// SPDX-License-Identifier: GPL-2.0-only
/*
 * CPU frequency scaling for DaVinci
 *
 * Copyright (C) 2009 Texas Instruments Incorporated - https://www.ti.com/
 *
 * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
 *
 *  Copyright (C) 2005 Nokia Corporation
 *  Written by Tony Lindgren <tony@atomide.com>
 *
 *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
 *
 * Copyright (C) 2007-2008 Texas Instruments, Inc.
 * Updated to support OMAP3
 * Rajendra Nayak <rnayak@ti.com>
 */
#include <linux/types.h>
#include <linux/cpufreq.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/platform_data/davinci-cpufreq.h>
#include <linux/platform_device.h>
#include <linux/export.h>

struct davinci_cpufreq {
        struct device *dev;
        struct clk *armclk;
        struct clk *asyncclk;
        unsigned long asyncrate;
};
static struct davinci_cpufreq cpufreq;

static int davinci_target(struct cpufreq_policy *policy, unsigned int idx)
{
        struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
        struct clk *armclk = cpufreq.armclk;
        unsigned int old_freq, new_freq;
        int ret = 0;

        old_freq = policy->cur;
        new_freq = pdata->freq_table[idx].frequency;

        /* if moving to higher frequency, up the voltage beforehand */
        if (pdata->set_voltage && new_freq > old_freq) {
                ret = pdata->set_voltage(idx);
                if (ret)
                        return ret;
        }

        ret = clk_set_rate(armclk, new_freq * 1000);
        if (ret)
                return ret;

        if (cpufreq.asyncclk) {
                ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
                if (ret)
                        return ret;
        }

        /* if moving to lower freq, lower the voltage after lowering freq */
        if (pdata->set_voltage && new_freq < old_freq)
                pdata->set_voltage(idx);

        return 0;
}

static int davinci_cpu_init(struct cpufreq_policy *policy)
{
        int result = 0;
        struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
        struct cpufreq_frequency_table *freq_table = pdata->freq_table;

        if (policy->cpu != 0)
                return -EINVAL;

        /* Finish platform specific initialization */
        if (pdata->init) {
                result = pdata->init();
                if (result)
                        return result;
        }

        policy->clk = cpufreq.armclk;

        /*
         * Time measurement across the target() function yields ~1500-1800us
         * time taken with no drivers on notification list.
         * Setting the latency to 2000 us to accommodate addition of drivers
         * to pre/post change notification list.
         */
        cpufreq_generic_init(policy, freq_table, 2000 * 1000);
        return 0;
}

static struct cpufreq_driver davinci_driver = {
        .flags          = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
        .verify         = cpufreq_generic_frequency_table_verify,
        .target_index   = davinci_target,
        .get            = cpufreq_generic_get,
        .init           = davinci_cpu_init,
        .name           = "davinci",
};

static int __init davinci_cpufreq_probe(struct platform_device *pdev)
{
        struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
        struct clk *asyncclk;

        if (!pdata)
                return -EINVAL;
        if (!pdata->freq_table)
                return -EINVAL;

        cpufreq.dev = &pdev->dev;

        cpufreq.armclk = clk_get(NULL, "arm");
        if (IS_ERR(cpufreq.armclk)) {
                dev_err(cpufreq.dev, "Unable to get ARM clock\n");
                return PTR_ERR(cpufreq.armclk);
        }

        asyncclk = clk_get(cpufreq.dev, "async");
        if (!IS_ERR(asyncclk)) {
                cpufreq.asyncclk = asyncclk;
                cpufreq.asyncrate = clk_get_rate(asyncclk);
        }

        return cpufreq_register_driver(&davinci_driver);
}

static void __exit davinci_cpufreq_remove(struct platform_device *pdev)
{
        cpufreq_unregister_driver(&davinci_driver);

        clk_put(cpufreq.armclk);

        if (cpufreq.asyncclk)
                clk_put(cpufreq.asyncclk);
}

static struct platform_driver davinci_cpufreq_driver = {
        .driver = {
                .name    = "cpufreq-davinci",
        },
        .remove = __exit_p(davinci_cpufreq_remove),
};

int __init davinci_cpufreq_init(void)
{
        return platform_driver_probe(&davinci_cpufreq_driver,
                                                        davinci_cpufreq_probe);
}