linux/arch/arm/mach-tegra/clock.c

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/*
*
* 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;
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 = 1;
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;
#ifdef CONFIG_DEBUG_FS
c->set = 1;
#endif
}
}
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)
{
if (!c->ops || !c->ops->set_rate)
return -ENOSYS;
if (rate > c->max_rate)
rate = c->max_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();
}
#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, *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;
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