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
  23static LIST_HEAD(clocks);
  24static DEFINE_MUTEX(clocks_mutex);
  25
  26/*
  27 * Find the correct struct clk for the device and connection ID.
  28 * We do slightly fuzzy matching here:
  29 *  An entry with a NULL ID is assumed to be a wildcard.
  30 *  If an entry has a device ID, it must match
  31 *  If an entry has a connection ID, it must match
  32 * Then we take the most specific entry - with the following
  33 * order of precedence: dev+con > dev only > con only.
  34 */
  35static struct clk_lookup *clk_find(const char *dev_id, const char *con_id)
  36{
  37        struct clk_lookup *p, *cl = NULL;
  38        int match, best = 0;
  39
  40        list_for_each_entry(p, &clocks, node) {
  41                match = 0;
  42                if (p->dev_id) {
  43                        if (!dev_id || strcmp(p->dev_id, dev_id))
  44                                continue;
  45                        match += 2;
  46                }
  47                if (p->con_id) {
  48                        if (!con_id || strcmp(p->con_id, con_id))
  49                                continue;
  50                        match += 1;
  51                }
  52
  53                if (match > best) {
  54                        cl = p;
  55                        if (match != 3)
  56                                best = match;
  57                        else
  58                                break;
  59                }
  60        }
  61        return cl;
  62}
  63
  64struct clk *clk_get_sys(const char *dev_id, const char *con_id)
  65{
  66        struct clk_lookup *cl;
  67
  68        mutex_lock(&clocks_mutex);
  69        cl = clk_find(dev_id, con_id);
  70        if (cl && !__clk_get(cl->clk))
  71                cl = NULL;
  72        mutex_unlock(&clocks_mutex);
  73
  74        return cl ? cl->clk : ERR_PTR(-ENOENT);
  75}
  76EXPORT_SYMBOL(clk_get_sys);
  77
  78struct clk *clk_get(struct device *dev, const char *con_id)
  79{
  80        const char *dev_id = dev ? dev_name(dev) : NULL;
  81
  82        return clk_get_sys(dev_id, con_id);
  83}
  84EXPORT_SYMBOL(clk_get);
  85
  86void clk_put(struct clk *clk)
  87{
  88        __clk_put(clk);
  89}
  90EXPORT_SYMBOL(clk_put);
  91
  92void clkdev_add(struct clk_lookup *cl)
  93{
  94        mutex_lock(&clocks_mutex);
  95        list_add_tail(&cl->node, &clocks);
  96        mutex_unlock(&clocks_mutex);
  97}
  98EXPORT_SYMBOL(clkdev_add);
  99
 100void __init clkdev_add_table(struct clk_lookup *cl, size_t num)
 101{
 102        mutex_lock(&clocks_mutex);
 103        while (num--) {
 104                list_add_tail(&cl->node, &clocks);
 105                cl++;
 106        }
 107        mutex_unlock(&clocks_mutex);
 108}
 109
 110#define MAX_DEV_ID      20
 111#define MAX_CON_ID      16
 112
 113struct clk_lookup_alloc {
 114        struct clk_lookup cl;
 115        char    dev_id[MAX_DEV_ID];
 116        char    con_id[MAX_CON_ID];
 117};
 118
 119struct clk_lookup * __init_refok
 120clkdev_alloc(struct clk *clk, const char *con_id, const char *dev_fmt, ...)
 121{
 122        struct clk_lookup_alloc *cla;
 123
 124        cla = __clkdev_alloc(sizeof(*cla));
 125        if (!cla)
 126                return NULL;
 127
 128        cla->cl.clk = clk;
 129        if (con_id) {
 130                strlcpy(cla->con_id, con_id, sizeof(cla->con_id));
 131                cla->cl.con_id = cla->con_id;
 132        }
 133
 134        if (dev_fmt) {
 135                va_list ap;
 136
 137                va_start(ap, dev_fmt);
 138                vscnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
 139                cla->cl.dev_id = cla->dev_id;
 140                va_end(ap);
 141        }
 142
 143        return &cla->cl;
 144}
 145EXPORT_SYMBOL(clkdev_alloc);
 146
 147int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
 148        struct device *dev)
 149{
 150        struct clk *r = clk_get(dev, id);
 151        struct clk_lookup *l;
 152
 153        if (IS_ERR(r))
 154                return PTR_ERR(r);
 155
 156        l = clkdev_alloc(r, alias, alias_dev_name);
 157        clk_put(r);
 158        if (!l)
 159                return -ENODEV;
 160        clkdev_add(l);
 161        return 0;
 162}
 163EXPORT_SYMBOL(clk_add_alias);
 164
 165/*
 166 * clkdev_drop - remove a clock dynamically allocated
 167 */
 168void clkdev_drop(struct clk_lookup *cl)
 169{
 170        mutex_lock(&clocks_mutex);
 171        list_del(&cl->node);
 172        mutex_unlock(&clocks_mutex);
 173        kfree(cl);
 174}
 175EXPORT_SYMBOL(clkdev_drop);
 176