/*
 * Copyright (c) 2013, The Linux Foundation. All rights reserved.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/kernel.h>
#include <linux/bitops.h>
#include <linux/err.h>
#include <linux/bug.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/clk-provider.h>
#include <linux/regmap.h>

#include <asm/div64.h>

#include "clk-pll.h"

#define PLL_OUTCTRL             BIT(0)
#define PLL_BYPASSNL            BIT(1)
#define PLL_RESET_N             BIT(2)
#define PLL_LOCK_COUNT_SHIFT    8
#define PLL_LOCK_COUNT_MASK     0x3f
#define PLL_BIAS_COUNT_SHIFT    14
#define PLL_BIAS_COUNT_MASK     0x3f
#define PLL_VOTE_FSM_ENA        BIT(20)
#define PLL_VOTE_FSM_RESET      BIT(21)

static int clk_pll_enable(struct clk_hw *hw)
{
        struct clk_pll *pll = to_clk_pll(hw);
        int ret;
        u32 mask, val;

        mask = PLL_OUTCTRL | PLL_RESET_N | PLL_BYPASSNL;
        ret = regmap_read(pll->clkr.regmap, pll->mode_reg, &val);
        if (ret)
                return ret;

        /* Skip if already enabled or in FSM mode */
        if ((val & mask) == mask || val & PLL_VOTE_FSM_ENA)
                return 0;

        /* Disable PLL bypass mode. */
        ret = regmap_update_bits(pll->clkr.regmap, pll->mode_reg, PLL_BYPASSNL,
                                 PLL_BYPASSNL);
        if (ret)
                return ret;

        /*
         * H/W requires a 5us delay between disabling the bypass and
         * de-asserting the reset. Delay 10us just to be safe.
         */
        udelay(10);

        /* De-assert active-low PLL reset. */
        ret = regmap_update_bits(pll->clkr.regmap, pll->mode_reg, PLL_RESET_N,
                                 PLL_RESET_N);
        if (ret)
                return ret;

        /* Wait until PLL is locked. */
        udelay(50);

        /* Enable PLL output. */
        return regmap_update_bits(pll->clkr.regmap, pll->mode_reg, PLL_OUTCTRL,
                                 PLL_OUTCTRL);
}

static void clk_pll_disable(struct clk_hw *hw)
{
        struct clk_pll *pll = to_clk_pll(hw);
        u32 mask;
        u32 val;

        regmap_read(pll->clkr.regmap, pll->mode_reg, &val);
        /* Skip if in FSM mode */
        if (val & PLL_VOTE_FSM_ENA)
                return;
        mask = PLL_OUTCTRL | PLL_RESET_N | PLL_BYPASSNL;
        regmap_update_bits(pll->clkr.regmap, pll->mode_reg, mask, 0);
}

static unsigned long
clk_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
{
        struct clk_pll *pll = to_clk_pll(hw);
        u32 l, m, n, config;
        unsigned long rate;
        u64 tmp;

        regmap_read(pll->clkr.regmap, pll->l_reg, &l);
        regmap_read(pll->clkr.regmap, pll->m_reg, &m);
        regmap_read(pll->clkr.regmap, pll->n_reg, &n);

        l &= 0x3ff;
        m &= 0x7ffff;
        n &= 0x7ffff;

        rate = parent_rate * l;
        if (n) {
                tmp = parent_rate;
                tmp *= m;
                do_div(tmp, n);
                rate += tmp;
        }
        if (pll->post_div_width) {
                regmap_read(pll->clkr.regmap, pll->config_reg, &config);
                config >>= pll->post_div_shift;
                config &= BIT(pll->post_div_width) - 1;
                rate /= config + 1;
        }

        return rate;
}

static const
struct pll_freq_tbl *find_freq(const struct pll_freq_tbl *f, unsigned long rate)
{
        if (!f)
                return NULL;

        for (; f->freq; f++)
                if (rate <= f->freq)
                        return f;

        return NULL;
}

static long
clk_pll_determine_rate(struct clk_hw *hw, unsigned long rate,
                       unsigned long min_rate, unsigned long max_rate,
                       unsigned long *p_rate, struct clk_hw **p)
{
        struct clk_pll *pll = to_clk_pll(hw);
        const struct pll_freq_tbl *f;

        f = find_freq(pll->freq_tbl, rate);
        if (!f)
                return clk_pll_recalc_rate(hw, *p_rate);

        return f->freq;
}

static int
clk_pll_set_rate(struct clk_hw *hw, unsigned long rate, unsigned long p_rate)
{
        struct clk_pll *pll = to_clk_pll(hw);
        const struct pll_freq_tbl *f;
        bool enabled;
        u32 mode;
        u32 enable_mask = PLL_OUTCTRL | PLL_BYPASSNL | PLL_RESET_N;

        f = find_freq(pll->freq_tbl, rate);
        if (!f)
                return -EINVAL;

        regmap_read(pll->clkr.regmap, pll->mode_reg, &mode);
        enabled = (mode & enable_mask) == enable_mask;

        if (enabled)
                clk_pll_disable(hw);

        regmap_update_bits(pll->clkr.regmap, pll->l_reg, 0x3ff, f->l);
        regmap_update_bits(pll->clkr.regmap, pll->m_reg, 0x7ffff, f->m);
        regmap_update_bits(pll->clkr.regmap, pll->n_reg, 0x7ffff, f->n);
        regmap_write(pll->clkr.regmap, pll->config_reg, f->ibits);

        if (enabled)
                clk_pll_enable(hw);

        return 0;
}

const struct clk_ops clk_pll_ops = {
        .enable = clk_pll_enable,
        .disable = clk_pll_disable,
        .recalc_rate = clk_pll_recalc_rate,
        .determine_rate = clk_pll_determine_rate,
        .set_rate = clk_pll_set_rate,
};
EXPORT_SYMBOL_GPL(clk_pll_ops);

static int wait_for_pll(struct clk_pll *pll)
{
        u32 val;
        int count;
        int ret;
        const char *name = __clk_get_name(pll->clkr.hw.clk);

        /* Wait for pll to enable. */
        for (count = 200; count > 0; count--) {
                ret = regmap_read(pll->clkr.regmap, pll->status_reg, &val);
                if (ret)
                        return ret;
                if (val & BIT(pll->status_bit))
                        return 0;
                udelay(1);
        }

        WARN(1, "%s didn't enable after voting for it!\n", name);
        return -ETIMEDOUT;
}

static int clk_pll_vote_enable(struct clk_hw *hw)
{
        int ret;
        struct clk_pll *p = to_clk_pll(__clk_get_hw(__clk_get_parent(hw->clk)));

        ret = clk_enable_regmap(hw);
        if (ret)
                return ret;

        return wait_for_pll(p);
}

const struct clk_ops clk_pll_vote_ops = {
        .enable = clk_pll_vote_enable,
        .disable = clk_disable_regmap,
};
EXPORT_SYMBOL_GPL(clk_pll_vote_ops);

static void
clk_pll_set_fsm_mode(struct clk_pll *pll, struct regmap *regmap, u8 lock_count)
{
        u32 val;
        u32 mask;

        /* De-assert reset to FSM */
        regmap_update_bits(regmap, pll->mode_reg, PLL_VOTE_FSM_RESET, 0);

        /* Program bias count and lock count */
        val = 1 << PLL_BIAS_COUNT_SHIFT | lock_count << PLL_LOCK_COUNT_SHIFT;
        mask = PLL_BIAS_COUNT_MASK << PLL_BIAS_COUNT_SHIFT;
        mask |= PLL_LOCK_COUNT_MASK << PLL_LOCK_COUNT_SHIFT;
        regmap_update_bits(regmap, pll->mode_reg, mask, val);

        /* Enable PLL FSM voting */
        regmap_update_bits(regmap, pll->mode_reg, PLL_VOTE_FSM_ENA,
                PLL_VOTE_FSM_ENA);
}

static void clk_pll_configure(struct clk_pll *pll, struct regmap *regmap,
        const struct pll_config *config)
{
        u32 val;
        u32 mask;

        regmap_write(regmap, pll->l_reg, config->l);
        regmap_write(regmap, pll->m_reg, config->m);
        regmap_write(regmap, pll->n_reg, config->n);

        val = config->vco_val;
        val |= config->pre_div_val;
        val |= config->post_div_val;
        val |= config->mn_ena_mask;
        val |= config->main_output_mask;
        val |= config->aux_output_mask;

        mask = config->vco_mask;
        mask |= config->pre_div_mask;
        mask |= config->post_div_mask;
        mask |= config->mn_ena_mask;
        mask |= config->main_output_mask;
        mask |= config->aux_output_mask;

        regmap_update_bits(regmap, pll->config_reg, mask, val);
}

void clk_pll_configure_sr(struct clk_pll *pll, struct regmap *regmap,
                const struct pll_config *config, bool fsm_mode)
{
        clk_pll_configure(pll, regmap, config);
        if (fsm_mode)
                clk_pll_set_fsm_mode(pll, regmap, 8);
}
EXPORT_SYMBOL_GPL(clk_pll_configure_sr);

void clk_pll_configure_sr_hpm_lp(struct clk_pll *pll, struct regmap *regmap,
                const struct pll_config *config, bool fsm_mode)
{
        clk_pll_configure(pll, regmap, config);
        if (fsm_mode)
                clk_pll_set_fsm_mode(pll, regmap, 0);
}
EXPORT_SYMBOL_GPL(clk_pll_configure_sr_hpm_lp);