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 #include <linux/slab.h>
  22
  23 #include <asm/clkdev.h>
  24 #include <mach/clkdev.h>
  25
  26 static LIST_HEAD(clocks);
  27 static DEFINE_MUTEX(clocks_mutex);
  28
  29 /*
  30  * Find the correct struct clk for the device and connection ID.
  31  * We do slightly fuzzy matching here:
  32  *  An entry with a NULL ID is assumed to be a wildcard.
  33  *  If an entry has a device ID, it must match
  34  *  If an entry has a connection ID, it must match
  35  * Then we take the most specific entry - with the following
  36  * order of precedence: dev+con > dev only > con only.
  37  */
  38 static struct clk *clk_find(const char *dev_id, const char *con_id)
  39 {
  40         struct clk_lookup *p;
  41         struct clk *clk = NULL;
  42         int match, best = 0;
  43
  44         list_for_each_entry(p, &clocks, node) {
  45                 match = 0;
  46                 if (p->dev_id) {
  47                         if (!dev_id || strcmp(p->dev_id, dev_id))
  48                                 continue;
  49                         match += 2;
  50                 }
  51                 if (p->con_id) {
  52                         if (!con_id || strcmp(p->con_id, con_id))
  53                                 continue;
  54                         match += 1;
  55                 }
  56
  57                 if (match > best) {
  58                         clk = p->clk;
  59                         if (match != 3)
  60                                 best = match;
  61                         else
  62                                 break;
  63                 }
  64         }
  65         return clk;
  66 }
  67
  68 struct clk *clk_get_sys(const char *dev_id, const char *con_id)
  69 {
  70         struct clk *clk;
  71
  72         mutex_lock(&clocks_mutex);
  73         clk = clk_find(dev_id, con_id);
  74         if (clk && !__clk_get(clk))
  75                 clk = NULL;
  76         mutex_unlock(&clocks_mutex);
  77
  78         return clk ? clk : ERR_PTR(-ENOENT);
  79 }
  80 EXPORT_SYMBOL(clk_get_sys);
  81
  82 struct clk *clk_get(struct device *dev, const char *con_id)
  83 {
  84         const char *dev_id = dev ? dev_name(dev) : NULL;
  85
  86         return clk_get_sys(dev_id, con_id);
  87 }
  88 EXPORT_SYMBOL(clk_get);
  89
  90 void clk_put(struct clk *clk)
  91 {
  92         __clk_put(clk);
  93 }
  94 EXPORT_SYMBOL(clk_put);
  95
  96 void clkdev_add(struct clk_lookup *cl)
  97 {
  98         mutex_lock(&clocks_mutex);
  99         list_add_tail(&cl->node, &clocks);
 100         mutex_unlock(&clocks_mutex);
 101 }
 102 EXPORT_SYMBOL(clkdev_add);
 103
 104 void __init clkdev_add_table(struct clk_lookup *cl, size_t num)
 105 {
 106         mutex_lock(&clocks_mutex);
 107         while (num--) {
 108                 list_add_tail(&cl->node, &clocks);
 109                 cl++;
 110         }
 111         mutex_unlock(&clocks_mutex);
 112 }
 113
 114 #define MAX_DEV_ID      20
 115 #define MAX_CON_ID      16
 116
 117 struct clk_lookup_alloc {
 118         struct clk_lookup cl;
 119         char    dev_id[MAX_DEV_ID];
 120         char    con_id[MAX_CON_ID];
 121 };
 122
 123 struct clk_lookup *clkdev_alloc(struct clk *clk, const char *con_id,
 124         const char *dev_fmt, ...)
 125 {
 126         struct clk_lookup_alloc *cla;
 127
 128         cla = kzalloc(sizeof(*cla), GFP_KERNEL);
 129         if (!cla)
 130                 return NULL;
 131
 132         cla->cl.clk = clk;
 133         if (con_id) {
 134                 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 135                 cla->cl.con_id = cla->con_id;
 136         }
 137
 138         if (dev_fmt) {
 139                 va_list ap;
 140
 141                 va_start(ap, dev_fmt);
 142                 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 143                 cla->cl.dev_id = cla->dev_id;
 144                 va_end(ap);
 145         }
 146
 147         return &cla->cl;
 148 }
 149 EXPORT_SYMBOL(clkdev_alloc);
 150
 151 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 152         struct device *dev)
 153 {
 154         struct clk *r = clk_get(dev, id);
 155         struct clk_lookup *l;
 156
 157         if (IS_ERR(r))
 158                 return PTR_ERR(r);
 159
 160         l = clkdev_alloc(r, alias, alias_dev_name);
 161         clk_put(r);
 162         if (!l)
 163                 return -ENODEV;
 164         clkdev_add(l);
 165         return 0;
 166 }
 167 EXPORT_SYMBOL(clk_add_alias);
 168
 169 /*
 170  * clkdev_drop - remove a clock dynamically allocated
 171  */
 172 void clkdev_drop(struct clk_lookup *cl)
 173 {
 174         mutex_lock(&clocks_mutex);
 175         list_del(&cl->node);
 176         mutex_unlock(&clocks_mutex);
 177         kfree(cl);
 178 }
 179 EXPORT_SYMBOL(clkdev_drop);