/*
 * Clock and PLL control for DaVinci devices
 *
 * Copyright (C) 2006-2007 Texas Instruments.
 * Copyright (C) 2008-2009 Deep Root Systems, LLC
 *
 * 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/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/io.h>
#include <linux/delay.h>

#include <mach/hardware.h>

#include <mach/clock.h>
#include <mach/psc.h>
#include <mach/cputype.h>
#include "clock.h"

static LIST_HEAD(clocks);
static DEFINE_MUTEX(clocks_mutex);
static DEFINE_SPINLOCK(clockfw_lock);

static void __clk_enable(struct clk *clk)
{
        if (clk->parent)
                __clk_enable(clk->parent);
        if (clk->usecount++ == 0 && (clk->flags & CLK_PSC))
                davinci_psc_config(clk->domain, clk->gpsc, clk->lpsc,
                                true, clk->flags);
}

static void __clk_disable(struct clk *clk)
{
        if (WARN_ON(clk->usecount == 0))
                return;
        if (--clk->usecount == 0 && !(clk->flags & CLK_PLL) &&
            (clk->flags & CLK_PSC))
                davinci_psc_config(clk->domain, clk->gpsc, clk->lpsc,
                                false, clk->flags);
        if (clk->parent)
                __clk_disable(clk->parent);
}

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

        if (clk == NULL || IS_ERR(clk))
                return -EINVAL;

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

        return 0;
}
EXPORT_SYMBOL(clk_enable);

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

        if (clk == NULL || IS_ERR(clk))
                return;

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

unsigned long clk_get_rate(struct clk *clk)
{
        if (clk == NULL || IS_ERR(clk))
                return -EINVAL;

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

long clk_round_rate(struct clk *clk, unsigned long rate)
{
        if (clk == NULL || IS_ERR(clk))
                return -EINVAL;

        if (clk->round_rate)
                return clk->round_rate(clk, rate);

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

/* Propagate rate to children */
static void propagate_rate(struct clk *root)
{
        struct clk *clk;

        list_for_each_entry(clk, &root->children, childnode) {
                if (clk->recalc)
                        clk->rate = clk->recalc(clk);
                propagate_rate(clk);
        }
}

int clk_set_rate(struct clk *clk, unsigned long rate)
{
        unsigned long flags;
        int ret = -EINVAL;

        if (clk == NULL || IS_ERR(clk))
                return ret;

        if (clk->set_rate)
                ret = clk->set_rate(clk, rate);

        spin_lock_irqsave(&clockfw_lock, flags);
        if (ret == 0) {
                if (clk->recalc)
                        clk->rate = clk->recalc(clk);
                propagate_rate(clk);
        }
        spin_unlock_irqrestore(&clockfw_lock, flags);

        return ret;
}
EXPORT_SYMBOL(clk_set_rate);

int clk_set_parent(struct clk *clk, struct clk *parent)
{
        unsigned long flags;

        if (clk == NULL || IS_ERR(clk))
                return -EINVAL;

        /* Cannot change parent on enabled clock */
        if (WARN_ON(clk->usecount))
                return -EINVAL;

        mutex_lock(&clocks_mutex);
        clk->parent = parent;
        list_del_init(&clk->childnode);
        list_add(&clk->childnode, &clk->parent->children);
        mutex_unlock(&clocks_mutex);

        spin_lock_irqsave(&clockfw_lock, flags);
        if (clk->recalc)
                clk->rate = clk->recalc(clk);
        propagate_rate(clk);
        spin_unlock_irqrestore(&clockfw_lock, flags);

        return 0;
}
EXPORT_SYMBOL(clk_set_parent);

int clk_register(struct clk *clk)
{
        if (clk == NULL || IS_ERR(clk))
                return -EINVAL;

        if (WARN(clk->parent && !clk->parent->rate,
                        "CLK: %s parent %s has no rate!\n",
                        clk->name, clk->parent->name))
                return -EINVAL;

        INIT_LIST_HEAD(&clk->children);

        mutex_lock(&clocks_mutex);
        list_add_tail(&clk->node, &clocks);
        if (clk->parent)
                list_add_tail(&clk->childnode, &clk->parent->children);
        mutex_unlock(&clocks_mutex);

        /* If rate is already set, use it */
        if (clk->rate)
                return 0;

        /* Else, see if there is a way to calculate it */
        if (clk->recalc)
                clk->rate = clk->recalc(clk);

        /* Otherwise, default to parent rate */
        else if (clk->parent)
                clk->rate = clk->parent->rate;

        return 0;
}
EXPORT_SYMBOL(clk_register);

void clk_unregister(struct clk *clk)
{
        if (clk == NULL || IS_ERR(clk))
                return;

        mutex_lock(&clocks_mutex);
        list_del(&clk->node);
        list_del(&clk->childnode);
        mutex_unlock(&clocks_mutex);
}
EXPORT_SYMBOL(clk_unregister);

#ifdef CONFIG_DAVINCI_RESET_CLOCKS
/*
 * Disable any unused clocks left on by the bootloader
 */
int __init davinci_clk_disable_unused(void)
{
        struct clk *ck;

        spin_lock_irq(&clockfw_lock);
        list_for_each_entry(ck, &clocks, node) {
                if (ck->usecount > 0)
                        continue;
                if (!(ck->flags & CLK_PSC))
                        continue;

                /* ignore if in Disabled or SwRstDisable states */
                if (!davinci_psc_is_clk_active(ck->gpsc, ck->lpsc))
                        continue;

                pr_debug("Clocks: disable unused %s\n", ck->name);

                davinci_psc_config(ck->domain, ck->gpsc, ck->lpsc,
                                false, ck->flags);
        }
        spin_unlock_irq(&clockfw_lock);

        return 0;
}
#endif

static unsigned long clk_sysclk_recalc(struct clk *clk)
{
        u32 v, plldiv;
        struct pll_data *pll;
        unsigned long rate = clk->rate;

        /* If this is the PLL base clock, no more calculations needed */
        if (clk->pll_data)
                return rate;

        if (WARN_ON(!clk->parent))
                return rate;

        rate = clk->parent->rate;

        /* Otherwise, the parent must be a PLL */
        if (WARN_ON(!clk->parent->pll_data))
                return rate;

        pll = clk->parent->pll_data;

        /* If pre-PLL, source clock is before the multiplier and divider(s) */
        if (clk->flags & PRE_PLL)
                rate = pll->input_rate;

        if (!clk->div_reg)
                return rate;

        v = __raw_readl(pll->base + clk->div_reg);
        if (v & PLLDIV_EN) {
                plldiv = (v & pll->div_ratio_mask) + 1;
                if (plldiv)
                        rate /= plldiv;
        }

        return rate;
}

int davinci_set_sysclk_rate(struct clk *clk, unsigned long rate)
{
        unsigned v;
        struct pll_data *pll;
        unsigned long input;
        unsigned ratio = 0;

        /* If this is the PLL base clock, wrong function to call */
        if (clk->pll_data)
                return -EINVAL;

        /* There must be a parent... */
        if (WARN_ON(!clk->parent))
                return -EINVAL;

        /* ... the parent must be a PLL... */
        if (WARN_ON(!clk->parent->pll_data))
                return -EINVAL;

        /* ... and this clock must have a divider. */
        if (WARN_ON(!clk->div_reg))
                return -EINVAL;

        pll = clk->parent->pll_data;

        input = clk->parent->rate;

        /* If pre-PLL, source clock is before the multiplier and divider(s) */
        if (clk->flags & PRE_PLL)
                input = pll->input_rate;

        if (input > rate) {
                /*
                 * Can afford to provide an output little higher than requested
                 * only if maximum rate supported by hardware on this sysclk
                 * is known.
                 */
                if (clk->maxrate) {
                        ratio = DIV_ROUND_CLOSEST(input, rate);
                        if (input / ratio > clk->maxrate)
                                ratio = 0;
                }

                if (ratio == 0)
                        ratio = DIV_ROUND_UP(input, rate);

                ratio--;
        }

        if (ratio > pll->div_ratio_mask)
                return -EINVAL;

        do {
                v = __raw_readl(pll->base + PLLSTAT);
        } while (v & PLLSTAT_GOSTAT);

        v = __raw_readl(pll->base + clk->div_reg);
        v &= ~pll->div_ratio_mask;
        v |= ratio | PLLDIV_EN;
        __raw_writel(v, pll->base + clk->div_reg);

        v = __raw_readl(pll->base + PLLCMD);
        v |= PLLCMD_GOSET;
        __raw_writel(v, pll->base + PLLCMD);

        do {
                v = __raw_readl(pll->base + PLLSTAT);
        } while (v & PLLSTAT_GOSTAT);

        return 0;
}
EXPORT_SYMBOL(davinci_set_sysclk_rate);

static unsigned long clk_leafclk_recalc(struct clk *clk)
{
        if (WARN_ON(!clk->parent))
                return clk->rate;

        return clk->parent->rate;
}

int davinci_simple_set_rate(struct clk *clk, unsigned long rate)
{
        clk->rate = rate;
        return 0;
}

static unsigned long clk_pllclk_recalc(struct clk *clk)
{
        u32 ctrl, mult = 1, prediv = 1, postdiv = 1;
        u8 bypass;
        struct pll_data *pll = clk->pll_data;
        unsigned long rate = clk->rate;

        ctrl = __raw_readl(pll->base + PLLCTL);
        rate = pll->input_rate = clk->parent->rate;

        if (ctrl & PLLCTL_PLLEN) {
                bypass = 0;
                mult = __raw_readl(pll->base + PLLM);
                if (cpu_is_davinci_dm365())
                        mult = 2 * (mult & PLLM_PLLM_MASK);
                else
                        mult = (mult & PLLM_PLLM_MASK) + 1;
        } else
                bypass = 1;

        if (pll->flags & PLL_HAS_PREDIV) {
                prediv = __raw_readl(pll->base + PREDIV);
                if (prediv & PLLDIV_EN)
                        prediv = (prediv & pll->div_ratio_mask) + 1;
                else
                        prediv = 1;
        }

        /* pre-divider is fixed, but (some?) chips won't report that */
        if (cpu_is_davinci_dm355() && pll->num == 1)
                prediv = 8;

        if (pll->flags & PLL_HAS_POSTDIV) {
                postdiv = __raw_readl(pll->base + POSTDIV);
                if (postdiv & PLLDIV_EN)
                        postdiv = (postdiv & pll->div_ratio_mask) + 1;
                else
                        postdiv = 1;
        }

        if (!bypass) {
                rate /= prediv;
                rate *= mult;
                rate /= postdiv;
        }

        pr_debug("PLL%d: input = %lu MHz [ ",
                 pll->num, clk->parent->rate / 1000000);
        if (bypass)
                pr_debug("bypass ");
        if (prediv > 1)
                pr_debug("/ %d ", prediv);
        if (mult > 1)
                pr_debug("* %d ", mult);
        if (postdiv > 1)
                pr_debug("/ %d ", postdiv);
        pr_debug("] --> %lu MHz output.\n", rate / 1000000);

        return rate;
}

/**
 * davinci_set_pllrate - set the output rate of a given PLL.
 *
 * Note: Currently tested to work with OMAP-L138 only.
 *
 * @pll: pll whose rate needs to be changed.
 * @prediv: The pre divider value. Passing 0 disables the pre-divider.
 * @pllm: The multiplier value. Passing 0 leads to multiply-by-one.
 * @postdiv: The post divider value. Passing 0 disables the post-divider.
 */
int davinci_set_pllrate(struct pll_data *pll, unsigned int prediv,
                                        unsigned int mult, unsigned int postdiv)
{
        u32 ctrl;
        unsigned int locktime;
        unsigned long flags;

        if (pll->base == NULL)
                return -EINVAL;

        /*
         *  PLL lock time required per OMAP-L138 datasheet is
         * (2000 * prediv)/sqrt(pllm) OSCIN cycles. We approximate sqrt(pllm)
         * as 4 and OSCIN cycle as 25 MHz.
         */
        if (prediv) {
                locktime = ((2000 * prediv) / 100);
                prediv = (prediv - 1) | PLLDIV_EN;
        } else {
                locktime = PLL_LOCK_TIME;
        }
        if (postdiv)
                postdiv = (postdiv - 1) | PLLDIV_EN;
        if (mult)
                mult = mult - 1;

        /* Protect against simultaneous calls to PLL setting seqeunce */
        spin_lock_irqsave(&clockfw_lock, flags);

        ctrl = __raw_readl(pll->base + PLLCTL);

        /* Switch the PLL to bypass mode */
        ctrl &= ~(PLLCTL_PLLENSRC | PLLCTL_PLLEN);
        __raw_writel(ctrl, pll->base + PLLCTL);

        udelay(PLL_BYPASS_TIME);

        /* Reset and enable PLL */
        ctrl &= ~(PLLCTL_PLLRST | PLLCTL_PLLDIS);
        __raw_writel(ctrl, pll->base + PLLCTL);

        if (pll->flags & PLL_HAS_PREDIV)
                __raw_writel(prediv, pll->base + PREDIV);

        __raw_writel(mult, pll->base + PLLM);

        if (pll->flags & PLL_HAS_POSTDIV)
                __raw_writel(postdiv, pll->base + POSTDIV);

        udelay(PLL_RESET_TIME);

        /* Bring PLL out of reset */
        ctrl |= PLLCTL_PLLRST;
        __raw_writel(ctrl, pll->base + PLLCTL);

        udelay(locktime);

        /* Remove PLL from bypass mode */
        ctrl |= PLLCTL_PLLEN;
        __raw_writel(ctrl, pll->base + PLLCTL);

        spin_unlock_irqrestore(&clockfw_lock, flags);

        return 0;
}
EXPORT_SYMBOL(davinci_set_pllrate);

/**
 * davinci_set_refclk_rate() - Set the reference clock rate
 * @rate:       The new rate.
 *
 * Sets the reference clock rate to a given value. This will most likely
 * result in the entire clock tree getting updated.
 *
 * This is used to support boards which use a reference clock different
 * than that used by default in <soc>.c file. The reference clock rate
 * should be updated early in the boot process; ideally soon after the
 * clock tree has been initialized once with the default reference clock
 * rate (davinci_common_init()).
 *
 * Returns 0 on success, error otherwise.
 */
int davinci_set_refclk_rate(unsigned long rate)
{
        struct clk *refclk;

        refclk = clk_get(NULL, "ref");
        if (IS_ERR(refclk)) {
                pr_err("%s: failed to get reference clock.\n", __func__);
                return PTR_ERR(refclk);
        }

        clk_set_rate(refclk, rate);

        clk_put(refclk);

        return 0;
}

int __init davinci_clk_init(struct clk_lookup *clocks)
  {
        struct clk_lookup *c;
        struct clk *clk;
        size_t num_clocks = 0;

        for (c = clocks; c->clk; c++) {
                clk = c->clk;

                if (!clk->recalc) {

                        /* Check if clock is a PLL */
                        if (clk->pll_data)
                                clk->recalc = clk_pllclk_recalc;

                        /* Else, if it is a PLL-derived clock */
                        else if (clk->flags & CLK_PLL)
                                clk->recalc = clk_sysclk_recalc;

                        /* Otherwise, it is a leaf clock (PSC clock) */
                        else if (clk->parent)
                                clk->recalc = clk_leafclk_recalc;
                }

                if (clk->pll_data) {
                        struct pll_data *pll = clk->pll_data;

                        if (!pll->div_ratio_mask)
                                pll->div_ratio_mask = PLLDIV_RATIO_MASK;

                        if (pll->phys_base && !pll->base) {
                                pll->base = ioremap(pll->phys_base, SZ_4K);
                                WARN_ON(!pll->base);
                        }
                }

                if (clk->recalc)
                        clk->rate = clk->recalc(clk);

                if (clk->lpsc)
                        clk->flags |= CLK_PSC;

                clk_register(clk);
                num_clocks++;

                /* Turn on clocks that Linux doesn't otherwise manage */
                if (clk->flags & ALWAYS_ENABLED)
                        clk_enable(clk);
        }

        clkdev_add_table(clocks, num_clocks);

        return 0;
}

#ifdef CONFIG_DEBUG_FS

#include <linux/debugfs.h>
#include <linux/seq_file.h>

#define CLKNAME_MAX     10              /* longest clock name */
#define NEST_DELTA      2
#define NEST_MAX        4

static void
dump_clock(struct seq_file *s, unsigned nest, struct clk *parent)
{
        char            *state;
        char            buf[CLKNAME_MAX + NEST_DELTA * NEST_MAX];
        struct clk      *clk;
        unsigned        i;

        if (parent->flags & CLK_PLL)
                state = "pll";
        else if (parent->flags & CLK_PSC)
                state = "psc";
        else
                state = "";

        /* <nest spaces> name <pad to end> */
        memset(buf, ' ', sizeof(buf) - 1);
        buf[sizeof(buf) - 1] = 0;
        i = strlen(parent->name);
        memcpy(buf + nest, parent->name,
                        min(i, (unsigned)(sizeof(buf) - 1 - nest)));

        seq_printf(s, "%s users=%2d %-3s %9ld Hz\n",
                   buf, parent->usecount, state, clk_get_rate(parent));
        /* REVISIT show device associations too */

        /* cost is now small, but not linear... */
        list_for_each_entry(clk, &parent->children, childnode) {
                dump_clock(s, nest + NEST_DELTA, clk);
        }
}

static int davinci_ck_show(struct seq_file *m, void *v)
{
        struct clk *clk;

        /*
         * Show clock tree; We trust nonzero usecounts equate to PSC enables...
         */
        mutex_lock(&clocks_mutex);
        list_for_each_entry(clk, &clocks, node)
                if (!clk->parent)
                        dump_clock(m, 0, clk);
        mutex_unlock(&clocks_mutex);

        return 0;
}

static int davinci_ck_open(struct inode *inode, struct file *file)
{
        return single_open(file, davinci_ck_show, NULL);
}

static const struct file_operations davinci_ck_operations = {
        .open           = davinci_ck_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int __init davinci_clk_debugfs_init(void)
{
        debugfs_create_file("davinci_clocks", S_IFREG | S_IRUGO, NULL, NULL,
                                                &davinci_ck_operations);
        return 0;

}
device_initcall(davinci_clk_debugfs_init);
#endif /* CONFIG_DEBUG_FS */