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/clk-provider.h>
  23 #include <linux/of.h>
  24
  25 #include "clk.h"
  26
  27 static LIST_HEAD(clocks);
  28 static DEFINE_MUTEX(clocks_mutex);
  29
  30 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
  31 static struct clk *__of_clk_get(struct device_node *np, int index,
  32                                const char *dev_id, const char *con_id)
  33 {
  34         struct of_phandle_args clkspec;
  35         struct clk *clk;
  36         int rc;
  37
  38         if (index < 0)
  39                 return ERR_PTR(-EINVAL);
  40
  41         rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index,
  42                                         &clkspec);
  43         if (rc)
  44                 return ERR_PTR(rc);
  45
  46         clk = __of_clk_get_from_provider(&clkspec, dev_id, con_id);
  47         of_node_put(clkspec.np);
  48
  49         return clk;
  50 }
  51
  52 struct clk *of_clk_get(struct device_node *np, int index)
  53 {
  54         return __of_clk_get(np, index, np->full_name, NULL);
  55 }
  56 EXPORT_SYMBOL(of_clk_get);
  57
  58 static struct clk *__of_clk_get_by_name(struct device_node *np,
  59                                         const char *dev_id,
  60                                         const char *name)
  61 {
  62         struct clk *clk = ERR_PTR(-ENOENT);
  63
  64         /* Walk up the tree of devices looking for a clock that matches */
  65         while (np) {
  66                 int index = 0;
  67
  68                 /*
  69                  * For named clocks, first look up the name in the
  70                  * "clock-names" property.  If it cannot be found, then
  71                  * index will be an error code, and of_clk_get() will fail.
  72                  */
  73                 if (name)
  74                         index = of_property_match_string(np, "clock-names", name);
  75                 clk = __of_clk_get(np, index, dev_id, name);
  76                 if (!IS_ERR(clk)) {
  77                         break;
  78                 } else if (name && index >= 0) {
  79                         if (PTR_ERR(clk) != -EPROBE_DEFER)
  80                                 pr_err("ERROR: could not get clock %s:%s(%i)\n",
  81                                         np->full_name, name ? name : "", index);
  82                         return clk;
  83                 }
  84
  85                 /*
  86                  * No matching clock found on this node.  If the parent node
  87                  * has a "clock-ranges" property, then we can try one of its
  88                  * clocks.
  89                  */
  90                 np = np->parent;
  91                 if (np && !of_get_property(np, "clock-ranges", NULL))
  92                         break;
  93         }
  94
  95         return clk;
  96 }
  97
  98 /**
  99  * of_clk_get_by_name() - Parse and lookup a clock referenced by a device node
 100  * @np: pointer to clock consumer node
 101  * @name: name of consumer's clock input, or NULL for the first clock reference
 102  *
 103  * This function parses the clocks and clock-names properties,
 104  * and uses them to look up the struct clk from the registered list of clock
 105  * providers.
 106  */
 107 struct clk *of_clk_get_by_name(struct device_node *np, const char *name)
 108 {
 109         if (!np)
 110                 return ERR_PTR(-ENOENT);
 111
 112         return __of_clk_get_by_name(np, np->full_name, name);
 113 }
 114 EXPORT_SYMBOL(of_clk_get_by_name);
 115
 116 #else /* defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK) */
 117
 118 static struct clk *__of_clk_get_by_name(struct device_node *np,
 119                                         const char *dev_id,
 120                                         const char *name)
 121 {
 122         return ERR_PTR(-ENOENT);
 123 }
 124 #endif
 125
 126 /*
 127  * Find the correct struct clk for the device and connection ID.
 128  * We do slightly fuzzy matching here:
 129  *  An entry with a NULL ID is assumed to be a wildcard.
 130  *  If an entry has a device ID, it must match
 131  *  If an entry has a connection ID, it must match
 132  * Then we take the most specific entry - with the following
 133  * order of precedence: dev+con > dev only > con only.
 134  */
 135 static struct clk_lookup *clk_find(const char *dev_id, const char *con_id)
 136 {
 137         struct clk_lookup *p, *cl = NULL;
 138         int match, best_found = 0, best_possible = 0;
 139
 140         if (dev_id)
 141                 best_possible += 2;
 142         if (con_id)
 143                 best_possible += 1;
 144
 145         list_for_each_entry(p, &clocks, node) {
 146                 match = 0;
 147                 if (p->dev_id) {
 148                         if (!dev_id || strcmp(p->dev_id, dev_id))
 149                                 continue;
 150                         match += 2;
 151                 }
 152                 if (p->con_id) {
 153                         if (!con_id || strcmp(p->con_id, con_id))
 154                                 continue;
 155                         match += 1;
 156                 }
 157
 158                 if (match > best_found) {
 159                         cl = p;
 160                         if (match != best_possible)
 161                                 best_found = match;
 162                         else
 163                                 break;
 164                 }
 165         }
 166         return cl;
 167 }
 168
 169 struct clk *clk_get_sys(const char *dev_id, const char *con_id)
 170 {
 171         struct clk_lookup *cl;
 172         struct clk *clk = NULL;
 173
 174         mutex_lock(&clocks_mutex);
 175
 176         cl = clk_find(dev_id, con_id);
 177         if (!cl)
 178                 goto out;
 179
 180         clk = __clk_create_clk(__clk_get_hw(cl->clk), dev_id, con_id);
 181         if (IS_ERR(clk))
 182                 goto out;
 183
 184         if (!__clk_get(clk)) {
 185                 __clk_free_clk(clk);
 186                 cl = NULL;
 187                 goto out;
 188         }
 189
 190 out:
 191         mutex_unlock(&clocks_mutex);
 192
 193         return cl ? clk : ERR_PTR(-ENOENT);
 194 }
 195 EXPORT_SYMBOL(clk_get_sys);
 196
 197 struct clk *clk_get(struct device *dev, const char *con_id)
 198 {
 199         const char *dev_id = dev ? dev_name(dev) : NULL;
 200         struct clk *clk;
 201
 202         if (dev) {
 203                 clk = __of_clk_get_by_name(dev->of_node, dev_id, con_id);
 204                 if (!IS_ERR(clk) || PTR_ERR(clk) == -EPROBE_DEFER)
 205                         return clk;
 206         }
 207
 208         return clk_get_sys(dev_id, con_id);
 209 }
 210 EXPORT_SYMBOL(clk_get);
 211
 212 void clk_put(struct clk *clk)
 213 {
 214         __clk_put(clk);
 215 }
 216 EXPORT_SYMBOL(clk_put);
 217
 218 void clkdev_add(struct clk_lookup *cl)
 219 {
 220         mutex_lock(&clocks_mutex);
 221         list_add_tail(&cl->node, &clocks);
 222         mutex_unlock(&clocks_mutex);
 223 }
 224 EXPORT_SYMBOL(clkdev_add);
 225
 226 void __init clkdev_add_table(struct clk_lookup *cl, size_t num)
 227 {
 228         mutex_lock(&clocks_mutex);
 229         while (num--) {
 230                 list_add_tail(&cl->node, &clocks);
 231                 cl++;
 232         }
 233         mutex_unlock(&clocks_mutex);
 234 }
 235
 236 #define MAX_DEV_ID      20
 237 #define MAX_CON_ID      16
 238
 239 struct clk_lookup_alloc {
 240         struct clk_lookup cl;
 241         char    dev_id[MAX_DEV_ID];
 242         char    con_id[MAX_CON_ID];
 243 };
 244
 245 static struct clk_lookup * __init_refok
 246 vclkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt,
 247         va_list ap)
 248 {
 249         struct clk_lookup_alloc *cla;
 250
 251         cla = __clkdev_alloc(sizeof(*cla));
 252         if (!cla)
 253                 return NULL;
 254
 255         cla->cl.clk = clk;
 256         if (con_id) {
 257                 strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 258                 cla->cl.con_id = cla->con_id;
 259         }
 260
 261         if (dev_fmt) {
 262                 vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 263                 cla->cl.dev_id = cla->dev_id;
 264         }
 265
 266         return &cla->cl;
 267 }
 268
 269 struct clk_lookup * __init_refok
 270 clkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt, ...)
 271 {
 272         struct clk_lookup *cl;
 273         va_list ap;
 274
 275         va_start(ap, dev_fmt);
 276         cl = vclkdev_alloc(clk, con_id, dev_fmt, ap);
 277         va_end(ap);
 278
 279         return cl;
 280 }
 281 EXPORT_SYMBOL(clkdev_alloc);
 282
 283 int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 284         struct device *dev)
 285 {
 286         struct clk *r = clk_get(dev, id);
 287         struct clk_lookup *l;
 288
 289         if (IS_ERR(r))
 290                 return PTR_ERR(r);
 291
 292         l = clkdev_alloc(r, alias, alias_dev_name);
 293         clk_put(r);
 294         if (!l)
 295                 return -ENODEV;
 296         clkdev_add(l);
 297         return 0;
 298 }
 299 EXPORT_SYMBOL(clk_add_alias);
 300
 301 /*
 302  * clkdev_drop - remove a clock dynamically allocated
 303  */
 304 void clkdev_drop(struct clk_lookup *cl)
 305 {
 306         mutex_lock(&clocks_mutex);
 307         list_del(&cl->node);
 308         mutex_unlock(&clocks_mutex);
 309         kfree(cl);
 310 }
 311 EXPORT_SYMBOL(clkdev_drop);
 312
 313 /**
 314  * clk_register_clkdev - register one clock lookup for a struct clk
 315  * @clk: struct clk to associate with all clk_lookups
 316  * @con_id: connection ID string on device
 317  * @dev_id: format string describing device name
 318  *
 319  * con_id or dev_id may be NULL as a wildcard, just as in the rest of
 320  * clkdev.
 321  *
 322  * To make things easier for mass registration, we detect error clks
 323  * from a previous clk_register() call, and return the error code for
 324  * those.  This is to permit this function to be called immediately
 325  * after clk_register().
 326  */
 327 int clk_register_clkdev(struct clk *clk, const char *con_id,
 328         const char *dev_fmt, ...)
 329 {
 330         struct clk_lookup *cl;
 331         va_list ap;
 332
 333         if (IS_ERR(clk))
 334                 return PTR_ERR(clk);
 335
 336         va_start(ap, dev_fmt);
 337         cl = vclkdev_alloc(clk, con_id, dev_fmt, ap);
 338         va_end(ap);
 339
 340         if (!cl)
 341                 return -ENOMEM;
 342
 343         clkdev_add(cl);
 344
 345         return 0;
 346 }
 347 EXPORT_SYMBOL(clk_register_clkdev);
 348
 349 /**
 350  * clk_register_clkdevs - register a set of clk_lookup for a struct clk
 351  * @clk: struct clk to associate with all clk_lookups
 352  * @cl: array of clk_lookup structures with con_id and dev_id pre-initialized
 353  * @num: number of clk_lookup structures to register
 354  *
 355  * To make things easier for mass registration, we detect error clks
 356  * from a previous clk_register() call, and return the error code for
 357  * those.  This is to permit this function to be called immediately
 358  * after clk_register().
 359  */
 360 int clk_register_clkdevs(struct clk *clk, struct clk_lookup *cl, size_t num)
 361 {
 362         unsigned i;
 363
 364         if (IS_ERR(clk))
 365                 return PTR_ERR(clk);
 366
 367         for (i = 0; i < num; i++, cl++) {
 368                 cl->clk = clk;
 369                 clkdev_add(cl);
 370         }
 371
 372         return 0;
 373 }
 374 EXPORT_SYMBOL(clk_register_clkdevs);