// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * processor_thermal.c - Passive cooling submodule of the ACPI processor driver
 *
 *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *  Copyright (C) 2004       Dominik Brodowski <linux@brodo.de>
 *  Copyright (C) 2004  Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
 *                      - Added processor hotplug support
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/acpi.h>
#include <acpi/processor.h>
#include <linux/uaccess.h>

#include "internal.h"

#ifdef CONFIG_CPU_FREQ

/* If a passive cooling situation is detected, primarily CPUfreq is used, as it
 * offers (in most cases) voltage scaling in addition to frequency scaling, and
 * thus a cubic (instead of linear) reduction of energy. Also, we allow for
 * _any_ cpufreq driver and not only the acpi-cpufreq driver.
 */

#define CPUFREQ_THERMAL_MIN_STEP 0

static int cpufreq_thermal_max_step __read_mostly = 3;

/*
 * Minimum throttle percentage for processor_thermal cooling device.
 * The processor_thermal driver uses it to calculate the percentage amount by
 * which cpu frequency must be reduced for each cooling state. This is also used
 * to calculate the maximum number of throttling steps or cooling states.
 */
static int cpufreq_thermal_reduction_pctg __read_mostly = 20;

static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_step);

#define reduction_step(cpu) \
        per_cpu(cpufreq_thermal_reduction_step, phys_package_first_cpu(cpu))

/*
 * Emulate "per package data" using per cpu data (which should really be
 * provided elsewhere)
 *
 * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
 * temporarily. Fortunately that's not a big issue here (I hope)
 */
static int phys_package_first_cpu(int cpu)
{
        int i;
        int id = topology_physical_package_id(cpu);

        for_each_online_cpu(i)
                if (topology_physical_package_id(i) == id)
                        return i;
        return 0;
}

static bool cpu_has_cpufreq(unsigned int cpu)
{
        if (!acpi_processor_cpufreq_init)
                return 0;

        struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpu);

        return policy != NULL;
}

static int cpufreq_get_max_state(unsigned int cpu)
{
        if (!cpu_has_cpufreq(cpu))
                return 0;

        return cpufreq_thermal_max_step;
}

static int cpufreq_get_cur_state(unsigned int cpu)
{
        if (!cpu_has_cpufreq(cpu))
                return 0;

        return reduction_step(cpu);
}

static bool cpufreq_update_thermal_limit(unsigned int cpu, struct acpi_processor *pr)
{
        unsigned long max_freq;
        int ret;

        struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpu);
        if (!policy)
                return false;

        max_freq = (policy->cpuinfo.max_freq *
                (100 - reduction_step(cpu) * cpufreq_thermal_reduction_pctg)) / 100;

        ret = freq_qos_update_request(&pr->thermal_req, max_freq);
        if (ret < 0) {
                pr_warn("Failed to update thermal freq constraint: CPU%d (%d)\n",
                        pr->id, ret);
        }

        return true;
}

static int cpufreq_set_cur_state(unsigned int cpu, int state)
{
        struct acpi_processor *pr;
        int i;

        if (!cpu_has_cpufreq(cpu))
                return 0;

        reduction_step(cpu) = state;

        /*
         * Update all the CPUs in the same package because they all
         * contribute to the temperature and often share the same
         * frequency.
         */
        for_each_online_cpu(i) {
                if (topology_physical_package_id(i) !=
                    topology_physical_package_id(cpu))
                        continue;

                pr = per_cpu(processors, i);

                if (unlikely(!freq_qos_request_active(&pr->thermal_req)))
                        continue;

                if (!cpufreq_update_thermal_limit(i, pr))
                        return -EINVAL;
        }
        return 0;
}

static void acpi_thermal_cpufreq_config(void)
{
        int cpufreq_pctg = acpi_arch_thermal_cpufreq_pctg();

        if (!cpufreq_pctg)
                return;

        cpufreq_thermal_reduction_pctg = cpufreq_pctg;

        /*
         * Derive the MAX_STEP from minimum throttle percentage so that the reduction
         * percentage doesn't end up becoming negative. Also, cap the MAX_STEP so that
         * the CPU performance doesn't become 0.
         */
        cpufreq_thermal_max_step = (100 / cpufreq_pctg) - 2;
}

void acpi_thermal_cpufreq_init(struct cpufreq_policy *policy)
{
        unsigned int cpu;

        acpi_thermal_cpufreq_config();

        for_each_cpu(cpu, policy->related_cpus) {
                struct acpi_processor *pr = per_cpu(processors, cpu);
                int ret;

                if (!pr)
                        continue;

                ret = freq_qos_add_request(&policy->constraints,
                                           &pr->thermal_req,
                                           FREQ_QOS_MAX, INT_MAX);
                if (ret < 0) {
                        pr_err("Failed to add freq constraint for CPU%d (%d)\n",
                               cpu, ret);
                        continue;
                }

                thermal_cooling_device_update(pr->cdev);
        }
}

void acpi_thermal_cpufreq_exit(struct cpufreq_policy *policy)
{
        unsigned int cpu;

        for_each_cpu(cpu, policy->related_cpus) {
                struct acpi_processor *pr = per_cpu(processors, cpu);

                if (!pr)
                        continue;

                freq_qos_remove_request(&pr->thermal_req);

                thermal_cooling_device_update(pr->cdev);
        }
}
#else                           /* ! CONFIG_CPU_FREQ */
static int cpufreq_get_max_state(unsigned int cpu)
{
        return 0;
}

static int cpufreq_get_cur_state(unsigned int cpu)
{
        return 0;
}

static int cpufreq_set_cur_state(unsigned int cpu, int state)
{
        return 0;
}

#endif

/* thermal cooling device callbacks */
static int acpi_processor_max_state(struct acpi_processor *pr)
{
        int max_state = 0;

        /*
         * There exists four states according to
         * cpufreq_thermal_reduction_step. 0, 1, 2, 3
         */
        max_state += cpufreq_get_max_state(pr->id);
        if (pr->flags.throttling)
                max_state += (pr->throttling.state_count -1);

        return max_state;
}
static int
processor_get_max_state(struct thermal_cooling_device *cdev,
                        unsigned long *state)
{
        struct acpi_device *device = cdev->devdata;
        struct acpi_processor *pr;

        if (!device)
                return -EINVAL;

        pr = acpi_driver_data(device);
        if (!pr)
                return -EINVAL;

        *state = acpi_processor_max_state(pr);
        return 0;
}

static int
processor_get_cur_state(struct thermal_cooling_device *cdev,
                        unsigned long *cur_state)
{
        struct acpi_device *device = cdev->devdata;
        struct acpi_processor *pr;

        if (!device)
                return -EINVAL;

        pr = acpi_driver_data(device);
        if (!pr)
                return -EINVAL;

        *cur_state = cpufreq_get_cur_state(pr->id);
        if (pr->flags.throttling)
                *cur_state += pr->throttling.state;
        return 0;
}

static int
processor_set_cur_state(struct thermal_cooling_device *cdev,
                        unsigned long state)
{
        struct acpi_device *device = cdev->devdata;
        struct acpi_processor *pr;
        int result = 0;
        int max_pstate;

        if (!device)
                return -EINVAL;

        pr = acpi_driver_data(device);
        if (!pr)
                return -EINVAL;

        max_pstate = cpufreq_get_max_state(pr->id);

        if (state > acpi_processor_max_state(pr))
                return -EINVAL;

        if (state <= max_pstate) {
                if (pr->flags.throttling && pr->throttling.state)
                        result = acpi_processor_set_throttling(pr, 0, false);
                cpufreq_set_cur_state(pr->id, state);
        } else {
                cpufreq_set_cur_state(pr->id, max_pstate);
                result = acpi_processor_set_throttling(pr,
                                state - max_pstate, false);
        }
        return result;
}

const struct thermal_cooling_device_ops processor_cooling_ops = {
        .get_max_state = processor_get_max_state,
        .get_cur_state = processor_get_cur_state,
        .set_cur_state = processor_set_cur_state,
};

int acpi_processor_thermal_init(struct acpi_processor *pr,
                                struct acpi_device *device)
{
        int result = 0;

        pr->cdev = thermal_cooling_device_register("Processor", device,
                                                   &processor_cooling_ops);
        if (IS_ERR(pr->cdev)) {
                result = PTR_ERR(pr->cdev);
                return result;
        }

        dev_dbg(&device->dev, "registered as cooling_device%d\n",
                pr->cdev->id);

        result = sysfs_create_link(&device->dev.kobj,
                                   &pr->cdev->device.kobj,
                                   "thermal_cooling");
        if (result) {
                dev_err(&device->dev,
                        "Failed to create sysfs link 'thermal_cooling'\n");
                goto err_thermal_unregister;
        }

        result = sysfs_create_link(&pr->cdev->device.kobj,
                                   &device->dev.kobj,
                                   "device");
        if (result) {
                dev_err(&pr->cdev->device,
                        "Failed to create sysfs link 'device'\n");
                goto err_remove_sysfs_thermal;
        }

        return 0;

err_remove_sysfs_thermal:
        sysfs_remove_link(&device->dev.kobj, "thermal_cooling");
err_thermal_unregister:
        thermal_cooling_device_unregister(pr->cdev);

        return result;
}

void acpi_processor_thermal_exit(struct acpi_processor *pr,
                                 struct acpi_device *device)
{
        if (pr->cdev) {
                sysfs_remove_link(&device->dev.kobj, "thermal_cooling");
                sysfs_remove_link(&pr->cdev->device.kobj, "device");
                thermal_cooling_device_unregister(pr->cdev);
                pr->cdev = NULL;
        }
}