ */
+int thermal_acpi_hot_trip_temp(struct acpi_device *adev, int *ret_temp)
+{
+	return thermal_acpi_trip_temp(adev, "_HOT", ret_temp);
+}
+EXPORT_SYMBOL_GPL(thermal_acpi_hot_trip_temp);
+
+/**
+ * thermal_acpi_critical_trip_temp - Retrieve critical trip point temperature
+ * @adev: Target thermal zone ACPI device object.
+ * @ret_temp: Address to store the retrieved temperature value on success.
+ *
+ * Evaluate the _CRT object for the thermal zone represented by @adev to obtain
+ * the temperature of the critical cooling trip point.
+ *
+ * Return 0 on success or -ENODATA on failure.
+ */
+int thermal_acpi_critical_trip_temp(struct acpi_device *adev, int *ret_temp)
+{
+	return thermal_acpi_trip_temp(adev, "_CRT", ret_temp);
+}
+EXPORT_SYMBOL_GPL(thermal_acpi_critical_trip_temp);