/*
 * 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/platform_device.h>
#include <linux/io.h>

#include <mach/hardware.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 unsigned psc_domain(struct clk *clk)
{
        return (clk->flags & PSC_DSP)
                ? DAVINCI_GPSC_DSPDOMAIN
                : DAVINCI_GPSC_ARMDOMAIN;
}

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(psc_domain(clk), clk->lpsc, 1);
}

static void __clk_disable(struct clk *clk)
{
        if (WARN_ON(clk->usecount == 0))
                return;
        if (--clk->usecount == 0 && !(clk->flags & CLK_PLL))
                davinci_psc_config(psc_domain(clk), clk->lpsc, 0);
        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;

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

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

        /* changing the clk rate is not supported */
        return -EINVAL;
}
EXPORT_SYMBOL(clk_set_rate);

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;

        mutex_lock(&clocks_mutex);
        list_add_tail(&clk->node, &clocks);
        mutex_unlock(&clocks_mutex);

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

        /* Otherwise, default to parent rate */
        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);
        mutex_unlock(&clocks_mutex);
}
EXPORT_SYMBOL(clk_unregister);

#ifdef CONFIG_DAVINCI_RESET_CLOCKS
/*
 * Disable any unused clocks left on by the bootloader
 */
static int __init 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->lpsc))
                        continue;

                pr_info("Clocks: disable unused %s\n", ck->name);
                davinci_psc_config(psc_domain(ck), ck->lpsc, 0);
        }
        spin_unlock_irq(&clockfw_lock);

        return 0;
}
late_initcall(clk_disable_unused);
#endif

static void clk_sysclk_recalc(struct clk *clk)
{
        u32 v, plldiv;
        struct pll_data *pll;

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

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

        clk->rate = clk->parent->rate;

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

        pll = clk->parent->pll_data;

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

        if (!clk->div_reg)
                return;

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

static void __init clk_pll_init(struct clk *clk)
{
        u32 ctrl, mult = 1, prediv = 1, postdiv = 1;
        u8 bypass;
        struct pll_data *pll = clk->pll_data;

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

        if (ctrl & PLLCTL_PLLEN) {
                bypass = 0;
                mult = __raw_readl(pll->base + PLLM);
                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 & PLLDIV_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 & PLLDIV_RATIO_MASK) + 1;
                else
                        postdiv = 1;
        }

        if (!bypass) {
                clk->rate /= prediv;
                clk->rate *= mult;
                clk->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", clk->rate / 1000000);
}

int __init davinci_clk_init(struct davinci_clk *clocks)
  {
        struct davinci_clk *c;
        struct clk *clk;

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

                if (clk->pll_data)
                        clk_pll_init(clk);

                /* Calculate rates for PLL-derived clocks */
                else if (clk->flags & CLK_PLL)
                        clk_sysclk_recalc(clk);

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

                clkdev_add(&c->lk);
                clk_register(clk);

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

        return 0;
}

#ifdef CONFIG_PROC_FS
#include <linux/proc_fs.h>
#include <linux/seq_file.h>

static void *davinci_ck_start(struct seq_file *m, loff_t *pos)
{
        return *pos < 1 ? (void *)1 : NULL;
}

static void *davinci_ck_next(struct seq_file *m, void *v, loff_t *pos)
{
        ++*pos;
        return NULL;
}

static void davinci_ck_stop(struct seq_file *m, void *v)
{
}

#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, &clocks, node) {
                if (clk->parent == parent)
                        dump_clock(s, nest + NEST_DELTA, clk);
        }
}

static int davinci_ck_show(struct seq_file *m, void *v)
{
        /* Show clock tree; we know the main oscillator is first.
         * We trust nonzero usecounts equate to PSC enables...
         */
        mutex_lock(&clocks_mutex);
        if (!list_empty(&clocks))
                dump_clock(m, 0, list_first_entry(&clocks, struct clk, node));
        mutex_unlock(&clocks_mutex);

        return 0;
}

static const struct seq_operations davinci_ck_op = {
        .start  = davinci_ck_start,
        .next   = davinci_ck_next,
        .stop   = davinci_ck_stop,
        .show   = davinci_ck_show
};

static int davinci_ck_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &davinci_ck_op);
}

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

static int __init davinci_ck_proc_init(void)
{
        proc_create("davinci_clocks", 0, NULL, &proc_davinci_ck_operations);
        return 0;

}
__initcall(davinci_ck_proc_init);
#endif /* CONFIG_DEBUG_PROC_FS */