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clock.c

/*
 * arch/arm/mach-ns9xxx/clock.c
 *
 * Copyright (C) 2007 by Digi International Inc.
 * All rights reserved.
 *
 * 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.
 */
#include <linux/err.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/clk.h>
#include <linux/string.h>
#include <linux/platform_device.h>
#include <linux/semaphore.h>

#include "clock.h"

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

struct clk *clk_get(struct device *dev, const char *id)
{
      struct clk *p, *ret = NULL, *retgen = NULL;
      unsigned long flags;
      int idno;

      if (dev == NULL || dev->bus != &platform_bus_type)
            idno = -1;
      else
            idno = to_platform_device(dev)->id;

      spin_lock_irqsave(&clk_lock, flags);
      list_for_each_entry(p, &clocks, node) {
            if (strcmp(id, p->name) == 0) {
                  if (p->id == idno) {
                        if (!try_module_get(p->owner))
                              continue;
                        ret = p;
                        break;
                  } else if (p->id == -1)
                        /* remember match with id == -1 in case there is
                         * no clock for idno */
                        retgen = p;
            }
      }

      if (!ret && retgen && try_module_get(retgen->owner))
            ret = retgen;

      if (ret)
            ++ret->refcount;

      spin_unlock_irqrestore(&clk_lock, flags);

      return ret ? ret : ERR_PTR(-ENOENT);
}
EXPORT_SYMBOL(clk_get);

void clk_put(struct clk *clk)
{
      module_put(clk->owner);
      --clk->refcount;
}
EXPORT_SYMBOL(clk_put);

static int clk_enable_unlocked(struct clk *clk)
{
      int ret = 0;
      if (clk->parent) {
            ret = clk_enable_unlocked(clk->parent);
            if (ret)
                  return ret;
      }

      if (clk->usage++ == 0 && clk->endisable)
            ret = clk->endisable(clk, 1);

      return ret;
}

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

      spin_lock_irqsave(&clk_lock, flags);

      ret = clk_enable_unlocked(clk);

      spin_unlock_irqrestore(&clk_lock, flags);

      return ret;
}
EXPORT_SYMBOL(clk_enable);

static void clk_disable_unlocked(struct clk *clk)
{
      if (--clk->usage == 0 && clk->endisable)
            clk->endisable(clk, 0);

      if (clk->parent)
            clk_disable_unlocked(clk->parent);
}

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

      spin_lock_irqsave(&clk_lock, flags);

      clk_disable_unlocked(clk);

      spin_unlock_irqrestore(&clk_lock, flags);
}
EXPORT_SYMBOL(clk_disable);

unsigned long clk_get_rate(struct clk *clk)
{
      if (clk->get_rate)
            return clk->get_rate(clk);

      if (clk->rate)
            return clk->rate;

      if (clk->parent)
            return clk_get_rate(clk->parent);

      return 0;
}
EXPORT_SYMBOL(clk_get_rate);

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

      spin_lock_irqsave(&clk_lock, flags);

      list_add(&clk->node, &clocks);

      if (clk->parent)
            ++clk->parent->refcount;

      spin_unlock_irqrestore(&clk_lock, flags);

      return 0;
}

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

      spin_lock_irqsave(&clk_lock, flags);

      if (clk->usage || clk->refcount)
            ret = -EBUSY;
      else
            list_del(&clk->node);

      if (clk->parent)
            --clk->parent->refcount;

      spin_unlock_irqrestore(&clk_lock, flags);

      return ret;
}

#if defined CONFIG_DEBUG_FS

#include <linux/debugfs.h>
#include <linux/seq_file.h>

static int clk_debugfs_show(struct seq_file *s, void *null)
{
      unsigned long flags;
      struct clk *p;

      spin_lock_irqsave(&clk_lock, flags);

      list_for_each_entry(p, &clocks, node)
            seq_printf(s, "%s.%d: usage=%lu refcount=%lu rate=%lu\n",
                        p->name, p->id, p->usage, p->refcount,
                        p->usage ? clk_get_rate(p) : 0);

      spin_unlock_irqrestore(&clk_lock, flags);

      return 0;
}

static int clk_debugfs_open(struct inode *inode, struct file *file)
{
      return single_open(file, clk_debugfs_show, NULL);
}

static struct file_operations clk_debugfs_operations = {
      .open = clk_debugfs_open,
      .read = seq_read,
      .llseek = seq_lseek,
      .release = single_release,
};

static int __init clk_debugfs_init(void)
{
      struct dentry *dentry;

      dentry = debugfs_create_file("clk", S_IFREG | S_IRUGO, NULL, NULL,
                  &clk_debugfs_operations);
      return IS_ERR(dentry) ? PTR_ERR(dentry) : 0;
}
subsys_initcall(clk_debugfs_init);

#endif /* if defined CONFIG_DEBUG_FS */

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