arch/arm/plat-mxc/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 #include <mach/hardware.h>
  43
  44 #ifndef CONFIG_COMMON_CLK
  45 static LIST_HEAD(clocks);
  46 static DEFINE_MUTEX(clocks_mutex);
  47
  48 /*-------------------------------------------------------------------------
  49  * Standard clock functions defined in include/linux/clk.h
  50  *-------------------------------------------------------------------------*/
  51
  52 static void __clk_disable(struct clk *clk)
  53 {
  54         if (clk == NULL || IS_ERR(clk))
  55                 return;
  56         WARN_ON(!clk->usecount);
  57
  58         if (!(--clk->usecount)) {
  59                 if (clk->disable)
  60                         clk->disable(clk);
  61                 __clk_disable(clk->parent);
  62                 __clk_disable(clk->secondary);
  63         }
  64 }
  65
  66 static int __clk_enable(struct clk *clk)
  67 {
  68         if (clk == NULL || IS_ERR(clk))
  69                 return -EINVAL;
  70
  71         if (clk->usecount++ == 0) {
  72                 __clk_enable(clk->parent);
  73                 __clk_enable(clk->secondary);
  74
  75                 if (clk->enable)
  76                         clk->enable(clk);
  77         }
  78         return 0;
  79 }
  80
  81 /* This function increments the reference count on the clock and enables the
  82  * clock if not already enabled. The parent clock tree is recursively enabled
  83  */
  84 int clk_enable(struct clk *clk)
  85 {
  86         int ret = 0;
  87
  88         if (clk == NULL || IS_ERR(clk))
  89                 return -EINVAL;
  90
  91         mutex_lock(&clocks_mutex);
  92         ret = __clk_enable(clk);
  93         mutex_unlock(&clocks_mutex);
  94
  95         return ret;
  96 }
  97 EXPORT_SYMBOL(clk_enable);
  98
  99 /* This function decrements the reference count on the clock and disables
 100  * the clock when reference count is 0. The parent clock tree is
 101  * recursively disabled
 102  */
 103 void clk_disable(struct clk *clk)
 104 {
 105         if (clk == NULL || IS_ERR(clk))
 106                 return;
 107
 108         mutex_lock(&clocks_mutex);
 109         __clk_disable(clk);
 110         mutex_unlock(&clocks_mutex);
 111 }
 112 EXPORT_SYMBOL(clk_disable);
 113
 114 /* Retrieve the *current* clock rate. If the clock itself
 115  * does not provide a special calculation routine, ask
 116  * its parent and so on, until one is able to return
 117  * a valid clock rate
 118  */
 119 unsigned long clk_get_rate(struct clk *clk)
 120 {
 121         if (clk == NULL || IS_ERR(clk))
 122                 return 0UL;
 123
 124         if (clk->get_rate)
 125                 return clk->get_rate(clk);
 126
 127         return clk_get_rate(clk->parent);
 128 }
 129 EXPORT_SYMBOL(clk_get_rate);
 130
 131 /* Round the requested clock rate to the nearest supported
 132  * rate that is less than or equal to the requested rate.
 133  * This is dependent on the clock's current parent.
 134  */
 135 long clk_round_rate(struct clk *clk, unsigned long rate)
 136 {
 137         if (clk == NULL || IS_ERR(clk) || !clk->round_rate)
 138                 return 0;
 139
 140         return clk->round_rate(clk, rate);
 141 }
 142 EXPORT_SYMBOL(clk_round_rate);
 143
 144 /* Set the clock to the requested clock rate. The rate must
 145  * match a supported rate exactly based on what clk_round_rate returns
 146  */
 147 int clk_set_rate(struct clk *clk, unsigned long rate)
 148 {
 149         int ret = -EINVAL;
 150
 151         if (clk == NULL || IS_ERR(clk) || clk->set_rate == NULL || rate == 0)
 152                 return ret;
 153
 154         mutex_lock(&clocks_mutex);
 155         ret = clk->set_rate(clk, rate);
 156         mutex_unlock(&clocks_mutex);
 157
 158         return ret;
 159 }
 160 EXPORT_SYMBOL(clk_set_rate);
 161
 162 /* Set the clock's parent to another clock source */
 163 int clk_set_parent(struct clk *clk, struct clk *parent)
 164 {
 165         int ret = -EINVAL;
 166         struct clk *old;
 167
 168         if (clk == NULL || IS_ERR(clk) || parent == NULL ||
 169             IS_ERR(parent) || clk->set_parent == NULL)
 170                 return ret;
 171
 172         if (clk->usecount)
 173                 clk_enable(parent);
 174
 175         mutex_lock(&clocks_mutex);
 176         ret = clk->set_parent(clk, parent);
 177         if (ret == 0) {
 178                 old = clk->parent;
 179                 clk->parent = parent;
 180         } else {
 181                 old = parent;
 182         }
 183         mutex_unlock(&clocks_mutex);
 184
 185         if (clk->usecount)
 186                 clk_disable(old);
 187
 188         return ret;
 189 }
 190 EXPORT_SYMBOL(clk_set_parent);
 191
 192 /* Retrieve the clock's parent clock source */
 193 struct clk *clk_get_parent(struct clk *clk)
 194 {
 195         struct clk *ret = NULL;
 196
 197         if (clk == NULL || IS_ERR(clk))
 198                 return ret;
 199
 200         return clk->parent;
 201 }
 202 EXPORT_SYMBOL(clk_get_parent);
 203
 204 #else
 205
 206 /*
 207  * Lock to protect the clock module (ccm) registers. Used
 208  * on all i.MXs
 209  */
 210 DEFINE_SPINLOCK(imx_ccm_lock);
 211
 212 #endif /* CONFIG_COMMON_CLK */