/*-
 * Copyright 2016 Michal Meloun <mmel@FreeBSD.org>
 * All rights reserved.
 *
 * 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/conf.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/systm.h>

#include <machine/bus.h>

#include <dev/clk/clk_div.h>

#include "clkdev_if.h"

#define WR4(_clk, off, val)                                             \
        CLKDEV_WRITE_4(clknode_get_device(_clk), off, val)
#define RD4(_clk, off, val)                                             \
        CLKDEV_READ_4(clknode_get_device(_clk), off, val)
#define MD4(_clk, off, clr, set )                                       \
        CLKDEV_MODIFY_4(clknode_get_device(_clk), off, clr, set)
#define DEVICE_LOCK(_clk)                                                       \
        CLKDEV_DEVICE_LOCK(clknode_get_device(_clk))
#define DEVICE_UNLOCK(_clk)                                             \
        CLKDEV_DEVICE_UNLOCK(clknode_get_device(_clk))

static int clknode_div_init(struct clknode *clk, device_t dev);
static int clknode_div_recalc(struct clknode *clk, uint64_t *req);
static int clknode_div_set_freq(struct clknode *clknode, uint64_t fin,
    uint64_t *fout, int flag, int *stop);

struct clknode_div_sc {
        struct mtx      *mtx;
        struct resource *mem_res;
        uint32_t        offset;
        uint32_t        i_shift;
        uint32_t        i_mask;
        uint32_t        i_width;
        uint32_t        f_shift;
        uint32_t        f_mask;
        uint32_t        f_width;
        int             div_flags;
        uint32_t        divider;        /* in natural form */

        struct clk_div_table    *div_table;
};

static clknode_method_t clknode_div_methods[] = {
        /* Device interface */
        CLKNODEMETHOD(clknode_init,             clknode_div_init),
        CLKNODEMETHOD(clknode_recalc_freq,      clknode_div_recalc),
        CLKNODEMETHOD(clknode_set_freq,         clknode_div_set_freq),
        CLKNODEMETHOD_END
};
DEFINE_CLASS_1(clknode_div, clknode_div_class, clknode_div_methods,
   sizeof(struct clknode_div_sc), clknode_class);

static uint32_t
clknode_div_table_get_divider(struct clknode_div_sc *sc, uint32_t divider)
{
        struct clk_div_table *table;

        if (!(sc->div_flags & CLK_DIV_WITH_TABLE))
                return (divider);

        for (table = sc->div_table; table->divider != 0; table++)
                if (table->value == sc->divider)
                        return (table->divider);

        return (0);
}

static int
clknode_div_table_get_value(struct clknode_div_sc *sc, uint32_t *divider)
{
        struct clk_div_table *table;

        if (!(sc->div_flags & CLK_DIV_WITH_TABLE))
                return (0);

        for (table = sc->div_table; table->divider != 0; table++)
                if (table->divider == *divider) {
                        *divider = table->value;
                        return (0);
                }

        return (ENOENT);
}

static int
clknode_div_init(struct clknode *clk, device_t dev)
{
        uint32_t reg;
        struct clknode_div_sc *sc;
        uint32_t i_div, f_div;
        int rv;

        sc = clknode_get_softc(clk);

        DEVICE_LOCK(clk);
        rv = RD4(clk, sc->offset, &reg);
        DEVICE_UNLOCK(clk);
        if (rv != 0)
                return (rv);

        i_div = (reg >> sc->i_shift) & sc->i_mask;
        if (!(sc->div_flags & CLK_DIV_WITH_TABLE) &&
            !(sc->div_flags & CLK_DIV_ZERO_BASED))
                i_div++;
        f_div = (reg >> sc->f_shift) & sc->f_mask;
        sc->divider = i_div << sc->f_width | f_div;

        sc->divider = clknode_div_table_get_divider(sc, sc->divider);
        if (sc->divider == 0)
                panic("%s: divider is zero!\n", clknode_get_name(clk));

        clknode_init_parent_idx(clk, 0);
        return(0);
}

static int
clknode_div_recalc(struct clknode *clk, uint64_t *freq)
{
        struct clknode_div_sc *sc;

        sc = clknode_get_softc(clk);
        if (sc->divider == 0) {
                printf("%s: %s divider is zero!\n", clknode_get_name(clk),
                __func__);
                *freq = 0;
                return(EINVAL);
        }
        *freq = (*freq << sc->f_width) / sc->divider;
        return (0);
}

static int
clknode_div_set_freq(struct clknode *clk, uint64_t fin, uint64_t *fout,
  int flags, int *stop)
{
        struct clknode_div_sc *sc;
        uint64_t divider, _fin, _fout;
        uint32_t reg, i_div, f_div, hw_i_div;
        int rv;

        sc = clknode_get_softc(clk);

        /* For fractional divider. */
        _fin = fin << sc->f_width;
        divider = (_fin + *fout / 2) / *fout;
        _fout = _fin / divider;

        /* Rounding. */
        if ((flags & CLK_SET_ROUND_UP) && (*fout < _fout))
                divider--;
        else if ((flags & CLK_SET_ROUND_DOWN) && (*fout > _fout))
                divider++;

        /* Break divider into integer and fractional parts. */
        i_div = divider >> sc->f_width;
        f_div = divider  & sc->f_mask;

        if (i_div == 0) {
                printf("%s: %s integer divider is zero!\n",
                     clknode_get_name(clk), __func__);
                return(EINVAL);
        }

        *stop = 1;
        hw_i_div = i_div;
        if (sc->div_flags & CLK_DIV_WITH_TABLE) {
                if (clknode_div_table_get_value(sc, &hw_i_div) != 0)
                                return (ERANGE);
        } else {
                if (!(sc->div_flags & CLK_DIV_ZERO_BASED))
                        hw_i_div--;

                if (i_div > sc->i_mask) {
                        /* XXX Pass to parent or return error? */
                        printf("%s: %s integer divider is too big: %u\n",
                            clknode_get_name(clk), __func__, i_div);
                        hw_i_div = sc->i_mask;
                        *stop = 0;
                }
                i_div = hw_i_div;
                if (!(sc->div_flags & CLK_DIV_ZERO_BASED))
                        i_div++;
        }

        divider = i_div << sc->f_width | f_div;

        if ((flags & CLK_SET_DRYRUN) == 0) {
                if ((*stop != 0) &&
                    ((flags & (CLK_SET_ROUND_UP | CLK_SET_ROUND_DOWN)) == 0) &&
                    (*fout != (_fin / divider)))
                        return (ERANGE);

                DEVICE_LOCK(clk);
                rv = MD4(clk, sc->offset,
                    (sc->i_mask << sc->i_shift) | (sc->f_mask << sc->f_shift),
                    (hw_i_div << sc->i_shift) | (f_div << sc->f_shift));
                if (rv != 0) {
                        DEVICE_UNLOCK(clk);
                        return (rv);
                }
                RD4(clk, sc->offset, &reg);
                DEVICE_UNLOCK(clk);

                sc->divider = divider;
        }

        *fout = _fin / divider;
        return (0);
}

int
clknode_div_register(struct clkdom *clkdom, struct clk_div_def *clkdef)
{
        struct clknode *clk;
        struct clknode_div_sc *sc;

        clk = clknode_create(clkdom, &clknode_div_class, &clkdef->clkdef);
        if (clk == NULL)
                return (1);

        sc = clknode_get_softc(clk);
        sc->offset = clkdef->offset;
        sc->i_shift = clkdef->i_shift;
        sc->i_width = clkdef->i_width;
        sc->i_mask = (1 << clkdef->i_width) - 1;
        sc->f_shift = clkdef->f_shift;
        sc->f_width = clkdef->f_width;
        sc->f_mask = (1 << clkdef->f_width) - 1;
        sc->div_flags = clkdef->div_flags;
        sc->div_table = clkdef->div_table;

        clknode_register(clkdom, clk);
        return (0);
}