/*
 * Helper routines for SuperH Clock Pulse Generator blocks (CPG).
 *
 *  Copyright (C) 2010  Magnus Damm
 *  Copyright (C) 2010 - 2012  Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/clk.h>
#include <linux/compiler.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/sh_clk.h>

#define CPG_CKSTP_BIT   BIT(8)

static unsigned int sh_clk_read(struct clk *clk)
{
        if (clk->flags & CLK_ENABLE_REG_8BIT)
                return ioread8(clk->mapped_reg);
        else if (clk->flags & CLK_ENABLE_REG_16BIT)
                return ioread16(clk->mapped_reg);

        return ioread32(clk->mapped_reg);
}

static void sh_clk_write(int value, struct clk *clk)
{
        if (clk->flags & CLK_ENABLE_REG_8BIT)
                iowrite8(value, clk->mapped_reg);
        else if (clk->flags & CLK_ENABLE_REG_16BIT)
                iowrite16(value, clk->mapped_reg);
        else
                iowrite32(value, clk->mapped_reg);
}

static int sh_clk_mstp_enable(struct clk *clk)
{
        sh_clk_write(sh_clk_read(clk) & ~(1 << clk->enable_bit), clk);
        if (clk->status_reg) {
                unsigned int (*read)(const void __iomem *addr);
                int i;
                void __iomem *mapped_status = (phys_addr_t)clk->status_reg -
                        (phys_addr_t)clk->enable_reg + clk->mapped_reg;

                if (clk->flags & CLK_ENABLE_REG_8BIT)
                        read = ioread8;
                else if (clk->flags & CLK_ENABLE_REG_16BIT)
                        read = ioread16;
                else
                        read = ioread32;

                for (i = 1000;
                     (read(mapped_status) & (1 << clk->enable_bit)) && i;
                     i--)
                        cpu_relax();
                if (!i) {
                        pr_err("cpg: failed to enable %p[%d]\n",
                               clk->enable_reg, clk->enable_bit);
                        return -ETIMEDOUT;
                }
        }
        return 0;
}

static void sh_clk_mstp_disable(struct clk *clk)
{
        sh_clk_write(sh_clk_read(clk) | (1 << clk->enable_bit), clk);
}

static struct sh_clk_ops sh_clk_mstp_clk_ops = {
        .enable         = sh_clk_mstp_enable,
        .disable        = sh_clk_mstp_disable,
        .recalc         = followparent_recalc,
};

int __init sh_clk_mstp_register(struct clk *clks, int nr)
{
        struct clk *clkp;
        int ret = 0;
        int k;

        for (k = 0; !ret && (k < nr); k++) {
                clkp = clks + k;
                clkp->ops = &sh_clk_mstp_clk_ops;
                ret |= clk_register(clkp);
        }

        return ret;
}

/*
 * Div/mult table lookup helpers
 */
static inline struct clk_div_table *clk_to_div_table(struct clk *clk)
{
        return clk->priv;
}

static inline struct clk_div_mult_table *clk_to_div_mult_table(struct clk *clk)
{
        return clk_to_div_table(clk)->div_mult_table;
}

/*
 * Common div ops
 */
static long sh_clk_div_round_rate(struct clk *clk, unsigned long rate)
{
        return clk_rate_table_round(clk, clk->freq_table, rate);
}

static unsigned long sh_clk_div_recalc(struct clk *clk)
{
        struct clk_div_mult_table *table = clk_to_div_mult_table(clk);
        unsigned int idx;

        clk_rate_table_build(clk, clk->freq_table, table->nr_divisors,
                             table, clk->arch_flags ? &clk->arch_flags : NULL);

        idx = (sh_clk_read(clk) >> clk->enable_bit) & clk->div_mask;

        return clk->freq_table[idx].frequency;
}

static int sh_clk_div_set_rate(struct clk *clk, unsigned long rate)
{
        struct clk_div_table *dt = clk_to_div_table(clk);
        unsigned long value;
        int idx;

        idx = clk_rate_table_find(clk, clk->freq_table, rate);
        if (idx < 0)
                return idx;

        value = sh_clk_read(clk);
        value &= ~(clk->div_mask << clk->enable_bit);
        value |= (idx << clk->enable_bit);
        sh_clk_write(value, clk);

        /* XXX: Should use a post-change notifier */
        if (dt->kick)
                dt->kick(clk);

        return 0;
}

static int sh_clk_div_enable(struct clk *clk)
{
        if (clk->div_mask == SH_CLK_DIV6_MSK) {
                int ret = sh_clk_div_set_rate(clk, clk->rate);
                if (ret < 0)
                        return ret;
        }

        sh_clk_write(sh_clk_read(clk) & ~CPG_CKSTP_BIT, clk);
        return 0;
}

static void sh_clk_div_disable(struct clk *clk)
{
        unsigned int val;

        val = sh_clk_read(clk);
        val |= CPG_CKSTP_BIT;

        /*
         * div6 clocks require the divisor field to be non-zero or the
         * above CKSTP toggle silently fails. Ensure that the divisor
         * array is reset to its initial state on disable.
         */
        if (clk->flags & CLK_MASK_DIV_ON_DISABLE)
                val |= clk->div_mask;

        sh_clk_write(val, clk);
}

static struct sh_clk_ops sh_clk_div_clk_ops = {
        .recalc         = sh_clk_div_recalc,
        .set_rate       = sh_clk_div_set_rate,
        .round_rate     = sh_clk_div_round_rate,
};

static struct sh_clk_ops sh_clk_div_enable_clk_ops = {
        .recalc         = sh_clk_div_recalc,
        .set_rate       = sh_clk_div_set_rate,
        .round_rate     = sh_clk_div_round_rate,
        .enable         = sh_clk_div_enable,
        .disable        = sh_clk_div_disable,
};

static int __init sh_clk_init_parent(struct clk *clk)
{
        u32 val;

        if (clk->parent)
                return 0;

        if (!clk->parent_table || !clk->parent_num)
                return 0;

        if (!clk->src_width) {
                pr_err("sh_clk_init_parent: cannot select parent clock\n");
                return -EINVAL;
        }

        val  = (sh_clk_read(clk) >> clk->src_shift);
        val &= (1 << clk->src_width) - 1;

        if (val >= clk->parent_num) {
                pr_err("sh_clk_init_parent: parent table size failed\n");
                return -EINVAL;
        }

        clk_reparent(clk, clk->parent_table[val]);
        if (!clk->parent) {
                pr_err("sh_clk_init_parent: unable to set parent");
                return -EINVAL;
        }

        return 0;
}

static int __init sh_clk_div_register_ops(struct clk *clks, int nr,
                        struct clk_div_table *table, struct sh_clk_ops *ops)
{
        struct clk *clkp;
        void *freq_table;
        int nr_divs = table->div_mult_table->nr_divisors;
        int freq_table_size = sizeof(struct cpufreq_frequency_table);
        int ret = 0;
        int k;

        freq_table_size *= (nr_divs + 1);
        freq_table = kcalloc(nr, freq_table_size, GFP_KERNEL);
        if (!freq_table) {
                pr_err("%s: unable to alloc memory\n", __func__);
                return -ENOMEM;
        }

        for (k = 0; !ret && (k < nr); k++) {
                clkp = clks + k;

                clkp->ops = ops;
                clkp->priv = table;

                clkp->freq_table = freq_table + (k * freq_table_size);
                clkp->freq_table[nr_divs].frequency = CPUFREQ_TABLE_END;

                ret = clk_register(clkp);
                if (ret == 0)
                        ret = sh_clk_init_parent(clkp);
        }

        return ret;
}

/*
 * div6 support
 */
static int sh_clk_div6_divisors[64] = {
        1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
        17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,
        33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
        49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64
};

static struct clk_div_mult_table div6_div_mult_table = {
        .divisors = sh_clk_div6_divisors,
        .nr_divisors = ARRAY_SIZE(sh_clk_div6_divisors),
};

static struct clk_div_table sh_clk_div6_table = {
        .div_mult_table = &div6_div_mult_table,
};

static int sh_clk_div6_set_parent(struct clk *clk, struct clk *parent)
{
        struct clk_div_mult_table *table = clk_to_div_mult_table(clk);
        u32 value;
        int ret, i;

        if (!clk->parent_table || !clk->parent_num)
                return -EINVAL;

        /* Search the parent */
        for (i = 0; i < clk->parent_num; i++)
                if (clk->parent_table[i] == parent)
                        break;

        if (i == clk->parent_num)
                return -ENODEV;

        ret = clk_reparent(clk, parent);
        if (ret < 0)
                return ret;

        value = sh_clk_read(clk) &
                ~(((1 << clk->src_width) - 1) << clk->src_shift);

        sh_clk_write(value | (i << clk->src_shift), clk);

        /* Rebuild the frequency table */
        clk_rate_table_build(clk, clk->freq_table, table->nr_divisors,
                             table, NULL);

        return 0;
}

static struct sh_clk_ops sh_clk_div6_reparent_clk_ops = {
        .recalc         = sh_clk_div_recalc,
        .round_rate     = sh_clk_div_round_rate,
        .set_rate       = sh_clk_div_set_rate,
        .enable         = sh_clk_div_enable,
        .disable        = sh_clk_div_disable,
        .set_parent     = sh_clk_div6_set_parent,
};

int __init sh_clk_div6_register(struct clk *clks, int nr)
{
        return sh_clk_div_register_ops(clks, nr, &sh_clk_div6_table,
                                       &sh_clk_div_enable_clk_ops);
}

int __init sh_clk_div6_reparent_register(struct clk *clks, int nr)
{
        return sh_clk_div_register_ops(clks, nr, &sh_clk_div6_table,
                                       &sh_clk_div6_reparent_clk_ops);
}

/*
 * div4 support
 */
static int sh_clk_div4_set_parent(struct clk *clk, struct clk *parent)
{
        struct clk_div_mult_table *table = clk_to_div_mult_table(clk);
        u32 value;
        int ret;

        /* we really need a better way to determine parent index, but for
         * now assume internal parent comes with CLK_ENABLE_ON_INIT set,
         * no CLK_ENABLE_ON_INIT means external clock...
         */

        if (parent->flags & CLK_ENABLE_ON_INIT)
                value = sh_clk_read(clk) & ~(1 << 7);
        else
                value = sh_clk_read(clk) | (1 << 7);

        ret = clk_reparent(clk, parent);
        if (ret < 0)
                return ret;

        sh_clk_write(value, clk);

        /* Rebiuld the frequency table */
        clk_rate_table_build(clk, clk->freq_table, table->nr_divisors,
                             table, &clk->arch_flags);

        return 0;
}

static struct sh_clk_ops sh_clk_div4_reparent_clk_ops = {
        .recalc         = sh_clk_div_recalc,
        .set_rate       = sh_clk_div_set_rate,
        .round_rate     = sh_clk_div_round_rate,
        .enable         = sh_clk_div_enable,
        .disable        = sh_clk_div_disable,
        .set_parent     = sh_clk_div4_set_parent,
};

int __init sh_clk_div4_register(struct clk *clks, int nr,
                                struct clk_div4_table *table)
{
        return sh_clk_div_register_ops(clks, nr, table, &sh_clk_div_clk_ops);
}

int __init sh_clk_div4_enable_register(struct clk *clks, int nr,
                                struct clk_div4_table *table)
{
        return sh_clk_div_register_ops(clks, nr, table,
                                       &sh_clk_div_enable_clk_ops);
}

int __init sh_clk_div4_reparent_register(struct clk *clks, int nr,
                                struct clk_div4_table *table)
{
        return sh_clk_div_register_ops(clks, nr, table,
                                       &sh_clk_div4_reparent_clk_ops);
}

/* FSI-DIV */
static unsigned long fsidiv_recalc(struct clk *clk)
{
        u32 value;

        value = __raw_readl(clk->mapping->base);

        value >>= 16;
        if (value < 2)
                return clk->parent->rate;

        return clk->parent->rate / value;
}

static long fsidiv_round_rate(struct clk *clk, unsigned long rate)
{
        return clk_rate_div_range_round(clk, 1, 0xffff, rate);
}

static void fsidiv_disable(struct clk *clk)
{
        __raw_writel(0, clk->mapping->base);
}

static int fsidiv_enable(struct clk *clk)
{
        u32 value;

        value  = __raw_readl(clk->mapping->base) >> 16;
        if (value < 2)
                return 0;

        __raw_writel((value << 16) | 0x3, clk->mapping->base);

        return 0;
}

static int fsidiv_set_rate(struct clk *clk, unsigned long rate)
{
        int idx;

        idx = (clk->parent->rate / rate) & 0xffff;
        if (idx < 2)
                __raw_writel(0, clk->mapping->base);
        else
                __raw_writel(idx << 16, clk->mapping->base);

        return 0;
}

static struct sh_clk_ops fsidiv_clk_ops = {
        .recalc         = fsidiv_recalc,
        .round_rate     = fsidiv_round_rate,
        .set_rate       = fsidiv_set_rate,
        .enable         = fsidiv_enable,
        .disable        = fsidiv_disable,
};

int __init sh_clk_fsidiv_register(struct clk *clks, int nr)
{
        struct clk_mapping *map;
        int i;

        for (i = 0; i < nr; i++) {

                map = kzalloc(sizeof(struct clk_mapping), GFP_KERNEL);
                if (!map) {
                        pr_err("%s: unable to alloc memory\n", __func__);
                        return -ENOMEM;
                }

                /* clks[i].enable_reg came from SH_CLK_FSIDIV() */
                map->phys               = (phys_addr_t)clks[i].enable_reg;
                map->len                = 8;

                clks[i].enable_reg      = 0; /* remove .enable_reg */
                clks[i].ops             = &fsidiv_clk_ops;
                clks[i].mapping         = map;

                clk_register(&clks[i]);
        }

        return 0;
}