// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
 */

#include <linux/clk-provider.h>
#include <linux/clkdev.h>
#include <linux/clk/at91_pmc.h>
#include <linux/of.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>

#include "pmc.h"

#define PLL_STATUS_MASK(id)     (1 << (1 + (id)))
#define PLL_REG(id)             (AT91_CKGR_PLLAR + ((id) * 4))
#define PLL_DIV_MASK            0xff
#define PLL_DIV_MAX             PLL_DIV_MASK
#define PLL_DIV(reg)            ((reg) & PLL_DIV_MASK)
#define PLL_MUL(reg, layout)    (((reg) >> (layout)->mul_shift) & \
                                 (layout)->mul_mask)
#define PLL_MUL_MIN             2
#define PLL_MUL_MASK(layout)    ((layout)->mul_mask)
#define PLL_MUL_MAX(layout)     (PLL_MUL_MASK(layout) + 1)
#define PLL_ICPR_SHIFT(id)      ((id) * 16)
#define PLL_ICPR_MASK(id)       (0xffff << PLL_ICPR_SHIFT(id))
#define PLL_MAX_COUNT           0x3f
#define PLL_COUNT_SHIFT         8
#define PLL_OUT_SHIFT           14
#define PLL_MAX_ID              1

#define to_clk_pll(hw) container_of(hw, struct clk_pll, hw)

struct clk_pll {
        struct clk_hw hw;
        struct regmap *regmap;
        u8 id;
        u8 div;
        u8 range;
        u16 mul;
        const struct clk_pll_layout *layout;
        const struct clk_pll_characteristics *characteristics;
};

static inline bool clk_pll_ready(struct regmap *regmap, int id)
{
        unsigned int status;

        regmap_read(regmap, AT91_PMC_SR, &status);

        return status & PLL_STATUS_MASK(id) ? 1 : 0;
}

static int clk_pll_prepare(struct clk_hw *hw)
{
        struct clk_pll *pll = to_clk_pll(hw);
        struct regmap *regmap = pll->regmap;
        const struct clk_pll_layout *layout = pll->layout;
        const struct clk_pll_characteristics *characteristics =
                                                        pll->characteristics;
        u8 id = pll->id;
        u32 mask = PLL_STATUS_MASK(id);
        int offset = PLL_REG(id);
        u8 out = 0;
        unsigned int pllr;
        unsigned int status;
        u8 div;
        u16 mul;

        regmap_read(regmap, offset, &pllr);
        div = PLL_DIV(pllr);
        mul = PLL_MUL(pllr, layout);

        regmap_read(regmap, AT91_PMC_SR, &status);
        if ((status & mask) &&
            (div == pll->div && mul == pll->mul))
                return 0;

        if (characteristics->out)
                out = characteristics->out[pll->range];

        if (characteristics->icpll)
                regmap_update_bits(regmap, AT91_PMC_PLLICPR, PLL_ICPR_MASK(id),
                        characteristics->icpll[pll->range] << PLL_ICPR_SHIFT(id));

        regmap_update_bits(regmap, offset, layout->pllr_mask,
                        pll->div | (PLL_MAX_COUNT << PLL_COUNT_SHIFT) |
                        (out << PLL_OUT_SHIFT) |
                        ((pll->mul & layout->mul_mask) << layout->mul_shift));

        while (!clk_pll_ready(regmap, pll->id))
                cpu_relax();

        return 0;
}

static int clk_pll_is_prepared(struct clk_hw *hw)
{
        struct clk_pll *pll = to_clk_pll(hw);

        return clk_pll_ready(pll->regmap, pll->id);
}

static void clk_pll_unprepare(struct clk_hw *hw)
{
        struct clk_pll *pll = to_clk_pll(hw);
        unsigned int mask = pll->layout->pllr_mask;

        regmap_update_bits(pll->regmap, PLL_REG(pll->id), mask, ~mask);
}

static unsigned long clk_pll_recalc_rate(struct clk_hw *hw,
                                         unsigned long parent_rate)
{
        struct clk_pll *pll = to_clk_pll(hw);

        if (!pll->div || !pll->mul)
                return 0;

        return (parent_rate / pll->div) * (pll->mul + 1);
}

static long clk_pll_get_best_div_mul(struct clk_pll *pll, unsigned long rate,
                                     unsigned long parent_rate,
                                     u32 *div, u32 *mul,
                                     u32 *index) {
        const struct clk_pll_layout *layout = pll->layout;
        const struct clk_pll_characteristics *characteristics =
                                                        pll->characteristics;
        unsigned long bestremainder = ULONG_MAX;
        unsigned long maxdiv, mindiv, tmpdiv;
        long bestrate = -ERANGE;
        unsigned long bestdiv;
        unsigned long bestmul;
        int i = 0;

        /* Check if parent_rate is a valid input rate */
        if (parent_rate < characteristics->input.min)
                return -ERANGE;

        /*
         * Calculate minimum divider based on the minimum multiplier, the
         * parent_rate and the requested rate.
         * Should always be 2 according to the input and output characteristics
         * of the PLL blocks.
         */
        mindiv = (parent_rate * PLL_MUL_MIN) / rate;
        if (!mindiv)
                mindiv = 1;

        if (parent_rate > characteristics->input.max) {
                tmpdiv = DIV_ROUND_UP(parent_rate, characteristics->input.max);
                if (tmpdiv > PLL_DIV_MAX)
                        return -ERANGE;

                if (tmpdiv > mindiv)
                        mindiv = tmpdiv;
        }

        /*
         * Calculate the maximum divider which is limited by PLL register
         * layout (limited by the MUL or DIV field size).
         */
        maxdiv = DIV_ROUND_UP(parent_rate * PLL_MUL_MAX(layout), rate);
        if (maxdiv > PLL_DIV_MAX)
                maxdiv = PLL_DIV_MAX;

        /*
         * Iterate over the acceptable divider values to find the best
         * divider/multiplier pair (the one that generates the closest
         * rate to the requested one).
         */
        for (tmpdiv = mindiv; tmpdiv <= maxdiv; tmpdiv++) {
                unsigned long remainder;
                unsigned long tmprate;
                unsigned long tmpmul;

                /*
                 * Calculate the multiplier associated with the current
                 * divider that provide the closest rate to the requested one.
                 */
                tmpmul = DIV_ROUND_CLOSEST(rate, parent_rate / tmpdiv);
                tmprate = (parent_rate / tmpdiv) * tmpmul;
                if (tmprate > rate)
                        remainder = tmprate - rate;
                else
                        remainder = rate - tmprate;

                /*
                 * Compare the remainder with the best remainder found until
                 * now and elect a new best multiplier/divider pair if the
                 * current remainder is smaller than the best one.
                 */
                if (remainder < bestremainder) {
                        bestremainder = remainder;
                        bestdiv = tmpdiv;
                        bestmul = tmpmul;
                        bestrate = tmprate;
                }

                /*
                 * We've found a perfect match!
                 * Stop searching now and use this multiplier/divider pair.
                 */
                if (!remainder)
                        break;
        }

        /* We haven't found any multiplier/divider pair => return -ERANGE */
        if (bestrate < 0)
                return bestrate;

        /* Check if bestrate is a valid output rate  */
        for (i = 0; i < characteristics->num_output; i++) {
                if (bestrate >= characteristics->output[i].min &&
                    bestrate <= characteristics->output[i].max)
                        break;
        }

        if (i >= characteristics->num_output)
                return -ERANGE;

        if (div)
                *div = bestdiv;
        if (mul)
                *mul = bestmul - 1;
        if (index)
                *index = i;

        return bestrate;
}

static long clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
                                        unsigned long *parent_rate)
{
        struct clk_pll *pll = to_clk_pll(hw);

        return clk_pll_get_best_div_mul(pll, rate, *parent_rate,
                                        NULL, NULL, NULL);
}

static int clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
                            unsigned long parent_rate)
{
        struct clk_pll *pll = to_clk_pll(hw);
        long ret;
        u32 div;
        u32 mul;
        u32 index;

        ret = clk_pll_get_best_div_mul(pll, rate, parent_rate,
                                       &div, &mul, &index);
        if (ret < 0)
                return ret;

        pll->range = index;
        pll->div = div;
        pll->mul = mul;

        return 0;
}

static const struct clk_ops pll_ops = {
        .prepare = clk_pll_prepare,
        .unprepare = clk_pll_unprepare,
        .is_prepared = clk_pll_is_prepared,
        .recalc_rate = clk_pll_recalc_rate,
        .round_rate = clk_pll_round_rate,
        .set_rate = clk_pll_set_rate,
};

struct clk_hw * __init
at91_clk_register_pll(struct regmap *regmap, const char *name,
                      const char *parent_name, u8 id,
                      const struct clk_pll_layout *layout,
                      const struct clk_pll_characteristics *characteristics)
{
        struct clk_pll *pll;
        struct clk_hw *hw;
        struct clk_init_data init;
        int offset = PLL_REG(id);
        unsigned int pllr;
        int ret;

        if (id > PLL_MAX_ID)
                return ERR_PTR(-EINVAL);

        pll = kzalloc(sizeof(*pll), GFP_KERNEL);
        if (!pll)
                return ERR_PTR(-ENOMEM);

        init.name = name;
        init.ops = &pll_ops;
        init.parent_names = &parent_name;
        init.num_parents = 1;
        init.flags = CLK_SET_RATE_GATE;

        pll->id = id;
        pll->hw.init = &init;
        pll->layout = layout;
        pll->characteristics = characteristics;
        pll->regmap = regmap;
        regmap_read(regmap, offset, &pllr);
        pll->div = PLL_DIV(pllr);
        pll->mul = PLL_MUL(pllr, layout);

        hw = &pll->hw;
        ret = clk_hw_register(NULL, &pll->hw);
        if (ret) {
                kfree(pll);
                hw = ERR_PTR(ret);
        }

        return hw;
}


const struct clk_pll_layout at91rm9200_pll_layout = {
        .pllr_mask = 0x7FFFFFF,
        .mul_shift = 16,
        .mul_mask = 0x7FF,
};

const struct clk_pll_layout at91sam9g45_pll_layout = {
        .pllr_mask = 0xFFFFFF,
        .mul_shift = 16,
        .mul_mask = 0xFF,
};

const struct clk_pll_layout at91sam9g20_pllb_layout = {
        .pllr_mask = 0x3FFFFF,
        .mul_shift = 16,
        .mul_mask = 0x3F,
};

const struct clk_pll_layout sama5d3_pll_layout = {
        .pllr_mask = 0x1FFFFFF,
        .mul_shift = 18,
        .mul_mask = 0x7F,
};