/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright 2020 Michal Meloun <mmel@FreeBSD.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/cpu.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>

#include <machine/bus.h>
#include <machine/cpu.h>

#include <dev/clk/clk.h>
#include <dev/regulator/regulator.h>
#include <dev/ofw/ofw_bus_subr.h>

#include <arm/nvidia/tegra_efuse.h>

#include "cpufreq_if.h"

/* CPU voltage table entry */
struct speedo_entry {
        uint64_t                freq;   /* Frequency point */
        int                     c0;     /* Coeeficient values for */
        int                     c1;     /* quadratic equation: */
        int                     c2;     /* c2 * speedo^2 + c1 * speedo + c0 */
};

struct cpu_volt_def {
        int                     min_uvolt;      /* Min allowed CPU voltage */
        int                     max_uvolt;      /* Max allowed CPU voltage */
        int                     step_uvolt;     /* Step of CPU voltage */
        int                     speedo_scale;   /* Scaling factor for cvt */
        int                     speedo_nitems;  /* Size of speedo table */
        struct speedo_entry     *speedo_tbl;    /* CPU voltage table */
};

struct cpu_speed_point {
        uint64_t                freq;           /* Frequecy */
        int                     uvolt;          /* Requested voltage */
};

static struct speedo_entry tegra210_speedo_tbl[] =
{
        {204000000UL,   1007452, -23865, 370},
        {306000000UL,   1052709, -24875, 370},
        {408000000UL,   1099069, -25895, 370},
        {510000000UL,   1146534, -26905, 370},
        {612000000UL,   1195102, -27915, 370},
        {714000000UL,   1244773, -28925, 370},
        {816000000UL,   1295549, -29935, 370},
        {918000000UL,   1347428, -30955, 370},
        {1020000000UL,  1400411, -31965, 370},
        {1122000000UL,  1454497, -32975, 370},
        {1224000000UL,  1509687, -33985, 370},
        {1326000000UL,  1565981, -35005, 370},
        {1428000000UL,  1623379, -36015, 370},
        {1530000000UL,  1681880, -37025, 370},
        {1632000000UL,  1741485, -38035, 370},
        {1734000000UL,  1802194, -39055, 370},
        {1836000000UL,  1864006, -40065, 370},
        {1912500000UL,  1910780, -40815, 370},
        {2014500000UL,  1227000,      0,   0},
        {2218500000UL,  1227000,      0,   0},
};

static struct cpu_volt_def tegra210_cpu_volt_def =
{
        .min_uvolt = 900000,            /* 0.9 V */
        .max_uvolt = 1227000,           /* 1.227 */
        .step_uvolt =  10000,           /* 10 mV */
        .speedo_scale = 100,
        .speedo_nitems = nitems(tegra210_speedo_tbl),
        .speedo_tbl = tegra210_speedo_tbl,
};

static uint64_t cpu_max_freq[] = {
        1912500000UL,
        1912500000UL,
        2218500000UL,
        1785000000UL,
        1632000000UL,
        1912500000UL,
        2014500000UL,
        1734000000UL,
        1683000000UL,
        1555500000UL,
        1504500000UL,
};

static uint64_t cpu_freq_tbl[] = {
         204000000UL,
         306000000UL,
         408000000UL,
         510000000UL,
         612000000UL,
         714000000UL,
         816000000UL,
         918000000UL,
        1020000000UL,
        1122000000UL,
        1224000000UL,
        1326000000UL,
        1428000000UL,
        1530000000UL,
        1632000000UL,
        1734000000UL,
        1836000000UL,
        1912500000UL,
        2014500000UL,
        2218500000UL,
};

struct tegra210_cpufreq_softc {
        device_t                dev;
        phandle_t               node;

        clk_t                   clk_cpu_g;
        clk_t                   clk_pll_x;
        clk_t                   clk_pll_p;
        clk_t                   clk_dfll;

        int                     process_id;
        int                     speedo_id;
        int                     speedo_value;

        uint64_t                cpu_max_freq;
        struct cpu_volt_def     *cpu_def;
        struct cpu_speed_point  *speed_points;
        int                     nspeed_points;

        struct cpu_speed_point  *act_speed_point;

        int                     latency;
};

static int cpufreq_lowest_freq = 1;
TUNABLE_INT("hw.tegra210.cpufreq.lowest_freq", &cpufreq_lowest_freq);

#define DIV_ROUND_CLOSEST(val, div)     (((val) + ((div) / 2)) / (div))

#define ROUND_UP(val, div)      roundup(val, div)
#define ROUND_DOWN(val, div)    rounddown(val, div)

/*
 * Compute requesetd voltage for given frequency and SoC process variations,
 * - compute base voltage from speedo value using speedo table
 * - round up voltage to next regulator step
 * - clamp it to regulator limits
 */
static int
freq_to_voltage(struct tegra210_cpufreq_softc *sc, uint64_t freq)
{
        int uv, scale, min_uvolt, max_uvolt, step_uvolt;
        struct speedo_entry *ent;
        int i;

        /* Get speedo entry with higher frequency */
        ent = NULL;
        for (i = 0; i < sc->cpu_def->speedo_nitems; i++) {
                if (sc->cpu_def->speedo_tbl[i].freq >= freq) {
                        ent = &sc->cpu_def->speedo_tbl[i];
                        break;
                }
        }
        if (ent == NULL)
                ent = &sc->cpu_def->speedo_tbl[sc->cpu_def->speedo_nitems - 1];
        scale = sc->cpu_def->speedo_scale;


        /* uV = (c2 * speedo / scale + c1) * speedo / scale + c0) */
        uv = DIV_ROUND_CLOSEST(ent->c2 * sc->speedo_value, scale);
        uv = DIV_ROUND_CLOSEST((uv + ent->c1) * sc->speedo_value, scale) +
            ent->c0;
        step_uvolt = sc->cpu_def->step_uvolt;
        /* Round up it to next regulator step */
        uv = ROUND_UP(uv, step_uvolt);

        /* Clamp result */
        min_uvolt = ROUND_UP(sc->cpu_def->min_uvolt, step_uvolt);
        max_uvolt = ROUND_DOWN(sc->cpu_def->max_uvolt, step_uvolt);
        if (uv < min_uvolt)
                uv =  min_uvolt;
        if (uv > max_uvolt)
                uv =  max_uvolt;
        return (uv);

}

static void
build_speed_points(struct tegra210_cpufreq_softc *sc) {
        int i;

        sc->nspeed_points = nitems(cpu_freq_tbl);
        sc->speed_points = malloc(sizeof(struct cpu_speed_point) *
            sc->nspeed_points, M_DEVBUF, M_NOWAIT);
        for (i = 0; i < sc->nspeed_points; i++) {
                sc->speed_points[i].freq = cpu_freq_tbl[i];
                sc->speed_points[i].uvolt = freq_to_voltage(sc,
                    cpu_freq_tbl[i]);
        }
}

static struct cpu_speed_point *
get_speed_point(struct tegra210_cpufreq_softc *sc, uint64_t freq)
{
        int i;

        if (sc->speed_points[0].freq >= freq)
                return (sc->speed_points + 0);

        for (i = 0; i < sc->nspeed_points - 1; i++) {
                if (sc->speed_points[i + 1].freq > freq)
                        return (sc->speed_points + i);
        }

        return (sc->speed_points + sc->nspeed_points - 1);
}

static int
tegra210_cpufreq_settings(device_t dev, struct cf_setting *sets, int *count)
{
        struct tegra210_cpufreq_softc *sc;
        int i, j;

        if (sets == NULL || count == NULL)
                return (EINVAL);

        sc = device_get_softc(dev);
        memset(sets, CPUFREQ_VAL_UNKNOWN, sizeof(*sets) * (*count));

        for (i = 0, j = sc->nspeed_points - 1; j >= 0; j--) {
                if (sc->cpu_max_freq < sc->speed_points[j].freq)
                        continue;
                sets[i].freq = sc->speed_points[j].freq / 1000000;
                sets[i].volts = sc->speed_points[j].uvolt / 1000;
                sets[i].lat = sc->latency;
                sets[i].dev = dev;
                i++;
        }
        *count = i;

        return (0);
}

static int
set_cpu_freq(struct tegra210_cpufreq_softc *sc, uint64_t freq)
{
        struct cpu_speed_point *point;
        int rv;

        point = get_speed_point(sc, freq);

        /* Set PLLX frequency */
        rv = clk_set_freq(sc->clk_pll_x, point->freq, CLK_SET_ROUND_DOWN);
        if (rv != 0) {
                device_printf(sc->dev, "Can't set CPU clock frequency\n");
                return (rv);
        }

        sc->act_speed_point = point;

        return (0);
}

static int
tegra210_cpufreq_set(device_t dev, const struct cf_setting *cf)
{
        struct tegra210_cpufreq_softc *sc;
        uint64_t freq;
        int rv;

        if (cf == NULL || cf->freq < 0)
                return (EINVAL);

        sc = device_get_softc(dev);

        freq = cf->freq;
        if (freq < cpufreq_lowest_freq)
                freq = cpufreq_lowest_freq;
        freq *= 1000000;
        if (freq >= sc->cpu_max_freq)
                freq = sc->cpu_max_freq;
        rv = set_cpu_freq(sc, freq);

        return (rv);
}

static int
tegra210_cpufreq_get(device_t dev, struct cf_setting *cf)
{
        struct tegra210_cpufreq_softc *sc;

        if (cf == NULL)
                return (EINVAL);

        sc = device_get_softc(dev);
        memset(cf, CPUFREQ_VAL_UNKNOWN, sizeof(*cf));
        cf->dev = NULL;
        cf->freq = sc->act_speed_point->freq / 1000000;
        cf->volts = sc->act_speed_point->uvolt / 1000;
        /* Transition latency in us. */
        cf->lat = sc->latency;
        /* Driver providing this setting. */
        cf->dev = dev;

        return (0);
}


static int
tegra210_cpufreq_type(device_t dev, int *type)
{

        if (type == NULL)
                return (EINVAL);
        *type = CPUFREQ_TYPE_ABSOLUTE;

        return (0);
}

static int
get_fdt_resources(struct tegra210_cpufreq_softc *sc, phandle_t node)
{
        int rv;
        device_t parent_dev;

        parent_dev =  device_get_parent(sc->dev);

        rv = clk_get_by_ofw_name(parent_dev, 0, "cpu_g", &sc->clk_cpu_g);
        if (rv != 0) {
                device_printf(sc->dev, "Cannot get 'cpu_g' clock: %d\n", rv);
                return (ENXIO);
        }

        rv = clk_get_by_ofw_name(parent_dev, 0, "pll_x", &sc->clk_pll_x);
        if (rv != 0) {
                device_printf(sc->dev, "Cannot get 'pll_x' clock\n");
                return (ENXIO);
        }
        rv = clk_get_by_ofw_name(parent_dev, 0, "pll_p", &sc->clk_pll_p);
        if (rv != 0) {
                device_printf(parent_dev, "Cannot get 'pll_p' clock\n");
                return (ENXIO);
        }
        rv = clk_get_by_ofw_name(parent_dev, 0, "dfll", &sc->clk_dfll);

        /* XXX DPLL is not implemented yet */
#if 0
        if (rv != 0) {
                device_printf(sc->dev, "Cannot get 'dfll' clock\n");
                return (ENXIO);
        }
#endif
        return (0);
}

static void
tegra210_cpufreq_identify(driver_t *driver, device_t parent)
{
        phandle_t root;

        root = OF_finddevice("/");
        if (!ofw_bus_node_is_compatible(root, "nvidia,tegra210"))
                return;

        if (device_get_unit(parent) != 0)
                return;
        if (device_find_child(parent, "tegra210_cpufreq", DEVICE_UNIT_ANY) != NULL)
                return;
        if (BUS_ADD_CHILD(parent, 0, "tegra210_cpufreq", DEVICE_UNIT_ANY) == NULL)
                device_printf(parent, "add child failed\n");
}

static int
tegra210_cpufreq_probe(device_t dev)
{

        device_set_desc(dev, "CPU Frequency Control");

        return (0);
}

static int
tegra210_cpufreq_attach(device_t dev)
{
        struct tegra210_cpufreq_softc *sc;
        uint64_t freq;
        int rv;

        sc = device_get_softc(dev);
        sc->dev = dev;
        sc->node = ofw_bus_get_node(device_get_parent(dev));

        sc->process_id = tegra_sku_info.cpu_process_id;
        sc->speedo_id = tegra_sku_info.cpu_speedo_id;
        sc->speedo_value = tegra_sku_info.cpu_speedo_value;

        sc->cpu_def = &tegra210_cpu_volt_def;

        rv = get_fdt_resources(sc, sc->node);
        if (rv !=  0) {
                return (rv);
        }

        build_speed_points(sc);

        rv = clk_get_freq(sc->clk_cpu_g, &freq);
        if (rv != 0) {
                device_printf(dev, "Can't get CPU clock frequency\n");
                return (rv);
        }
        if (sc->speedo_id < nitems(cpu_max_freq))
                sc->cpu_max_freq = cpu_max_freq[sc->speedo_id];
        else
                sc->cpu_max_freq = cpu_max_freq[0];
        sc->act_speed_point = get_speed_point(sc, freq);

        /* Set safe startup CPU frequency. */
        rv = set_cpu_freq(sc, 1632000000);
        if (rv != 0) {
                device_printf(dev, "Can't set initial CPU clock frequency\n");
                return (rv);
        }

        /* This device is controlled by cpufreq(4). */
        cpufreq_register(dev);

        return (0);
}

static int
tegra210_cpufreq_detach(device_t dev)
{
        struct tegra210_cpufreq_softc *sc;

        sc = device_get_softc(dev);
        cpufreq_unregister(dev);

        if (sc->clk_cpu_g != NULL)
                clk_release(sc->clk_cpu_g);
        if (sc->clk_pll_x != NULL)
                clk_release(sc->clk_pll_x);
        if (sc->clk_pll_p != NULL)
                clk_release(sc->clk_pll_p);
        if (sc->clk_dfll != NULL)
                clk_release(sc->clk_dfll);
        return (0);
}

static device_method_t tegra210_cpufreq_methods[] = {
        /* Device interface */
        DEVMETHOD(device_identify,      tegra210_cpufreq_identify),
        DEVMETHOD(device_probe,         tegra210_cpufreq_probe),
        DEVMETHOD(device_attach,        tegra210_cpufreq_attach),
        DEVMETHOD(device_detach,        tegra210_cpufreq_detach),

        /* cpufreq interface */
        DEVMETHOD(cpufreq_drv_set,      tegra210_cpufreq_set),
        DEVMETHOD(cpufreq_drv_get,      tegra210_cpufreq_get),
        DEVMETHOD(cpufreq_drv_settings, tegra210_cpufreq_settings),
        DEVMETHOD(cpufreq_drv_type,     tegra210_cpufreq_type),

        DEVMETHOD_END
};

static DEFINE_CLASS_0(tegra210_cpufreq, tegra210_cpufreq_driver,
    tegra210_cpufreq_methods, sizeof(struct tegra210_cpufreq_softc));
DRIVER_MODULE(tegra210_cpufreq, cpu, tegra210_cpufreq_driver, NULL, NULL);