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