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 #include <linux/of.h>
  23
  24 #include "clk.h"
  25
  26 static LIST_HEAD(clocks);
  27 static DEFINE_MUTEX(clocks_mutex);
  28
  29 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
  30
  31 /**
  32  * of_clk_get_by_clkspec() - Lookup a clock form a clock provider
  33  * @clkspec: pointer to a clock specifier data structure
  34  *
  35  * This function looks up a struct clk from the registered list of clock
  36  * providers, an input is a clock specifier data structure as returned
  37  * from the of_parse_phandle_with_args() function call.
  38  */
  39 struct clk *of_clk_get_by_clkspec(struct of_phandle_args *clkspec)
  40 {
  41         struct clk *clk;
  42
  43         if (!clkspec)
  44                 return ERR_PTR(-EINVAL);
  45
  46         of_clk_lock();
  47         clk = __of_clk_get_from_provider(clkspec);
  48
  49         if (!IS_ERR(clk) && !__clk_get(clk))
  50                 clk = ERR_PTR(-ENOENT);
  51
  52         of_clk_unlock();
  53         return clk;
  54 }
  55
  56 struct clk *of_clk_get(struct device_node *np, int index)
  57 {
  58         struct of_phandle_args clkspec;
  59         struct clk *clk;
  60         int rc;
  61
  62         if (index < 0)
  63                 return ERR_PTR(-EINVAL);
  64
  65         rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index,
  66                                         &clkspec);
  67         if (rc)
  68                 return ERR_PTR(rc);
  69
  70         clk = of_clk_get_by_clkspec(&clkspec);
  71         of_node_put(clkspec.np);
  72         return clk;
  73 }
  74 EXPORT_SYMBOL(of_clk_get);
  75
  76 /**
  77  * of_clk_get_by_name() - Parse and lookup a clock referenced by a device node
  78  * @np: pointer to clock consumer node
  79  * @name: name of consumer's clock input, or NULL for the first clock reference
  80  *
  81  * This function parses the clocks and clock-names properties,
  82  * and uses them to look up the struct clk from the registered list of clock
  83  * providers.
  84  */
  85 struct clk *of_clk_get_by_name(struct device_node *np, const char *name)
  86 {
  87         struct clk *clk = ERR_PTR(-ENOENT);
  88
  89         /* Walk up the tree of devices looking for a clock that matches */
  90         while (np) {
  91                 int index = 0;
  92
  93                 /*
  94                  * For named clocks, first look up the name in the
  95                  * "clock-names" property.  If it cannot be found, then
  96                  * index will be an error code, and of_clk_get() will fail.
  97                  */
  98                 if (name)
  99                         index = of_property_match_string(np, "clock-names", name);
 100                 clk = of_clk_get(np, index);
 101                 if (!IS_ERR(clk))
 102                         break;
 103                 else if (name && index >= 0) {
 104                         if (PTR_ERR(clk) != -EPROBE_DEFER)
 105                                 pr_err("ERROR: could not get clock %s:%s(%i)\n",
 106                                         np->full_name, name ? name : "", index);
 107                         return clk;
 108                 }
 109
 110                 /*
 111                  * No matching clock found on this node.  If the parent node
 112                  * has a "clock-ranges" property, then we can try one of its
 113                  * clocks.
 114                  */
 115                 np = np->parent;
 116                 if (np && !of_get_property(np, "clock-ranges", NULL))
 117                         break;
 118         }
 119
 120         return clk;
 121 }
 122 EXPORT_SYMBOL(of_clk_get_by_name);
 123 #endif
 124
 125 /*
 126  * Find the correct struct clk for the device and connection ID.
 127  * We do slightly fuzzy matching here:
 128  *  An entry with a NULL ID is assumed to be a wildcard.
 129  *  If an entry has a device ID, it must match
 130  *  If an entry has a connection ID, it must match
 131  * Then we take the most specific entry - with the following
 132  * order of precedence: dev+con > dev only > con only.
 133  */
 134 static struct clk_lookup *clk_find(const char *dev_id, const char *con_id)
 135 {
 136         struct clk_lookup *p, *cl = NULL;
 137         int match, best_found = 0, best_possible = 0;
 138
 139         if (dev_id)
 140                 best_possible += 2;
 141         if (con_id)
 142                 best_possible += 1;
 143
 144         list_for_each_entry(p, &clocks, node) {
 145                 match = 0;
 146                 if (p->dev_id) {
 147                         if (!dev_id || strcmp(p->dev_id, dev_id))
 148                                 continue;
 149                         match += 2;
 150                 }
 151                 if (p->con_id) {
 152                         if (!con_id || strcmp(p->con_id, con_id))
 153                                 continue;
 154                         match += 1;
 155                 }
 156
 157                 if (match > best_found) {
 158                         cl = p;
 159                         if (match != best_possible)
 160                                 best_found = match;
 161                         else
 162                                 break;
 163                 }
 164         }
 165         return cl;
 166 }
 167
 168 struct clk *clk_get_sys(const char *dev_id, const char *con_id)
 169 {
 170         struct clk_lookup *cl;
 171
 172         mutex_lock(&clocks_mutex);
 173         cl = clk_find(dev_id, con_id);
 174         if (cl && !__clk_get(cl->clk))
 175                 cl = NULL;
 176         mutex_unlock(&clocks_mutex);
 177
 178         return cl ? cl->clk : ERR_PTR(-ENOENT);
 179 }
 180 EXPORT_SYMBOL(clk_get_sys);
 181
 182 struct clk *clk_get(struct device *dev, const char *con_id)
 183 {
 184         const char *dev_id = dev ? dev_name(dev) : NULL;
 185         struct clk *clk;
 186
 187         if (dev) {
 188                 clk = of_clk_get_by_name(dev->of_node, con_id);
 189                 if (!IS_ERR(clk))
 190                         return clk;
 191                 if (PTR_ERR(clk) == -EPROBE_DEFER)
 192                         return clk;
 193         }
 194
 195         return clk_get_sys(dev_id, con_id);
 196 }
 197 EXPORT_SYMBOL(clk_get);
 198
 199 void clk_put(struct clk *clk)
 200 {
 201         __clk_put(clk);
 202 }
 203 EXPORT_SYMBOL(clk_put);
 204
 205 void clkdev_add(struct clk_lookup *cl)
 206 {
 207         mutex_lock(&clocks_mutex);
 208         list_add_tail(&cl->node, &clocks);
 209         mutex_unlock(&clocks_mutex);
 210 }
 211 EXPORT_SYMBOL(clkdev_add);
 212
 213 void __init clkdev_add_table(struct clk_lookup *cl, size_t num)
 214 {
 215         mutex_lock(&clocks_mutex);
 216         while (num--) {
 217                 list_add_tail(&cl->node, &clocks);
 218                 cl++;
 219         }
 220         mutex_unlock(&clocks_mutex);
 221 }
 222
 223 #define MAX_DEV_ID      20
 224 #define MAX_CON_ID      16
 225
 226 struct clk_lookup_alloc {
 227         struct clk_lookup cl;
 228         char    dev_id[MAX_DEV_ID];
 229         char    con_id[MAX_CON_ID];
 230 };
 231
 232 static struct clk_lookup * __init_refok
 233 vclkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt,
 234         va_list ap)
 235 {
 236         struct clk_lookup_alloc *cla;
 237
 238         cla = __clkdev_alloc(sizeof(*cla));
 239         if (!cla)
 240                 return NULL;
 241
 242         cla->cl.clk = clk;
 243         if (con_id) {
 244                 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 245                 cla->cl.con_id = cla->con_id;
 246         }
 247
 248         if (dev_fmt) {
 249                 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 250                 cla->cl.dev_id = cla->dev_id;
 251         }
 252
 253         return &cla->cl;
 254 }
 255
 256 struct clk_lookup * __init_refok
 257 clkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt, ...)
 258 {
 259         struct clk_lookup *cl;
 260         va_list ap;
 261
 262         va_start(ap, dev_fmt);
 263         cl = vclkdev_alloc(clk, con_id, dev_fmt, ap);
 264         va_end(ap);
 265
 266         return cl;
 267 }
 268 EXPORT_SYMBOL(clkdev_alloc);
 269
 270 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 271         struct device *dev)
 272 {
 273         struct clk *r = clk_get(dev, id);
 274         struct clk_lookup *l;
 275
 276         if (IS_ERR(r))
 277                 return PTR_ERR(r);
 278
 279         l = clkdev_alloc(r, alias, alias_dev_name);
 280         clk_put(r);
 281         if (!l)
 282                 return -ENODEV;
 283         clkdev_add(l);
 284         return 0;
 285 }
 286 EXPORT_SYMBOL(clk_add_alias);
 287
 288 /*
 289  * clkdev_drop - remove a clock dynamically allocated
 290  */
 291 void clkdev_drop(struct clk_lookup *cl)
 292 {
 293         mutex_lock(&clocks_mutex);
 294         list_del(&cl->node);
 295         mutex_unlock(&clocks_mutex);
 296         kfree(cl);
 297 }
 298 EXPORT_SYMBOL(clkdev_drop);
 299
 300 /**
 301  * clk_register_clkdev - register one clock lookup for a struct clk
 302  * @clk: struct clk to associate with all clk_lookups
 303  * @con_id: connection ID string on device
 304  * @dev_id: format string describing device name
 305  *
 306  * con_id or dev_id may be NULL as a wildcard, just as in the rest of
 307  * clkdev.
 308  *
 309  * To make things easier for mass registration, we detect error clks
 310  * from a previous clk_register() call, and return the error code for
 311  * those.  This is to permit this function to be called immediately
 312  * after clk_register().
 313  */
 314 int clk_register_clkdev(struct clk *clk, const char *con_id,
 315         const char *dev_fmt, ...)
 316 {
 317         struct clk_lookup *cl;
 318         va_list ap;
 319
 320         if (IS_ERR(clk))
 321                 return PTR_ERR(clk);
 322
 323         va_start(ap, dev_fmt);
 324         cl = vclkdev_alloc(clk, con_id, dev_fmt, ap);
 325         va_end(ap);
 326
 327         if (!cl)
 328                 return -ENOMEM;
 329
 330         clkdev_add(cl);
 331
 332         return 0;
 333 }
 334
 335 /**
 336  * clk_register_clkdevs - register a set of clk_lookup for a struct clk
 337  * @clk: struct clk to associate with all clk_lookups
 338  * @cl: array of clk_lookup structures with con_id and dev_id pre-initialized
 339  * @num: number of clk_lookup structures to register
 340  *
 341  * To make things easier for mass registration, we detect error clks
 342  * from a previous clk_register() call, and return the error code for
 343  * those.  This is to permit this function to be called immediately
 344  * after clk_register().
 345  */
 346 int clk_register_clkdevs(struct clk *clk, struct clk_lookup *cl, size_t num)
 347 {
 348         unsigned i;
 349
 350         if (IS_ERR(clk))
 351                 return PTR_ERR(clk);
 352
 353         for (i = 0; i < num; i++, cl++) {
 354                 cl->clk = clk;
 355                 clkdev_add(cl);
 356         }
 357
 358         return 0;
 359 }
 360 EXPORT_SYMBOL(clk_register_clkdevs);