// SPDX-License-Identifier: GPL-2.0-only
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/pm_qos.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>

#include "windfarm.h"

#define VERSION "0.3"

static int clamped;
static struct wf_control *clamp_control;
static struct freq_qos_request qos_req;
static unsigned int min_freq, max_freq;

static int clamp_set(struct wf_control *ct, s32 value)
{
        unsigned int freq;

        if (value) {
                freq = min_freq;
                printk(KERN_INFO "windfarm: Clamping CPU frequency to "
                       "minimum !\n");
        } else {
                freq = max_freq;
                printk(KERN_INFO "windfarm: CPU frequency unclamped !\n");
        }
        clamped = value;

        return freq_qos_update_request(&qos_req, freq);
}

static int clamp_get(struct wf_control *ct, s32 *value)
{
        *value = clamped;
        return 0;
}

static s32 clamp_min(struct wf_control *ct)
{
        return 0;
}

static s32 clamp_max(struct wf_control *ct)
{
        return 1;
}

static const struct wf_control_ops clamp_ops = {
        .set_value      = clamp_set,
        .get_value      = clamp_get,
        .get_min        = clamp_min,
        .get_max        = clamp_max,
        .owner          = THIS_MODULE,
};

static int __init wf_cpufreq_clamp_init(void)
{
        struct cpufreq_policy *policy;
        struct wf_control *clamp;
        struct device *dev;
        int ret;

        policy = cpufreq_cpu_get(0);
        if (!policy) {
                pr_warn("%s: cpufreq policy not found cpu0\n", __func__);
                return -EPROBE_DEFER;
        }

        min_freq = policy->cpuinfo.min_freq;
        max_freq = policy->cpuinfo.max_freq;

        ret = freq_qos_add_request(&policy->constraints, &qos_req, FREQ_QOS_MAX,
                                   max_freq);

        cpufreq_cpu_put(policy);

        if (ret < 0) {
                pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
                       ret);
                return ret;
        }

        dev = get_cpu_device(0);
        if (unlikely(!dev)) {
                pr_warn("%s: No cpu device for cpu0\n", __func__);
                ret = -ENODEV;
                goto fail;
        }

        clamp = kmalloc_obj(struct wf_control);
        if (clamp == NULL) {
                ret = -ENOMEM;
                goto fail;
        }

        clamp->ops = &clamp_ops;
        clamp->name = "cpufreq-clamp";
        ret = wf_register_control(clamp);
        if (ret)
                goto free;

        clamp_control = clamp;
        return 0;

 free:
        kfree(clamp);
 fail:
        freq_qos_remove_request(&qos_req);
        return ret;
}

static void __exit wf_cpufreq_clamp_exit(void)
{
        if (clamp_control) {
                wf_unregister_control(clamp_control);
                freq_qos_remove_request(&qos_req);
        }
}


module_init(wf_cpufreq_clamp_init);
module_exit(wf_cpufreq_clamp_exit);

MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");
MODULE_LICENSE("GPL");