linux/drivers/thermal/intel/int340x_thermal/platform_temperature_control.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * processor thermal device platform temperature controls
 * Copyright (c) 2025, Intel Corporation.
 */

/*
 * Platform temperature controls hardware interface
 *
 * The hardware control interface is via MMIO offsets in the processor
 * thermal device MMIO space. There are three instances of MMIO registers.
 * All registers are 64 bit wide with RW access.
 *
 * Name: PLATFORM_TEMPERATURE_CONTROL
 * Offsets: 0x5B20, 0x5B28, 0x5B30
 *
 *   Bits    Description
 *   7:0     TARGET_TEMP : Target temperature limit to which the control
 *           mechanism is regulating. Units: 0.5C.
 *   8:8     ENABLE: Read current enable status of the feature or enable
 *           feature.
 *   11:9    GAIN: Sets the aggressiveness of control loop from 0 to 7
 *           7 graceful, favors performance at the expense of temperature
 *           overshoots
 *           0 aggressive, favors tight regulation over performance
 *   12:12   TEMPERATURE_OVERRIDE_EN
 *           When set, hardware will use TEMPERATURE_OVERRIDE values instead
 *           of reading from corresponding sensor.
 *   15:13   RESERVED
 *   23:16   MIN_PERFORMANCE_LEVEL: Minimum Performance level below which the
 *           there will be no throttling. 0 - all levels of throttling allowed
 *           including survivability actions. 255 - no throttling allowed.
 *   31:24   TEMPERATURE_OVERRIDE: Allows SW to override the input temperature.
 *           hardware will use this value instead of the sensor temperature.
 *           Units: 0.5C.
 *   63:32   RESERVED
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/pci.h>
#include "processor_thermal_device.h"

struct mmio_reg {
	int bits;
	u16 mask;
	u16 shift;
	u16 units;
};

#define MAX_ATTR_GROUP_NAME_LEN	32
#define PTC_MAX_ATTRS		4

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;
	struct device_attribute enable_attr;
	struct device_attribute thermal_tolerance_attr;
	char group_name[MAX_ATTR_GROUP_NAME_LEN];
};

static const struct mmio_reg ptc_mmio_regs[] = {
	{ 8, 0xFF, 0, 500}, /* temperature_target, units 0.5C*/
	{ 1, 0x01, 8, 0}, /* enable */
	{ 3, 0x7, 9, 0}, /* gain */
	{ 8, 0xFF, 16, 0}, /* min_performance_level */
	{ 1, 0x1, 12, 0}, /* temperature_override_enable */
	{ 8, 0xFF, 24, 500}, /* temperature_override, units 0.5C */
};

#define PTC_MAX_INSTANCES	3

/* Unique offset for each PTC instance */
static u32 ptc_offsets[PTC_MAX_INSTANCES] = {0x5B20, 0x5B28, 0x5B30};

/* These will represent sysfs attribute names */
static const char * const ptc_strings[] = {
	"temperature_target",
	"enable",
	"thermal_tolerance",
	NULL
};

/* Lock to protect concurrent read/write and read-modify-write */
static DEFINE_MUTEX(ptc_lock);

static ssize_t ptc_mmio_show(struct ptc_data *data, struct device *dev,
			     struct device_attribute *attr, char *buf)
{
	struct pci_dev *pdev = to_pci_dev(dev);
	struct proc_thermal_device *proc_priv;
	const struct mmio_reg *mmio_regs;
	int ret, units;
	u64 reg_val;

	proc_priv = pci_get_drvdata(pdev);
	mmio_regs = ptc_mmio_regs;
	ret = match_string(ptc_strings, -1, attr->attr.name);
	if (ret < 0)
		return ret;

	units = mmio_regs[ret].units;

	guard(mutex)(&ptc_lock);

	reg_val = readq((void __iomem *) (proc_priv->mmio_base + data->offset));
	ret = (reg_val >> mmio_regs[ret].shift) & mmio_regs[ret].mask;
	if (units)
		ret *= units;

	return sysfs_emit(buf, "%d\n", ret);
}

#define PTC_SHOW(suffix)\
static ssize_t suffix##_show(struct device *dev,\
			     struct device_attribute *attr,\
			     char *buf)\
{\
	struct ptc_data *data = container_of(attr, struct ptc_data, suffix##_attr);\
	return ptc_mmio_show(data, dev, attr, buf);\
}

static void ptc_mmio_write(struct pci_dev *pdev, u32 offset, int index, u32 value)
{
	struct proc_thermal_device *proc_priv;
	u64 mask, reg_val;

	proc_priv = pci_get_drvdata(pdev);

	mask = GENMASK_ULL(ptc_mmio_regs[index].shift + ptc_mmio_regs[index].bits - 1,
			   ptc_mmio_regs[index].shift);

	guard(mutex)(&ptc_lock);

	reg_val = readq((void __iomem *) (proc_priv->mmio_base + offset));
	reg_val &= ~mask;
	reg_val |= (value << ptc_mmio_regs[index].shift);
	writeq(reg_val, (void __iomem *) (proc_priv->mmio_base + offset));
}

static int ptc_store(struct ptc_data *data, struct device *dev, struct device_attribute *attr,
		     const char *buf,  size_t count)
{
	struct pci_dev *pdev = to_pci_dev(dev);
	unsigned int input;
	int ret;

	ret = kstrtouint(buf, 10, &input);
	if (ret)
		return ret;

	ret = match_string(ptc_strings, -1, attr->attr.name);
	if (ret < 0)
		return ret;

	if (ptc_mmio_regs[ret].units)
		input /= ptc_mmio_regs[ret].units;

	if (input > ptc_mmio_regs[ret].mask)
		return -EINVAL;

	ptc_mmio_write(pdev, data->offset, ret, input);

	return count;
}

#define PTC_STORE(suffix)\
static ssize_t suffix##_store(struct device *dev,\
			      struct device_attribute *attr,\
			      const char *buf, size_t count)\
{\
	struct ptc_data *data = container_of(attr, struct ptc_data, suffix##_attr);\
	return ptc_store(data, dev, attr, buf, count);\
}

PTC_SHOW(temperature_target);
PTC_STORE(temperature_target);
PTC_SHOW(enable);
PTC_STORE(enable);
PTC_SHOW(thermal_tolerance);
PTC_STORE(thermal_tolerance);

#define ptc_init_attribute(_name)\
	do {\
		sysfs_attr_init(&data->_name##_attr.attr);\
		data->_name##_attr.show = _name##_show;\
		data->_name##_attr.store = _name##_store;\
		data->_name##_attr.attr.name = #_name;\
		data->_name##_attr.attr.mode = 0644;\
	} while (0)

static int ptc_create_groups(struct pci_dev *pdev, int instance, struct ptc_data *data)
{
	int ret, index = 0;

	ptc_init_attribute(temperature_target);
	ptc_init_attribute(enable);
	ptc_init_attribute(thermal_tolerance);

	data->ptc_attrs[index++] = &data->temperature_target_attr.attr;
	data->ptc_attrs[index++] = &data->enable_attr.attr;
	data->ptc_attrs[index++] = &data->thermal_tolerance_attr.attr;
	data->ptc_attrs[index] = NULL;

	snprintf(data->group_name, MAX_ATTR_GROUP_NAME_LEN,
		"ptc_%d_control", instance);
	data->ptc_attr_group.name = data->group_name;
	data->ptc_attr_group.attrs = data->ptc_attrs;

	ret = sysfs_create_group(&pdev->dev.kobj, &data->ptc_attr_group);

	return ret;
}

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)
{
	if (proc_priv->mmio_feature_mask & PROC_THERMAL_FEATURE_PTC) {
		int i;

		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;
}
EXPORT_SYMBOL_GPL(proc_thermal_ptc_add);

void proc_thermal_ptc_remove(struct pci_dev *pdev)
{
	struct proc_thermal_device *proc_priv = pci_get_drvdata(pdev);

	if (proc_priv->mmio_feature_mask & PROC_THERMAL_FEATURE_PTC) {
		int i;

		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);

MODULE_IMPORT_NS("INT340X_THERMAL");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Processor Thermal PTC Interface");