path: root/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/debugfs.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/slab.h>

#include <asm/clkdev.h>

#include <mach/clk.h>

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

/*
 * Locking:
 *
 * Each struct clk has a lock.  Depending on the cansleep flag, that lock
 * may be a spinlock or a mutex.  For most clocks, the spinlock is sufficient,
 * and using the spinlock allows the clock to be manipulated from an interrupt
 * or while holding a spinlock.  Some clocks may need to adjust a regulator
 * in order to maintain the required voltage for a new frequency.  Those
 * clocks set the cansleep flag, and take a mutex so that the regulator api
 * can be used while holding the lock.
 *
 * 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 are two exceptions to this ordering:
 *  1. When setting a clock as cansleep, in which case the entire list of clocks
 *     is traversed to set the children as cansleep as well.  This must occur
 *     during init, before any calls to clk_get, so no other clock locks can
 *     get taken.
 *  2. 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 clk_trylock fails, a 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.  Any clock operation can call
 * any other clock operation on any of it's possible parents.
 *
 * clk_set_cansleep is used to mark a clock as sleeping.  It is called during
 * dvfs (Dynamic Voltage and Frequency Scaling) init on any clock that has a
 * dvfs requirement.  It can only be called on clocks that are the sole parent
 * of all of their child clocks, meaning the child clock can not be reparented
 * onto a different, possibly non-sleeping, clock.  This is inherently true
 * of all leaf clocks in the clock tree
 *
 * An additional lock, 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);

static inline bool clk_is_auto_dvfs(struct clk *c)
{
	return c->auto_dvfs;
}

static inline bool clk_is_dvfs(struct clk *c)
{
	return (c->dvfs != NULL);
}

static inline bool clk_cansleep(struct clk *c)
{
	return c->cansleep;
}

#define clk_lock_save(c, flags)						\
	do {								\
		if (clk_cansleep(c)) {					\
			flags = 0;					\
			mutex_lock(&c->mutex);				\
		} else {						\
			spin_lock_irqsave(&c->spinlock, flags);		\
		}							\
	} while (0)

#define clk_unlock_restore(c, flags)					\
	do {								\
		if (clk_cansleep(c))					\
			mutex_unlock(&c->mutex);			\
		else							\
			spin_unlock_irqrestore(&c->spinlock, flags);	\
	} while (0)

static inline void clk_lock_init(struct clk *c)
{
	mutex_init(&c->mutex);
	spin_lock_init(&c->spinlock);
}

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 clk_lock(c) 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 / 2; /* round up */
		do_div(rate, c->div);
	}

	return rate;
}

/* Must be called with clk_lock(c) 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;

	clk_lock_save(c, flags);

	rate = clk_get_rate_locked(c);

	clk_unlock_restore(c, flags);

	return rate;
}
EXPORT_SYMBOL(clk_get_rate);

static void __clk_set_cansleep(struct clk *c)
{
	struct clk *child;
	BUG_ON(mutex_is_locked(&c->mutex));
	BUG_ON(spin_is_locked(&c->spinlock));

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

		WARN(child->ops && child->ops->set_parent,
			"can't make child clock %s of %s "
			"sleepable if it's parent could change",
			child->name, c->name);

		__clk_set_cansleep(child);
	}

	c->cansleep = true;
}

/* Must be called before any clk_get calls */
void clk_set_cansleep(struct clk *c)
{

	mutex_lock(&clock_list_lock);
	__clk_set_cansleep(c);
	mutex_unlock(&clock_list_lock);
}

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

void clk_init(struct clk *c)
{
	clk_lock_init(c);

	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;

	clk_lock_save(c, flags);

	if (clk_is_auto_dvfs(c)) {
		ret = tegra_dvfs_set_rate(c, clk_get_rate_locked(c));
		if (ret)
			goto out;
	}

	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:
	clk_unlock_restore(c, flags);
	return ret;
}
EXPORT_SYMBOL(clk_enable);

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

	clk_lock_save(c, flags);

	if (c->refcnt == 0) {
		WARN(1, "Attempting to disable clock %s with refcnt 0", c->name);
		clk_unlock_restore(c, 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--;

	if (clk_is_auto_dvfs(c) && c->refcnt == 0)
		tegra_dvfs_set_rate(c, 0);

	clk_unlock_restore(c, flags);
}
EXPORT_SYMBOL(clk_disable);

int clk_set_parent(struct clk *c, struct clk *parent)
{
	int ret = 0;
	unsigned long flags;
	unsigned long new_rate;
	unsigned long old_rate;

	clk_lock_save(c, 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);

	if (clk_is_auto_dvfs(c) && c->refcnt > 0 &&
			(!c->parent || new_rate > old_rate)) {
		ret = tegra_dvfs_set_rate(c, new_rate);
		if (ret)
			goto out;
	}

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

	if (clk_is_auto_dvfs(c) && c->refcnt > 0 &&
			new_rate < old_rate)
		ret = tegra_dvfs_set_rate(c, new_rate);

out:
	clk_unlock_restore(c, 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(struct clk *c, unsigned long rate)
{
	int ret = 0;
	unsigned long flags;
	unsigned long old_rate;
	long new_rate;

	clk_lock_save(c, flags);

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

	old_rate = clk_get_rate_locked(c);

	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) {
			ret = new_rate;
			goto out;
		}

		rate = new_rate;
	}

	if (clk_is_auto_dvfs(c) && rate > old_rate && c->refcnt > 0) {
		ret = tegra_dvfs_set_rate(c, rate);
		if (ret)
			goto out;
	}

	ret = c->ops->set_rate(c, rate);
	if (ret)
		goto out;

	if (clk_is_auto_dvfs(c) && rate < old_rate && c->refcnt > 0)
		ret = tegra_dvfs_set_rate(c, rate);

out:
	clk_unlock_restore(c, 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;

	clk_lock_save(c, 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:
	clk_unlock_restore(c, 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();
	tegra2_init_dvfs();
}

/*
 * Iterate through all clocks, disabling any for which the refcount is 0
 * but the clock init detected the bootloader left the clock on.
 */
int __init tegra_disable_boot_clocks(void)
{
	unsigned long flags;
	struct clk *c;

	mutex_lock(&clock_list_lock);

	list_for_each_entry(c, &clocks, node) {
		clk_lock_save(c, flags);
		if (c->refcnt == 0 && c->state == ON &&
				c->ops && c->ops->disable) {
			pr_warning("Disabling clock %s left on by bootloader\n",
				c->name);
			c->ops->disable(c);
			c->state = OFF;
		}
		clk_unlock_restore(c, flags);
	}

	mutex_unlock(&clock_list_lock);
	return 0;
}

int __init tegra_late_init_clock(void)
{
	tegra_dvfs_late_init();
	tegra_disable_boot_clocks();
	return 0;
}
late_initcall(tegra_late_init_clock);

/* 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;

	clk_lock_save(c, flags);
	tegra2_sdmmc_tap_delay(c, delay);
	clk_unlock_restore(c, flags);
}

#ifdef CONFIG_DEBUG_FS

/*
 * Attempt to lock all the clocks that are marked cansleep
 * Must be called with irqs enabled
 */
static int __clk_lock_all_mutexes(void)
{
	struct clk *c;

	might_sleep();

	list_for_each_entry(c, &clocks, node)
		if (clk_cansleep(c))
			if (!mutex_trylock(&c->mutex))
				goto unlock_mutexes;

	return 0;

unlock_mutexes:
	list_for_each_entry_continue_reverse(c, &clocks, node)
		if (clk_cansleep(c))
			mutex_unlock(&c->mutex);

	return -EAGAIN;
}

/*
 * Attempt to lock all the clocks that are not marked cansleep
 * Must be called with irqs disabled
 */
static int __clk_lock_all_spinlocks(void)
{
	struct clk *c;

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

	return 0;

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

	return -EAGAIN;
}

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

	list_for_each_entry_reverse(c, &clocks, node)
		if (clk_cansleep(c))
			mutex_unlock(&c->mutex);
}

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

	list_for_each_entry_reverse(c, &clocks, node)
		if (!clk_cansleep(c))
			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:
	ret = __clk_lock_all_mutexes();
	if (ret)
		goto failed_mutexes;

	local_irq_disable();

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

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

failed_spinlocks:
	local_irq_enable();
	__clk_unlock_all_mutexes();
failed_mutexes:
	msleep(1);
	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();

	__clk_unlock_all_mutexes();
}

static struct dentry *clk_debugfs_root;

static void dvfs_show_one(struct seq_file *s, struct dvfs *d, int level)
{
	seq_printf(s, "%*s  %-*s%21s%d mV\n",
			level * 3 + 1, "",
			30 - level * 3, d->dvfs_rail->reg_id,
			"",
			d->cur_millivolts);
}

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));

	if (c->dvfs)
		dvfs_show_one(s, c->dvfs, level + 1);

	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, *child, *child_tmp;

	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:
	d = c->dent;
	list_for_each_entry_safe(child, child_tmp, &d->d_subdirs, d_u.d_child)
		debugfs_remove(child);
	debugfs_remove(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;

	if (dvfs_debugfs_init(clk_debugfs_root))
		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