/*
 * MVEBU Core divider clock
 *
 * Copyright (C) 2013 Marvell
 *
 * Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2.  This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/kernel.h>
#include <linux/clk-provider.h>
#include <linux/of_address.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include "common.h"

#define CORE_CLK_DIV_RATIO_MASK         0xff

/*
 * This structure describes the hardware details (bit offset and mask)
 * to configure one particular core divider clock. Those hardware
 * details may differ from one SoC to another. This structure is
 * therefore typically instantiated statically to describe the
 * hardware details.
 */
struct clk_corediv_desc {
        unsigned int mask;
        unsigned int offset;
        unsigned int fieldbit;
};

/*
 * This structure describes the hardware details to configure the core
 * divider clocks on a given SoC. Amongst others, it points to the
 * array of core divider clock descriptors for this SoC, as well as
 * the corresponding operations to manipulate them.
 */
struct clk_corediv_soc_desc {
        const struct clk_corediv_desc *descs;
        unsigned int ndescs;
        const struct clk_ops ops;
        u32 ratio_reload;
        u32 enable_bit_offset;
        u32 ratio_offset;
};

/*
 * This structure represents one core divider clock for the clock
 * framework, and is dynamically allocated for each core divider clock
 * existing in the current SoC.
 */
struct clk_corediv {
        struct clk_hw hw;
        void __iomem *reg;
        const struct clk_corediv_desc *desc;
        const struct clk_corediv_soc_desc *soc_desc;
        spinlock_t lock;
};

static struct clk_onecell_data clk_data;

/*
 * Description of the core divider clocks available. For now, we
 * support only NAND, and it is available at the same register
 * locations regardless of the SoC.
 */
static const struct clk_corediv_desc mvebu_corediv_desc[] = {
        { .mask = 0x3f, .offset = 8, .fieldbit = 1 }, /* NAND clock */
};

#define to_corediv_clk(p) container_of(p, struct clk_corediv, hw)

static int clk_corediv_is_enabled(struct clk_hw *hwclk)
{
        struct clk_corediv *corediv = to_corediv_clk(hwclk);
        const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
        const struct clk_corediv_desc *desc = corediv->desc;
        u32 enable_mask = BIT(desc->fieldbit) << soc_desc->enable_bit_offset;

        return !!(readl(corediv->reg) & enable_mask);
}

static int clk_corediv_enable(struct clk_hw *hwclk)
{
        struct clk_corediv *corediv = to_corediv_clk(hwclk);
        const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
        const struct clk_corediv_desc *desc = corediv->desc;
        unsigned long flags = 0;
        u32 reg;

        spin_lock_irqsave(&corediv->lock, flags);

        reg = readl(corediv->reg);
        reg |= (BIT(desc->fieldbit) << soc_desc->enable_bit_offset);
        writel(reg, corediv->reg);

        spin_unlock_irqrestore(&corediv->lock, flags);

        return 0;
}

static void clk_corediv_disable(struct clk_hw *hwclk)
{
        struct clk_corediv *corediv = to_corediv_clk(hwclk);
        const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
        const struct clk_corediv_desc *desc = corediv->desc;
        unsigned long flags = 0;
        u32 reg;

        spin_lock_irqsave(&corediv->lock, flags);

        reg = readl(corediv->reg);
        reg &= ~(BIT(desc->fieldbit) << soc_desc->enable_bit_offset);
        writel(reg, corediv->reg);

        spin_unlock_irqrestore(&corediv->lock, flags);
}

static unsigned long clk_corediv_recalc_rate(struct clk_hw *hwclk,
                                         unsigned long parent_rate)
{
        struct clk_corediv *corediv = to_corediv_clk(hwclk);
        const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
        const struct clk_corediv_desc *desc = corediv->desc;
        u32 reg, div;

        reg = readl(corediv->reg + soc_desc->ratio_offset);
        div = (reg >> desc->offset) & desc->mask;
        return parent_rate / div;
}

static long clk_corediv_round_rate(struct clk_hw *hwclk, unsigned long rate,
                               unsigned long *parent_rate)
{
        /* Valid ratio are 1:4, 1:5, 1:6 and 1:8 */
        u32 div;

        div = *parent_rate / rate;
        if (div < 4)
                div = 4;
        else if (div > 6)
                div = 8;

        return *parent_rate / div;
}

static int clk_corediv_set_rate(struct clk_hw *hwclk, unsigned long rate,
                            unsigned long parent_rate)
{
        struct clk_corediv *corediv = to_corediv_clk(hwclk);
        const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
        const struct clk_corediv_desc *desc = corediv->desc;
        unsigned long flags = 0;
        u32 reg, div;

        div = parent_rate / rate;

        spin_lock_irqsave(&corediv->lock, flags);

        /* Write new divider to the divider ratio register */
        reg = readl(corediv->reg + soc_desc->ratio_offset);
        reg &= ~(desc->mask << desc->offset);
        reg |= (div & desc->mask) << desc->offset;
        writel(reg, corediv->reg + soc_desc->ratio_offset);

        /* Set reload-force for this clock */
        reg = readl(corediv->reg) | BIT(desc->fieldbit);
        writel(reg, corediv->reg);

        /* Now trigger the clock update */
        reg = readl(corediv->reg) | soc_desc->ratio_reload;
        writel(reg, corediv->reg);

        /*
         * Wait for clocks to settle down, and then clear all the
         * ratios request and the reload request.
         */
        udelay(1000);
        reg &= ~(CORE_CLK_DIV_RATIO_MASK | soc_desc->ratio_reload);
        writel(reg, corediv->reg);
        udelay(1000);

        spin_unlock_irqrestore(&corediv->lock, flags);

        return 0;
}

static const struct clk_corediv_soc_desc armada370_corediv_soc = {
        .descs = mvebu_corediv_desc,
        .ndescs = ARRAY_SIZE(mvebu_corediv_desc),
        .ops = {
                .enable = clk_corediv_enable,
                .disable = clk_corediv_disable,
                .is_enabled = clk_corediv_is_enabled,
                .recalc_rate = clk_corediv_recalc_rate,
                .round_rate = clk_corediv_round_rate,
                .set_rate = clk_corediv_set_rate,
        },
        .ratio_reload = BIT(8),
        .enable_bit_offset = 24,
        .ratio_offset = 0x8,
};

static const struct clk_corediv_soc_desc armada380_corediv_soc = {
        .descs = mvebu_corediv_desc,
        .ndescs = ARRAY_SIZE(mvebu_corediv_desc),
        .ops = {
                .enable = clk_corediv_enable,
                .disable = clk_corediv_disable,
                .is_enabled = clk_corediv_is_enabled,
                .recalc_rate = clk_corediv_recalc_rate,
                .round_rate = clk_corediv_round_rate,
                .set_rate = clk_corediv_set_rate,
        },
        .ratio_reload = BIT(8),
        .enable_bit_offset = 16,
        .ratio_offset = 0x4,
};

static const struct clk_corediv_soc_desc armada375_corediv_soc = {
        .descs = mvebu_corediv_desc,
        .ndescs = ARRAY_SIZE(mvebu_corediv_desc),
        .ops = {
                .recalc_rate = clk_corediv_recalc_rate,
                .round_rate = clk_corediv_round_rate,
                .set_rate = clk_corediv_set_rate,
        },
        .ratio_reload = BIT(8),
        .ratio_offset = 0x4,
};

static void __init
mvebu_corediv_clk_init(struct device_node *node,
                       const struct clk_corediv_soc_desc *soc_desc)
{
        struct clk_init_data init;
        struct clk_corediv *corediv;
        struct clk **clks;
        void __iomem *base;
        const char *parent_name;
        const char *clk_name;
        int i;

        base = of_iomap(node, 0);
        if (WARN_ON(!base))
                return;

        parent_name = of_clk_get_parent_name(node, 0);

        clk_data.clk_num = soc_desc->ndescs;

        /* clks holds the clock array */
        clks = kcalloc(clk_data.clk_num, sizeof(struct clk *),
                                GFP_KERNEL);
        if (WARN_ON(!clks))
                goto err_unmap;
        /* corediv holds the clock specific array */
        corediv = kcalloc(clk_data.clk_num, sizeof(struct clk_corediv),
                                GFP_KERNEL);
        if (WARN_ON(!corediv))
                goto err_free_clks;

        spin_lock_init(&corediv->lock);

        for (i = 0; i < clk_data.clk_num; i++) {
                of_property_read_string_index(node, "clock-output-names",
                                              i, &clk_name);
                init.num_parents = 1;
                init.parent_names = &parent_name;
                init.name = clk_name;
                init.ops = &soc_desc->ops;
                init.flags = 0;

                corediv[i].soc_desc = soc_desc;
                corediv[i].desc = soc_desc->descs + i;
                corediv[i].reg = base;
                corediv[i].hw.init = &init;

                clks[i] = clk_register(NULL, &corediv[i].hw);
                WARN_ON(IS_ERR(clks[i]));
        }

        clk_data.clks = clks;
        of_clk_add_provider(node, of_clk_src_onecell_get, &clk_data);
        return;

err_free_clks:
        kfree(clks);
err_unmap:
        iounmap(base);
}

static void __init armada370_corediv_clk_init(struct device_node *node)
{
        return mvebu_corediv_clk_init(node, &armada370_corediv_soc);
}
CLK_OF_DECLARE(armada370_corediv_clk, "marvell,armada-370-corediv-clock",
               armada370_corediv_clk_init);

static void __init armada375_corediv_clk_init(struct device_node *node)
{
        return mvebu_corediv_clk_init(node, &armada375_corediv_soc);
}
CLK_OF_DECLARE(armada375_corediv_clk, "marvell,armada-375-corediv-clock",
               armada375_corediv_clk_init);

static void __init armada380_corediv_clk_init(struct device_node *node)
{
        return mvebu_corediv_clk_init(node, &armada380_corediv_soc);
}
CLK_OF_DECLARE(armada380_corediv_clk, "marvell,armada-380-corediv-clock",
               armada380_corediv_clk_init);