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