arch/arm/common/clkdev.c

   1 /*
   2  *  arch/arm/common/clkdev.c
   3  *
   4  *  Copyright (C) 2008 Russell King.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Helper for the clk API to assist looking up a struct clk.
  11  */
  12 #include <linux/module.h>
  13 #include <linux/kernel.h>
  14 #include <linux/device.h>
  15 #include <linux/list.h>
  16 #include <linux/errno.h>
  17 #include <linux/err.h>
  18 #include <linux/string.h>
  19 #include <linux/mutex.h>
  20
  21 #include <asm/clkdev.h>
  22 #include <mach/clkdev.h>
  23
  24 static LIST_HEAD(clocks);
  25 static DEFINE_MUTEX(clocks_mutex);
  26
  27 static struct clk *clk_find(const char *dev_id, const char *con_id)
  28 {
  29         struct clk_lookup *p;
  30         struct clk *clk = NULL;
  31         int match, best = 0;
  32
  33         list_for_each_entry(p, &clocks, node) {
  34                 if ((p->dev_id && !dev_id) || (p->con_id && !con_id))
  35                         continue;
  36                 match = 0;
  37                 if (p->dev_id)
  38                         match += 2 * (strcmp(p->dev_id, dev_id) == 0);
  39                 if (p->con_id)
  40                         match += 1 * (strcmp(p->con_id, con_id) == 0);
  41                 if (match == 0)
  42                         continue;
  43
  44                 if (match > best) {
  45                         clk = p->clk;
  46                         best = match;
  47                 }
  48         }
  49         return clk;
  50 }
  51
  52 struct clk *clk_get(struct device *dev, const char *con_id)
  53 {
  54         const char *dev_id = dev ? dev_name(dev) : NULL;
  55         struct clk *clk;
  56
  57         mutex_lock(&clocks_mutex);
  58         clk = clk_find(dev_id, con_id);
  59         if (clk && !__clk_get(clk))
  60                 clk = NULL;
  61         mutex_unlock(&clocks_mutex);
  62
  63         return clk ? clk : ERR_PTR(-ENOENT);
  64 }
  65 EXPORT_SYMBOL(clk_get);
  66
  67 void clk_put(struct clk *clk)
  68 {
  69         __clk_put(clk);
  70 }
  71 EXPORT_SYMBOL(clk_put);
  72
  73 void clkdev_add(struct clk_lookup *cl)
  74 {
  75         mutex_lock(&clocks_mutex);
  76         list_add_tail(&cl->node, &clocks);
  77         mutex_unlock(&clocks_mutex);
  78 }
  79 EXPORT_SYMBOL(clkdev_add);
  80
  81 #define MAX_DEV_ID      20
  82 #define MAX_CON_ID      16
  83
  84 struct clk_lookup_alloc {
  85         struct clk_lookup cl;
  86         char    dev_id[MAX_DEV_ID];
  87         char    con_id[MAX_CON_ID];
  88 };
  89
  90 struct clk_lookup *clkdev_alloc(struct clk *clk, const char *con_id,
  91         const char *dev_fmt, ...)
  92 {
  93         struct clk_lookup_alloc *cla;
  94
  95         cla = kzalloc(sizeof(*cla), GFP_KERNEL);
  96         if (!cla)
  97                 return NULL;
  98
  99         cla->cl.clk = clk;
 100         if (con_id) {
 101                 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 102                 cla->cl.con_id = cla->con_id;
 103         }
 104
 105         if (dev_fmt) {
 106                 va_list ap;
 107
 108                 va_start(ap, dev_fmt);
 109                 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 110                 cla->cl.dev_id = cla->dev_id;
 111                 va_end(ap);
 112         }
 113
 114         return &cla->cl;
 115 }
 116 EXPORT_SYMBOL(clkdev_alloc);
 117
 118 /*
 119  * clkdev_drop - remove a clock dynamically allocated
 120  */
 121 void clkdev_drop(struct clk_lookup *cl)
 122 {
 123         mutex_lock(&clocks_mutex);
 124         list_del(&cl->node);
 125         mutex_unlock(&clocks_mutex);
 126         kfree(cl);
 127 }
 128 EXPORT_SYMBOL(clkdev_drop);