linux/drivers/clk/clkdev.c
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   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
  24static LIST_HEAD(clocks);
  25static DEFINE_MUTEX(clocks_mutex);
  26
  27#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
  28struct 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}
  46EXPORT_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 */
  57struct 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}
  93EXPORT_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 */
 105static 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
 139struct 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}
 151EXPORT_SYMBOL(clk_get_sys);
 152
 153struct 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}
 166EXPORT_SYMBOL(clk_get);
 167
 168void clk_put(struct clk *clk)
 169{
 170        __clk_put(clk);
 171}
 172EXPORT_SYMBOL(clk_put);
 173
 174void 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}
 180EXPORT_SYMBOL(clkdev_add);
 181
 182void __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
 195struct clk_lookup_alloc {
 196        struct clk_lookup cl;
 197        char    dev_id[MAX_DEV_ID];
 198        char    con_id[MAX_CON_ID];
 199};
 200
 201static struct clk_lookup * __init_refok
 202vclkdev_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
 225struct clk_lookup * __init_refok
 226clkdev_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}
 237EXPORT_SYMBOL(clkdev_alloc);
 238
 239int 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}
 255EXPORT_SYMBOL(clk_add_alias);
 256
 257/*
 258 * clkdev_drop - remove a clock dynamically allocated
 259 */
 260void 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}
 267EXPORT_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 */
 283int 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 */
 315int 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}
 329EXPORT_SYMBOL(clk_register_clkdevs);
 330
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