LXR linux/arch/arm/common/clkdev.c

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