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_sys(const char *dev_id, const char *con_id)
  66 {
  67         struct clk *clk;
  68
  69         mutex_lock(&clocks_mutex);
  70         clk = clk_find(dev_id, con_id);
  71         if (clk && !__clk_get(clk))
  72                 clk = NULL;
  73         mutex_unlock(&clocks_mutex);
  74
  75         return clk ? clk : ERR_PTR(-ENOENT);
  76 }
  77 EXPORT_SYMBOL(clk_get_sys);
  78
  79 struct clk *clk_get(struct device *dev, const char *con_id)
  80 {
  81         const char *dev_id = dev ? dev_name(dev) : NULL;
  82
  83         return clk_get_sys(dev_id, con_id);
  84 }
  85 EXPORT_SYMBOL(clk_get);
  86
  87 void clk_put(struct clk *clk)
  88 {
  89         __clk_put(clk);
  90 }
  91 EXPORT_SYMBOL(clk_put);
  92
  93 void clkdev_add(struct clk_lookup *cl)
  94 {
  95         mutex_lock(&clocks_mutex);
  96         list_add_tail(&cl->node, &clocks);
  97         mutex_unlock(&clocks_mutex);
  98 }
  99 EXPORT_SYMBOL(clkdev_add);
 100
 101 #define MAX_DEV_ID      20
 102 #define MAX_CON_ID      16
 103
 104 struct clk_lookup_alloc {
 105         struct clk_lookup cl;
 106         char    dev_id[MAX_DEV_ID];
 107         char    con_id[MAX_CON_ID];
 108 };
 109
 110 struct clk_lookup *clkdev_alloc(struct clk *clk, const char *con_id,
 111         const char *dev_fmt, ...)
 112 {
 113         struct clk_lookup_alloc *cla;
 114
 115         cla = kzalloc(sizeof(*cla), GFP_KERNEL);
 116         if (!cla)
 117                 return NULL;
 118
 119         cla->cl.clk = clk;
 120         if (con_id) {
 121                 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 122                 cla->cl.con_id = cla->con_id;
 123         }
 124
 125         if (dev_fmt) {
 126                 va_list ap;
 127
 128                 va_start(ap, dev_fmt);
 129                 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 130                 cla->cl.dev_id = cla->dev_id;
 131                 va_end(ap);
 132         }
 133
 134         return &cla->cl;
 135 }
 136 EXPORT_SYMBOL(clkdev_alloc);
 137
 138 /*
 139  * clkdev_drop - remove a clock dynamically allocated
 140  */
 141 void clkdev_drop(struct clk_lookup *cl)
 142 {
 143         mutex_lock(&clocks_mutex);
 144         list_del(&cl->node);
 145         mutex_unlock(&clocks_mutex);
 146         kfree(cl);
 147 }
 148 EXPORT_SYMBOL(clkdev_drop);