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 #include <linux/version.h>
  41
  42 #include <asm/arch/clock.h>
  43
  44 static LIST_HEAD(clocks);
  45 static DEFINE_MUTEX(clocks_mutex);
  46
  47 /*-------------------------------------------------------------------------
  48  * Standard clock functions defined in include/linux/clk.h
  49  *-------------------------------------------------------------------------*/
  50
  51 /*
  52  * Retrieve a clock by name.
  53  *
  54  * Note that we first try to use device id on the bus
  55  * and clock name. If this fails, we try to use "<name>.<id>". If this fails,
  56  * we try to use clock name only.
  57  * The reference count to the clock's module owner ref count is incremented.
  58  */
  59 struct clk *clk_get(struct device *dev, const char *id)
  60 {
  61         struct clk *p, *clk = ERR_PTR(-ENOENT);
  62         int idno;
  63         const char *str;
  64
  65         if (id == NULL)
  66                 return clk;
  67
  68         if (dev == NULL || dev->bus != &platform_bus_type)
  69                 idno = -1;
  70         else
  71                 idno = to_platform_device(dev)->id;
  72
  73         mutex_lock(&clocks_mutex);
  74
  75         list_for_each_entry(p, &clocks, node) {
  76                 if (p->id == idno &&
  77                     strcmp(id, p->name) == 0 && try_module_get(p->owner)) {
  78                         clk = p;
  79                         goto found;
  80                 }
  81         }
  82
  83         str = strrchr(id, '.');
  84         if (str) {
  85                 int cnt = str - id;
  86                 str++;
  87                 idno = simple_strtol(str, NULL, 10);
  88                 list_for_each_entry(p, &clocks, node) {
  89                         if (p->id == idno &&
  90                             strlen(p->name) == cnt &&
  91                             strncmp(id, p->name, cnt) == 0 &&
  92                             try_module_get(p->owner)) {
  93                                 clk = p;
  94                                 goto found;
  95                         }
  96                 }
  97         }
  98
  99         list_for_each_entry(p, &clocks, node) {
 100                 if (strcmp(id, p->name) == 0 && try_module_get(p->owner)) {
 101                         clk = p;
 102                         goto found;
 103                 }
 104         }
 105
 106         printk(KERN_WARNING "clk: Unable to get requested clock: %s\n", id);
 107
 108 found:
 109         mutex_unlock(&clocks_mutex);
 110
 111         return clk;
 112 }
 113 EXPORT_SYMBOL(clk_get);
 114
 115 static void __clk_disable(struct clk *clk)
 116 {
 117         if (clk == NULL || IS_ERR(clk))
 118                 return;
 119
 120         __clk_disable(clk->parent);
 121         __clk_disable(clk->secondary);
 122
 123         if (!(--clk->usecount) && clk->disable)
 124                 clk->disable(clk);
 125 }
 126
 127 static int __clk_enable(struct clk *clk)
 128 {
 129         if (clk == NULL || IS_ERR(clk))
 130                 return -EINVAL;
 131
 132         __clk_enable(clk->parent);
 133         __clk_enable(clk->secondary);
 134
 135         if (clk->usecount++ == 0 && clk->enable)
 136                 clk->enable(clk);
 137
 138         return 0;
 139 }
 140
 141 /* This function increments the reference count on the clock and enables the
 142  * clock if not already enabled. The parent clock tree is recursively enabled
 143  */
 144 int clk_enable(struct clk *clk)
 145 {
 146         int ret = 0;
 147
 148         if (clk == NULL || IS_ERR(clk))
 149                 return -EINVAL;
 150
 151         mutex_lock(&clocks_mutex);
 152         ret = __clk_enable(clk);
 153         mutex_unlock(&clocks_mutex);
 154
 155         return ret;
 156 }
 157 EXPORT_SYMBOL(clk_enable);
 158
 159 /* This function decrements the reference count on the clock and disables
 160  * the clock when reference count is 0. The parent clock tree is
 161  * recursively disabled
 162  */
 163 void clk_disable(struct clk *clk)
 164 {
 165         if (clk == NULL || IS_ERR(clk))
 166                 return;
 167
 168         mutex_lock(&clocks_mutex);
 169         __clk_disable(clk);
 170         mutex_unlock(&clocks_mutex);
 171 }
 172 EXPORT_SYMBOL(clk_disable);
 173
 174 /* Retrieve the *current* clock rate. If the clock itself
 175  * does not provide a special calculation routine, ask
 176  * its parent and so on, until one is able to return
 177  * a valid clock rate
 178  */
 179 unsigned long clk_get_rate(struct clk *clk)
 180 {
 181         if (clk == NULL || IS_ERR(clk))
 182                 return 0UL;
 183
 184         if (clk->get_rate)
 185                 return clk->get_rate(clk);
 186
 187         return clk_get_rate(clk->parent);
 188 }
 189 EXPORT_SYMBOL(clk_get_rate);
 190
 191 /* Decrement the clock's module reference count */
 192 void clk_put(struct clk *clk)
 193 {
 194         if (clk && !IS_ERR(clk))
 195                 module_put(clk->owner);
 196 }
 197 EXPORT_SYMBOL(clk_put);
 198
 199 /* Round the requested clock rate to the nearest supported
 200  * rate that is less than or equal to the requested rate.
 201  * This is dependent on the clock's current parent.
 202  */
 203 long clk_round_rate(struct clk *clk, unsigned long rate)
 204 {
 205         if (clk == NULL || IS_ERR(clk) || !clk->round_rate)
 206                 return 0;
 207
 208         return clk->round_rate(clk, rate);
 209 }
 210 EXPORT_SYMBOL(clk_round_rate);
 211
 212 /* Set the clock to the requested clock rate. The rate must
 213  * match a supported rate exactly based on what clk_round_rate returns
 214  */
 215 int clk_set_rate(struct clk *clk, unsigned long rate)
 216 {
 217         int ret = -EINVAL;
 218
 219         if (clk == NULL || IS_ERR(clk) || clk->set_rate == NULL || rate == 0)
 220                 return ret;
 221
 222         mutex_lock(&clocks_mutex);
 223         ret = clk->set_rate(clk, rate);
 224         mutex_unlock(&clocks_mutex);
 225
 226         return ret;
 227 }
 228 EXPORT_SYMBOL(clk_set_rate);
 229
 230 /* Set the clock's parent to another clock source */
 231 int clk_set_parent(struct clk *clk, struct clk *parent)
 232 {
 233         int ret = -EINVAL;
 234
 235         if (clk == NULL || IS_ERR(clk) || parent == NULL ||
 236             IS_ERR(parent) || clk->set_parent == NULL)
 237                 return ret;
 238
 239         mutex_lock(&clocks_mutex);
 240         ret = clk->set_parent(clk, parent);
 241         if (ret == 0)
 242                 clk->parent = parent;
 243         mutex_unlock(&clocks_mutex);
 244
 245         return ret;
 246 }
 247 EXPORT_SYMBOL(clk_set_parent);
 248
 249 /* Retrieve the clock's parent clock source */
 250 struct clk *clk_get_parent(struct clk *clk)
 251 {
 252         struct clk *ret = NULL;
 253
 254         if (clk == NULL || IS_ERR(clk))
 255                 return ret;
 256
 257         return clk->parent;
 258 }
 259 EXPORT_SYMBOL(clk_get_parent);
 260
 261 /*
 262  * Add a new clock to the clock tree.
 263  */
 264 int clk_register(struct clk *clk)
 265 {
 266         if (clk == NULL || IS_ERR(clk))
 267                 return -EINVAL;
 268
 269         mutex_lock(&clocks_mutex);
 270         list_add(&clk->node, &clocks);
 271         mutex_unlock(&clocks_mutex);
 272
 273         return 0;
 274 }
 275 EXPORT_SYMBOL(clk_register);
 276
 277 /* Remove a clock from the clock tree */
 278 void clk_unregister(struct clk *clk)
 279 {
 280         if (clk == NULL || IS_ERR(clk))
 281                 return;
 282
 283         mutex_lock(&clocks_mutex);
 284         list_del(&clk->node);
 285         mutex_unlock(&clocks_mutex);
 286 }
 287 EXPORT_SYMBOL(clk_unregister);
 288
 289 #ifdef CONFIG_PROC_FS
 290 static int mxc_clock_read_proc(char *page, char **start, off_t off,
 291                                 int count, int *eof, void *data)
 292 {
 293         struct clk *clkp;
 294         char *p = page;
 295         int len;
 296
 297         list_for_each_entry(clkp, &clocks, node) {
 298                 p += sprintf(p, "%s-%d:\t\t%lu, %d", clkp->name, clkp->id,
 299                                 clk_get_rate(clkp), clkp->usecount);
 300                 if (clkp->parent)
 301                         p += sprintf(p, ", %s-%d\n", clkp->parent->name,
 302                                      clkp->parent->id);
 303                 else
 304                         p += sprintf(p, "\n");
 305         }
 306
 307         len = (p - page) - off;
 308         if (len < 0)
 309                 len = 0;
 310
 311         *eof = (len <= count) ? 1 : 0;
 312         *start = page + off;
 313
 314         return len;
 315 }
 316
 317 static int __init mxc_setup_proc_entry(void)
 318 {
 319         struct proc_dir_entry *res;
 320
 321         res = create_proc_read_entry("cpu/clocks", 0, NULL,
 322                                      mxc_clock_read_proc, NULL);
 323         if (!res) {
 324                 printk(KERN_ERR "Failed to create proc/cpu/clocks\n");
 325                 return -ENOMEM;
 326         }
 327         return 0;
 328 }
 329
 330 late_initcall(mxc_setup_proc_entry);
 331 #endif