/*
 * linux/arch/arm/mach-at91/clock.c
 *
 * Copyright (C) 2005 David Brownell
 * Copyright (C) 2005 Ivan Kokshaysky
 *
 * 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/fs.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/spinlock.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <linux/io.h>

#include <mach/hardware.h>
#include <mach/at91_pmc.h>
#include <mach/cpu.h>

#include "clock.h"


/*
 * There's a lot more which can be done with clocks, including cpufreq
 * integration, slow clock mode support (for system suspend), letting
 * PLLB be used at other rates (on boards that don't need USB), etc.
 */

#define clk_is_primary(x)       ((x)->type & CLK_TYPE_PRIMARY)
#define clk_is_programmable(x)  ((x)->type & CLK_TYPE_PROGRAMMABLE)
#define clk_is_peripheral(x)    ((x)->type & CLK_TYPE_PERIPHERAL)
#define clk_is_sys(x)           ((x)->type & CLK_TYPE_SYSTEM)


/*
 * Chips have some kind of clocks : group them by functionality
 */
#define cpu_has_utmi()          (  cpu_is_at91cap9() \
                                || cpu_is_at91sam9rl() \
                                || cpu_is_at91sam9g45())

#define cpu_has_800M_plla()     (  cpu_is_at91sam9g20() \
                                || cpu_is_at91sam9g45())

#define cpu_has_300M_plla()     (cpu_is_at91sam9g10())

#define cpu_has_pllb()          (!(cpu_is_at91sam9rl() \
                                || cpu_is_at91sam9g45()))

#define cpu_has_upll()          (cpu_is_at91sam9g45())

/* USB host HS & FS */
#define cpu_has_uhp()           (!cpu_is_at91sam9rl())

/* USB device FS only */
#define cpu_has_udpfs()         (!(cpu_is_at91sam9rl() \
                                || cpu_is_at91sam9g45()))

static LIST_HEAD(clocks);
static DEFINE_SPINLOCK(clk_lock);

static u32 at91_pllb_usb_init;

/*
 * Four primary clock sources:  two crystal oscillators (32K, main), and
 * two PLLs.  PLLA usually runs the master clock; and PLLB must run at
 * 48 MHz (unless no USB function clocks are needed).  The main clock and
 * both PLLs are turned off to run in "slow clock mode" (system suspend).
 */
static struct clk clk32k = {
        .name           = "clk32k",
        .rate_hz        = AT91_SLOW_CLOCK,
        .users          = 1,            /* always on */
        .id             = 0,
        .type           = CLK_TYPE_PRIMARY,
};
static struct clk main_clk = {
        .name           = "main",
        .pmc_mask       = AT91_PMC_MOSCS,       /* in PMC_SR */
        .id             = 1,
        .type           = CLK_TYPE_PRIMARY,
};
static struct clk plla = {
        .name           = "plla",
        .parent         = &main_clk,
        .pmc_mask       = AT91_PMC_LOCKA,       /* in PMC_SR */
        .id             = 2,
        .type           = CLK_TYPE_PRIMARY | CLK_TYPE_PLL,
};

static void pllb_mode(struct clk *clk, int is_on)
{
        u32     value;

        if (is_on) {
                is_on = AT91_PMC_LOCKB;
                value = at91_pllb_usb_init;
        } else
                value = 0;

        // REVISIT: Add work-around for AT91RM9200 Errata #26 ?
        at91_sys_write(AT91_CKGR_PLLBR, value);

        do {
                cpu_relax();
        } while ((at91_sys_read(AT91_PMC_SR) & AT91_PMC_LOCKB) != is_on);
}

static struct clk pllb = {
        .name           = "pllb",
        .parent         = &main_clk,
        .pmc_mask       = AT91_PMC_LOCKB,       /* in PMC_SR */
        .mode           = pllb_mode,
        .id             = 3,
        .type           = CLK_TYPE_PRIMARY | CLK_TYPE_PLL,
};

static void pmc_sys_mode(struct clk *clk, int is_on)
{
        if (is_on)
                at91_sys_write(AT91_PMC_SCER, clk->pmc_mask);
        else
                at91_sys_write(AT91_PMC_SCDR, clk->pmc_mask);
}

static void pmc_uckr_mode(struct clk *clk, int is_on)
{
        unsigned int uckr = at91_sys_read(AT91_CKGR_UCKR);

        if (cpu_is_at91sam9g45()) {
                if (is_on)
                        uckr |= AT91_PMC_BIASEN;
                else
                        uckr &= ~AT91_PMC_BIASEN;
        }

        if (is_on) {
                is_on = AT91_PMC_LOCKU;
                at91_sys_write(AT91_CKGR_UCKR, uckr | clk->pmc_mask);
        } else
                at91_sys_write(AT91_CKGR_UCKR, uckr & ~(clk->pmc_mask));

        do {
                cpu_relax();
        } while ((at91_sys_read(AT91_PMC_SR) & AT91_PMC_LOCKU) != is_on);
}

/* USB function clocks (PLLB must be 48 MHz) */
static struct clk udpck = {
        .name           = "udpck",
        .parent         = &pllb,
        .mode           = pmc_sys_mode,
};
static struct clk utmi_clk = {
        .name           = "utmi_clk",
        .parent         = &main_clk,
        .pmc_mask       = AT91_PMC_UPLLEN,      /* in CKGR_UCKR */
        .mode           = pmc_uckr_mode,
        .type           = CLK_TYPE_PLL,
};
static struct clk uhpck = {
        .name           = "uhpck",
        /*.parent               = ... we choose parent at runtime */
        .mode           = pmc_sys_mode,
};


/*
 * The master clock is divided from the CPU clock (by 1-4).  It's used for
 * memory, interfaces to on-chip peripherals, the AIC, and sometimes more
 * (e.g baud rate generation).  It's sourced from one of the primary clocks.
 */
static struct clk mck = {
        .name           = "mck",
        .pmc_mask       = AT91_PMC_MCKRDY,      /* in PMC_SR */
};

static void pmc_periph_mode(struct clk *clk, int is_on)
{
        if (is_on)
                at91_sys_write(AT91_PMC_PCER, clk->pmc_mask);
        else
                at91_sys_write(AT91_PMC_PCDR, clk->pmc_mask);
}

static struct clk __init *at91_css_to_clk(unsigned long css)
{
        switch (css) {
                case AT91_PMC_CSS_SLOW:
                        return &clk32k;
                case AT91_PMC_CSS_MAIN:
                        return &main_clk;
                case AT91_PMC_CSS_PLLA:
                        return &plla;
                case AT91_PMC_CSS_PLLB:
                        if (cpu_has_upll())
                                /* CSS_PLLB == CSS_UPLL */
                                return &utmi_clk;
                        else if (cpu_has_pllb())
                                return &pllb;
        }

        return NULL;
}

/*
 * Associate a particular clock with a function (eg, "uart") and device.
 * The drivers can then request the same 'function' with several different
 * devices and not care about which clock name to use.
 */
void __init at91_clock_associate(const char *id, struct device *dev, const char *func)
{
        struct clk *clk = clk_get(NULL, id);

        if (!dev || !clk || !IS_ERR(clk_get(dev, func)))
                return;

        clk->function = func;
        clk->dev = dev;
}

/* clocks cannot be de-registered no refcounting necessary */
struct clk *clk_get(struct device *dev, const char *id)
{
        struct clk *clk;

        list_for_each_entry(clk, &clocks, node) {
                if (strcmp(id, clk->name) == 0)
                        return clk;
                if (clk->function && (dev == clk->dev) && strcmp(id, clk->function) == 0)
                        return clk;
        }

        return ERR_PTR(-ENOENT);
}
EXPORT_SYMBOL(clk_get);

void clk_put(struct clk *clk)
{
}
EXPORT_SYMBOL(clk_put);

static void __clk_enable(struct clk *clk)
{
        if (clk->parent)
                __clk_enable(clk->parent);
        if (clk->users++ == 0 && clk->mode)
                clk->mode(clk, 1);
}

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

        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)
{
        BUG_ON(clk->users == 0);
        if (--clk->users == 0 && clk->mode)
                clk->mode(clk, 0);
        if (clk->parent)
                __clk_disable(clk->parent);
}

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

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

unsigned long clk_get_rate(struct clk *clk)
{
        unsigned long   flags;
        unsigned long   rate;

        spin_lock_irqsave(&clk_lock, flags);
        for (;;) {
                rate = clk->rate_hz;
                if (rate || !clk->parent)
                        break;
                clk = clk->parent;
        }
        spin_unlock_irqrestore(&clk_lock, flags);
        return rate;
}
EXPORT_SYMBOL(clk_get_rate);

/*------------------------------------------------------------------------*/

#ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS

/*
 * For now, only the programmable clocks support reparenting (MCK could
 * do this too, with care) or rate changing (the PLLs could do this too,
 * ditto MCK but that's more for cpufreq).  Drivers may reparent to get
 * a better rate match; we don't.
 */

long clk_round_rate(struct clk *clk, unsigned long rate)
{
        unsigned long   flags;
        unsigned        prescale;
        unsigned long   actual;
        unsigned long   prev = ULONG_MAX;

        if (!clk_is_programmable(clk))
                return -EINVAL;
        spin_lock_irqsave(&clk_lock, flags);

        actual = clk->parent->rate_hz;
        for (prescale = 0; prescale < 7; prescale++) {
                if (actual > rate)
                        prev = actual;

                if (actual && actual <= rate) {
                        if ((prev - rate) < (rate - actual)) {
                                actual = prev;
                                prescale--;
                        }
                        break;
                }
                actual >>= 1;
        }

        spin_unlock_irqrestore(&clk_lock, flags);
        return (prescale < 7) ? actual : -ENOENT;
}
EXPORT_SYMBOL(clk_round_rate);

int clk_set_rate(struct clk *clk, unsigned long rate)
{
        unsigned long   flags;
        unsigned        prescale;
        unsigned long   actual;

        if (!clk_is_programmable(clk))
                return -EINVAL;
        if (clk->users)
                return -EBUSY;
        spin_lock_irqsave(&clk_lock, flags);

        actual = clk->parent->rate_hz;
        for (prescale = 0; prescale < 7; prescale++) {
                if (actual && actual <= rate) {
                        u32     pckr;

                        pckr = at91_sys_read(AT91_PMC_PCKR(clk->id));
                        pckr &= AT91_PMC_CSS;   /* clock selection */
                        pckr |= prescale << 2;
                        at91_sys_write(AT91_PMC_PCKR(clk->id), pckr);
                        clk->rate_hz = actual;
                        break;
                }
                actual >>= 1;
        }

        spin_unlock_irqrestore(&clk_lock, flags);
        return (prescale < 7) ? actual : -ENOENT;
}
EXPORT_SYMBOL(clk_set_rate);

struct clk *clk_get_parent(struct clk *clk)
{
        return clk->parent;
}
EXPORT_SYMBOL(clk_get_parent);

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

        if (clk->users)
                return -EBUSY;
        if (!clk_is_primary(parent) || !clk_is_programmable(clk))
                return -EINVAL;

        if (cpu_is_at91sam9rl() && parent->id == AT91_PMC_CSS_PLLB)
                return -EINVAL;

        spin_lock_irqsave(&clk_lock, flags);

        clk->rate_hz = parent->rate_hz;
        clk->parent = parent;
        at91_sys_write(AT91_PMC_PCKR(clk->id), parent->id);

        spin_unlock_irqrestore(&clk_lock, flags);
        return 0;
}
EXPORT_SYMBOL(clk_set_parent);

/* establish PCK0..PCKN parentage and rate */
static void __init init_programmable_clock(struct clk *clk)
{
        struct clk      *parent;
        u32             pckr;

        pckr = at91_sys_read(AT91_PMC_PCKR(clk->id));
        parent = at91_css_to_clk(pckr & AT91_PMC_CSS);
        clk->parent = parent;
        clk->rate_hz = parent->rate_hz / (1 << ((pckr & AT91_PMC_PRES) >> 2));
}

#endif  /* CONFIG_AT91_PROGRAMMABLE_CLOCKS */

/*------------------------------------------------------------------------*/

#ifdef CONFIG_DEBUG_FS

static int at91_clk_show(struct seq_file *s, void *unused)
{
        u32             scsr, pcsr, uckr = 0, sr;
        struct clk      *clk;

        seq_printf(s, "SCSR = %8x\n", scsr = at91_sys_read(AT91_PMC_SCSR));
        seq_printf(s, "PCSR = %8x\n", pcsr = at91_sys_read(AT91_PMC_PCSR));
        seq_printf(s, "MOR  = %8x\n", at91_sys_read(AT91_CKGR_MOR));
        seq_printf(s, "MCFR = %8x\n", at91_sys_read(AT91_CKGR_MCFR));
        seq_printf(s, "PLLA = %8x\n", at91_sys_read(AT91_CKGR_PLLAR));
        if (cpu_has_pllb())
                seq_printf(s, "PLLB = %8x\n", at91_sys_read(AT91_CKGR_PLLBR));
        if (cpu_has_utmi())
                seq_printf(s, "UCKR = %8x\n", uckr = at91_sys_read(AT91_CKGR_UCKR));
        seq_printf(s, "MCKR = %8x\n", at91_sys_read(AT91_PMC_MCKR));
        if (cpu_has_upll())
                seq_printf(s, "USB  = %8x\n", at91_sys_read(AT91_PMC_USB));
        seq_printf(s, "SR   = %8x\n", sr = at91_sys_read(AT91_PMC_SR));

        seq_printf(s, "\n");

        list_for_each_entry(clk, &clocks, node) {
                char    *state;

                if (clk->mode == pmc_sys_mode)
                        state = (scsr & clk->pmc_mask) ? "on" : "off";
                else if (clk->mode == pmc_periph_mode)
                        state = (pcsr & clk->pmc_mask) ? "on" : "off";
                else if (clk->mode == pmc_uckr_mode)
                        state = (uckr & clk->pmc_mask) ? "on" : "off";
                else if (clk->pmc_mask)
                        state = (sr & clk->pmc_mask) ? "on" : "off";
                else if (clk == &clk32k || clk == &main_clk)
                        state = "on";
                else
                        state = "";

                seq_printf(s, "%-10s users=%2d %-3s %9ld Hz %s\n",
                        clk->name, clk->users, state, clk_get_rate(clk),
                        clk->parent ? clk->parent->name : "");
        }
        return 0;
}

static int at91_clk_open(struct inode *inode, struct file *file)
{
        return single_open(file, at91_clk_show, NULL);
}

static const struct file_operations at91_clk_operations = {
        .open           = at91_clk_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static int __init at91_clk_debugfs_init(void)
{
        /* /sys/kernel/debug/at91_clk */
        (void) debugfs_create_file("at91_clk", S_IFREG | S_IRUGO, NULL, NULL, &at91_clk_operations);

        return 0;
}
postcore_initcall(at91_clk_debugfs_init);

#endif

/*------------------------------------------------------------------------*/

/* Register a new clock */
int __init clk_register(struct clk *clk)
{
        if (clk_is_peripheral(clk)) {
                clk->parent = &mck;
                clk->mode = pmc_periph_mode;
                list_add_tail(&clk->node, &clocks);
        }
        else if (clk_is_sys(clk)) {
                clk->parent = &mck;
                clk->mode = pmc_sys_mode;

                list_add_tail(&clk->node, &clocks);
        }
#ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
        else if (clk_is_programmable(clk)) {
                clk->mode = pmc_sys_mode;
                init_programmable_clock(clk);
                list_add_tail(&clk->node, &clocks);
        }
#endif

        return 0;
}


/*------------------------------------------------------------------------*/

static u32 __init at91_pll_rate(struct clk *pll, u32 freq, u32 reg)
{
        unsigned mul, div;

        div = reg & 0xff;
        mul = (reg >> 16) & 0x7ff;
        if (div && mul) {
                freq /= div;
                freq *= mul + 1;
        } else
                freq = 0;

        return freq;
}

static u32 __init at91_usb_rate(struct clk *pll, u32 freq, u32 reg)
{
        if (pll == &pllb && (reg & AT91_PMC_USB96M))
                return freq / 2;
        else
                return freq;
}

static unsigned __init at91_pll_calc(unsigned main_freq, unsigned out_freq)
{
        unsigned i, div = 0, mul = 0, diff = 1 << 30;
        unsigned ret = (out_freq > 155000000) ? 0xbe00 : 0x3e00;

        /* PLL output max 240 MHz (or 180 MHz per errata) */
        if (out_freq > 240000000)
                goto fail;

        for (i = 1; i < 256; i++) {
                int diff1;
                unsigned input, mul1;

                /*
                 * PLL input between 1MHz and 32MHz per spec, but lower
                 * frequences seem necessary in some cases so allow 100K.
                 * Warning: some newer products need 2MHz min.
                 */
                input = main_freq / i;
                if (cpu_is_at91sam9g20() && input < 2000000)
                        continue;
                if (input < 100000)
                        continue;
                if (input > 32000000)
                        continue;

                mul1 = out_freq / input;
                if (cpu_is_at91sam9g20() && mul > 63)
                        continue;
                if (mul1 > 2048)
                        continue;
                if (mul1 < 2)
                        goto fail;

                diff1 = out_freq - input * mul1;
                if (diff1 < 0)
                        diff1 = -diff1;
                if (diff > diff1) {
                        diff = diff1;
                        div = i;
                        mul = mul1;
                        if (diff == 0)
                                break;
                }
        }
        if (i == 256 && diff > (out_freq >> 5))
                goto fail;
        return ret | ((mul - 1) << 16) | div;
fail:
        return 0;
}

static struct clk *const standard_pmc_clocks[] __initdata = {
        /* four primary clocks */
        &clk32k,
        &main_clk,
        &plla,

        /* MCK */
        &mck
};

/* PLLB generated USB full speed clock init */
static void __init at91_pllb_usbfs_clock_init(unsigned long main_clock)
{
        /*
         * USB clock init:  choose 48 MHz PLLB value,
         * disable 48MHz clock during usb peripheral suspend.
         *
         * REVISIT:  assumes MCK doesn't derive from PLLB!
         */
        uhpck.parent = &pllb;

        at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) | AT91_PMC_USB96M;
        pllb.rate_hz = at91_pll_rate(&pllb, main_clock, at91_pllb_usb_init);
        if (cpu_is_at91rm9200()) {
                uhpck.pmc_mask = AT91RM9200_PMC_UHP;
                udpck.pmc_mask = AT91RM9200_PMC_UDP;
                at91_sys_write(AT91_PMC_SCER, AT91RM9200_PMC_MCKUDP);
        } else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() ||
                   cpu_is_at91sam9263() || cpu_is_at91sam9g20() ||
                   cpu_is_at91sam9g10()) {
                uhpck.pmc_mask = AT91SAM926x_PMC_UHP;
                udpck.pmc_mask = AT91SAM926x_PMC_UDP;
        } else if (cpu_is_at91cap9()) {
                uhpck.pmc_mask = AT91CAP9_PMC_UHP;
        }
        at91_sys_write(AT91_CKGR_PLLBR, 0);

        udpck.rate_hz = at91_usb_rate(&pllb, pllb.rate_hz, at91_pllb_usb_init);
        uhpck.rate_hz = at91_usb_rate(&pllb, pllb.rate_hz, at91_pllb_usb_init);
}

/* UPLL generated USB full speed clock init */
static void __init at91_upll_usbfs_clock_init(unsigned long main_clock)
{
        /*
         * USB clock init: choose 480 MHz from UPLL,
         */
        unsigned int usbr = AT91_PMC_USBS_UPLL;

        /* Setup divider by 10 to reach 48 MHz */
        usbr |= ((10 - 1) << 8) & AT91_PMC_OHCIUSBDIV;

        at91_sys_write(AT91_PMC_USB, usbr);

        /* Now set uhpck values */
        uhpck.parent = &utmi_clk;
        uhpck.pmc_mask = AT91SAM926x_PMC_UHP;
        uhpck.rate_hz = utmi_clk.parent->rate_hz;
        uhpck.rate_hz /= 1 + ((at91_sys_read(AT91_PMC_USB) & AT91_PMC_OHCIUSBDIV) >> 8);
}

int __init at91_clock_init(unsigned long main_clock)
{
        unsigned tmp, freq, mckr;
        int i;
        int pll_overclock = false;

        /*
         * When the bootloader initialized the main oscillator correctly,
         * there's no problem using the cycle counter.  But if it didn't,
         * or when using oscillator bypass mode, we must be told the speed
         * of the main clock.
         */
        if (!main_clock) {
                do {
                        tmp = at91_sys_read(AT91_CKGR_MCFR);
                } while (!(tmp & AT91_PMC_MAINRDY));
                main_clock = (tmp & AT91_PMC_MAINF) * (AT91_SLOW_CLOCK / 16);
        }
        main_clk.rate_hz = main_clock;

        /* report if PLLA is more than mildly overclocked */
        plla.rate_hz = at91_pll_rate(&plla, main_clock, at91_sys_read(AT91_CKGR_PLLAR));
        if (cpu_has_300M_plla()) {
                if (plla.rate_hz > 300000000)
                        pll_overclock = true;
        } else if (cpu_has_800M_plla()) {
                if (plla.rate_hz > 800000000)
                        pll_overclock = true;
        } else {
                if (plla.rate_hz > 209000000)
                        pll_overclock = true;
        }
        if (pll_overclock)
                pr_info("Clocks: PLLA overclocked, %ld MHz\n", plla.rate_hz / 1000000);

        if (cpu_is_at91sam9g45()) {
                mckr = at91_sys_read(AT91_PMC_MCKR);
                plla.rate_hz /= (1 << ((mckr & AT91_PMC_PLLADIV2) >> 12));      /* plla divisor by 2 */
        }

        if (!cpu_has_pllb() && cpu_has_upll()) {
                /* setup UTMI clock as the fourth primary clock
                 * (instead of pllb) */
                utmi_clk.type |= CLK_TYPE_PRIMARY;
                utmi_clk.id = 3;
        }


        /*
         * USB HS clock init
         */
        if (cpu_has_utmi())
                /*
                 * multiplier is hard-wired to 40
                 * (obtain the USB High Speed 480 MHz when input is 12 MHz)
                 */
                utmi_clk.rate_hz = 40 * utmi_clk.parent->rate_hz;

        /*
         * USB FS clock init
         */
        if (cpu_has_pllb())
                at91_pllb_usbfs_clock_init(main_clock);
        if (cpu_has_upll())
                /* assumes that we choose UPLL for USB and not PLLA */
                at91_upll_usbfs_clock_init(main_clock);

        /*
         * MCK and CPU derive from one of those primary clocks.
         * For now, assume this parentage won't change.
         */
        mckr = at91_sys_read(AT91_PMC_MCKR);
        mck.parent = at91_css_to_clk(mckr & AT91_PMC_CSS);
        freq = mck.parent->rate_hz;
        freq /= (1 << ((mckr & AT91_PMC_PRES) >> 2));                           /* prescale */
        if (cpu_is_at91rm9200()) {
                mck.rate_hz = freq / (1 + ((mckr & AT91_PMC_MDIV) >> 8));       /* mdiv */
        } else if (cpu_is_at91sam9g20()) {
                mck.rate_hz = (mckr & AT91_PMC_MDIV) ?
                        freq / ((mckr & AT91_PMC_MDIV) >> 7) : freq;    /* mdiv ; (x >> 7) = ((x >> 8) * 2) */
                if (mckr & AT91_PMC_PDIV)
                        freq /= 2;              /* processor clock division */
        } else if (cpu_is_at91sam9g45()) {
                mck.rate_hz = (mckr & AT91_PMC_MDIV) == AT91SAM9_PMC_MDIV_3 ?
                        freq / 3 : freq / (1 << ((mckr & AT91_PMC_MDIV) >> 8)); /* mdiv */
        } else {
                mck.rate_hz = freq / (1 << ((mckr & AT91_PMC_MDIV) >> 8));      /* mdiv */
        }

        /* Register the PMC's standard clocks */
        for (i = 0; i < ARRAY_SIZE(standard_pmc_clocks); i++)
                list_add_tail(&standard_pmc_clocks[i]->node, &clocks);

        if (cpu_has_pllb())
                list_add_tail(&pllb.node, &clocks);

        if (cpu_has_uhp())
                list_add_tail(&uhpck.node, &clocks);

        if (cpu_has_udpfs())
                list_add_tail(&udpck.node, &clocks);

        if (cpu_has_utmi())
                list_add_tail(&utmi_clk.node, &clocks);

        /* MCK and CPU clock are "always on" */
        clk_enable(&mck);

        printk("Clocks: CPU %u MHz, master %u MHz, main %u.%03u MHz\n",
                freq / 1000000, (unsigned) mck.rate_hz / 1000000,
                (unsigned) main_clock / 1000000,
                ((unsigned) main_clock % 1000000) / 1000);

        return 0;
}

/*
 * Several unused clocks may be active.  Turn them off.
 */
static int __init at91_clock_reset(void)
{
        unsigned long pcdr = 0;
        unsigned long scdr = 0;
        struct clk *clk;

        list_for_each_entry(clk, &clocks, node) {
                if (clk->users > 0)
                        continue;

                if (clk->mode == pmc_periph_mode)
                        pcdr |= clk->pmc_mask;

                if (clk->mode == pmc_sys_mode)
                        scdr |= clk->pmc_mask;

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

        at91_sys_write(AT91_PMC_PCDR, pcdr);
        at91_sys_write(AT91_PMC_SCDR, scdr);

        return 0;
}
late_initcall(at91_clock_reset);