release/src-rt-6.x.4708/linux/linux-2.6.36/arch/sh/kernel/clkdev.c

   1 /*
   2  * arch/sh/kernel/clkdev.c
   3  *
   4  * Cloned from arch/arm/common/clkdev.c:
   5  *
   6  *  Copyright (C) 2008 Russell King.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * Helper for the clk API to assist looking up a struct clk.
  13  */
  14 #include <linux/module.h>
  15 #include <linux/kernel.h>
  16 #include <linux/device.h>
  17 #include <linux/list.h>
  18 #include <linux/errno.h>
  19 #include <linux/err.h>
  20 #include <linux/string.h>
  21 #include <linux/mutex.h>
  22 #include <linux/clk.h>
  23 #include <linux/slab.h>
  24 #include <linux/bootmem.h>
  25 #include <linux/mm.h>
  26 #include <asm/clock.h>
  27 #include <asm/clkdev.h>
  28
  29 static LIST_HEAD(clocks);
  30 static DEFINE_MUTEX(clocks_mutex);
  31
  32 /*
  33  * Find the correct struct clk for the device and connection ID.
  34  * We do slightly fuzzy matching here:
  35  *  An entry with a NULL ID is assumed to be a wildcard.
  36  *  If an entry has a device ID, it must match
  37  *  If an entry has a connection ID, it must match
  38  * Then we take the most specific entry - with the following
  39  * order of precedence: dev+con > dev only > con only.
  40  */
  41 static struct clk *clk_find(const char *dev_id, const char *con_id)
  42 {
  43         struct clk_lookup *p;
  44         struct clk *clk = NULL;
  45         int match, best = 0;
  46
  47         list_for_each_entry(p, &clocks, node) {
  48                 match = 0;
  49                 if (p->dev_id) {
  50                         if (!dev_id || strcmp(p->dev_id, dev_id))
  51                                 continue;
  52                         match += 2;
  53                 }
  54                 if (p->con_id) {
  55                         if (!con_id || strcmp(p->con_id, con_id))
  56                                 continue;
  57                         match += 1;
  58                 }
  59                 if (match == 0)
  60                         continue;
  61
  62                 if (match > best) {
  63                         clk = p->clk;
  64                         best = match;
  65                 }
  66         }
  67         return clk;
  68 }
  69
  70 struct clk *clk_get_sys(const char *dev_id, const char *con_id)
  71 {
  72         struct clk *clk;
  73
  74         mutex_lock(&clocks_mutex);
  75         clk = clk_find(dev_id, con_id);
  76         mutex_unlock(&clocks_mutex);
  77
  78         return clk ? clk : ERR_PTR(-ENOENT);
  79 }
  80 EXPORT_SYMBOL(clk_get_sys);
  81
  82 void clkdev_add(struct clk_lookup *cl)
  83 {
  84         mutex_lock(&clocks_mutex);
  85         list_add_tail(&cl->node, &clocks);
  86         mutex_unlock(&clocks_mutex);
  87 }
  88 EXPORT_SYMBOL(clkdev_add);
  89
  90 void __init clkdev_add_table(struct clk_lookup *cl, size_t num)
  91 {
  92         mutex_lock(&clocks_mutex);
  93         while (num--) {
  94                 list_add_tail(&cl->node, &clocks);
  95                 cl++;
  96         }
  97         mutex_unlock(&clocks_mutex);
  98 }
  99
 100 #define MAX_DEV_ID      20
 101 #define MAX_CON_ID      16
 102
 103 struct clk_lookup_alloc {
 104         struct clk_lookup cl;
 105         char    dev_id[MAX_DEV_ID];
 106         char    con_id[MAX_CON_ID];
 107 };
 108
 109 struct clk_lookup * __init_refok
 110 clkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt, ...)
 111 {
 112         struct clk_lookup_alloc *cla;
 113
 114         if (!slab_is_available())
 115                 cla = alloc_bootmem_low_pages(sizeof(*cla));
 116         else
 117                 cla = kzalloc(sizeof(*cla), GFP_KERNEL);
 118
 119         if (!cla)
 120                 return NULL;
 121
 122         cla->cl.clk = clk;
 123         if (con_id) {
 124                 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 125                 cla->cl.con_id = cla->con_id;
 126         }
 127
 128         if (dev_fmt) {
 129                 va_list ap;
 130
 131                 va_start(ap, dev_fmt);
 132                 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 133                 cla->cl.dev_id = cla->dev_id;
 134                 va_end(ap);
 135         }
 136
 137         return &cla->cl;
 138 }
 139 EXPORT_SYMBOL(clkdev_alloc);
 140
 141 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 142         struct device *dev)
 143 {
 144         struct clk *r = clk_get(dev, id);
 145         struct clk_lookup *l;
 146
 147         if (IS_ERR(r))
 148                 return PTR_ERR(r);
 149
 150         l = clkdev_alloc(r, alias, alias_dev_name);
 151         clk_put(r);
 152         if (!l)
 153                 return -ENODEV;
 154         clkdev_add(l);
 155         return 0;
 156 }
 157 EXPORT_SYMBOL(clk_add_alias);
 158
 159 /*
 160  * clkdev_drop - remove a clock dynamically allocated
 161  */
 162 void clkdev_drop(struct clk_lookup *cl)
 163 {
 164         mutex_lock(&clocks_mutex);
 165         list_del(&cl->node);
 166         mutex_unlock(&clocks_mutex);
 167         kfree(cl);
 168 }
 169 EXPORT_SYMBOL(clkdev_drop);