/*
 * Copyright (c) 2006-2008 Simtec Electronics
 *      http://armlinux.simtec.co.uk/
 *      Ben Dooks <ben@simtec.co.uk>
 *
 * S3C24XX CPU Frequency scaling
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
*/

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/cpufreq.h>
#include <linux/cpu.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/device.h>
#include <linux/sysfs.h>
#include <linux/slab.h>

#include <asm/mach/arch.h>
#include <asm/mach/map.h>

#include <plat/cpu.h>
#include <plat/cpu-freq-core.h>

#include <mach/regs-clock.h>

/* note, cpufreq support deals in kHz, no Hz */

static struct cpufreq_driver s3c24xx_driver;
static struct s3c_cpufreq_config cpu_cur;
static struct s3c_iotimings s3c24xx_iotiming;
static struct cpufreq_frequency_table *pll_reg;
static unsigned int last_target = ~0;
static unsigned int ftab_size;
static struct cpufreq_frequency_table *ftab;

static struct clk *_clk_mpll;
static struct clk *_clk_xtal;
static struct clk *clk_fclk;
static struct clk *clk_hclk;
static struct clk *clk_pclk;
static struct clk *clk_arm;

#ifdef CONFIG_ARM_S3C24XX_CPUFREQ_DEBUGFS
struct s3c_cpufreq_config *s3c_cpufreq_getconfig(void)
{
        return &cpu_cur;
}

struct s3c_iotimings *s3c_cpufreq_getiotimings(void)
{
        return &s3c24xx_iotiming;
}
#endif /* CONFIG_ARM_S3C24XX_CPUFREQ_DEBUGFS */

static void s3c_cpufreq_getcur(struct s3c_cpufreq_config *cfg)
{
        unsigned long fclk, pclk, hclk, armclk;

        cfg->freq.fclk = fclk = clk_get_rate(clk_fclk);
        cfg->freq.hclk = hclk = clk_get_rate(clk_hclk);
        cfg->freq.pclk = pclk = clk_get_rate(clk_pclk);
        cfg->freq.armclk = armclk = clk_get_rate(clk_arm);

        cfg->pll.driver_data = __raw_readl(S3C2410_MPLLCON);
        cfg->pll.frequency = fclk;

        cfg->freq.hclk_tns = 1000000000 / (cfg->freq.hclk / 10);

        cfg->divs.h_divisor = fclk / hclk;
        cfg->divs.p_divisor = fclk / pclk;
}

static inline void s3c_cpufreq_calc(struct s3c_cpufreq_config *cfg)
{
        unsigned long pll = cfg->pll.frequency;

        cfg->freq.fclk = pll;
        cfg->freq.hclk = pll / cfg->divs.h_divisor;
        cfg->freq.pclk = pll / cfg->divs.p_divisor;

        /* convert hclk into 10ths of nanoseconds for io calcs */
        cfg->freq.hclk_tns = 1000000000 / (cfg->freq.hclk / 10);
}

static inline int closer(unsigned int target, unsigned int n, unsigned int c)
{
        int diff_cur = abs(target - c);
        int diff_new = abs(target - n);

        return (diff_new < diff_cur);
}

static void s3c_cpufreq_show(const char *pfx,
                                 struct s3c_cpufreq_config *cfg)
{
        s3c_freq_dbg("%s: Fvco=%u, F=%lu, A=%lu, H=%lu (%u), P=%lu (%u)\n",
                     pfx, cfg->pll.frequency, cfg->freq.fclk, cfg->freq.armclk,
                     cfg->freq.hclk, cfg->divs.h_divisor,
                     cfg->freq.pclk, cfg->divs.p_divisor);
}

/* functions to wrapper the driver info calls to do the cpu specific work */

static void s3c_cpufreq_setio(struct s3c_cpufreq_config *cfg)
{
        if (cfg->info->set_iotiming)
                (cfg->info->set_iotiming)(cfg, &s3c24xx_iotiming);
}

static int s3c_cpufreq_calcio(struct s3c_cpufreq_config *cfg)
{
        if (cfg->info->calc_iotiming)
                return (cfg->info->calc_iotiming)(cfg, &s3c24xx_iotiming);

        return 0;
}

static void s3c_cpufreq_setrefresh(struct s3c_cpufreq_config *cfg)
{
        (cfg->info->set_refresh)(cfg);
}

static void s3c_cpufreq_setdivs(struct s3c_cpufreq_config *cfg)
{
        (cfg->info->set_divs)(cfg);
}

static int s3c_cpufreq_calcdivs(struct s3c_cpufreq_config *cfg)
{
        return (cfg->info->calc_divs)(cfg);
}

static void s3c_cpufreq_setfvco(struct s3c_cpufreq_config *cfg)
{
        cfg->mpll = _clk_mpll;
        (cfg->info->set_fvco)(cfg);
}

static inline void s3c_cpufreq_updateclk(struct clk *clk,
                                         unsigned int freq)
{
        clk_set_rate(clk, freq);
}

static int s3c_cpufreq_settarget(struct cpufreq_policy *policy,
                                 unsigned int target_freq,
                                 struct cpufreq_frequency_table *pll)
{
        struct s3c_cpufreq_freqs freqs;
        struct s3c_cpufreq_config cpu_new;
        unsigned long flags;

        cpu_new = cpu_cur;  /* copy new from current */

        s3c_cpufreq_show("cur", &cpu_cur);

        /* TODO - check for DMA currently outstanding */

        cpu_new.pll = pll ? *pll : cpu_cur.pll;

        if (pll)
                freqs.pll_changing = 1;

        /* update our frequencies */

        cpu_new.freq.armclk = target_freq;
        cpu_new.freq.fclk = cpu_new.pll.frequency;

        if (s3c_cpufreq_calcdivs(&cpu_new) < 0) {
                pr_err("no divisors for %d\n", target_freq);
                goto err_notpossible;
        }

        s3c_freq_dbg("%s: got divs\n", __func__);

        s3c_cpufreq_calc(&cpu_new);

        s3c_freq_dbg("%s: calculated frequencies for new\n", __func__);

        if (cpu_new.freq.hclk != cpu_cur.freq.hclk) {
                if (s3c_cpufreq_calcio(&cpu_new) < 0) {
                        pr_err("%s: no IO timings\n", __func__);
                        goto err_notpossible;
                }
        }

        s3c_cpufreq_show("new", &cpu_new);

        /* setup our cpufreq parameters */

        freqs.old = cpu_cur.freq;
        freqs.new = cpu_new.freq;

        freqs.freqs.old = cpu_cur.freq.armclk / 1000;
        freqs.freqs.new = cpu_new.freq.armclk / 1000;

        /* update f/h/p clock settings before we issue the change
         * notification, so that drivers do not need to do anything
         * special if they want to recalculate on CPUFREQ_PRECHANGE. */

        s3c_cpufreq_updateclk(_clk_mpll, cpu_new.pll.frequency);
        s3c_cpufreq_updateclk(clk_fclk, cpu_new.freq.fclk);
        s3c_cpufreq_updateclk(clk_hclk, cpu_new.freq.hclk);
        s3c_cpufreq_updateclk(clk_pclk, cpu_new.freq.pclk);

        /* start the frequency change */
        cpufreq_freq_transition_begin(policy, &freqs.freqs);

        /* If hclk is staying the same, then we do not need to
         * re-write the IO or the refresh timings whilst we are changing
         * speed. */

        local_irq_save(flags);

        /* is our memory clock slowing down? */
        if (cpu_new.freq.hclk < cpu_cur.freq.hclk) {
                s3c_cpufreq_setrefresh(&cpu_new);
                s3c_cpufreq_setio(&cpu_new);
        }

        if (cpu_new.freq.fclk == cpu_cur.freq.fclk) {
                /* not changing PLL, just set the divisors */

                s3c_cpufreq_setdivs(&cpu_new);
        } else {
                if (cpu_new.freq.fclk < cpu_cur.freq.fclk) {
                        /* slow the cpu down, then set divisors */

                        s3c_cpufreq_setfvco(&cpu_new);
                        s3c_cpufreq_setdivs(&cpu_new);
                } else {
                        /* set the divisors, then speed up */

                        s3c_cpufreq_setdivs(&cpu_new);
                        s3c_cpufreq_setfvco(&cpu_new);
                }
        }

        /* did our memory clock speed up */
        if (cpu_new.freq.hclk > cpu_cur.freq.hclk) {
                s3c_cpufreq_setrefresh(&cpu_new);
                s3c_cpufreq_setio(&cpu_new);
        }

        /* update our current settings */
        cpu_cur = cpu_new;

        local_irq_restore(flags);

        /* notify everyone we've done this */
        cpufreq_freq_transition_end(policy, &freqs.freqs, 0);

        s3c_freq_dbg("%s: finished\n", __func__);
        return 0;

 err_notpossible:
        pr_err("no compatible settings for %d\n", target_freq);
        return -EINVAL;
}

/* s3c_cpufreq_target
 *
 * called by the cpufreq core to adjust the frequency that the CPU
 * is currently running at.
 */

static int s3c_cpufreq_target(struct cpufreq_policy *policy,
                              unsigned int target_freq,
                              unsigned int relation)
{
        struct cpufreq_frequency_table *pll;
        unsigned int index;

        /* avoid repeated calls which cause a needless amout of duplicated
         * logging output (and CPU time as the calculation process is
         * done) */
        if (target_freq == last_target)
                return 0;

        last_target = target_freq;

        s3c_freq_dbg("%s: policy %p, target %u, relation %u\n",
                     __func__, policy, target_freq, relation);

        if (ftab) {
                index = cpufreq_frequency_table_target(policy, target_freq,
                                                       relation);

                s3c_freq_dbg("%s: adjust %d to entry %d (%u)\n", __func__,
                             target_freq, index, ftab[index].frequency);
                target_freq = ftab[index].frequency;
        }

        target_freq *= 1000;  /* convert target to Hz */

        /* find the settings for our new frequency */

        if (!pll_reg || cpu_cur.lock_pll) {
                /* either we've not got any PLL values, or we've locked
                 * to the current one. */
                pll = NULL;
        } else {
                struct cpufreq_policy tmp_policy;

                /* we keep the cpu pll table in Hz, to ensure we get an
                 * accurate value for the PLL output. */

                tmp_policy.min = policy->min * 1000;
                tmp_policy.max = policy->max * 1000;
                tmp_policy.cpu = policy->cpu;
                tmp_policy.freq_table = pll_reg;

                /* cpufreq_frequency_table_target returns the index
                 * of the table entry, not the value of
                 * the table entry's index field. */

                index = cpufreq_frequency_table_target(&tmp_policy, target_freq,
                                                       relation);
                pll = pll_reg + index;

                s3c_freq_dbg("%s: target %u => %u\n",
                             __func__, target_freq, pll->frequency);

                target_freq = pll->frequency;
        }

        return s3c_cpufreq_settarget(policy, target_freq, pll);
}

struct clk *s3c_cpufreq_clk_get(struct device *dev, const char *name)
{
        struct clk *clk;

        clk = clk_get(dev, name);
        if (IS_ERR(clk))
                pr_err("failed to get clock '%s'\n", name);

        return clk;
}

static int s3c_cpufreq_init(struct cpufreq_policy *policy)
{
        policy->clk = clk_arm;
        return cpufreq_generic_init(policy, ftab, cpu_cur.info->latency);
}

static int __init s3c_cpufreq_initclks(void)
{
        _clk_mpll = s3c_cpufreq_clk_get(NULL, "mpll");
        _clk_xtal = s3c_cpufreq_clk_get(NULL, "xtal");
        clk_fclk = s3c_cpufreq_clk_get(NULL, "fclk");
        clk_hclk = s3c_cpufreq_clk_get(NULL, "hclk");
        clk_pclk = s3c_cpufreq_clk_get(NULL, "pclk");
        clk_arm = s3c_cpufreq_clk_get(NULL, "armclk");

        if (IS_ERR(clk_fclk) || IS_ERR(clk_hclk) || IS_ERR(clk_pclk) ||
            IS_ERR(_clk_mpll) || IS_ERR(clk_arm) || IS_ERR(_clk_xtal)) {
                pr_err("%s: could not get clock(s)\n", __func__);
                return -ENOENT;
        }

        pr_info("%s: clocks f=%lu,h=%lu,p=%lu,a=%lu\n",
                __func__,
                clk_get_rate(clk_fclk) / 1000,
                clk_get_rate(clk_hclk) / 1000,
                clk_get_rate(clk_pclk) / 1000,
                clk_get_rate(clk_arm) / 1000);

        return 0;
}

#ifdef CONFIG_PM
static struct cpufreq_frequency_table suspend_pll;
static unsigned int suspend_freq;

static int s3c_cpufreq_suspend(struct cpufreq_policy *policy)
{
        suspend_pll.frequency = clk_get_rate(_clk_mpll);
        suspend_pll.driver_data = __raw_readl(S3C2410_MPLLCON);
        suspend_freq = clk_get_rate(clk_arm);

        return 0;
}

static int s3c_cpufreq_resume(struct cpufreq_policy *policy)
{
        int ret;

        s3c_freq_dbg("%s: resuming with policy %p\n", __func__, policy);

        last_target = ~0;       /* invalidate last_target setting */

        /* whilst we will be called later on, we try and re-set the
         * cpu frequencies as soon as possible so that we do not end
         * up resuming devices and then immediately having to re-set
         * a number of settings once these devices have restarted.
         *
         * as a note, it is expected devices are not used until they
         * have been un-suspended and at that time they should have
         * used the updated clock settings.
         */

        ret = s3c_cpufreq_settarget(NULL, suspend_freq, &suspend_pll);
        if (ret) {
                pr_err("%s: failed to reset pll/freq\n", __func__);
                return ret;
        }

        return 0;
}
#else
#define s3c_cpufreq_resume NULL
#define s3c_cpufreq_suspend NULL
#endif

static struct cpufreq_driver s3c24xx_driver = {
        .flags          = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
        .target         = s3c_cpufreq_target,
        .get            = cpufreq_generic_get,
        .init           = s3c_cpufreq_init,
        .suspend        = s3c_cpufreq_suspend,
        .resume         = s3c_cpufreq_resume,
        .name           = "s3c24xx",
};


int s3c_cpufreq_register(struct s3c_cpufreq_info *info)
{
        if (!info || !info->name) {
                pr_err("%s: failed to pass valid information\n", __func__);
                return -EINVAL;
        }

        pr_info("S3C24XX CPU Frequency driver, %s cpu support\n",
                info->name);

        /* check our driver info has valid data */

        BUG_ON(info->set_refresh == NULL);
        BUG_ON(info->set_divs == NULL);
        BUG_ON(info->calc_divs == NULL);

        /* info->set_fvco is optional, depending on whether there
         * is a need to set the clock code. */

        cpu_cur.info = info;

        /* Note, driver registering should probably update locktime */

        return 0;
}

int __init s3c_cpufreq_setboard(struct s3c_cpufreq_board *board)
{
        struct s3c_cpufreq_board *ours;

        if (!board) {
                pr_info("%s: no board data\n", __func__);
                return -EINVAL;
        }

        /* Copy the board information so that each board can make this
         * initdata. */

        ours = kzalloc(sizeof(*ours), GFP_KERNEL);
        if (ours == NULL) {
                pr_err("%s: no memory\n", __func__);
                return -ENOMEM;
        }

        *ours = *board;
        cpu_cur.board = ours;

        return 0;
}

static int __init s3c_cpufreq_auto_io(void)
{
        int ret;

        if (!cpu_cur.info->get_iotiming) {
                pr_err("%s: get_iotiming undefined\n", __func__);
                return -ENOENT;
        }

        pr_info("%s: working out IO settings\n", __func__);

        ret = (cpu_cur.info->get_iotiming)(&cpu_cur, &s3c24xx_iotiming);
        if (ret)
                pr_err("%s: failed to get timings\n", __func__);

        return ret;
}

/* if one or is zero, then return the other, otherwise return the min */
#define do_min(_a, _b) ((_a) == 0 ? (_b) : (_b) == 0 ? (_a) : min(_a, _b))

/**
 * s3c_cpufreq_freq_min - find the minimum settings for the given freq.
 * @dst: The destination structure
 * @a: One argument.
 * @b: The other argument.
 *
 * Create a minimum of each frequency entry in the 'struct s3c_freq',
 * unless the entry is zero when it is ignored and the non-zero argument
 * used.
 */
static void s3c_cpufreq_freq_min(struct s3c_freq *dst,
                                 struct s3c_freq *a, struct s3c_freq *b)
{
        dst->fclk = do_min(a->fclk, b->fclk);
        dst->hclk = do_min(a->hclk, b->hclk);
        dst->pclk = do_min(a->pclk, b->pclk);
        dst->armclk = do_min(a->armclk, b->armclk);
}

static inline u32 calc_locktime(u32 freq, u32 time_us)
{
        u32 result;

        result = freq * time_us;
        result = DIV_ROUND_UP(result, 1000 * 1000);

        return result;
}

static void s3c_cpufreq_update_loctkime(void)
{
        unsigned int bits = cpu_cur.info->locktime_bits;
        u32 rate = (u32)clk_get_rate(_clk_xtal);
        u32 val;

        if (bits == 0) {
                WARN_ON(1);
                return;
        }

        val = calc_locktime(rate, cpu_cur.info->locktime_u) << bits;
        val |= calc_locktime(rate, cpu_cur.info->locktime_m);

        pr_info("%s: new locktime is 0x%08x\n", __func__, val);
        __raw_writel(val, S3C2410_LOCKTIME);
}

static int s3c_cpufreq_build_freq(void)
{
        int size, ret;

        kfree(ftab);

        size = cpu_cur.info->calc_freqtable(&cpu_cur, NULL, 0);
        size++;

        ftab = kzalloc(sizeof(*ftab) * size, GFP_KERNEL);
        if (!ftab) {
                pr_err("%s: no memory for tables\n", __func__);
                return -ENOMEM;
        }

        ftab_size = size;

        ret = cpu_cur.info->calc_freqtable(&cpu_cur, ftab, size);
        s3c_cpufreq_addfreq(ftab, ret, size, CPUFREQ_TABLE_END);

        return 0;
}

static int __init s3c_cpufreq_initcall(void)
{
        int ret = 0;

        if (cpu_cur.info && cpu_cur.board) {
                ret = s3c_cpufreq_initclks();
                if (ret)
                        goto out;

                /* get current settings */
                s3c_cpufreq_getcur(&cpu_cur);
                s3c_cpufreq_show("cur", &cpu_cur);

                if (cpu_cur.board->auto_io) {
                        ret = s3c_cpufreq_auto_io();
                        if (ret) {
                                pr_err("%s: failed to get io timing\n",
                                       __func__);
                                goto out;
                        }
                }

                if (cpu_cur.board->need_io && !cpu_cur.info->set_iotiming) {
                        pr_err("%s: no IO support registered\n", __func__);
                        ret = -EINVAL;
                        goto out;
                }

                if (!cpu_cur.info->need_pll)
                        cpu_cur.lock_pll = 1;

                s3c_cpufreq_update_loctkime();

                s3c_cpufreq_freq_min(&cpu_cur.max, &cpu_cur.board->max,
                                     &cpu_cur.info->max);

                if (cpu_cur.info->calc_freqtable)
                        s3c_cpufreq_build_freq();

                ret = cpufreq_register_driver(&s3c24xx_driver);
        }

 out:
        return ret;
}

late_initcall(s3c_cpufreq_initcall);

/**
 * s3c_plltab_register - register CPU PLL table.
 * @plls: The list of PLL entries.
 * @plls_no: The size of the PLL entries @plls.
 *
 * Register the given set of PLLs with the system.
 */
int s3c_plltab_register(struct cpufreq_frequency_table *plls,
                               unsigned int plls_no)
{
        struct cpufreq_frequency_table *vals;
        unsigned int size;

        size = sizeof(*vals) * (plls_no + 1);

        vals = kzalloc(size, GFP_KERNEL);
        if (vals) {
                memcpy(vals, plls, size);
                pll_reg = vals;

                /* write a terminating entry, we don't store it in the
                 * table that is stored in the kernel */
                vals += plls_no;
                vals->frequency = CPUFREQ_TABLE_END;

                pr_info("%d PLL entries\n", plls_no);
        } else
                pr_err("no memory for PLL tables\n");

        return vals ? 0 : -ENOMEM;
}