/* $NetBSD: sunxi_ccu_div.c,v 1.6 2019/11/17 17:33:17 jmcneill Exp $ */

/*-
 * Copyright (c) 2017 Jared McNeill <jmcneill@invisible.ca>
 * 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 ``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 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sunxi_ccu_div.c,v 1.6 2019/11/17 17:33:17 jmcneill Exp $");

#include <sys/param.h>
#include <sys/bus.h>

#include <dev/clk/clk_backend.h>

#include <arm/sunxi/sunxi_ccu.h>

int
sunxi_ccu_div_enable(struct sunxi_ccu_softc *sc, struct sunxi_ccu_clk *clk,
    int enable)
{
        struct sunxi_ccu_div *div = &clk->u.div;
        uint32_t val;

        KASSERT(clk->type == SUNXI_CCU_DIV);

        if (!div->enable)
                return enable ? 0 : EINVAL;

        val = CCU_READ(sc, div->reg);
        if (enable)
                val |= div->enable;
        else
                val &= ~div->enable;
        CCU_WRITE(sc, div->reg, val);

        return 0;
}

u_int
sunxi_ccu_div_get_rate(struct sunxi_ccu_softc *sc,
    struct sunxi_ccu_clk *clk)
{
        struct sunxi_ccu_div *div = &clk->u.div;
        struct clk *clkp, *clkp_parent;
        u_int rate, ratio;
        uint32_t val;

        KASSERT(clk->type == SUNXI_CCU_DIV);

        clkp = &clk->base;
        clkp_parent = clk_get_parent(clkp);
        if (clkp_parent == NULL)
                return 0;

        rate = clk_get_rate(clkp_parent);
        if (rate == 0)
                return 0;

        val = CCU_READ(sc, div->reg);
        if (div->div)
                ratio = __SHIFTOUT(val, div->div);
        else
                ratio = 0;

        if ((div->flags & SUNXI_CCU_DIV_ZERO_IS_ONE) != 0 && ratio == 0)
                ratio = 1;
        if (div->flags & SUNXI_CCU_DIV_POWER_OF_TWO)
                ratio = 1 << ratio;
        else if (div->flags & SUNXI_CCU_DIV_TIMES_TWO) {
                ratio = ratio << 1;
                if (ratio == 0)
                        ratio = 1;
        } else
                ratio++;

        return rate / ratio;
}

static int
sunxi_ccu_div_select_parent(struct sunxi_ccu_softc *sc,
    struct sunxi_ccu_clk *clk, u_int new_rate)
{
        struct sunxi_ccu_div *div = &clk->u.div;
        struct sunxi_ccu_clk *clk_parent;
        struct clk *best_parent;
        u_int index, best_diff;
        const char *pname;

        best_parent = NULL;
        best_diff = ~0u;
        for (index = 0; index < div->nparents; index++) {
                pname = div->parents[index];
                if (pname == NULL)
                        continue;
                clk_parent = sunxi_ccu_clock_find(sc, pname);
                if (clk_parent == NULL)
                        continue;
                const u_int rate = clk_get_rate(&clk_parent->base);
                const u_int diff = abs((int)rate - (int)new_rate);
                if (diff < best_diff) {
                        best_diff = diff;
                        best_parent = &clk_parent->base;
                }
        }
        if (best_diff == ~0u)
                return EINVAL;

        return clk_set_parent(&clk->base, best_parent);
}

int
sunxi_ccu_div_set_rate(struct sunxi_ccu_softc *sc,
    struct sunxi_ccu_clk *clk, u_int new_rate)
{
        struct sunxi_ccu_div *div = &clk->u.div;
        struct clk *clkp, *clkp_parent;
        int parent_rate;
        uint32_t val, raw_div;
        int ratio;

        KASSERT(clk->type == SUNXI_CCU_DIV);

        clkp = &clk->base;
        clkp_parent = clk_get_parent(clkp);
        if (clkp_parent == NULL)
                return ENXIO;

        if (div->div == 0) {
                if ((div->flags & SUNXI_CCU_DIV_SET_RATE_PARENT) != 0)
                        return clk_set_rate(clkp_parent, new_rate);
                else
                        return sunxi_ccu_div_select_parent(sc, clk, new_rate);
        }

        val = CCU_READ(sc, div->reg);

        parent_rate = clk_get_rate(clkp_parent);
        if (parent_rate == 0)
                return (new_rate == 0) ? 0 : ERANGE;

        ratio = howmany(parent_rate, new_rate);
        if ((div->flags & SUNXI_CCU_DIV_TIMES_TWO) != 0) {
                if (ratio > 1 && (ratio & 1) != 0)
                        ratio++;
                raw_div = ratio >> 1;
        } else if ((div->flags & SUNXI_CCU_DIV_POWER_OF_TWO) != 0) {
                return EINVAL;
        } else {
                raw_div = (ratio > 0 ) ? ratio - 1 : 0;
        }
        if (raw_div > __SHIFTOUT_MASK(div->div))
                return ERANGE;

        val &= ~div->div;
        val |= __SHIFTIN(raw_div, div->div);
        CCU_WRITE(sc, div->reg, val);

        return 0;
}

int
sunxi_ccu_div_set_parent(struct sunxi_ccu_softc *sc,
    struct sunxi_ccu_clk *clk, const char *name)
{
        struct sunxi_ccu_div *div = &clk->u.div;
        uint32_t val;
        u_int index;

        KASSERT(clk->type == SUNXI_CCU_DIV);

        if (div->sel == 0)
                return ENODEV;

        for (index = 0; index < div->nparents; index++) {
                if (div->parents[index] != NULL &&
                    strcmp(div->parents[index], name) == 0)
                        break;
        }
        if (index == div->nparents)
                return EINVAL;

        val = CCU_READ(sc, div->reg);
        val &= ~div->sel;
        val |= __SHIFTIN(index, div->sel);
        CCU_WRITE(sc, div->reg, val);

        return 0;
}

const char *
sunxi_ccu_div_get_parent(struct sunxi_ccu_softc *sc,
    struct sunxi_ccu_clk *clk)
{
        struct sunxi_ccu_div *div = &clk->u.div;
        u_int index;
        uint32_t val;

        KASSERT(clk->type == SUNXI_CCU_DIV);

        if (div->sel == 0)
                return div->parents[0];

        val = CCU_READ(sc, div->reg);
        index = __SHIFTOUT(val, div->sel);

        return div->parents[index];
}