thermal/intel: Fix intel_tcc_get_temp() to support negative CPU temperature

CPU temperature can be negative in some cases. Thus the negative CPU
temperature should not be considered as a failure.

Fix intel_tcc_get_temp() and its users to support negative CPU
temperature.

Fixes: a3c1f06 ("thermal/intel: Introduce Intel TCC library")
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Cc: 6.3+ <stable@vger.kernel.org> # 6.3+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: zhang-rui

drivers/thermal/intel/int340x_thermal/processor_thermal_device.c

@@ -176,14 +176,14 @@ static int proc_thermal_get_zone_temp(struct thermal_zone_device *zone,
 					 int *temp)
 {
 	int cpu;
-	int curr_temp;
+	int curr_temp, ret;
 
 	*temp = 0;
 
 	for_each_online_cpu(cpu) {
-		curr_temp = intel_tcc_get_temp(cpu, false);
-		if (curr_temp < 0)
-			return curr_temp;
+		ret = intel_tcc_get_temp(cpu, &curr_temp, false);
+		if (ret < 0)
+			return ret;
 		if (!*temp || curr_temp > *temp)
 			*temp = curr_temp;
 	}

drivers/thermal/intel/intel_tcc.c

@@ -103,18 +103,19 @@ 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.
+ * @temp: pointer to the memory for saving cpu temperature.
  * @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.
+ * Return: 0 on success, negative error code otherwise.
  */
-int intel_tcc_get_temp(int cpu, bool pkg)
+int intel_tcc_get_temp(int cpu, int *temp, bool pkg)
 {
 	u32 low, high;
 	u32 msr = pkg ? MSR_IA32_PACKAGE_THERM_STATUS : MSR_IA32_THERM_STATUS;
-	int tjmax, temp, err;
+	int tjmax, err;
 
 	tjmax = intel_tcc_get_tjmax(cpu);
 	if (tjmax < 0)
@@ -131,9 +132,8 @@ int intel_tcc_get_temp(int cpu, bool pkg)
 	if (!(low & BIT(31)))
 		return -ENODATA;
 
-	temp = tjmax - ((low >> 16) & 0x7f);
+	*temp = tjmax - ((low >> 16) & 0x7f);
 
-	/* Do not allow negative CPU temperature */
-	return temp >= 0 ? temp : -ENODATA;
+	return 0;
 }
 EXPORT_SYMBOL_NS_GPL(intel_tcc_get_temp, INTEL_TCC);

drivers/thermal/intel/x86_pkg_temp_thermal.c

@@ -108,11 +108,11 @@ static struct zone_device *pkg_temp_thermal_get_dev(unsigned int cpu)
 static int sys_get_curr_temp(struct thermal_zone_device *tzd, int *temp)
 {
 	struct zone_device *zonedev = thermal_zone_device_priv(tzd);
-	int val;
+	int val, ret;
 
-	val = intel_tcc_get_temp(zonedev->cpu, true);
-	if (val < 0)
-		return val;
+	ret = intel_tcc_get_temp(zonedev->cpu, &val, true);
+	if (ret < 0)
+		return ret;
 
 	*temp = val * 1000;
 	pr_debug("sys_get_curr_temp %d\n", *temp);

include/linux/intel_tcc.h

@@ -13,6 +13,6 @@
 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);
+int intel_tcc_get_temp(int cpu, int *temp, bool pkg);
 
 #endif /* __INTEL_TCC_H__ */