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

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Processor thermal device module for registering and processing
 * power floor. When the hardware reduces the power to the minimum
 * possible, the power floor is notified via an interrupt.
 *
 * Operation:
 * When user space enables power floor reporting:
 * - Use mailbox to:
 *	Enable processor thermal device interrupt
 *
 * - Current status of power floor is read from offset 0x5B18
 *   bit 39.
 *
 * Two interface functions are provided to call when there is a
 * thermal device interrupt:
 * - proc_thermal_power_floor_intr():
 *	Check if the interrupt is for change in power floor.
 *	Called from interrupt context.
 *
 * - proc_thermal_power_floor_intr_callback():
 *	Callback for interrupt processing in thread context. This involves
 *	sending notification to user space that there is a change in the
 *	power floor status.
 *
 * Copyright (c) 2023, Intel Corporation.
 */

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

#define SOC_POWER_FLOOR_STATUS		BIT(39)
#define SOC_POWER_FLOOR_SHIFT		39

#define SOC_POWER_FLOOR_INT_ENABLE_BIT	31
#define SOC_POWER_FLOOR_INT_ACTIVE	BIT(3)

int proc_thermal_read_power_floor_status(struct proc_thermal_device *proc_priv)
{
	u64 status = 0;

	status = readq(proc_priv->mmio_base + SOC_WT_RES_INT_STATUS_OFFSET);
	return (status & SOC_POWER_FLOOR_STATUS) >> SOC_POWER_FLOOR_SHIFT;
}
EXPORT_SYMBOL_NS_GPL(proc_thermal_read_power_floor_status, INT340X_THERMAL);

static bool enable_state;
static DEFINE_MUTEX(pf_lock);

int proc_thermal_power_floor_set_state(struct proc_thermal_device *proc_priv, bool enable)
{
	int ret = 0;

	mutex_lock(&pf_lock);
	if (enable_state == enable)
		goto pf_unlock;

	/*
	 * Time window parameter is not applicable to power floor interrupt configuration.
	 * Hence use -1 for time window.
	 */
	ret = processor_thermal_mbox_interrupt_config(to_pci_dev(proc_priv->dev), enable,
						      SOC_POWER_FLOOR_INT_ENABLE_BIT, -1);
	if (!ret)
		enable_state = enable;

pf_unlock:
	mutex_unlock(&pf_lock);

	return ret;
}
EXPORT_SYMBOL_NS_GPL(proc_thermal_power_floor_set_state, INT340X_THERMAL);

bool proc_thermal_power_floor_get_state(struct proc_thermal_device *proc_priv)
{
	return enable_state;
}
EXPORT_SYMBOL_NS_GPL(proc_thermal_power_floor_get_state, INT340X_THERMAL);

/**
 * proc_thermal_check_power_floor_intr() - Check power floor interrupt.
 * @proc_priv: Processor thermal device instance.
 *
 * Callback to check if the interrupt for power floor is active.
 *
 * Context: Called from interrupt context.
 *
 * Return: true if power floor is active, false when not active.
 */
bool proc_thermal_check_power_floor_intr(struct proc_thermal_device *proc_priv)
{
	u64 int_status;

	int_status = readq(proc_priv->mmio_base + SOC_WT_RES_INT_STATUS_OFFSET);
	return !!(int_status & SOC_POWER_FLOOR_INT_ACTIVE);
}
EXPORT_SYMBOL_NS_GPL(proc_thermal_check_power_floor_intr, INT340X_THERMAL);

/**
 * proc_thermal_power_floor_intr_callback() - Process power floor notification
 * @pdev:	PCI device instance
 * @proc_priv: Processor thermal device instance.
 *
 * Check if the power floor interrupt is active, if active send notification to
 * user space for the attribute "power_limits", so that user can read the attribute
 * and take action.
 *
 * Context: Called from interrupt thread context.
 *
 * Return: None.
 */
void proc_thermal_power_floor_intr_callback(struct pci_dev *pdev,
					    struct proc_thermal_device *proc_priv)
{
	u64 status;

	status = readq(proc_priv->mmio_base + SOC_WT_RES_INT_STATUS_OFFSET);
	if (!(status & SOC_POWER_FLOOR_INT_ACTIVE))
		return;

	sysfs_notify(&pdev->dev.kobj, "power_limits", "power_floor_status");
}
EXPORT_SYMBOL_NS_GPL(proc_thermal_power_floor_intr_callback, INT340X_THERMAL);

MODULE_IMPORT_NS(INT340X_THERMAL);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Processor Thermal power floor notification Interface");