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                 __clk_disable(clk->secondary);
  61         }
  62 }
  63
  64 static int __clk_enable(struct clk *clk)
  65 {
  66         if (clk == NULL || IS_ERR(clk))
  67                 return -EINVAL;
  68
  69         if (clk->usecount++ == 0) {
  70                 __clk_enable(clk->parent);
  71                 __clk_enable(clk->secondary);
  72
  73                 if (clk->enable)
  74                         clk->enable(clk);
  75         }
  76         return 0;
  77 }
  78
  79 /* This function increments the reference count on the clock and enables the
  80  * clock if not already enabled. The parent clock tree is recursively enabled
  81  */
  82 int clk_enable(struct clk *clk)
  83 {
  84         int ret = 0;
  85
  86         if (clk == NULL || IS_ERR(clk))
  87                 return -EINVAL;
  88
  89         mutex_lock(&clocks_mutex);
  90         ret = __clk_enable(clk);
  91         mutex_unlock(&clocks_mutex);
  92
  93         return ret;
  94 }
  95 EXPORT_SYMBOL(clk_enable);
  96
  97 /* This function decrements the reference count on the clock and disables
  98  * the clock when reference count is 0. The parent clock tree is
  99  * recursively disabled
 100  */
 101 void clk_disable(struct clk *clk)
 102 {
 103         if (clk == NULL || IS_ERR(clk))
 104                 return;
 105
 106         mutex_lock(&clocks_mutex);
 107         __clk_disable(clk);
 108         mutex_unlock(&clocks_mutex);
 109 }
 110 EXPORT_SYMBOL(clk_disable);
 111
 112 /* Retrieve the *current* clock rate. If the clock itself
 113  * does not provide a special calculation routine, ask
 114  * its parent and so on, until one is able to return
 115  * a valid clock rate
 116  */
 117 unsigned long clk_get_rate(struct clk *clk)
 118 {
 119         if (clk == NULL || IS_ERR(clk))
 120                 return 0UL;
 121
 122         if (clk->get_rate)
 123                 return clk->get_rate(clk);
 124
 125         return clk_get_rate(clk->parent);
 126 }
 127 EXPORT_SYMBOL(clk_get_rate);
 128
 129 /* Round the requested clock rate to the nearest supported
 130  * rate that is less than or equal to the requested rate.
 131  * This is dependent on the clock's current parent.
 132  */
 133 long clk_round_rate(struct clk *clk, unsigned long rate)
 134 {
 135         if (clk == NULL || IS_ERR(clk) || !clk->round_rate)
 136                 return 0;
 137
 138         return clk->round_rate(clk, rate);
 139 }
 140 EXPORT_SYMBOL(clk_round_rate);
 141
 142 /* Set the clock to the requested clock rate. The rate must
 143  * match a supported rate exactly based on what clk_round_rate returns
 144  */
 145 int clk_set_rate(struct clk *clk, unsigned long rate)
 146 {
 147         int ret = -EINVAL;
 148
 149         if (clk == NULL || IS_ERR(clk) || clk->set_rate == NULL || rate == 0)
 150                 return ret;
 151
 152         mutex_lock(&clocks_mutex);
 153         ret = clk->set_rate(clk, rate);
 154         mutex_unlock(&clocks_mutex);
 155
 156         return ret;
 157 }
 158 EXPORT_SYMBOL(clk_set_rate);
 159
 160 /* Set the clock's parent to another clock source */
 161 int clk_set_parent(struct clk *clk, struct clk *parent)
 162 {
 163         int ret = -EINVAL;
 164         struct clk *old;
 165
 166         if (clk == NULL || IS_ERR(clk) || parent == NULL ||
 167             IS_ERR(parent) || clk->set_parent == NULL)
 168                 return ret;
 169
 170         if (clk->usecount)
 171                 clk_enable(parent);
 172
 173         mutex_lock(&clocks_mutex);
 174         ret = clk->set_parent(clk, parent);
 175         if (ret == 0) {
 176                 old = clk->parent;
 177                 clk->parent = parent;
 178         } else {
 179                 old = parent;
 180         }
 181         mutex_unlock(&clocks_mutex);
 182
 183         if (clk->usecount)
 184                 clk_disable(old);
 185
 186         return ret;
 187 }
 188 EXPORT_SYMBOL(clk_set_parent);
 189
 190 /* Retrieve the clock's parent clock source */
 191 struct clk *clk_get_parent(struct clk *clk)
 192 {
 193         struct clk *ret = NULL;
 194
 195         if (clk == NULL || IS_ERR(clk))
 196                 return ret;
 197
 198         return clk->parent;
 199 }
 200 EXPORT_SYMBOL(clk_get_parent);