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clkdev.c

/*
 *  arch/arm/common/clkdev.c
 *
 *  Copyright (C) 2008 Russell King.
 *
 * 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.
 *
 * Helper for the clk API to assist looking up a struct clk.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/string.h>
#include <linux/mutex.h>
#include <linux/clk.h>

#include <asm/clkdev.h>
#include <mach/clkdev.h>

static LIST_HEAD(clocks);
static DEFINE_MUTEX(clocks_mutex);

/*
 * Find the correct struct clk for the device and connection ID.
 * We do slightly fuzzy matching here:
 *  An entry with a NULL ID is assumed to be a wildcard.
 *  If an entry has a device ID, it must match
 *  If an entry has a connection ID, it must match
 * Then we take the most specific entry - with the following
 * order of precidence: dev+con > dev only > con only.
 */
static struct clk *clk_find(const char *dev_id, const char *con_id)
{
      struct clk_lookup *p;
      struct clk *clk = NULL;
      int match, best = 0;

      list_for_each_entry(p, &clocks, node) {
            match = 0;
            if (p->dev_id) {
                  if (!dev_id || strcmp(p->dev_id, dev_id))
                        continue;
                  match += 2;
            }
            if (p->con_id) {
                  if (!con_id || strcmp(p->con_id, con_id))
                        continue;
                  match += 1;
            }
            if (match == 0)
                  continue;

            if (match > best) {
                  clk = p->clk;
                  best = match;
            }
      }
      return clk;
}

struct clk *clk_get_sys(const char *dev_id, const char *con_id)
{
      struct clk *clk;

      mutex_lock(&clocks_mutex);
      clk = clk_find(dev_id, con_id);
      if (clk && !__clk_get(clk))
            clk = NULL;
      mutex_unlock(&clocks_mutex);

      return clk ? clk : ERR_PTR(-ENOENT);
}
EXPORT_SYMBOL(clk_get_sys);

struct clk *clk_get(struct device *dev, const char *con_id)
{
      const char *dev_id = dev ? dev_name(dev) : NULL;

      return clk_get_sys(dev_id, con_id);
}
EXPORT_SYMBOL(clk_get);

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

void clkdev_add(struct clk_lookup *cl)
{
      mutex_lock(&clocks_mutex);
      list_add_tail(&cl->node, &clocks);
      mutex_unlock(&clocks_mutex);
}
EXPORT_SYMBOL(clkdev_add);

#define MAX_DEV_ID      20
#define MAX_CON_ID      16

00105 struct clk_lookup_alloc {
      struct clk_lookup cl;
      char  dev_id[MAX_DEV_ID];
      char  con_id[MAX_CON_ID];
};

struct clk_lookup *clkdev_alloc(struct clk *clk, const char *con_id,
      const char *dev_fmt, ...)
{
      struct clk_lookup_alloc *cla;

      cla = kzalloc(sizeof(*cla), GFP_KERNEL);
      if (!cla)
            return NULL;

      cla->cl.clk = clk;
      if (con_id) {
            strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
            cla->cl.con_id = cla->con_id;
      }

      if (dev_fmt) {
            va_list ap;

            va_start(ap, dev_fmt);
            vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
            cla->cl.dev_id = cla->dev_id;
            va_end(ap);
      }

      return &cla->cl;
}
EXPORT_SYMBOL(clkdev_alloc);

int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
      struct device *dev)
{
      struct clk *r = clk_get(dev, id);
      struct clk_lookup *l;

      if (IS_ERR(r))
            return PTR_ERR(r);

      l = clkdev_alloc(r, alias, alias_dev_name);
      clk_put(r);
      if (!l)
            return -ENODEV;
      clkdev_add(l);
      return 0;
}
EXPORT_SYMBOL(clk_add_alias);

/*
 * clkdev_drop - remove a clock dynamically allocated
 */
void clkdev_drop(struct clk_lookup *cl)
{
      mutex_lock(&clocks_mutex);
      list_del(&cl->node);
      mutex_unlock(&clocks_mutex);
      kfree(cl);
}
EXPORT_SYMBOL(clkdev_drop);

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