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 #include <linux/clk.h>
  21
  22 #include <asm/clkdev.h>
  23 #include <mach/clkdev.h>
  24
  25 static LIST_HEAD(clocks);
  26 static DEFINE_MUTEX(clocks_mutex);
  27
  28 /*
  29  * Find the correct struct clk for the device and connection ID.
  30  * We do slightly fuzzy matching here:
  31  *  An entry with a NULL ID is assumed to be a wildcard.
  32  *  If an entry has a device ID, it must match
  33  *  If an entry has a connection ID, it must match
  34  * Then we take the most specific entry - with the following
  35  * order of precidence: dev+con > dev only > con only.
  36  */
  37 static struct clk *clk_find(const char *dev_id, const char *con_id)
  38 {
  39         struct clk_lookup *p;
  40         struct clk *clk = NULL;
  41         int match, best = 0;
  42
  43         list_for_each_entry(p, &clocks, node) {
  44                 match = 0;
  45                 if (p->dev_id) {
  46                         if (!dev_id || strcmp(p->dev_id, dev_id))
  47                                 continue;
  48                         match += 2;
  49                 }
  50                 if (p->con_id) {
  51                         if (!con_id || strcmp(p->con_id, con_id))
  52                                 continue;
  53                         match += 1;
  54                 }
  55                 if (match == 0)
  56                         continue;
  57
  58                 if (match > best) {
  59                         clk = p->clk;
  60                         best = match;
  61                 }
  62         }
  63         return clk;
  64 }
  65
  66 struct clk *clk_get_sys(const char *dev_id, const char *con_id)
  67 {
  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_sys);
  79
  80 struct clk *clk_get(struct device *dev, const char *con_id)
  81 {
  82         const char *dev_id = dev ? dev_name(dev) : NULL;
  83
  84         return clk_get_sys(dev_id, con_id);
  85 }
  86 EXPORT_SYMBOL(clk_get);
  87
  88 void clk_put(struct clk *clk)
  89 {
  90         __clk_put(clk);
  91 }
  92 EXPORT_SYMBOL(clk_put);
  93
  94 void clkdev_add(struct clk_lookup *cl)
  95 {
  96         mutex_lock(&clocks_mutex);
  97         list_add_tail(&cl->node, &clocks);
  98         mutex_unlock(&clocks_mutex);
  99 }
 100 EXPORT_SYMBOL(clkdev_add);
 101
 102 #define MAX_DEV_ID      20
 103 #define MAX_CON_ID      16
 104
 105 struct clk_lookup_alloc {
 106         struct clk_lookup cl;
 107         char    dev_id[MAX_DEV_ID];
 108         char    con_id[MAX_CON_ID];
 109 };
 110
 111 struct clk_lookup *clkdev_alloc(struct clk *clk, const char *con_id,
 112         const char *dev_fmt, ...)
 113 {
 114         struct clk_lookup_alloc *cla;
 115
 116         cla = kzalloc(sizeof(*cla), GFP_KERNEL);
 117         if (!cla)
 118                 return NULL;
 119
 120         cla->cl.clk = clk;
 121         if (con_id) {
 122                 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 123                 cla->cl.con_id = cla->con_id;
 124         }
 125
 126         if (dev_fmt) {
 127                 va_list ap;
 128
 129                 va_start(ap, dev_fmt);
 130                 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 131                 cla->cl.dev_id = cla->dev_id;
 132                 va_end(ap);
 133         }
 134
 135         return &cla->cl;
 136 }
 137 EXPORT_SYMBOL(clkdev_alloc);
 138
 139 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 140         struct device *dev)
 141 {
 142         struct clk *r = clk_get(dev, id);
 143         struct clk_lookup *l;
 144
 145         if (IS_ERR(r))
 146                 return PTR_ERR(r);
 147
 148         l = clkdev_alloc(r, alias, alias_dev_name);
 149         clk_put(r);
 150         if (!l)
 151                 return -ENODEV;
 152         clkdev_add(l);
 153         return 0;
 154 }
 155 EXPORT_SYMBOL(clk_add_alias);
 156
 157 /*
 158  * clkdev_drop - remove a clock dynamically allocated
 159  */
 160 void clkdev_drop(struct clk_lookup *cl)
 161 {
 162         mutex_lock(&clocks_mutex);
 163         list_del(&cl->node);
 164         mutex_unlock(&clocks_mutex);
 165         kfree(cl);
 166 }
 167 EXPORT_SYMBOL(clkdev_drop);