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