/* $NetBSD: rk_cru_composite.c,v 1.8 2022/08/23 05:39:06 ryo Exp $ */

/*-
 * Copyright (c) 2018 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: rk_cru_composite.c,v 1.8 2022/08/23 05:39:06 ryo Exp $");

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

#include <dev/clk/clk_backend.h>

#include <arm/rockchip/rk_cru.h>

#include <dev/fdt/fdtvar.h>

int
rk_cru_composite_enable(struct rk_cru_softc *sc, struct rk_cru_clk *clk,
    int enable)
{
        struct rk_cru_composite *composite = &clk->u.composite;

        KASSERT(clk->type == RK_CRU_COMPOSITE);

        if (composite->gate_mask == 0)
                return enable ? 0 : ENXIO;

        const uint32_t write_mask = composite->gate_mask << 16;
        const uint32_t write_val = enable ? 0 : composite->gate_mask;

        CRU_WRITE(sc, composite->gate_reg, write_mask | write_val);

        return 0;
}

u_int
rk_cru_composite_get_rate(struct rk_cru_softc *sc,
    struct rk_cru_clk *clk)
{
        struct rk_cru_composite *composite = &clk->u.composite;
        struct clk *clkp, *clkp_parent;

        KASSERT(clk->type == RK_CRU_COMPOSITE);

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

        const u_int prate = clk_get_rate(clkp_parent);
        if (prate == 0)
                return 0;

        if (composite->flags & RK_COMPOSITE_FRACDIV) {
                const uint32_t val = CRU_READ(sc, composite->frac_reg);
                const u_int num = (val >> 16) & 0xffff;
                const u_int den = val & 0xffff;

                return (u_int)((uint64_t)prate * num / den);
        } else {
                const uint32_t val = CRU_READ(sc, composite->muxdiv_reg);
                u_int div;

                if (composite->flags & RK_COMPOSITE_POW2) {
                        div = 1U << __SHIFTOUT(val, composite->div_mask);
                } else if (composite->flags & RK_COMPOSITE_HALFDIV) {
                        div = __SHIFTOUT(val, composite->div_mask) * 2 + 3;
                        return ((uint64_t)prate * 2 + div - 1) / div;
                } else {
                        div = (composite->div_mask != 0)
                            ? __SHIFTOUT(val, composite->div_mask) + 1 : 1;
                }
                return prate / div;
        }
}

static u_int
rk_cru_composite_get_frac_div(u_int n, u_int d)
{
        u_int tmp;

        while (d > 0) {
                tmp = d;
                d = n % d;
                n = tmp;
        }

        return n;
}

static int
rk_cru_composite_set_rate_frac(struct rk_cru_softc *sc,
    struct rk_cru_clk *clk, u_int rate)
{
        struct rk_cru_composite *composite = &clk->u.composite;
        struct clk *clk_parent;

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

        const u_int prate = clk_get_rate(clk_parent);
        const u_int v = rk_cru_composite_get_frac_div(prate, rate);
        const u_int num = (prate / v) & 0xffff;
        const u_int den = (rate / v) & 0xffff;
        if (prate / num * den != rate)
                return EINVAL;

        CRU_WRITE(sc, composite->frac_reg, (den << 16) | num);

        return 0;
}

int
rk_cru_composite_set_rate(struct rk_cru_softc *sc,
    struct rk_cru_clk *clk, u_int rate)
{
        struct rk_cru_composite *composite = &clk->u.composite;
        u_int best_div, best_mux, best_diff;
        struct rk_cru_clk *rclk_parent;
        struct clk *clk_parent;

        KASSERT(clk->type == RK_CRU_COMPOSITE);

        if (composite->flags & RK_COMPOSITE_SET_RATE_PARENT) {
                clk_parent = clk_get_parent(&clk->base);
                if (clk_parent == NULL)
                        return ENXIO;
                return clk_set_rate(clk_parent, rate);
        }

        if (composite->flags & RK_COMPOSITE_FRACDIV) {
                return rk_cru_composite_set_rate_frac(sc, clk, rate);
        }

        if (composite->flags & RK_COMPOSITE_POW2) {
                return ENXIO;   /* TODO */
        }
        if (composite->flags & RK_COMPOSITE_HALFDIV) {
                return ENXIO;   /* TODO */
        }

        best_div = 0;
        best_mux = 0;
        best_diff = INT_MAX;
        for (u_int mux = 0; mux < composite->nparents; mux++) {
                rclk_parent = rk_cru_clock_find(sc, composite->parents[mux]);
                if (rclk_parent != NULL)
                        clk_parent = &rclk_parent->base;
                else
                        clk_parent = fdtbus_clock_byname(composite->parents[mux]);
                if (clk_parent == NULL)
                        continue;

                const u_int prate = clk_get_rate(clk_parent);
                if (prate == 0)
                        continue;

                for (u_int div = 1; div <= __SHIFTOUT_MASK(composite->div_mask) + 1; div++) {
                        const u_int cur_rate = prate / div;
                        const int diff = (int)rate - (int)cur_rate;
                        if (composite->flags & RK_COMPOSITE_ROUND_DOWN) {
                                if (diff >= 0 && diff < best_diff) {
                                        best_diff = diff;
                                        best_mux = mux;
                                        best_div = div;
                                }
                        } else {
                                if (abs(diff) < best_diff) {
                                        best_diff = abs(diff);
                                        best_mux = mux;
                                        best_div = div;
                                }
                        }
                }
        }
        if (best_diff == INT_MAX)
                return ERANGE;

        uint32_t write_mask = composite->div_mask << 16;
        uint32_t write_val = __SHIFTIN(best_div - 1, composite->div_mask);
        if (composite->mux_mask) {
                write_mask |= composite->mux_mask << 16;
                write_val |= __SHIFTIN(best_mux, composite->mux_mask);
        }

        CRU_WRITE(sc, composite->muxdiv_reg, write_mask | write_val);

        return 0;
}

const char *
rk_cru_composite_get_parent(struct rk_cru_softc *sc,
    struct rk_cru_clk *clk)
{
        struct rk_cru_composite *composite = &clk->u.composite;
        uint32_t val;
        u_int mux;

        KASSERT(clk->type == RK_CRU_COMPOSITE);

        if (composite->mux_mask) {
                val = CRU_READ(sc, composite->muxdiv_reg);
                mux = __SHIFTOUT(val, composite->mux_mask);
        } else {
                mux = 0;
        }

        return composite->parents[mux];
}

int
rk_cru_composite_set_parent(struct rk_cru_softc *sc,
    struct rk_cru_clk *clk, const char *parent)
{
        struct rk_cru_composite *composite = &clk->u.composite;

        KASSERT(clk->type == RK_CRU_COMPOSITE);

        if (!composite->mux_mask)
                return EINVAL;

        for (u_int mux = 0; mux < composite->nparents; mux++) {
                if (strcmp(composite->parents[mux], parent) == 0) {
                        const uint32_t write_mask = composite->mux_mask << 16;
                        const uint32_t write_val = __SHIFTIN(mux, composite->mux_mask);

                        CRU_WRITE(sc, composite->muxdiv_reg, write_mask | write_val);
                        return 0;
                }
        }

        return EINVAL;
}