drivers/clk/clkdev.c

   1 /*
   2  * drivers/clk/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 #include <linux/clkdev.h>
  22
  23 static LIST_HEAD(clocks);
  24 static DEFINE_MUTEX(clocks_mutex);
  25
  26 /*
  27  * Find the correct struct clk for the device and connection ID.
  28  * We do slightly fuzzy matching here:
  29  *  An entry with a NULL ID is assumed to be a wildcard.
  30  *  If an entry has a device ID, it must match
  31  *  If an entry has a connection ID, it must match
  32  * Then we take the most specific entry - with the following
  33  * order of precedence: dev+con > dev only > con only.
  34  */
  35 static struct clk_lookup *clk_find(const char *dev_id, const char *con_id)
  36 {
  37         struct clk_lookup *p, *cl = NULL;
  38         int match, best = 0;
  39
  40         list_for_each_entry(p, &clocks, node) {
  41                 match = 0;
  42                 if (p->dev_id) {
  43                         if (!dev_id || strcmp(p->dev_id, dev_id))
  44                                 continue;
  45                         match += 2;
  46                 }
  47                 if (p->con_id) {
  48                         if (!con_id || strcmp(p->con_id, con_id))
  49                                 continue;
  50                         match += 1;
  51                 }
  52
  53                 if (match > best) {
  54                         cl = p;
  55                         if (match != 3)
  56                                 best = match;
  57                         else
  58                                 break;
  59                 }
  60         }
  61         return cl;
  62 }
  63
  64 struct clk *clk_get_sys(const char *dev_id, const char *con_id)
  65 {
  66         struct clk_lookup *cl;
  67
  68         mutex_lock(&clocks_mutex);
  69         cl = clk_find(dev_id, con_id);
  70         if (cl && !__clk_get(cl->clk))
  71                 cl = NULL;
  72         mutex_unlock(&clocks_mutex);
  73
  74         return cl ? cl->clk : ERR_PTR(-ENOENT);
  75 }
  76 EXPORT_SYMBOL(clk_get_sys);
  77
  78 struct clk *clk_get(struct device *dev, const char *con_id)
  79 {
  80         const char *dev_id = dev ? dev_name(dev) : NULL;
  81
  82         return clk_get_sys(dev_id, con_id);
  83 }
  84 EXPORT_SYMBOL(clk_get);
  85
  86 void clk_put(struct clk *clk)
  87 {
  88         __clk_put(clk);
  89 }
  90 EXPORT_SYMBOL(clk_put);
  91
  92 void clkdev_add(struct clk_lookup *cl)
  93 {
  94         mutex_lock(&clocks_mutex);
  95         list_add_tail(&cl->node, &clocks);
  96         mutex_unlock(&clocks_mutex);
  97 }
  98 EXPORT_SYMBOL(clkdev_add);
  99
 100 void __init clkdev_add_table(struct clk_lookup *cl, size_t num)
 101 {
 102         mutex_lock(&clocks_mutex);
 103         while (num--) {
 104                 list_add_tail(&cl->node, &clocks);
 105                 cl++;
 106         }
 107         mutex_unlock(&clocks_mutex);
 108 }
 109
 110 #define MAX_DEV_ID      20
 111 #define MAX_CON_ID      16
 112
 113 struct clk_lookup_alloc {
 114         struct clk_lookup cl;
 115         char    dev_id[MAX_DEV_ID];
 116         char    con_id[MAX_CON_ID];
 117 };
 118
 119 struct clk_lookup * __init_refok
 120 clkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt, ...)
 121 {
 122         struct clk_lookup_alloc *cla;
 123
 124         cla = __clkdev_alloc(sizeof(*cla));
 125         if (!cla)
 126                 return NULL;
 127
 128         cla->cl.clk = clk;
 129         if (con_id) {
 130                 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 131                 cla->cl.con_id = cla->con_id;
 132         }
 133
 134         if (dev_fmt) {
 135                 va_list ap;
 136
 137                 va_start(ap, dev_fmt);
 138                 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 139                 cla->cl.dev_id = cla->dev_id;
 140                 va_end(ap);
 141         }
 142
 143         return &cla->cl;
 144 }
 145 EXPORT_SYMBOL(clkdev_alloc);
 146
 147 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 148         struct device *dev)
 149 {
 150         struct clk *r = clk_get(dev, id);
 151         struct clk_lookup *l;
 152
 153         if (IS_ERR(r))
 154                 return PTR_ERR(r);
 155
 156         l = clkdev_alloc(r, alias, alias_dev_name);
 157         clk_put(r);
 158         if (!l)
 159                 return -ENODEV;
 160         clkdev_add(l);
 161         return 0;
 162 }
 163 EXPORT_SYMBOL(clk_add_alias);
 164
 165 /*
 166  * clkdev_drop - remove a clock dynamically allocated
 167  */
 168 void clkdev_drop(struct clk_lookup *cl)
 169 {
 170         mutex_lock(&clocks_mutex);
 171         list_del(&cl->node);
 172         mutex_unlock(&clocks_mutex);
 173         kfree(cl);
 174 }
 175 EXPORT_SYMBOL(clkdev_drop);