thermal/intel: Introduce Intel TCC library

There are several different drivers that accesses the Intel TCC
(thermal control circuitry) MSRs, and each of them has its own
implementation for the same functionalities, e.g. getting the current
temperature, getting the tj_max, and getting/setting the tj_max offset.

Introduce a library to unify the code for Intel CPU TCC MSR access.

At the same time, ensure the temperature is got based on the updated
tjmax value because tjmax can be changed at runtime for cases like
the Intel SST-PP (Intel Speed Select Technology - Performance Profile)
level change.

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

drivers/thermal/intel/Kconfig

@@ -12,6 +12,10 @@ config X86_THERMAL_VECTOR
 	def_bool y
 	depends on X86 && CPU_SUP_INTEL && X86_LOCAL_APIC
 
+config INTEL_TCC
+	bool
+	depends on X86
+
 config X86_PKG_TEMP_THERMAL
 	tristate "X86 package temperature thermal driver"
 	depends on X86_THERMAL_VECTOR

drivers/thermal/intel/Makefile

@@ -2,6 +2,7 @@
 #
 # Makefile for various Intel thermal drivers.
 
+obj-$(CONFIG_INTEL_TCC)	+= intel_tcc.o
 obj-$(CONFIG_INTEL_POWERCLAMP)	+= intel_powerclamp.o
 obj-$(CONFIG_X86_PKG_TEMP_THERMAL)	+= x86_pkg_temp_thermal.o
 obj-$(CONFIG_INTEL_SOC_DTS_IOSF_CORE)	+= intel_soc_dts_iosf.o

drivers/thermal/intel/intel_tcc.c

@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * intel_tcc.c - Library for Intel TCC (thermal control circuitry) MSR access
+ * Copyright (c) 2022, Intel Corporation.
+ */
+
+#include <linux/errno.h>
+#include <linux/intel_tcc.h>
+#include <asm/msr.h>
+
+/**
+ * intel_tcc_get_tjmax() - returns the default TCC activation Temperature
+ * @cpu: cpu that the MSR should be run on, nagative value means any cpu.
+ *
+ * Get the TjMax value, which is the default thermal throttling or TCC
+ * activation temperature in degrees C.
+ *
+ * Return: Tjmax value in degrees C on success, negative error code otherwise.
+ */
+int intel_tcc_get_tjmax(int cpu)
+{
+	u32 low, high;
+	int val, err;
+
+	if (cpu < 0)
+		err = rdmsr_safe(MSR_IA32_TEMPERATURE_TARGET, &low, &high);
+	else
+		err = rdmsr_safe_on_cpu(cpu, MSR_IA32_TEMPERATURE_TARGET, &low, &high);
+	if (err)
+		return err;
+
+	val = (low >> 16) & 0xff;
+
+	return val ? val : -ENODATA;
+}
+EXPORT_SYMBOL_NS_GPL(intel_tcc_get_tjmax, INTEL_TCC);
+
+/**
+ * intel_tcc_get_offset() - returns the TCC Offset value to Tjmax
+ * @cpu: cpu that the MSR should be run on, nagative value means any cpu.
+ *
+ * Get the TCC offset value to Tjmax. The effective thermal throttling or TCC
+ * activation temperature equals "Tjmax" - "TCC Offset", in degrees C.
+ *
+ * Return: Tcc offset value in degrees C on success, negative error code otherwise.
+ */
+int intel_tcc_get_offset(int cpu)
+{
+	u32 low, high;
+	int err;
+
+	if (cpu < 0)
+		err = rdmsr_safe(MSR_IA32_TEMPERATURE_TARGET, &low, &high);
+	else
+		err = rdmsr_safe_on_cpu(cpu, MSR_IA32_TEMPERATURE_TARGET, &low, &high);
+	if (err)
+		return err;
+
+	return (low >> 24) & 0x3f;
+}
+EXPORT_SYMBOL_NS_GPL(intel_tcc_get_offset, INTEL_TCC);
+
+/**
+ * intel_tcc_set_offset() - set the TCC offset value to Tjmax
+ * @cpu: cpu that the MSR should be run on, nagative value means any cpu.
+ * @offset: TCC offset value in degree C
+ *
+ * Set the TCC Offset value to Tjmax. The effective thermal throttling or TCC
+ * activation temperature equals "Tjmax" - "TCC Offset", in degree C.
+ *
+ * Return: On success returns 0, negative error code otherwise.
+ */
+
+int intel_tcc_set_offset(int cpu, int offset)
+{
+	u32 low, high;
+	int err;
+
+	if (offset < 0 || offset > 0x3f)
+		return -EINVAL;
+
+	if (cpu < 0)
+		err = rdmsr_safe(MSR_IA32_TEMPERATURE_TARGET, &low, &high);
+	else
+		err = rdmsr_safe_on_cpu(cpu, MSR_IA32_TEMPERATURE_TARGET, &low, &high);
+	if (err)
+		return err;
+
+	/* MSR Locked */
+	if (low & BIT(31))
+		return -EPERM;
+
+	low &= ~(0x3f << 24);
+	low |= offset << 24;
+
+	if (cpu < 0)
+		return wrmsr_safe(MSR_IA32_TEMPERATURE_TARGET, low, high);
+	else
+		return wrmsr_safe_on_cpu(cpu, MSR_IA32_TEMPERATURE_TARGET, low, high);
+}
+EXPORT_SYMBOL_NS_GPL(intel_tcc_set_offset, INTEL_TCC);
+
+/**
+ * intel_tcc_get_temp() - returns the current temperature
+ * @cpu: cpu that the MSR should be run on, nagative value means any cpu.
+ * @pkg: true: Package Thermal Sensor. false: Core Thermal Sensor.
+ *
+ * Get the current temperature returned by the CPU core/package level
+ * thermal sensor, in degrees C.
+ *
+ * Return: Temperature in degrees C on success, negative error code otherwise.
+ */
+int intel_tcc_get_temp(int cpu, bool pkg)
+{
+	u32 low, high;
+	u32 msr = pkg ? MSR_IA32_PACKAGE_THERM_STATUS : MSR_IA32_THERM_STATUS;
+	int tjmax, temp, err;
+
+	tjmax = intel_tcc_get_tjmax(cpu);
+	if (tjmax < 0)
+		return tjmax;
+
+	if (cpu < 0)
+		err = rdmsr_safe(msr, &low, &high);
+	else
+		err = rdmsr_safe_on_cpu(cpu, msr, &low, &high);
+	if (err)
+		return err;
+
+	/* Temperature is beyond the valid thermal sensor range */
+	if (!(low & BIT(31)))
+		return -ENODATA;
+
+	temp = tjmax - ((low >> 16) & 0x7f);
+
+	/* Do not allow negative CPU temperature */
+	return temp >= 0 ? temp : -ENODATA;
+}
+EXPORT_SYMBOL_NS_GPL(intel_tcc_get_temp, INTEL_TCC);

include/linux/intel_tcc.h

@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *  header for Intel TCC (thermal control circuitry) library
+ *
+ *  Copyright (C) 2022  Intel Corporation.
+ */
+
+#ifndef __INTEL_TCC_H__
+#define __INTEL_TCC_H__
+
+#include <linux/types.h>
+
+int intel_tcc_get_tjmax(int cpu);
+int intel_tcc_get_offset(int cpu);
+int intel_tcc_set_offset(int cpu, int offset);
+int intel_tcc_get_temp(int cpu, bool pkg);
+
+#endif /* __INTEL_TCC_H__ */