// 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>

#define PREFIX "ACPI: "

#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
#define CPUFREQ_THERMAL_MAX_STEP 3

static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);

#define reduction_pctg(cpu) \
        per_cpu(cpufreq_thermal_reduction_pctg, 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 int cpu_has_cpufreq(unsigned int cpu)
{
        struct cpufreq_policy policy;
        if (!acpi_processor_cpufreq_init || cpufreq_get_policy(&policy, cpu))
                return 0;
        return 1;
}

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_pctg(cpu);
}

static int cpufreq_set_cur_state(unsigned int cpu, int state)
{
        struct cpufreq_policy *policy;
        struct acpi_processor *pr;
        unsigned long max_freq;
        int i, ret;

        if (!cpu_has_cpufreq(cpu))
                return 0;

        reduction_pctg(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;

                policy = cpufreq_cpu_get(i);
                if (!policy)
                        return -EINVAL;

                max_freq = (policy->cpuinfo.max_freq * (100 - reduction_pctg(i) * 20)) / 100;

                cpufreq_cpu_put(policy);

                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 0;
}

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

        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);
        }
}

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, policy->cpu);

                if (pr)
                        freq_qos_remove_request(&pr->thermal_req);
        }
}
#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_pctg. 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,
};