arch/arm/plat-tcc/clock.c

   1 /*
   2  * Clock framework for Telechips SoCs
   3  * Based on arch/arm/plat-mxc/clock.c
   4  *
   5  * Copyright (C) 2004 - 2005 Nokia corporation
   6  * Written by Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
   7  * Modified for omap shared clock framework by Tony Lindgren <tony@atomide.com>
   8  * Copyright 2007 Freescale Semiconductor, Inc. All Rights Reserved.
   9  * Copyright 2008 Juergen Beisert, kernel@pengutronix.de
  10  * Copyright 2010 Hans J. Koch, hjk@linutronix.de
  11  *
  12  * Licensed under the terms of the GPL v2.
  13  */
  14
  15 #include <linux/clk.h>
  16 #include <linux/err.h>
  17 #include <linux/errno.h>
  18 #include <linux/module.h>
  19 #include <linux/mutex.h>
  20 #include <linux/string.h>
  21
  22 #include <mach/clock.h>
  23 #include <mach/hardware.h>
  24
  25 static DEFINE_MUTEX(clocks_mutex);
  26
  27 /*-------------------------------------------------------------------------
  28  * Standard clock functions defined in include/linux/clk.h
  29  *-------------------------------------------------------------------------*/
  30
  31 static void __clk_disable(struct clk *clk)
  32 {
  33         BUG_ON(clk->refcount == 0);
  34
  35         if (!(--clk->refcount) && clk->disable) {
  36                 /* Unconditionally disable the clock in hardware */
  37                 clk->disable(clk);
  38                 /* recursively disable parents */
  39                 if (clk->parent)
  40                         __clk_disable(clk->parent);
  41         }
  42 }
  43
  44 static int __clk_enable(struct clk *clk)
  45 {
  46         int ret = 0;
  47
  48         if (clk->refcount++ == 0 && clk->enable) {
  49                 if (clk->parent)
  50                         ret = __clk_enable(clk->parent);
  51                 if (ret)
  52                         return ret;
  53                 else
  54                         return clk->enable(clk);
  55         }
  56
  57         return 0;
  58 }
  59
  60 /* This function increments the reference count on the clock and enables the
  61  * clock if not already enabled. The parent clock tree is recursively enabled
  62  */
  63 int clk_enable(struct clk *clk)
  64 {
  65         int ret = 0;
  66
  67         if (!clk)
  68                 return -EINVAL;
  69
  70         mutex_lock(&clocks_mutex);
  71         ret = __clk_enable(clk);
  72         mutex_unlock(&clocks_mutex);
  73
  74         return ret;
  75 }
  76 EXPORT_SYMBOL_GPL(clk_enable);
  77
  78 /* This function decrements the reference count on the clock and disables
  79  * the clock when reference count is 0. The parent clock tree is
  80  * recursively disabled
  81  */
  82 void clk_disable(struct clk *clk)
  83 {
  84         if (!clk)
  85                 return;
  86
  87         mutex_lock(&clocks_mutex);
  88         __clk_disable(clk);
  89         mutex_unlock(&clocks_mutex);
  90 }
  91 EXPORT_SYMBOL_GPL(clk_disable);
  92
  93 /* Retrieve the *current* clock rate. If the clock itself
  94  * does not provide a special calculation routine, ask
  95  * its parent and so on, until one is able to return
  96  * a valid clock rate
  97  */
  98 unsigned long clk_get_rate(struct clk *clk)
  99 {
 100         if (!clk)
 101                 return 0UL;
 102
 103         if (clk->get_rate)
 104                 return clk->get_rate(clk);
 105
 106         return clk_get_rate(clk->parent);
 107 }
 108 EXPORT_SYMBOL_GPL(clk_get_rate);
 109
 110 /* Round the requested clock rate to the nearest supported
 111  * rate that is less than or equal to the requested rate.
 112  * This is dependent on the clock's current parent.
 113  */
 114 long clk_round_rate(struct clk *clk, unsigned long rate)
 115 {
 116         if (!clk)
 117                 return 0;
 118         if (!clk->round_rate)
 119                 return 0;
 120
 121         return clk->round_rate(clk, rate);
 122 }
 123 EXPORT_SYMBOL_GPL(clk_round_rate);
 124
 125 /* Set the clock to the requested clock rate. The rate must
 126  * match a supported rate exactly based on what clk_round_rate returns
 127  */
 128 int clk_set_rate(struct clk *clk, unsigned long rate)
 129 {
 130         int ret = -EINVAL;
 131
 132         if (!clk)
 133                 return ret;
 134         if (!clk->set_rate || !rate)
 135                 return ret;
 136
 137         mutex_lock(&clocks_mutex);
 138         ret = clk->set_rate(clk, rate);
 139         mutex_unlock(&clocks_mutex);
 140
 141         return ret;
 142 }
 143 EXPORT_SYMBOL_GPL(clk_set_rate);
 144
 145 /* Set the clock's parent to another clock source */
 146 int clk_set_parent(struct clk *clk, struct clk *parent)
 147 {
 148         struct clk *old;
 149         int ret = -EINVAL;
 150
 151         if (!clk)
 152                 return ret;
 153         if (!clk->set_parent || !parent)
 154                 return ret;
 155
 156         mutex_lock(&clocks_mutex);
 157         old = clk->parent;
 158         if (clk->refcount)
 159                 __clk_enable(parent);
 160         ret = clk->set_parent(clk, parent);
 161         if (ret)
 162                 old = parent;
 163         if (clk->refcount)
 164                 __clk_disable(old);
 165         mutex_unlock(&clocks_mutex);
 166
 167         return ret;
 168 }
 169 EXPORT_SYMBOL_GPL(clk_set_parent);
 170
 171 /* Retrieve the clock's parent clock source */
 172 struct clk *clk_get_parent(struct clk *clk)
 173 {
 174         if (!clk)
 175                 return NULL;
 176
 177         return clk->parent;
 178 }
 179 EXPORT_SYMBOL_GPL(clk_get_parent);