thermal: intel: int340x: Allow temperature override

JIRA: https://issues.redhat.com/browse/RHEL-85463

commit ea78eed
Author: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Date:   Fri Jun 13 14:49:23 2025 -0700

    thermal: intel: int340x: Allow temperature override

    Add debugfs interface to override hardware provide temperature. This
    interface can be used primarily for debug. Alternatively this can
    be also used to use hardware control loops to manage temperature for
    virtual sensors. Virtual sensors are soft sensors created by kernel/
    user space aggregating other sensors.

    There are three attributes to override the maximum three instances of
    platform temperature control.
    /sys/kernel/debug/platform_temperature_control/
    ├── temperature_0
    ├── temperature_1
    └── temperature_2

    These are write only attributes requires admin privilege. Any value
    greater than 0, will override the temperature. A value of 0 will
    stop overriding the temperature.

    Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
    Reviewed-by: Zhang Rui <rui.zhang@intel.com>
    Link: https://patch.msgid.link/20250613214923.2910397-2-srinivas.pandruvada@linux.intel.com
    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Signed-off-by: David Arcari <darcari@redhat.com>

Author: darcari

drivers/thermal/intel/int340x_thermal/platform_temperature_control.c

@@ -38,6 +38,7 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/debugfs.h>
 #include <linux/pci.h>
 #include "processor_thermal_device.h"
 
@@ -53,6 +54,7 @@ struct mmio_reg {
 
 struct ptc_data {
 	u32 offset;
+	struct pci_dev *pdev;
 	struct attribute_group ptc_attr_group;
 	struct attribute *ptc_attrs[PTC_MAX_ATTRS];
 	struct device_attribute temperature_target_attr;
@@ -215,6 +217,63 @@ static int ptc_create_groups(struct pci_dev *pdev, int instance, struct ptc_data
 }
 
 static struct ptc_data ptc_instance[PTC_MAX_INSTANCES];
+static struct dentry *ptc_debugfs;
+
+#define PTC_TEMP_OVERRIDE_ENABLE_INDEX	4
+#define PTC_TEMP_OVERRIDE_INDEX		5
+
+static ssize_t ptc_temperature_write(struct file *file, const char __user *data,
+				     size_t count, loff_t *ppos)
+{
+	struct ptc_data *ptc_instance = file->private_data;
+	struct pci_dev *pdev = ptc_instance->pdev;
+	char buf[32];
+	ssize_t len;
+	u32 value;
+
+	len = min(count, sizeof(buf) - 1);
+	if (copy_from_user(buf, data, len))
+		return -EFAULT;
+
+	buf[len] = '\0';
+	if (kstrtouint(buf, 0, &value))
+		return -EINVAL;
+
+	if (ptc_mmio_regs[PTC_TEMP_OVERRIDE_INDEX].units)
+		value /= ptc_mmio_regs[PTC_TEMP_OVERRIDE_INDEX].units;
+
+	if (value > ptc_mmio_regs[PTC_TEMP_OVERRIDE_INDEX].mask)
+		return -EINVAL;
+
+	if (!value) {
+		ptc_mmio_write(pdev, ptc_instance->offset, PTC_TEMP_OVERRIDE_ENABLE_INDEX, 0);
+	} else {
+		ptc_mmio_write(pdev, ptc_instance->offset, PTC_TEMP_OVERRIDE_INDEX, value);
+		ptc_mmio_write(pdev, ptc_instance->offset, PTC_TEMP_OVERRIDE_ENABLE_INDEX, 1);
+	}
+
+	return count;
+}
+
+static const struct file_operations ptc_fops = {
+	.open = simple_open,
+	.write = ptc_temperature_write,
+	.llseek = generic_file_llseek,
+};
+
+static void ptc_create_debugfs(void)
+{
+	ptc_debugfs = debugfs_create_dir("platform_temperature_control", NULL);
+
+	debugfs_create_file("temperature_0",  0200, ptc_debugfs,  &ptc_instance[0], &ptc_fops);
+	debugfs_create_file("temperature_1",  0200, ptc_debugfs,  &ptc_instance[1], &ptc_fops);
+	debugfs_create_file("temperature_2",  0200, ptc_debugfs,  &ptc_instance[2], &ptc_fops);
+}
+
+static void ptc_delete_debugfs(void)
+{
+	debugfs_remove_recursive(ptc_debugfs);
+}
 
 int proc_thermal_ptc_add(struct pci_dev *pdev, struct proc_thermal_device *proc_priv)
 {
@@ -223,8 +282,11 @@ int proc_thermal_ptc_add(struct pci_dev *pdev, struct proc_thermal_device *proc_
 
 		for (i = 0; i < PTC_MAX_INSTANCES; i++) {
 			ptc_instance[i].offset = ptc_offsets[i];
+			ptc_instance[i].pdev = pdev;
 			ptc_create_groups(pdev, i, &ptc_instance[i]);
 		}
+
+		ptc_create_debugfs();
 	}
 
 	return 0;
@@ -240,6 +302,8 @@ void proc_thermal_ptc_remove(struct pci_dev *pdev)
 
 		for (i = 0; i < PTC_MAX_INSTANCES; i++)
 			sysfs_remove_group(&pdev->dev.kobj, &ptc_instance[i].ptc_attr_group);
+
+		ptc_delete_debugfs();
 	}
 }
 EXPORT_SYMBOL_GPL(proc_thermal_ptc_remove);