arch/arm/mach-mxs/clock.c

   1 /*
   2  * Based on arch/arm/plat-omap/clock.c
   3  *
   4  * Copyright (C) 2004 - 2005 Nokia corporation
   5  * Written by Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
   6  * Modified for omap shared clock framework by Tony Lindgren <tony@atomide.com>
   7  * Copyright 2007 Freescale Semiconductor, Inc. All Rights Reserved.
   8  * Copyright 2008 Juergen Beisert, kernel@pengutronix.de
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  22  * MA  02110-1301, USA.
  23  */
  24
  25 /* #define DEBUG */
  26
  27 #include <linux/clk.h>
  28 #include <linux/err.h>
  29 #include <linux/errno.h>
  30 #include <linux/init.h>
  31 #include <linux/io.h>
  32 #include <linux/kernel.h>
  33 #include <linux/list.h>
  34 #include <linux/module.h>
  35 #include <linux/mutex.h>
  36 #include <linux/platform_device.h>
  37 #include <linux/proc_fs.h>
  38 #include <linux/semaphore.h>
  39 #include <linux/string.h>
  40
  41 #include <mach/clock.h>
  42
  43 static LIST_HEAD(clocks);
  44 static DEFINE_MUTEX(clocks_mutex);
  45
  46 /*-------------------------------------------------------------------------
  47  * Standard clock functions defined in include/linux/clk.h
  48  *-------------------------------------------------------------------------*/
  49
  50 static void __clk_disable(struct clk *clk)
  51 {
  52         if (clk == NULL || IS_ERR(clk))
  53                 return;
  54         WARN_ON(!clk->usecount);
  55
  56         if (!(--clk->usecount)) {
  57                 if (clk->disable)
  58                         clk->disable(clk);
  59                 __clk_disable(clk->parent);
  60         }
  61 }
  62
  63 static int __clk_enable(struct clk *clk)
  64 {
  65         if (clk == NULL || IS_ERR(clk))
  66                 return -EINVAL;
  67
  68         if (clk->usecount++ == 0) {
  69                 __clk_enable(clk->parent);
  70
  71                 if (clk->enable)
  72                         clk->enable(clk);
  73         }
  74         return 0;
  75 }
  76
  77 /*
  78  * The clk_enable/clk_disable could be called by drivers in atomic context,
  79  * so they should not really hold mutex.  Instead, clk_prepare/clk_unprepare
  80  * can hold a mutex, as the pair will only be called in non-atomic context.
  81  * Before migrating to common clk framework, we can have __clk_enable and
  82  * __clk_disable called in clk_prepare/clk_unprepare with mutex held and
  83  * leave clk_enable/clk_disable as the dummy functions.
  84  */
  85 int clk_prepare(struct clk *clk)
  86 {
  87         int ret = 0;
  88
  89         if (clk == NULL || IS_ERR(clk))
  90                 return -EINVAL;
  91
  92         mutex_lock(&clocks_mutex);
  93         ret = __clk_enable(clk);
  94         mutex_unlock(&clocks_mutex);
  95
  96         return ret;
  97 }
  98 EXPORT_SYMBOL(clk_prepare);
  99
 100 void clk_unprepare(struct clk *clk)
 101 {
 102         if (clk == NULL || IS_ERR(clk))
 103                 return;
 104
 105         mutex_lock(&clocks_mutex);
 106         __clk_disable(clk);
 107         mutex_unlock(&clocks_mutex);
 108 }
 109 EXPORT_SYMBOL(clk_unprepare);
 110
 111 int clk_enable(struct clk *clk)
 112 {
 113         return 0;
 114 }
 115 EXPORT_SYMBOL(clk_enable);
 116
 117 void clk_disable(struct clk *clk)
 118 {
 119         /* nothing to do */
 120 }
 121 EXPORT_SYMBOL(clk_disable);
 122
 123 /* Retrieve the *current* clock rate. If the clock itself
 124  * does not provide a special calculation routine, ask
 125  * its parent and so on, until one is able to return
 126  * a valid clock rate
 127  */
 128 unsigned long clk_get_rate(struct clk *clk)
 129 {
 130         if (clk == NULL || IS_ERR(clk))
 131                 return 0UL;
 132
 133         if (clk->get_rate)
 134                 return clk->get_rate(clk);
 135
 136         return clk_get_rate(clk->parent);
 137 }
 138 EXPORT_SYMBOL(clk_get_rate);
 139
 140 /* Round the requested clock rate to the nearest supported
 141  * rate that is less than or equal to the requested rate.
 142  * This is dependent on the clock's current parent.
 143  */
 144 long clk_round_rate(struct clk *clk, unsigned long rate)
 145 {
 146         if (clk == NULL || IS_ERR(clk) || !clk->round_rate)
 147                 return 0;
 148
 149         return clk->round_rate(clk, rate);
 150 }
 151 EXPORT_SYMBOL(clk_round_rate);
 152
 153 /* Set the clock to the requested clock rate. The rate must
 154  * match a supported rate exactly based on what clk_round_rate returns
 155  */
 156 int clk_set_rate(struct clk *clk, unsigned long rate)
 157 {
 158         int ret = -EINVAL;
 159
 160         if (clk == NULL || IS_ERR(clk) || clk->set_rate == NULL || rate == 0)
 161                 return ret;
 162
 163         mutex_lock(&clocks_mutex);
 164         ret = clk->set_rate(clk, rate);
 165         mutex_unlock(&clocks_mutex);
 166
 167         return ret;
 168 }
 169 EXPORT_SYMBOL(clk_set_rate);
 170
 171 /* Set the clock's parent to another clock source */
 172 int clk_set_parent(struct clk *clk, struct clk *parent)
 173 {
 174         int ret = -EINVAL;
 175         struct clk *old;
 176
 177         if (clk == NULL || IS_ERR(clk) || parent == NULL ||
 178             IS_ERR(parent) || clk->set_parent == NULL)
 179                 return ret;
 180
 181         if (clk->usecount)
 182                 clk_prepare_enable(parent);
 183
 184         mutex_lock(&clocks_mutex);
 185         ret = clk->set_parent(clk, parent);
 186         if (ret == 0) {
 187                 old = clk->parent;
 188                 clk->parent = parent;
 189         } else {
 190                 old = parent;
 191         }
 192         mutex_unlock(&clocks_mutex);
 193
 194         if (clk->usecount)
 195                 clk_disable(old);
 196
 197         return ret;
 198 }
 199 EXPORT_SYMBOL(clk_set_parent);
 200
 201 /* Retrieve the clock's parent clock source */
 202 struct clk *clk_get_parent(struct clk *clk)
 203 {
 204         struct clk *ret = NULL;
 205
 206         if (clk == NULL || IS_ERR(clk))
 207                 return ret;
 208
 209         return clk->parent;
 210 }
 211 EXPORT_SYMBOL(clk_get_parent);