// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 Calxeda, Inc.
 *
 * This driver provides the clk notifier callbacks that are used when
 * the cpufreq-dt driver changes to frequency to alert the highbank
 * EnergyCore Management Engine (ECME) about the need to change
 * voltage. The ECME interfaces with the actual voltage regulators.
 */

#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/clk.h>
#include <linux/cpu.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/pl320-ipc.h>
#include <linux/platform_device.h>

#define HB_CPUFREQ_CHANGE_NOTE  0x80000001
#define HB_CPUFREQ_IPC_LEN      7
#define HB_CPUFREQ_VOLT_RETRIES 15

static int hb_voltage_change(unsigned int freq)
{
        u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000};

        return pl320_ipc_transmit(msg);
}

static int hb_cpufreq_clk_notify(struct notifier_block *nb,
                                unsigned long action, void *hclk)
{
        struct clk_notifier_data *clk_data = hclk;
        int i = 0;

        if (action == PRE_RATE_CHANGE) {
                if (clk_data->new_rate > clk_data->old_rate)
                        while (hb_voltage_change(clk_data->new_rate))
                                if (i++ > HB_CPUFREQ_VOLT_RETRIES)
                                        return NOTIFY_BAD;
        } else if (action == POST_RATE_CHANGE) {
                if (clk_data->new_rate < clk_data->old_rate)
                        while (hb_voltage_change(clk_data->new_rate))
                                if (i++ > HB_CPUFREQ_VOLT_RETRIES)
                                        return NOTIFY_BAD;
        }

        return NOTIFY_DONE;
}

static struct notifier_block hb_cpufreq_clk_nb = {
        .notifier_call = hb_cpufreq_clk_notify,
};

static int __init hb_cpufreq_driver_init(void)
{
        struct platform_device_info devinfo = { .name = "cpufreq-dt", };
        struct device *cpu_dev;
        struct clk *cpu_clk;
        struct device_node *np;
        int ret;

        if ((!of_machine_is_compatible("calxeda,highbank")) &&
                (!of_machine_is_compatible("calxeda,ecx-2000")))
                return -ENODEV;

        cpu_dev = get_cpu_device(0);
        if (!cpu_dev) {
                pr_err("failed to get highbank cpufreq device\n");
                return -ENODEV;
        }

        np = of_node_get(cpu_dev->of_node);
        if (!np) {
                pr_err("failed to find highbank cpufreq node\n");
                return -ENOENT;
        }

        cpu_clk = clk_get(cpu_dev, NULL);
        if (IS_ERR(cpu_clk)) {
                ret = PTR_ERR(cpu_clk);
                pr_err("failed to get cpu0 clock: %d\n", ret);
                goto out_put_node;
        }

        ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb);
        if (ret) {
                pr_err("failed to register clk notifier: %d\n", ret);
                goto out_put_node;
        }

        /* Instantiate cpufreq-dt */
        platform_device_register_full(&devinfo);

out_put_node:
        of_node_put(np);
        return ret;
}
module_init(hb_cpufreq_driver_init);

static const struct of_device_id __maybe_unused hb_cpufreq_of_match[] = {
        { .compatible = "calxeda,highbank" },
        { .compatible = "calxeda,ecx-2000" },
        { },
};
MODULE_DEVICE_TABLE(of, hb_cpufreq_of_match);

MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
MODULE_LICENSE("GPL");