/*
 * arch/arm/mach-ep93xx/clock.c
 * Clock control for Cirrus EP93xx chips.
 *
 * Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
 *
 * 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.
 */

#include <linux/kernel.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/io.h>
#include <linux/spinlock.h>

#include <mach/hardware.h>

#include <asm/clkdev.h>
#include <asm/div64.h>


struct clk {
        struct clk      *parent;
        unsigned long   rate;
        int             users;
        int             sw_locked;
        void __iomem    *enable_reg;
        u32             enable_mask;

        unsigned long   (*get_rate)(struct clk *clk);
        int             (*set_rate)(struct clk *clk, unsigned long rate);
};


static unsigned long get_uart_rate(struct clk *clk);

static int set_keytchclk_rate(struct clk *clk, unsigned long rate);
static int set_div_rate(struct clk *clk, unsigned long rate);


static struct clk clk_xtali = {
        .rate           = EP93XX_EXT_CLK_RATE,
};
static struct clk clk_uart1 = {
        .parent         = &clk_xtali,
        .sw_locked      = 1,
        .enable_reg     = EP93XX_SYSCON_DEVCFG,
        .enable_mask    = EP93XX_SYSCON_DEVCFG_U1EN,
        .get_rate       = get_uart_rate,
};
static struct clk clk_uart2 = {
        .parent         = &clk_xtali,
        .sw_locked      = 1,
        .enable_reg     = EP93XX_SYSCON_DEVCFG,
        .enable_mask    = EP93XX_SYSCON_DEVCFG_U2EN,
        .get_rate       = get_uart_rate,
};
static struct clk clk_uart3 = {
        .parent         = &clk_xtali,
        .sw_locked      = 1,
        .enable_reg     = EP93XX_SYSCON_DEVCFG,
        .enable_mask    = EP93XX_SYSCON_DEVCFG_U3EN,
        .get_rate       = get_uart_rate,
};
static struct clk clk_pll1 = {
        .parent         = &clk_xtali,
};
static struct clk clk_f = {
        .parent         = &clk_pll1,
};
static struct clk clk_h = {
        .parent         = &clk_pll1,
};
static struct clk clk_p = {
        .parent         = &clk_pll1,
};
static struct clk clk_pll2 = {
        .parent         = &clk_xtali,
};
static struct clk clk_usb_host = {
        .parent         = &clk_pll2,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_USH_EN,
};
static struct clk clk_keypad = {
        .parent         = &clk_xtali,
        .sw_locked      = 1,
        .enable_reg     = EP93XX_SYSCON_KEYTCHCLKDIV,
        .enable_mask    = EP93XX_SYSCON_KEYTCHCLKDIV_KEN,
        .set_rate       = set_keytchclk_rate,
};
static struct clk clk_pwm = {
        .parent         = &clk_xtali,
        .rate           = EP93XX_EXT_CLK_RATE,
};

static struct clk clk_video = {
        .sw_locked      = 1,
        .enable_reg     = EP93XX_SYSCON_VIDCLKDIV,
        .enable_mask    = EP93XX_SYSCON_CLKDIV_ENABLE,
        .set_rate       = set_div_rate,
};

/* DMA Clocks */
static struct clk clk_m2p0 = {
        .parent         = &clk_h,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P0,
};
static struct clk clk_m2p1 = {
        .parent         = &clk_h,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P1,
};
static struct clk clk_m2p2 = {
        .parent         = &clk_h,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P2,
};
static struct clk clk_m2p3 = {
        .parent         = &clk_h,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P3,
};
static struct clk clk_m2p4 = {
        .parent         = &clk_h,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P4,
};
static struct clk clk_m2p5 = {
        .parent         = &clk_h,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P5,
};
static struct clk clk_m2p6 = {
        .parent         = &clk_h,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P6,
};
static struct clk clk_m2p7 = {
        .parent         = &clk_h,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P7,
};
static struct clk clk_m2p8 = {
        .parent         = &clk_h,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P8,
};
static struct clk clk_m2p9 = {
        .parent         = &clk_h,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P9,
};
static struct clk clk_m2m0 = {
        .parent         = &clk_h,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2M0,
};
static struct clk clk_m2m1 = {
        .parent         = &clk_h,
        .enable_reg     = EP93XX_SYSCON_PWRCNT,
        .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2M1,
};

#define INIT_CK(dev,con,ck)                                     \
        { .dev_id = dev, .con_id = con, .clk = ck }

static struct clk_lookup clocks[] = {
        INIT_CK(NULL,                   "xtali",        &clk_xtali),
        INIT_CK("apb:uart1",            NULL,           &clk_uart1),
        INIT_CK("apb:uart2",            NULL,           &clk_uart2),
        INIT_CK("apb:uart3",            NULL,           &clk_uart3),
        INIT_CK(NULL,                   "pll1",         &clk_pll1),
        INIT_CK(NULL,                   "fclk",         &clk_f),
        INIT_CK(NULL,                   "hclk",         &clk_h),
        INIT_CK(NULL,                   "pclk",         &clk_p),
        INIT_CK(NULL,                   "pll2",         &clk_pll2),
        INIT_CK("ep93xx-ohci",          NULL,           &clk_usb_host),
        INIT_CK("ep93xx-keypad",        NULL,           &clk_keypad),
        INIT_CK("ep93xx-fb",            NULL,           &clk_video),
        INIT_CK(NULL,                   "pwm_clk",      &clk_pwm),
        INIT_CK(NULL,                   "m2p0",         &clk_m2p0),
        INIT_CK(NULL,                   "m2p1",         &clk_m2p1),
        INIT_CK(NULL,                   "m2p2",         &clk_m2p2),
        INIT_CK(NULL,                   "m2p3",         &clk_m2p3),
        INIT_CK(NULL,                   "m2p4",         &clk_m2p4),
        INIT_CK(NULL,                   "m2p5",         &clk_m2p5),
        INIT_CK(NULL,                   "m2p6",         &clk_m2p6),
        INIT_CK(NULL,                   "m2p7",         &clk_m2p7),
        INIT_CK(NULL,                   "m2p8",         &clk_m2p8),
        INIT_CK(NULL,                   "m2p9",         &clk_m2p9),
        INIT_CK(NULL,                   "m2m0",         &clk_m2m0),
        INIT_CK(NULL,                   "m2m1",         &clk_m2m1),
};

static DEFINE_SPINLOCK(clk_lock);

static void __clk_enable(struct clk *clk)
{
        if (!clk->users++) {
                if (clk->parent)
                        __clk_enable(clk->parent);

                if (clk->enable_reg) {
                        u32 v;

                        v = __raw_readl(clk->enable_reg);
                        v |= clk->enable_mask;
                        if (clk->sw_locked)
                                ep93xx_syscon_swlocked_write(v, clk->enable_reg);
                        else
                                __raw_writel(v, clk->enable_reg);
                }
        }
}

int clk_enable(struct clk *clk)
{
        unsigned long flags;

        if (!clk)
                return -EINVAL;

        spin_lock_irqsave(&clk_lock, flags);
        __clk_enable(clk);
        spin_unlock_irqrestore(&clk_lock, flags);

        return 0;
}
EXPORT_SYMBOL(clk_enable);

static void __clk_disable(struct clk *clk)
{
        if (!--clk->users) {
                if (clk->enable_reg) {
                        u32 v;

                        v = __raw_readl(clk->enable_reg);
                        v &= ~clk->enable_mask;
                        if (clk->sw_locked)
                                ep93xx_syscon_swlocked_write(v, clk->enable_reg);
                        else
                                __raw_writel(v, clk->enable_reg);
                }

                if (clk->parent)
                        __clk_disable(clk->parent);
        }
}

void clk_disable(struct clk *clk)
{
        unsigned long flags;

        if (!clk)
                return;

        spin_lock_irqsave(&clk_lock, flags);
        __clk_disable(clk);
        spin_unlock_irqrestore(&clk_lock, flags);
}
EXPORT_SYMBOL(clk_disable);

static unsigned long get_uart_rate(struct clk *clk)
{
        unsigned long rate = clk_get_rate(clk->parent);
        u32 value;

        value = __raw_readl(EP93XX_SYSCON_PWRCNT);
        if (value & EP93XX_SYSCON_PWRCNT_UARTBAUD)
                return rate;
        else
                return rate / 2;
}

unsigned long clk_get_rate(struct clk *clk)
{
        if (clk->get_rate)
                return clk->get_rate(clk);

        return clk->rate;
}
EXPORT_SYMBOL(clk_get_rate);

static int set_keytchclk_rate(struct clk *clk, unsigned long rate)
{
        u32 val;
        u32 div_bit;

        val = __raw_readl(clk->enable_reg);

        /*
         * The Key Matrix and ADC clocks are configured using the same
         * System Controller register.  The clock used will be either
         * 1/4 or 1/16 the external clock rate depending on the
         * EP93XX_SYSCON_KEYTCHCLKDIV_KDIV/EP93XX_SYSCON_KEYTCHCLKDIV_ADIV
         * bit being set or cleared.
         */
        div_bit = clk->enable_mask >> 15;

        if (rate == EP93XX_KEYTCHCLK_DIV4)
                val |= div_bit;
        else if (rate == EP93XX_KEYTCHCLK_DIV16)
                val &= ~div_bit;
        else
                return -EINVAL;

        ep93xx_syscon_swlocked_write(val, clk->enable_reg);
        clk->rate = rate;
        return 0;
}

static int calc_clk_div(struct clk *clk, unsigned long rate,
                        int *psel, int *esel, int *pdiv, int *div)
{
        struct clk *mclk;
        unsigned long max_rate, actual_rate, mclk_rate, rate_err = -1;
        int i, found = 0, __div = 0, __pdiv = 0;

        /* Don't exceed the maximum rate */
        max_rate = max(max(clk_pll1.rate / 4, clk_pll2.rate / 4),
                       clk_xtali.rate / 4);
        rate = min(rate, max_rate);

        /*
         * Try the two pll's and the external clock
         * Because the valid predividers are 2, 2.5 and 3, we multiply
         * all the clocks by 2 to avoid floating point math.
         *
         * This is based on the algorithm in the ep93xx raster guide:
         * http://be-a-maverick.com/en/pubs/appNote/AN269REV1.pdf
         *
         */
        for (i = 0; i < 3; i++) {
                if (i == 0)
                        mclk = &clk_xtali;
                else if (i == 1)
                        mclk = &clk_pll1;
                else
                        mclk = &clk_pll2;
                mclk_rate = mclk->rate * 2;

                /* Try each predivider value */
                for (__pdiv = 4; __pdiv <= 6; __pdiv++) {
                        __div = mclk_rate / (rate * __pdiv);
                        if (__div < 2 || __div > 127)
                                continue;

                        actual_rate = mclk_rate / (__pdiv * __div);

                        if (!found || abs(actual_rate - rate) < rate_err) {
                                *pdiv = __pdiv - 3;
                                *div = __div;
                                *psel = (i == 2);
                                *esel = (i != 0);
                                clk->parent = mclk;
                                clk->rate = actual_rate;
                                rate_err = abs(actual_rate - rate);
                                found = 1;
                        }
                }
        }

        if (!found)
                return -EINVAL;

        return 0;
}

static int set_div_rate(struct clk *clk, unsigned long rate)
{
        int err, psel = 0, esel = 0, pdiv = 0, div = 0;
        u32 val;

        err = calc_clk_div(clk, rate, &psel, &esel, &pdiv, &div);
        if (err)
                return err;

        /* Clear the esel, psel, pdiv and div bits */
        val = __raw_readl(clk->enable_reg);
        val &= ~0x7fff;

        /* Set the new esel, psel, pdiv and div bits for the new clock rate */
        val |= (esel ? EP93XX_SYSCON_CLKDIV_ESEL : 0) |
                (psel ? EP93XX_SYSCON_CLKDIV_PSEL : 0) |
                (pdiv << EP93XX_SYSCON_CLKDIV_PDIV_SHIFT) | div;
        ep93xx_syscon_swlocked_write(val, clk->enable_reg);
        return 0;
}

int clk_set_rate(struct clk *clk, unsigned long rate)
{
        if (clk->set_rate)
                return clk->set_rate(clk, rate);

        return -EINVAL;
}
EXPORT_SYMBOL(clk_set_rate);


static char fclk_divisors[] = { 1, 2, 4, 8, 16, 1, 1, 1 };
static char hclk_divisors[] = { 1, 2, 4, 5, 6, 8, 16, 32 };
static char pclk_divisors[] = { 1, 2, 4, 8 };

/*
 * PLL rate = 14.7456 MHz * (X1FBD + 1) * (X2FBD + 1) / (X2IPD + 1) / 2^PS
 */
static unsigned long calc_pll_rate(u32 config_word)
{
        unsigned long long rate;
        int i;

        rate = clk_xtali.rate;
        rate *= ((config_word >> 11) & 0x1f) + 1;               /* X1FBD */
        rate *= ((config_word >> 5) & 0x3f) + 1;                /* X2FBD */
        do_div(rate, (config_word & 0x1f) + 1);                 /* X2IPD */
        for (i = 0; i < ((config_word >> 16) & 3); i++)         /* PS */
                rate >>= 1;

        return (unsigned long)rate;
}

static void __init ep93xx_dma_clock_init(void)
{
        clk_m2p0.rate = clk_h.rate;
        clk_m2p1.rate = clk_h.rate;
        clk_m2p2.rate = clk_h.rate;
        clk_m2p3.rate = clk_h.rate;
        clk_m2p4.rate = clk_h.rate;
        clk_m2p5.rate = clk_h.rate;
        clk_m2p6.rate = clk_h.rate;
        clk_m2p7.rate = clk_h.rate;
        clk_m2p8.rate = clk_h.rate;
        clk_m2p9.rate = clk_h.rate;
        clk_m2m0.rate = clk_h.rate;
        clk_m2m1.rate = clk_h.rate;
}

static int __init ep93xx_clock_init(void)
{
        u32 value;
        int i;

        value = __raw_readl(EP93XX_SYSCON_CLOCK_SET1);
        if (!(value & 0x00800000)) {                    /* PLL1 bypassed?  */
                clk_pll1.rate = clk_xtali.rate;
        } else {
                clk_pll1.rate = calc_pll_rate(value);
        }
        clk_f.rate = clk_pll1.rate / fclk_divisors[(value >> 25) & 0x7];
        clk_h.rate = clk_pll1.rate / hclk_divisors[(value >> 20) & 0x7];
        clk_p.rate = clk_h.rate / pclk_divisors[(value >> 18) & 0x3];
        ep93xx_dma_clock_init();

        value = __raw_readl(EP93XX_SYSCON_CLOCK_SET2);
        if (!(value & 0x00080000)) {                    /* PLL2 bypassed?  */
                clk_pll2.rate = clk_xtali.rate;
        } else if (value & 0x00040000) {                /* PLL2 enabled?  */
                clk_pll2.rate = calc_pll_rate(value);
        } else {
                clk_pll2.rate = 0;
        }
        clk_usb_host.rate = clk_pll2.rate / (((value >> 28) & 0xf) + 1);

        printk(KERN_INFO "ep93xx: PLL1 running at %ld MHz, PLL2 at %ld MHz\n",
                clk_pll1.rate / 1000000, clk_pll2.rate / 1000000);
        printk(KERN_INFO "ep93xx: FCLK %ld MHz, HCLK %ld MHz, PCLK %ld MHz\n",
                clk_f.rate / 1000000, clk_h.rate / 1000000,
                clk_p.rate / 1000000);

        for (i = 0; i < ARRAY_SIZE(clocks); i++)
                clkdev_add(&clocks[i]);
        return 0;
}
arch_initcall(ep93xx_clock_init);