/*
 * Copyright 2013 Emilio López
 *
 * Emilio López <emilio@elopez.com.ar>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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/clk.h>
#include <linux/clk-provider.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#include "clk-factors.h"

/**
 * sun4i_a10_get_mod0_factors() - calculates m, n factors for MOD0-style clocks
 * MOD0 rate is calculated as follows
 * rate = (parent_rate >> p) / (m + 1);
 */

static void sun4i_a10_get_mod0_factors(struct factors_request *req)
{
        u8 div, calcm, calcp;

        /* These clocks can only divide, so we will never be able to achieve
         * frequencies higher than the parent frequency */
        if (req->rate > req->parent_rate)
                req->rate = req->parent_rate;

        div = DIV_ROUND_UP(req->parent_rate, req->rate);

        if (div < 16)
                calcp = 0;
        else if (div / 2 < 16)
                calcp = 1;
        else if (div / 4 < 16)
                calcp = 2;
        else
                calcp = 3;

        calcm = DIV_ROUND_UP(div, 1 << calcp);

        req->rate = (req->parent_rate >> calcp) / calcm;
        req->m = calcm - 1;
        req->p = calcp;
}

/* user manual says "n" but it's really "p" */
static const struct clk_factors_config sun4i_a10_mod0_config = {
        .mshift = 0,
        .mwidth = 4,
        .pshift = 16,
        .pwidth = 2,
};

static const struct factors_data sun4i_a10_mod0_data = {
        .enable = 31,
        .mux = 24,
        .muxmask = BIT(1) | BIT(0),
        .table = &sun4i_a10_mod0_config,
        .getter = sun4i_a10_get_mod0_factors,
};

static DEFINE_SPINLOCK(sun4i_a10_mod0_lock);

static void __init sun4i_a10_mod0_setup(struct device_node *node)
{
        void __iomem *reg;

        reg = of_iomap(node, 0);
        if (!reg) {
                /*
                 * This happens with mod0 clk nodes instantiated through
                 * mfd, as those do not have their resources assigned at
                 * CLK_OF_DECLARE time yet, so do not print an error.
                 */
                return;
        }

        sunxi_factors_register(node, &sun4i_a10_mod0_data,
                               &sun4i_a10_mod0_lock, reg);
}
CLK_OF_DECLARE_DRIVER(sun4i_a10_mod0, "allwinner,sun4i-a10-mod0-clk",
                      sun4i_a10_mod0_setup);

static int sun4i_a10_mod0_clk_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        struct resource *r;
        void __iomem *reg;

        if (!np)
                return -ENODEV;

        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        reg = devm_ioremap_resource(&pdev->dev, r);
        if (IS_ERR(reg))
                return PTR_ERR(reg);

        sunxi_factors_register(np, &sun4i_a10_mod0_data,
                               &sun4i_a10_mod0_lock, reg);
        return 0;
}

static const struct of_device_id sun4i_a10_mod0_clk_dt_ids[] = {
        { .compatible = "allwinner,sun4i-a10-mod0-clk" },
        { /* sentinel */ }
};

static struct platform_driver sun4i_a10_mod0_clk_driver = {
        .driver = {
                .name = "sun4i-a10-mod0-clk",
                .of_match_table = sun4i_a10_mod0_clk_dt_ids,
        },
        .probe = sun4i_a10_mod0_clk_probe,
};
builtin_platform_driver(sun4i_a10_mod0_clk_driver);

static const struct factors_data sun9i_a80_mod0_data __initconst = {
        .enable = 31,
        .mux = 24,
        .muxmask = BIT(3) | BIT(2) | BIT(1) | BIT(0),
        .table = &sun4i_a10_mod0_config,
        .getter = sun4i_a10_get_mod0_factors,
};

static void __init sun9i_a80_mod0_setup(struct device_node *node)
{
        void __iomem *reg;

        reg = of_io_request_and_map(node, 0, of_node_full_name(node));
        if (IS_ERR(reg)) {
                pr_err("Could not get registers for mod0-clk: %s\n",
                       node->name);
                return;
        }

        sunxi_factors_register(node, &sun9i_a80_mod0_data,
                               &sun4i_a10_mod0_lock, reg);
}
CLK_OF_DECLARE(sun9i_a80_mod0, "allwinner,sun9i-a80-mod0-clk", sun9i_a80_mod0_setup);

static DEFINE_SPINLOCK(sun5i_a13_mbus_lock);

static void __init sun5i_a13_mbus_setup(struct device_node *node)
{
        void __iomem *reg;

        reg = of_iomap(node, 0);
        if (!reg) {
                pr_err("Could not get registers for a13-mbus-clk\n");
                return;
        }

        /* The MBUS clocks needs to be always enabled */
        sunxi_factors_register_critical(node, &sun4i_a10_mod0_data,
                                        &sun5i_a13_mbus_lock, reg);
}
CLK_OF_DECLARE(sun5i_a13_mbus, "allwinner,sun5i-a13-mbus-clk", sun5i_a13_mbus_setup);

struct mmc_phase {
        struct clk_hw           hw;
        u8                      offset;
        void __iomem            *reg;
        spinlock_t              *lock;
};

#define to_mmc_phase(_hw) container_of(_hw, struct mmc_phase, hw)

static int mmc_get_phase(struct clk_hw *hw)
{
        struct clk *mmc, *mmc_parent, *clk = hw->clk;
        struct mmc_phase *phase = to_mmc_phase(hw);
        unsigned int mmc_rate, mmc_parent_rate;
        u16 step, mmc_div;
        u32 value;
        u8 delay;

        value = readl(phase->reg);
        delay = (value >> phase->offset) & 0x3;

        if (!delay)
                return 180;

        /* Get the main MMC clock */
        mmc = clk_get_parent(clk);
        if (!mmc)
                return -EINVAL;

        /* And its rate */
        mmc_rate = clk_get_rate(mmc);
        if (!mmc_rate)
                return -EINVAL;

        /* Now, get the MMC parent (most likely some PLL) */
        mmc_parent = clk_get_parent(mmc);
        if (!mmc_parent)
                return -EINVAL;

        /* And its rate */
        mmc_parent_rate = clk_get_rate(mmc_parent);
        if (!mmc_parent_rate)
                return -EINVAL;

        /* Get MMC clock divider */
        mmc_div = mmc_parent_rate / mmc_rate;

        step = DIV_ROUND_CLOSEST(360, mmc_div);
        return delay * step;
}

static int mmc_set_phase(struct clk_hw *hw, int degrees)
{
        struct clk *mmc, *mmc_parent, *clk = hw->clk;
        struct mmc_phase *phase = to_mmc_phase(hw);
        unsigned int mmc_rate, mmc_parent_rate;
        unsigned long flags;
        u32 value;
        u8 delay;

        /* Get the main MMC clock */
        mmc = clk_get_parent(clk);
        if (!mmc)
                return -EINVAL;

        /* And its rate */
        mmc_rate = clk_get_rate(mmc);
        if (!mmc_rate)
                return -EINVAL;

        /* Now, get the MMC parent (most likely some PLL) */
        mmc_parent = clk_get_parent(mmc);
        if (!mmc_parent)
                return -EINVAL;

        /* And its rate */
        mmc_parent_rate = clk_get_rate(mmc_parent);
        if (!mmc_parent_rate)
                return -EINVAL;

        if (degrees != 180) {
                u16 step, mmc_div;

                /* Get MMC clock divider */
                mmc_div = mmc_parent_rate / mmc_rate;

                /*
                 * We can only outphase the clocks by multiple of the
                 * PLL's period.
                 *
                 * Since the MMC clock in only a divider, and the
                 * formula to get the outphasing in degrees is deg =
                 * 360 * delta / period
                 *
                 * If we simplify this formula, we can see that the
                 * only thing that we're concerned about is the number
                 * of period we want to outphase our clock from, and
                 * the divider set by the MMC clock.
                 */
                step = DIV_ROUND_CLOSEST(360, mmc_div);
                delay = DIV_ROUND_CLOSEST(degrees, step);
        } else {
                delay = 0;
        }

        spin_lock_irqsave(phase->lock, flags);
        value = readl(phase->reg);
        value &= ~GENMASK(phase->offset + 3, phase->offset);
        value |= delay << phase->offset;
        writel(value, phase->reg);
        spin_unlock_irqrestore(phase->lock, flags);

        return 0;
}

static const struct clk_ops mmc_clk_ops = {
        .get_phase      = mmc_get_phase,
        .set_phase      = mmc_set_phase,
};

/*
 * sunxi_mmc_setup - Common setup function for mmc module clocks
 *
 * The only difference between module clocks on different platforms is the
 * width of the mux register bits and the valid values, which are passed in
 * through struct factors_data. The phase clocks parts are identical.
 */
static void __init sunxi_mmc_setup(struct device_node *node,
                                   const struct factors_data *data,
                                   spinlock_t *lock)
{
        struct clk_onecell_data *clk_data;
        const char *parent;
        void __iomem *reg;
        int i;

        reg = of_io_request_and_map(node, 0, of_node_full_name(node));
        if (IS_ERR(reg)) {
                pr_err("Couldn't map the %s clock registers\n", node->name);
                return;
        }

        clk_data = kmalloc(sizeof(*clk_data), GFP_KERNEL);
        if (!clk_data)
                return;

        clk_data->clks = kcalloc(3, sizeof(*clk_data->clks), GFP_KERNEL);
        if (!clk_data->clks)
                goto err_free_data;

        clk_data->clk_num = 3;
        clk_data->clks[0] = sunxi_factors_register(node, data, lock, reg);
        if (!clk_data->clks[0])
                goto err_free_clks;

        parent = __clk_get_name(clk_data->clks[0]);

        for (i = 1; i < 3; i++) {
                struct clk_init_data init = {
                        .num_parents    = 1,
                        .parent_names   = &parent,
                        .ops            = &mmc_clk_ops,
                };
                struct mmc_phase *phase;

                phase = kmalloc(sizeof(*phase), GFP_KERNEL);
                if (!phase)
                        continue;

                phase->hw.init = &init;
                phase->reg = reg;
                phase->lock = lock;

                if (i == 1)
                        phase->offset = 8;
                else
                        phase->offset = 20;

                if (of_property_read_string_index(node, "clock-output-names",
                                                  i, &init.name))
                        init.name = node->name;

                clk_data->clks[i] = clk_register(NULL, &phase->hw);
                if (IS_ERR(clk_data->clks[i])) {
                        kfree(phase);
                        continue;
                }
        }

        of_clk_add_provider(node, of_clk_src_onecell_get, clk_data);

        return;

err_free_clks:
        kfree(clk_data->clks);
err_free_data:
        kfree(clk_data);
}

static DEFINE_SPINLOCK(sun4i_a10_mmc_lock);

static void __init sun4i_a10_mmc_setup(struct device_node *node)
{
        sunxi_mmc_setup(node, &sun4i_a10_mod0_data, &sun4i_a10_mmc_lock);
}
CLK_OF_DECLARE(sun4i_a10_mmc, "allwinner,sun4i-a10-mmc-clk", sun4i_a10_mmc_setup);

static DEFINE_SPINLOCK(sun9i_a80_mmc_lock);

static void __init sun9i_a80_mmc_setup(struct device_node *node)
{
        sunxi_mmc_setup(node, &sun9i_a80_mod0_data, &sun9i_a80_mmc_lock);
}
CLK_OF_DECLARE(sun9i_a80_mmc, "allwinner,sun9i-a80-mmc-clk", sun9i_a80_mmc_setup);