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_found = 0, best_possible = 0;
  39
  40         if (dev_id)
  41                 best_possible += 2;
  42         if (con_id)
  43                 best_possible += 1;
  44
  45         list_for_each_entry(p, &clocks, node) {
  46                 match = 0;
  47                 if (p->dev_id) {
  48                         if (!dev_id || strcmp(p->dev_id, dev_id))
  49                                 continue;
  50                         match += 2;
  51                 }
  52                 if (p->con_id) {
  53                         if (!con_id || strcmp(p->con_id, con_id))
  54                                 continue;
  55                         match += 1;
  56                 }
  57
  58                 if (match > best_found) {
  59                         cl = p;
  60                         if (match != best_possible)
  61                                 best_found = match;
  62                         else
  63                                 break;
  64                 }
  65         }
  66         return cl;
  67 }
  68
  69 struct clk *clk_get_sys(const char *dev_id, const char *con_id)
  70 {
  71         struct clk_lookup *cl;
  72
  73         mutex_lock(&clocks_mutex);
  74         cl = clk_find(dev_id, con_id);
  75         if (cl && !__clk_get(cl->clk))
  76                 cl = NULL;
  77         mutex_unlock(&clocks_mutex);
  78
  79         return cl ? cl->clk : ERR_PTR(-ENOENT);
  80 }
  81 EXPORT_SYMBOL(clk_get_sys);
  82
  83 struct clk *clk_get(struct device *dev, const char *con_id)
  84 {
  85         const char *dev_id = dev ? dev_name(dev) : NULL;
  86
  87         return clk_get_sys(dev_id, con_id);
  88 }
  89 EXPORT_SYMBOL(clk_get);
  90
  91 void clk_put(struct clk *clk)
  92 {
  93         __clk_put(clk);
  94 }
  95 EXPORT_SYMBOL(clk_put);
  96
  97 static void devm_clk_release(struct device *dev, void *res)
  98 {
  99         clk_put(*(struct clk **)res);
 100 }
 101
 102 struct clk *devm_clk_get(struct device *dev, const char *id)
 103 {
 104         struct clk **ptr, *clk;
 105
 106         ptr = devres_alloc(devm_clk_release, sizeof(*ptr), GFP_KERNEL);
 107         if (!ptr)
 108                 return ERR_PTR(-ENOMEM);
 109
 110         clk = clk_get(dev, id);
 111         if (!IS_ERR(clk)) {
 112                 *ptr = clk;
 113                 devres_add(dev, ptr);
 114         } else {
 115                 devres_free(ptr);
 116         }
 117
 118         return clk;
 119 }
 120 EXPORT_SYMBOL(devm_clk_get);
 121
 122 static int devm_clk_match(struct device *dev, void *res, void *data)
 123 {
 124         struct clk **c = res;
 125         if (!c || !*c) {
 126                 WARN_ON(!c || !*c);
 127                 return 0;
 128         }
 129         return *c == data;
 130 }
 131
 132 void devm_clk_put(struct device *dev, struct clk *clk)
 133 {
 134         int ret;
 135
 136         ret = devres_destroy(dev, devm_clk_release, devm_clk_match, clk);
 137
 138         WARN_ON(ret);
 139 }
 140 EXPORT_SYMBOL(devm_clk_put);
 141
 142 void clkdev_add(struct clk_lookup *cl)
 143 {
 144         mutex_lock(&clocks_mutex);
 145         list_add_tail(&cl->node, &clocks);
 146         mutex_unlock(&clocks_mutex);
 147 }
 148 EXPORT_SYMBOL(clkdev_add);
 149
 150 void __init clkdev_add_table(struct clk_lookup *cl, size_t num)
 151 {
 152         mutex_lock(&clocks_mutex);
 153         while (num--) {
 154                 list_add_tail(&cl->node, &clocks);
 155                 cl++;
 156         }
 157         mutex_unlock(&clocks_mutex);
 158 }
 159
 160 #define MAX_DEV_ID      20
 161 #define MAX_CON_ID      16
 162
 163 struct clk_lookup_alloc {
 164         struct clk_lookup cl;
 165         char    dev_id[MAX_DEV_ID];
 166         char    con_id[MAX_CON_ID];
 167 };
 168
 169 static struct clk_lookup * __init_refok
 170 vclkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt,
 171         va_list ap)
 172 {
 173         struct clk_lookup_alloc *cla;
 174
 175         cla = __clkdev_alloc(sizeof(*cla));
 176         if (!cla)
 177                 return NULL;
 178
 179         cla->cl.clk = clk;
 180         if (con_id) {
 181                 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 182                 cla->cl.con_id = cla->con_id;
 183         }
 184
 185         if (dev_fmt) {
 186                 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 187                 cla->cl.dev_id = cla->dev_id;
 188         }
 189
 190         return &cla->cl;
 191 }
 192
 193 struct clk_lookup * __init_refok
 194 clkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt, ...)
 195 {
 196         struct clk_lookup *cl;
 197         va_list ap;
 198
 199         va_start(ap, dev_fmt);
 200         cl = vclkdev_alloc(clk, con_id, dev_fmt, ap);
 201         va_end(ap);
 202
 203         return cl;
 204 }
 205 EXPORT_SYMBOL(clkdev_alloc);
 206
 207 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 208         struct device *dev)
 209 {
 210         struct clk *r = clk_get(dev, id);
 211         struct clk_lookup *l;
 212
 213         if (IS_ERR(r))
 214                 return PTR_ERR(r);
 215
 216         l = clkdev_alloc(r, alias, alias_dev_name);
 217         clk_put(r);
 218         if (!l)
 219                 return -ENODEV;
 220         clkdev_add(l);
 221         return 0;
 222 }
 223 EXPORT_SYMBOL(clk_add_alias);
 224
 225 /*
 226  * clkdev_drop - remove a clock dynamically allocated
 227  */
 228 void clkdev_drop(struct clk_lookup *cl)
 229 {
 230         mutex_lock(&clocks_mutex);
 231         list_del(&cl->node);
 232         mutex_unlock(&clocks_mutex);
 233         kfree(cl);
 234 }
 235 EXPORT_SYMBOL(clkdev_drop);
 236
 237 /**
 238  * clk_register_clkdev - register one clock lookup for a struct clk
 239  * @clk: struct clk to associate with all clk_lookups
 240  * @con_id: connection ID string on device
 241  * @dev_id: format string describing device name
 242  *
 243  * con_id or dev_id may be NULL as a wildcard, just as in the rest of
 244  * clkdev.
 245  *
 246  * To make things easier for mass registration, we detect error clks
 247  * from a previous clk_register() call, and return the error code for
 248  * those.  This is to permit this function to be called immediately
 249  * after clk_register().
 250  */
 251 int clk_register_clkdev(struct clk *clk, const char *con_id,
 252         const char *dev_fmt, ...)
 253 {
 254         struct clk_lookup *cl;
 255         va_list ap;
 256
 257         if (IS_ERR(clk))
 258                 return PTR_ERR(clk);
 259
 260         va_start(ap, dev_fmt);
 261         cl = vclkdev_alloc(clk, con_id, dev_fmt, ap);
 262         va_end(ap);
 263
 264         if (!cl)
 265                 return -ENOMEM;
 266
 267         clkdev_add(cl);
 268
 269         return 0;
 270 }
 271
 272 /**
 273  * clk_register_clkdevs - register a set of clk_lookup for a struct clk
 274  * @clk: struct clk to associate with all clk_lookups
 275  * @cl: array of clk_lookup structures with con_id and dev_id pre-initialized
 276  * @num: number of clk_lookup structures to register
 277  *
 278  * To make things easier for mass registration, we detect error clks
 279  * from a previous clk_register() call, and return the error code for
 280  * those.  This is to permit this function to be called immediately
 281  * after clk_register().
 282  */
 283 int clk_register_clkdevs(struct clk *clk, struct clk_lookup *cl, size_t num)
 284 {
 285         unsigned i;
 286
 287         if (IS_ERR(clk))
 288                 return PTR_ERR(clk);
 289
 290         for (i = 0; i < num; i++, cl++) {
 291                 cl->clk = clk;
 292                 clkdev_add(cl);
 293         }
 294
 295         return 0;
 296 }
 297 EXPORT_SYMBOL(clk_register_clkdevs);