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 *clk_find(const char *dev_id, const char *con_id)
  36 {
  37         struct clk_lookup *p;
  38         struct clk *clk = NULL;
  39         int match, best = 0;
  40
  41         list_for_each_entry(p, &clocks, node) {
  42                 match = 0;
  43                 if (p->dev_id) {
  44                         if (!dev_id || strcmp(p->dev_id, dev_id))
  45                                 continue;
  46                         match += 2;
  47                 }
  48                 if (p->con_id) {
  49                         if (!con_id || strcmp(p->con_id, con_id))
  50                                 continue;
  51                         match += 1;
  52                 }
  53
  54                 if (match > best) {
  55                         clk = p->clk;
  56                         if (match != 3)
  57                                 best = match;
  58                         else
  59                                 break;
  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 void __init clkdev_add_table(struct clk_lookup *cl, size_t num)
 102 {
 103         mutex_lock(&clocks_mutex);
 104         while (num--) {
 105                 list_add_tail(&cl->node, &clocks);
 106                 cl++;
 107         }
 108         mutex_unlock(&clocks_mutex);
 109 }
 110
 111 #define MAX_DEV_ID      20
 112 #define MAX_CON_ID      16
 113
 114 struct clk_lookup_alloc {
 115         struct clk_lookup cl;
 116         char    dev_id[MAX_DEV_ID];
 117         char    con_id[MAX_CON_ID];
 118 };
 119
 120 struct clk_lookup * __init_refok
 121 clkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt, ...)
 122 {
 123         struct clk_lookup_alloc *cla;
 124
 125         cla = __clkdev_alloc(sizeof(*cla));
 126         if (!cla)
 127                 return NULL;
 128
 129         cla->cl.clk = clk;
 130         if (con_id) {
 131                 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 132                 cla->cl.con_id = cla->con_id;
 133         }
 134
 135         if (dev_fmt) {
 136                 va_list ap;
 137
 138                 va_start(ap, dev_fmt);
 139                 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 140                 cla->cl.dev_id = cla->dev_id;
 141                 va_end(ap);
 142         }
 143
 144         return &cla->cl;
 145 }
 146 EXPORT_SYMBOL(clkdev_alloc);
 147
 148 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 149         struct device *dev)
 150 {
 151         struct clk *r = clk_get(dev, id);
 152         struct clk_lookup *l;
 153
 154         if (IS_ERR(r))
 155                 return PTR_ERR(r);
 156
 157         l = clkdev_alloc(r, alias, alias_dev_name);
 158         clk_put(r);
 159         if (!l)
 160                 return -ENODEV;
 161         clkdev_add(l);
 162         return 0;
 163 }
 164 EXPORT_SYMBOL(clk_add_alias);
 165
 166 /*
 167  * clkdev_drop - remove a clock dynamically allocated
 168  */
 169 void clkdev_drop(struct clk_lookup *cl)
 170 {
 171         mutex_lock(&clocks_mutex);
 172         list_del(&cl->node);
 173         mutex_unlock(&clocks_mutex);
 174         kfree(cl);
 175 }
 176 EXPORT_SYMBOL(clkdev_drop);