Contributors: 4
Author Tokens Token Proportion Commits Commit Proportion
Srinivas Pandruvada 940 98.22% 13 72.22%
Rui Zhang 15 1.57% 3 16.67%
Thomas Gleixner 1 0.10% 1 5.56%
Peter Zijlstra 1 0.10% 1 5.56%
Total 957 18 


// SPDX-License-Identifier: GPL-2.0-only
/*
 * Processor Thermal Device Interface for Reading and Writing
 * SoC Power Slider Values from User Space.
 *
 * Operation:
 * The SOC_EFFICIENCY_SLIDER_0_0_0_MCHBAR register is accessed
 * using the MMIO (Memory-Mapped I/O) interface with an MMIO offset of 0x5B38.
 * Although this register is 64 bits wide, only bits 7:0 are used,
 * and the other bits remain unchanged.
 *
 * Bit definitions
 *
 * Bits 2:0 (Slider value):
 * The SoC optimizer slider value indicates the system wide energy performance
 * hint. The slider has no specific units and ranges from 0 (highest
 * performance) to 6 (highest energy efficiency). Value of 7 is reserved.
 * Bits 3 : Reserved
 * Bits 6:4 (Offset)
 * Offset allows the SoC to automatically switch slider position in range
 * [slider value (bits 2:0) + offset] to improve power efficiency based on
 * internal SoC algorithms.
 * Bit 7 (Enable):
 * If this bit is set, the SoC Optimization sliders will be processed by the
 * SoC firmware.
 *
 * Copyright (c) 2025, Intel Corporation.
 */

#include <linux/bitfield.h>
#include <linux/pci.h>
#include <linux/platform_profile.h>
#include "processor_thermal_device.h"

#define SOC_POWER_SLIDER_OFFSET	0x5B38

enum power_slider_preference {
	SOC_POWER_SLIDER_PERFORMANCE,
	SOC_POWER_SLIDER_BALANCE,
	SOC_POWER_SLIDER_POWERSAVE,
};

#define SOC_SLIDER_VALUE_MINIMUM	0x00
#define SOC_SLIDER_VALUE_BALANCE	0x03
#define SOC_SLIDER_VALUE_MAXIMUM	0x06

#define SLIDER_MASK		GENMASK_ULL(2, 0)
#define SLIDER_ENABLE_BIT	7

static u8 slider_values[] = {
	[SOC_POWER_SLIDER_PERFORMANCE] = SOC_SLIDER_VALUE_MINIMUM,
	[SOC_POWER_SLIDER_BALANCE] = SOC_SLIDER_VALUE_BALANCE,
	[SOC_POWER_SLIDER_POWERSAVE] = SOC_SLIDER_VALUE_MAXIMUM,
};

/* Lock to protect module param updates */
static DEFINE_MUTEX(slider_param_lock);

static int slider_balanced_param = SOC_SLIDER_VALUE_BALANCE;

static int slider_def_balance_set(const char *arg, const struct kernel_param *kp)
{
	u8 slider_val;
	int ret;

	guard(mutex)(&slider_param_lock);

	ret = kstrtou8(arg, 16, &slider_val);
	if (!ret) {
		if (slider_val <= slider_values[SOC_POWER_SLIDER_PERFORMANCE] ||
		    slider_val >= slider_values[SOC_POWER_SLIDER_POWERSAVE])
			return -EINVAL;

		slider_balanced_param = slider_val;
	}

	return ret;
}

static int slider_def_balance_get(char *buf, const struct kernel_param *kp)
{
	guard(mutex)(&slider_param_lock);
	return sysfs_emit(buf, "%02x\n", slider_values[SOC_POWER_SLIDER_BALANCE]);
}

static const struct kernel_param_ops slider_def_balance_ops = {
	.set = slider_def_balance_set,
	.get = slider_def_balance_get,
};

module_param_cb(slider_balance, &slider_def_balance_ops, NULL, 0644);
MODULE_PARM_DESC(slider_balance, "Set slider default value for balance");

static u8 slider_offset;

static int slider_def_offset_set(const char *arg, const struct kernel_param *kp)
{
	u8 offset;
	int ret;

	guard(mutex)(&slider_param_lock);

	ret = kstrtou8(arg, 16, &offset);
	if (!ret) {
		if (offset > SOC_SLIDER_VALUE_MAXIMUM)
			return -EINVAL;

		slider_offset = offset;
	}

	return ret;
}

static int slider_def_offset_get(char *buf, const struct kernel_param *kp)
{
	guard(mutex)(&slider_param_lock);
	return sysfs_emit(buf, "%02x\n", slider_offset);
}

static const struct kernel_param_ops slider_offset_ops = {
	.set = slider_def_offset_set,
	.get = slider_def_offset_get,
};

/*
 * To enhance power efficiency dynamically, the firmware can optionally
 * auto-adjust the slider value based on the current workload. This
 * adjustment is controlled by the "slider_offset" module parameter.
 * This offset permits the firmware to increase the slider value
 * up to and including "SoC slider + slider offset,".
 */
module_param_cb(slider_offset, &slider_offset_ops, NULL, 0644);
MODULE_PARM_DESC(slider_offset, "Set slider offset");

/* Convert from platform power profile option to SoC slider value */
static int convert_profile_to_power_slider(enum platform_profile_option profile)
{
	switch (profile) {
	case PLATFORM_PROFILE_LOW_POWER:
		return slider_values[SOC_POWER_SLIDER_POWERSAVE];
	case PLATFORM_PROFILE_BALANCED:
		return slider_values[SOC_POWER_SLIDER_BALANCE];
	case PLATFORM_PROFILE_PERFORMANCE:
		return slider_values[SOC_POWER_SLIDER_PERFORMANCE];
	default:
		break;
	}

	return -EOPNOTSUPP;
}

/* Convert to platform power profile option from SoC slider values */
static int convert_power_slider_to_profile(u8 slider)
{
	if (slider == slider_values[SOC_POWER_SLIDER_PERFORMANCE])
		return PLATFORM_PROFILE_PERFORMANCE;
	if (slider == slider_values[SOC_POWER_SLIDER_BALANCE])
		return PLATFORM_PROFILE_BALANCED;
	if (slider == slider_values[SOC_POWER_SLIDER_POWERSAVE])
		return PLATFORM_PROFILE_LOW_POWER;

	return -EOPNOTSUPP;
}

static inline u64 read_soc_slider(struct proc_thermal_device *proc_priv)
{
	return readq(proc_priv->mmio_base + SOC_POWER_SLIDER_OFFSET);
}

static inline void write_soc_slider(struct proc_thermal_device *proc_priv, u64 val)
{
	writeq(val, proc_priv->mmio_base + SOC_POWER_SLIDER_OFFSET);
}

#define SLIDER_OFFSET_MASK	GENMASK_ULL(6, 4)

static void set_soc_power_profile(struct proc_thermal_device *proc_priv, int slider)
{
	u64 val;

	val = read_soc_slider(proc_priv);
	val &= ~SLIDER_MASK;
	val |= FIELD_PREP(SLIDER_MASK, slider) | BIT(SLIDER_ENABLE_BIT);

	/* Set the slider offset from module params */
	val &= ~SLIDER_OFFSET_MASK;
	val |= FIELD_PREP(SLIDER_OFFSET_MASK, slider_offset);

	write_soc_slider(proc_priv, val);
}

/* profile get/set callbacks are called with a profile lock, so no need for local locks */

static int power_slider_platform_profile_set(struct device *dev,
					     enum platform_profile_option profile)
{
	struct proc_thermal_device *proc_priv;
	int slider;

	proc_priv = dev_get_drvdata(dev);
	if (!proc_priv)
		return -EOPNOTSUPP;

	guard(mutex)(&slider_param_lock);

	slider_values[SOC_POWER_SLIDER_BALANCE] = slider_balanced_param;

	slider = convert_profile_to_power_slider(profile);
	if (slider < 0)
		return slider;

	set_soc_power_profile(proc_priv, slider);

	return 0;
}

static int power_slider_platform_profile_get(struct device *dev,
					     enum platform_profile_option *profile)
{
	struct proc_thermal_device *proc_priv;
	int slider, ret;
	u64 val;

	proc_priv = dev_get_drvdata(dev);
	if (!proc_priv)
		return -EOPNOTSUPP;

	val = read_soc_slider(proc_priv);
	slider = FIELD_GET(SLIDER_MASK, val);

	ret = convert_power_slider_to_profile(slider);
	if (ret < 0)
		return ret;

	*profile = ret;

	return 0;
}

static int power_slider_platform_profile_probe(void *drvdata, unsigned long *choices)
{
	set_bit(PLATFORM_PROFILE_LOW_POWER, choices);
	set_bit(PLATFORM_PROFILE_BALANCED, choices);
	set_bit(PLATFORM_PROFILE_PERFORMANCE, choices);

	return 0;
}

static const struct platform_profile_ops power_slider_platform_profile_ops = {
	.probe = power_slider_platform_profile_probe,
	.profile_get = power_slider_platform_profile_get,
	.profile_set = power_slider_platform_profile_set,
};

int proc_thermal_soc_power_slider_add(struct pci_dev *pdev, struct proc_thermal_device *proc_priv)
{
	struct device *ppdev;

	set_soc_power_profile(proc_priv, slider_values[SOC_POWER_SLIDER_BALANCE]);

	ppdev = devm_platform_profile_register(&pdev->dev, "SoC Power Slider", proc_priv,
					       &power_slider_platform_profile_ops);

	return PTR_ERR_OR_ZERO(ppdev);
}
EXPORT_SYMBOL_NS_GPL(proc_thermal_soc_power_slider_add, "INT340X_THERMAL");

static u64 soc_slider_save;

void proc_thermal_soc_power_slider_suspend(struct proc_thermal_device *proc_priv)
{
	soc_slider_save = read_soc_slider(proc_priv);
}
EXPORT_SYMBOL_NS_GPL(proc_thermal_soc_power_slider_suspend, "INT340X_THERMAL");

void proc_thermal_soc_power_slider_resume(struct proc_thermal_device *proc_priv)
{
	write_soc_slider(proc_priv, soc_slider_save);
}
EXPORT_SYMBOL_NS_GPL(proc_thermal_soc_power_slider_resume, "INT340X_THERMAL");

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