sysfs: Remove support for tagged directories with untagged members (again)

[linux-btrfs-devel.git] / arch / arm / mach-tegra / clock.c

/*
 *
 * Copyright (C) 2010 Google, Inc.
 *
 * Author:
 *      Colin Cross <ccross@google.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <linux/kernel.h>
#include <linux/clk.h>
#include <linux/clkdev.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/slab.h>

#include <mach/clk.h>

#include "board.h"
#include "clock.h"

/*
 * Locking:
 *
 * Each struct clk has a spinlock.
 *
 * To avoid AB-BA locking problems, locks must always be traversed from child
 * clock to parent clock.  For example, when enabling a clock, the clock's lock
 * is taken, and then clk_enable is called on the parent, which take's the
 * parent clock's lock.  There is one exceptions to this ordering: When dumping
 * the clock tree through debugfs.  In this case, clk_lock_all is called,
 * which attemps to iterate through the entire list of clocks and take every
 * clock lock.  If any call to spin_trylock fails, all locked clocks are
 * unlocked, and the process is retried.  When all the locks are held,
 * the only clock operation that can be called is clk_get_rate_all_locked.
 *
 * Within a single clock, no clock operation can call another clock operation
 * on itself, except for clk_get_rate_locked and clk_set_rate_locked.  Any
 * clock operation can call any other clock operation on any of it's possible
 * parents.
 *
 * An additional mutex, clock_list_lock, is used to protect the list of all
 * clocks.
 *
 * The clock operations must lock internally to protect against
 * read-modify-write on registers that are shared by multiple clocks
 */
static DEFINE_MUTEX(clock_list_lock);
static LIST_HEAD(clocks);

struct clk *tegra_get_clock_by_name(const char *name)
{
        struct clk *c;
        struct clk *ret = NULL;
        mutex_lock(&clock_list_lock);
        list_for_each_entry(c, &clocks, node) {
                if (strcmp(c->name, name) == 0) {
                        ret = c;
                        break;
                }
        }
        mutex_unlock(&clock_list_lock);
        return ret;
}

/* Must be called with c->spinlock held */
static unsigned long clk_predict_rate_from_parent(struct clk *c, struct clk *p)
{
        u64 rate;

        rate = clk_get_rate(p);

        if (c->mul != 0 && c->div != 0) {
                rate *= c->mul;
                rate += c->div - 1; /* round up */
                do_div(rate, c->div);
        }

        return rate;
}

/* Must be called with c->spinlock held */
unsigned long clk_get_rate_locked(struct clk *c)
{
        unsigned long rate;

        if (c->parent)
                rate = clk_predict_rate_from_parent(c, c->parent);
        else
                rate = c->rate;

        return rate;
}

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

        spin_lock_irqsave(&c->spinlock, flags);

        rate = clk_get_rate_locked(c);

        spin_unlock_irqrestore(&c->spinlock, flags);

        return rate;
}
EXPORT_SYMBOL(clk_get_rate);

int clk_reparent(struct clk *c, struct clk *parent)
{
        c->parent = parent;
        return 0;
}

void clk_init(struct clk *c)
{
        spin_lock_init(&c->spinlock);

        if (c->ops && c->ops->init)
                c->ops->init(c);

        if (!c->ops || !c->ops->enable) {
                c->refcnt++;
                c->set = true;
                if (c->parent)
                        c->state = c->parent->state;
                else
                        c->state = ON;
        }

        mutex_lock(&clock_list_lock);
        list_add(&c->node, &clocks);
        mutex_unlock(&clock_list_lock);
}

int clk_enable(struct clk *c)
{
        int ret = 0;
        unsigned long flags;

        spin_lock_irqsave(&c->spinlock, flags);

        if (c->refcnt == 0) {
                if (c->parent) {
                        ret = clk_enable(c->parent);
                        if (ret)
                                goto out;
                }

                if (c->ops && c->ops->enable) {
                        ret = c->ops->enable(c);
                        if (ret) {
                                if (c->parent)
                                        clk_disable(c->parent);
                                goto out;
                        }
                        c->state = ON;
                        c->set = true;
                }
        }
        c->refcnt++;
out:
        spin_unlock_irqrestore(&c->spinlock, flags);
        return ret;
}
EXPORT_SYMBOL(clk_enable);

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

        spin_lock_irqsave(&c->spinlock, flags);

        if (c->refcnt == 0) {
                WARN(1, "Attempting to disable clock %s with refcnt 0", c->name);
                spin_unlock_irqrestore(&c->spinlock, flags);
                return;
        }
        if (c->refcnt == 1) {
                if (c->ops && c->ops->disable)
                        c->ops->disable(c);

                if (c->parent)
                        clk_disable(c->parent);

                c->state = OFF;
        }
        c->refcnt--;

        spin_unlock_irqrestore(&c->spinlock, flags);
}
EXPORT_SYMBOL(clk_disable);

int clk_set_parent(struct clk *c, struct clk *parent)
{
        int ret;
        unsigned long flags;
        unsigned long new_rate;
        unsigned long old_rate;

        spin_lock_irqsave(&c->spinlock, flags);

        if (!c->ops || !c->ops->set_parent) {
                ret = -ENOSYS;
                goto out;
        }

        new_rate = clk_predict_rate_from_parent(c, parent);
        old_rate = clk_get_rate_locked(c);

        ret = c->ops->set_parent(c, parent);
        if (ret)
                goto out;

out:
        spin_unlock_irqrestore(&c->spinlock, flags);
        return ret;
}
EXPORT_SYMBOL(clk_set_parent);

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

int clk_set_rate_locked(struct clk *c, unsigned long rate)
{
        long new_rate;

        if (!c->ops || !c->ops->set_rate)
                return -ENOSYS;

        if (rate > c->max_rate)
                rate = c->max_rate;

        if (c->ops && c->ops->round_rate) {
                new_rate = c->ops->round_rate(c, rate);

                if (new_rate < 0)
                        return new_rate;

                rate = new_rate;
        }

        return c->ops->set_rate(c, rate);
}

int clk_set_rate(struct clk *c, unsigned long rate)
{
        int ret;
        unsigned long flags;

        spin_lock_irqsave(&c->spinlock, flags);

        ret = clk_set_rate_locked(c, rate);

        spin_unlock_irqrestore(&c->spinlock, flags);

        return ret;
}
EXPORT_SYMBOL(clk_set_rate);


/* Must be called with clocks lock and all indvidual clock locks held */
unsigned long clk_get_rate_all_locked(struct clk *c)
{
        u64 rate;
        int mul = 1;
        int div = 1;
        struct clk *p = c;

        while (p) {
                c = p;
                if (c->mul != 0 && c->div != 0) {
                        mul *= c->mul;
                        div *= c->div;
                }
                p = c->parent;
        }

        rate = c->rate;
        rate *= mul;
        do_div(rate, div);

        return rate;
}

long clk_round_rate(struct clk *c, unsigned long rate)
{
        unsigned long flags;
        long ret;

        spin_lock_irqsave(&c->spinlock, flags);

        if (!c->ops || !c->ops->round_rate) {
                ret = -ENOSYS;
                goto out;
        }

        if (rate > c->max_rate)
                rate = c->max_rate;

        ret = c->ops->round_rate(c, rate);

out:
        spin_unlock_irqrestore(&c->spinlock, flags);
        return ret;
}
EXPORT_SYMBOL(clk_round_rate);

static int tegra_clk_init_one_from_table(struct tegra_clk_init_table *table)
{
        struct clk *c;
        struct clk *p;

        int ret = 0;

        c = tegra_get_clock_by_name(table->name);

        if (!c) {
                pr_warning("Unable to initialize clock %s\n",
                        table->name);
                return -ENODEV;
        }

        if (table->parent) {
                p = tegra_get_clock_by_name(table->parent);
                if (!p) {
                        pr_warning("Unable to find parent %s of clock %s\n",
                                table->parent, table->name);
                        return -ENODEV;
                }

                if (c->parent != p) {
                        ret = clk_set_parent(c, p);
                        if (ret) {
                                pr_warning("Unable to set parent %s of clock %s: %d\n",
                                        table->parent, table->name, ret);
                                return -EINVAL;
                        }
                }
        }

        if (table->rate && table->rate != clk_get_rate(c)) {
                ret = clk_set_rate(c, table->rate);
                if (ret) {
                        pr_warning("Unable to set clock %s to rate %lu: %d\n",
                                table->name, table->rate, ret);
                        return -EINVAL;
                }
        }

        if (table->enabled) {
                ret = clk_enable(c);
                if (ret) {
                        pr_warning("Unable to enable clock %s: %d\n",
                                table->name, ret);
                        return -EINVAL;
                }
        }

        return 0;
}

void tegra_clk_init_from_table(struct tegra_clk_init_table *table)
{
        for (; table->name; table++)
                tegra_clk_init_one_from_table(table);
}
EXPORT_SYMBOL(tegra_clk_init_from_table);

void tegra_periph_reset_deassert(struct clk *c)
{
        tegra2_periph_reset_deassert(c);
}
EXPORT_SYMBOL(tegra_periph_reset_deassert);

void tegra_periph_reset_assert(struct clk *c)
{
        tegra2_periph_reset_assert(c);
}
EXPORT_SYMBOL(tegra_periph_reset_assert);

void __init tegra_init_clock(void)
{
        tegra2_init_clocks();
}

/*
 * The SDMMC controllers have extra bits in the clock source register that
 * adjust the delay between the clock and data to compenstate for delays
 * on the PCB.
 */
void tegra_sdmmc_tap_delay(struct clk *c, int delay)
{
        unsigned long flags;

        spin_lock_irqsave(&c->spinlock, flags);
        tegra2_sdmmc_tap_delay(c, delay);
        spin_unlock_irqrestore(&c->spinlock, flags);
}

#ifdef CONFIG_DEBUG_FS

static int __clk_lock_all_spinlocks(void)
{
        struct clk *c;

        list_for_each_entry(c, &clocks, node)
                if (!spin_trylock(&c->spinlock))
                        goto unlock_spinlocks;

        return 0;

unlock_spinlocks:
        list_for_each_entry_continue_reverse(c, &clocks, node)
                spin_unlock(&c->spinlock);

        return -EAGAIN;
}

static void __clk_unlock_all_spinlocks(void)
{
        struct clk *c;

        list_for_each_entry_reverse(c, &clocks, node)
                spin_unlock(&c->spinlock);
}

/*
 * This function retries until it can take all locks, and may take
 * an arbitrarily long time to complete.
 * Must be called with irqs enabled, returns with irqs disabled
 * Must be called with clock_list_lock held
 */
static void clk_lock_all(void)
{
        int ret;
retry:
        local_irq_disable();

        ret = __clk_lock_all_spinlocks();
        if (ret)
                goto failed_spinlocks;

        /* All locks taken successfully, return */
        return;

failed_spinlocks:
        local_irq_enable();
        yield();
        goto retry;
}

/*
 * Unlocks all clocks after a clk_lock_all
 * Must be called with irqs disabled, returns with irqs enabled
 * Must be called with clock_list_lock held
 */
static void clk_unlock_all(void)
{
        __clk_unlock_all_spinlocks();

        local_irq_enable();
}

static struct dentry *clk_debugfs_root;


static void clock_tree_show_one(struct seq_file *s, struct clk *c, int level)
{
        struct clk *child;
        const char *state = "uninit";
        char div[8] = {0};

        if (c->state == ON)
                state = "on";
        else if (c->state == OFF)
                state = "off";

        if (c->mul != 0 && c->div != 0) {
                if (c->mul > c->div) {
                        int mul = c->mul / c->div;
                        int mul2 = (c->mul * 10 / c->div) % 10;
                        int mul3 = (c->mul * 10) % c->div;
                        if (mul2 == 0 && mul3 == 0)
                                snprintf(div, sizeof(div), "x%d", mul);
                        else if (mul3 == 0)
                                snprintf(div, sizeof(div), "x%d.%d", mul, mul2);
                        else
                                snprintf(div, sizeof(div), "x%d.%d..", mul, mul2);
                } else {
                        snprintf(div, sizeof(div), "%d%s", c->div / c->mul,
                                (c->div % c->mul) ? ".5" : "");
                }
        }

        seq_printf(s, "%*s%c%c%-*s %-6s %-3d %-8s %-10lu\n",
                level * 3 + 1, "",
                c->rate > c->max_rate ? '!' : ' ',
                !c->set ? '*' : ' ',
                30 - level * 3, c->name,
                state, c->refcnt, div, clk_get_rate_all_locked(c));

        list_for_each_entry(child, &clocks, node) {
                if (child->parent != c)
                        continue;

                clock_tree_show_one(s, child, level + 1);
        }
}

static int clock_tree_show(struct seq_file *s, void *data)
{
        struct clk *c;
        seq_printf(s, "   clock                          state  ref div      rate\n");
        seq_printf(s, "--------------------------------------------------------------\n");

        mutex_lock(&clock_list_lock);

        clk_lock_all();

        list_for_each_entry(c, &clocks, node)
                if (c->parent == NULL)
                        clock_tree_show_one(s, c, 0);

        clk_unlock_all();

        mutex_unlock(&clock_list_lock);
        return 0;
}

static int clock_tree_open(struct inode *inode, struct file *file)
{
        return single_open(file, clock_tree_show, inode->i_private);
}

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

static int possible_parents_show(struct seq_file *s, void *data)
{
        struct clk *c = s->private;
        int i;

        for (i = 0; c->inputs[i].input; i++) {
                char *first = (i == 0) ? "" : " ";
                seq_printf(s, "%s%s", first, c->inputs[i].input->name);
        }
        seq_printf(s, "\n");
        return 0;
}

static int possible_parents_open(struct inode *inode, struct file *file)
{
        return single_open(file, possible_parents_show, inode->i_private);
}

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

static int clk_debugfs_register_one(struct clk *c)
{
        struct dentry *d;

        d = debugfs_create_dir(c->name, clk_debugfs_root);
        if (!d)
                return -ENOMEM;
        c->dent = d;

        d = debugfs_create_u8("refcnt", S_IRUGO, c->dent, (u8 *)&c->refcnt);
        if (!d)
                goto err_out;

        d = debugfs_create_u32("rate", S_IRUGO, c->dent, (u32 *)&c->rate);
        if (!d)
                goto err_out;

        d = debugfs_create_x32("flags", S_IRUGO, c->dent, (u32 *)&c->flags);
        if (!d)
                goto err_out;

        if (c->inputs) {
                d = debugfs_create_file("possible_parents", S_IRUGO, c->dent,
                        c, &possible_parents_fops);
                if (!d)
                        goto err_out;
        }

        return 0;

err_out:
        debugfs_remove_recursive(c->dent);
        return -ENOMEM;
}

static int clk_debugfs_register(struct clk *c)
{
        int err;
        struct clk *pa = c->parent;

        if (pa && !pa->dent) {
                err = clk_debugfs_register(pa);
                if (err)
                        return err;
        }

        if (!c->dent) {
                err = clk_debugfs_register_one(c);
                if (err)
                        return err;
        }
        return 0;
}

static int __init clk_debugfs_init(void)
{
        struct clk *c;
        struct dentry *d;
        int err = -ENOMEM;

        d = debugfs_create_dir("clock", NULL);
        if (!d)
                return -ENOMEM;
        clk_debugfs_root = d;

        d = debugfs_create_file("clock_tree", S_IRUGO, clk_debugfs_root, NULL,
                &clock_tree_fops);
        if (!d)
                goto err_out;

        list_for_each_entry(c, &clocks, node) {
                err = clk_debugfs_register(c);
                if (err)
                        goto err_out;
        }
        return 0;
err_out:
        debugfs_remove_recursive(clk_debugfs_root);
        return err;
}

late_initcall(clk_debugfs_init);
#endif