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 /*
  28  * Find the correct struct clk for the device and connection ID.
  29  * We do slightly fuzzy matching here:
  30  *  An entry with a NULL ID is assumed to be a wildcard.
  31  *  If an entry has a device ID, it must match
  32  *  If an entry has a connection ID, it must match
  33  * Then we take the most specific entry - with the following
  34  * order of precidence: dev+con > dev only > con only.
  35  */
  36 static struct clk *clk_find(const char *dev_id, const char *con_id)
  37 {
  38         struct clk_lookup *p;
  39         struct clk *clk = NULL;
  40         int match, best = 0;
  41
  42         list_for_each_entry(p, &clocks, node) {
  43                 match = 0;
  44                 if (p->dev_id) {
  45                         if (!dev_id || strcmp(p->dev_id, dev_id))
  46                                 continue;
  47                         match += 2;
  48                 }
  49                 if (p->con_id) {
  50                         if (!con_id || strcmp(p->con_id, con_id))
  51                                 continue;
  52                         match += 1;
  53                 }
  54                 if (match == 0)
  55                         continue;
  56
  57                 if (match > best) {
  58                         clk = p->clk;
  59                         best = match;
  60                 }
  61         }
  62         return clk;
  63 }
  64
  65 struct clk *clk_get(struct device *dev, const char *con_id)
  66 {
  67         const char *dev_id = dev ? dev_name(dev) : NULL;
  68         struct clk *clk;
  69
  70         mutex_lock(&clocks_mutex);
  71         clk = clk_find(dev_id, con_id);
  72         if (clk && !__clk_get(clk))
  73                 clk = NULL;
  74         mutex_unlock(&clocks_mutex);
  75
  76         return clk ? clk : ERR_PTR(-ENOENT);
  77 }
  78 EXPORT_SYMBOL(clk_get);
  79
  80 void clk_put(struct clk *clk)
  81 {
  82         __clk_put(clk);
  83 }
  84 EXPORT_SYMBOL(clk_put);
  85
  86 void clkdev_add(struct clk_lookup *cl)
  87 {
  88         mutex_lock(&clocks_mutex);
  89         list_add_tail(&cl->node, &clocks);
  90         mutex_unlock(&clocks_mutex);
  91 }
  92 EXPORT_SYMBOL(clkdev_add);
  93
  94 #define MAX_DEV_ID      20
  95 #define MAX_CON_ID      16
  96
  97 struct clk_lookup_alloc {
  98         struct clk_lookup cl;
  99         char    dev_id[MAX_DEV_ID];
 100         char    con_id[MAX_CON_ID];
 101 };
 102
 103 struct clk_lookup *clkdev_alloc(struct clk *clk, const char *con_id,
 104         const char *dev_fmt, ...)
 105 {
 106         struct clk_lookup_alloc *cla;
 107
 108         cla = kzalloc(sizeof(*cla), GFP_KERNEL);
 109         if (!cla)
 110                 return NULL;
 111
 112         cla->cl.clk = clk;
 113         if (con_id) {
 114                 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 115                 cla->cl.con_id = cla->con_id;
 116         }
 117
 118         if (dev_fmt) {
 119                 va_list ap;
 120
 121                 va_start(ap, dev_fmt);
 122                 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 123                 cla->cl.dev_id = cla->dev_id;
 124                 va_end(ap);
 125         }
 126
 127         return &cla->cl;
 128 }
 129 EXPORT_SYMBOL(clkdev_alloc);
 130
 131 /*
 132  * clkdev_drop - remove a clock dynamically allocated
 133  */
 134 void clkdev_drop(struct clk_lookup *cl)
 135 {
 136         mutex_lock(&clocks_mutex);
 137         list_del(&cl->node);
 138         mutex_unlock(&clocks_mutex);
 139         kfree(cl);
 140 }
 141 EXPORT_SYMBOL(clkdev_drop);