drivers/media/v4l2-core/v4l2-clk.c

   1 /*
   2  * V4L2 clock service
   3  *
   4  * Copyright (C) 2012-2013, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/atomic.h>
  12 #include <linux/clk.h>
  13 #include <linux/device.h>
  14 #include <linux/errno.h>
  15 #include <linux/list.h>
  16 #include <linux/module.h>
  17 #include <linux/mutex.h>
  18 #include <linux/of.h>
  19 #include <linux/slab.h>
  20 #include <linux/string.h>
  21
  22 #include <media/v4l2-clk.h>
  23 #include <media/v4l2-subdev.h>
  24
  25 static DEFINE_MUTEX(clk_lock);
  26 static LIST_HEAD(clk_list);
  27
  28 static struct v4l2_clk *v4l2_clk_find(const char *dev_id)
  29 {
  30         struct v4l2_clk *clk;
  31
  32         list_for_each_entry(clk, &clk_list, list)
  33                 if (!strcmp(dev_id, clk->dev_id))
  34                         return clk;
  35
  36         return ERR_PTR(-ENODEV);
  37 }
  38
  39 struct v4l2_clk *v4l2_clk_get(struct device *dev, const char *id)
  40 {
  41         struct v4l2_clk *clk;
  42         struct clk *ccf_clk = clk_get(dev, id);
  43         char clk_name[V4L2_CLK_NAME_SIZE];
  44
  45         if (PTR_ERR(ccf_clk) == -EPROBE_DEFER)
  46                 return ERR_PTR(-EPROBE_DEFER);
  47
  48         if (!IS_ERR_OR_NULL(ccf_clk)) {
  49                 clk = kzalloc(sizeof(*clk), GFP_KERNEL);
  50                 if (!clk) {
  51                         clk_put(ccf_clk);
  52                         return ERR_PTR(-ENOMEM);
  53                 }
  54                 clk->clk = ccf_clk;
  55
  56                 return clk;
  57         }
  58
  59         mutex_lock(&clk_lock);
  60         clk = v4l2_clk_find(dev_name(dev));
  61
  62         /* if dev_name is not found, try use the OF name to find again  */
  63         if (PTR_ERR(clk) == -ENODEV && dev->of_node) {
  64                 v4l2_clk_name_of(clk_name, sizeof(clk_name), dev->of_node);
  65                 clk = v4l2_clk_find(clk_name);
  66         }
  67
  68         if (!IS_ERR(clk))
  69                 atomic_inc(&clk->use_count);
  70         mutex_unlock(&clk_lock);
  71
  72         return clk;
  73 }
  74 EXPORT_SYMBOL(v4l2_clk_get);
  75
  76 void v4l2_clk_put(struct v4l2_clk *clk)
  77 {
  78         struct v4l2_clk *tmp;
  79
  80         if (IS_ERR(clk))
  81                 return;
  82
  83         if (clk->clk) {
  84                 clk_put(clk->clk);
  85                 kfree(clk);
  86                 return;
  87         }
  88
  89         mutex_lock(&clk_lock);
  90
  91         list_for_each_entry(tmp, &clk_list, list)
  92                 if (tmp == clk)
  93                         atomic_dec(&clk->use_count);
  94
  95         mutex_unlock(&clk_lock);
  96 }
  97 EXPORT_SYMBOL(v4l2_clk_put);
  98
  99 static int v4l2_clk_lock_driver(struct v4l2_clk *clk)
 100 {
 101         struct v4l2_clk *tmp;
 102         int ret = -ENODEV;
 103
 104         mutex_lock(&clk_lock);
 105
 106         list_for_each_entry(tmp, &clk_list, list)
 107                 if (tmp == clk) {
 108                         ret = !try_module_get(clk->ops->owner);
 109                         if (ret)
 110                                 ret = -EFAULT;
 111                         break;
 112                 }
 113
 114         mutex_unlock(&clk_lock);
 115
 116         return ret;
 117 }
 118
 119 static void v4l2_clk_unlock_driver(struct v4l2_clk *clk)
 120 {
 121         module_put(clk->ops->owner);
 122 }
 123
 124 int v4l2_clk_enable(struct v4l2_clk *clk)
 125 {
 126         int ret;
 127
 128         if (clk->clk)
 129                 return clk_prepare_enable(clk->clk);
 130
 131         ret = v4l2_clk_lock_driver(clk);
 132         if (ret < 0)
 133                 return ret;
 134
 135         mutex_lock(&clk->lock);
 136
 137         if (++clk->enable == 1 && clk->ops->enable) {
 138                 ret = clk->ops->enable(clk);
 139                 if (ret < 0)
 140                         clk->enable--;
 141         }
 142
 143         mutex_unlock(&clk->lock);
 144
 145         return ret;
 146 }
 147 EXPORT_SYMBOL(v4l2_clk_enable);
 148
 149 /*
 150  * You might Oops if you try to disabled a disabled clock, because then the
 151  * driver isn't locked and could have been unloaded by now, so, don't do that
 152  */
 153 void v4l2_clk_disable(struct v4l2_clk *clk)
 154 {
 155         int enable;
 156
 157         if (clk->clk)
 158                 return clk_disable_unprepare(clk->clk);
 159
 160         mutex_lock(&clk->lock);
 161
 162         enable = --clk->enable;
 163         if (WARN(enable < 0, "Unbalanced %s() on %s!\n", __func__,
 164                  clk->dev_id))
 165                 clk->enable++;
 166         else if (!enable && clk->ops->disable)
 167                 clk->ops->disable(clk);
 168
 169         mutex_unlock(&clk->lock);
 170
 171         v4l2_clk_unlock_driver(clk);
 172 }
 173 EXPORT_SYMBOL(v4l2_clk_disable);
 174
 175 unsigned long v4l2_clk_get_rate(struct v4l2_clk *clk)
 176 {
 177         int ret;
 178
 179         if (clk->clk)
 180                 return clk_get_rate(clk->clk);
 181
 182         ret = v4l2_clk_lock_driver(clk);
 183         if (ret < 0)
 184                 return ret;
 185
 186         mutex_lock(&clk->lock);
 187         if (!clk->ops->get_rate)
 188                 ret = -ENOSYS;
 189         else
 190                 ret = clk->ops->get_rate(clk);
 191         mutex_unlock(&clk->lock);
 192
 193         v4l2_clk_unlock_driver(clk);
 194
 195         return ret;
 196 }
 197 EXPORT_SYMBOL(v4l2_clk_get_rate);
 198
 199 int v4l2_clk_set_rate(struct v4l2_clk *clk, unsigned long rate)
 200 {
 201         int ret;
 202
 203         if (clk->clk) {
 204                 long r = clk_round_rate(clk->clk, rate);
 205                 if (r < 0)
 206                         return r;
 207                 return clk_set_rate(clk->clk, r);
 208         }
 209
 210         ret = v4l2_clk_lock_driver(clk);
 211
 212         if (ret < 0)
 213                 return ret;
 214
 215         mutex_lock(&clk->lock);
 216         if (!clk->ops->set_rate)
 217                 ret = -ENOSYS;
 218         else
 219                 ret = clk->ops->set_rate(clk, rate);
 220         mutex_unlock(&clk->lock);
 221
 222         v4l2_clk_unlock_driver(clk);
 223
 224         return ret;
 225 }
 226 EXPORT_SYMBOL(v4l2_clk_set_rate);
 227
 228 struct v4l2_clk *v4l2_clk_register(const struct v4l2_clk_ops *ops,
 229                                    const char *dev_id,
 230                                    void *priv)
 231 {
 232         struct v4l2_clk *clk;
 233         int ret;
 234
 235         if (!ops || !dev_id)
 236                 return ERR_PTR(-EINVAL);
 237
 238         clk = kzalloc(sizeof(struct v4l2_clk), GFP_KERNEL);
 239         if (!clk)
 240                 return ERR_PTR(-ENOMEM);
 241
 242         clk->dev_id = kstrdup(dev_id, GFP_KERNEL);
 243         if (!clk->dev_id) {
 244                 ret = -ENOMEM;
 245                 goto ealloc;
 246         }
 247         clk->ops = ops;
 248         clk->priv = priv;
 249         atomic_set(&clk->use_count, 0);
 250         mutex_init(&clk->lock);
 251
 252         mutex_lock(&clk_lock);
 253         if (!IS_ERR(v4l2_clk_find(dev_id))) {
 254                 mutex_unlock(&clk_lock);
 255                 ret = -EEXIST;
 256                 goto eexist;
 257         }
 258         list_add_tail(&clk->list, &clk_list);
 259         mutex_unlock(&clk_lock);
 260
 261         return clk;
 262
 263 eexist:
 264 ealloc:
 265         kfree(clk->dev_id);
 266         kfree(clk);
 267         return ERR_PTR(ret);
 268 }
 269 EXPORT_SYMBOL(v4l2_clk_register);
 270
 271 void v4l2_clk_unregister(struct v4l2_clk *clk)
 272 {
 273         if (WARN(atomic_read(&clk->use_count),
 274                  "%s(): Refusing to unregister ref-counted %s clock!\n",
 275                  __func__, clk->dev_id))
 276                 return;
 277
 278         mutex_lock(&clk_lock);
 279         list_del(&clk->list);
 280         mutex_unlock(&clk_lock);
 281
 282         kfree(clk->dev_id);
 283         kfree(clk);
 284 }
 285 EXPORT_SYMBOL(v4l2_clk_unregister);
 286
 287 struct v4l2_clk_fixed {
 288         unsigned long rate;
 289         struct v4l2_clk_ops ops;
 290 };
 291
 292 static unsigned long fixed_get_rate(struct v4l2_clk *clk)
 293 {
 294         struct v4l2_clk_fixed *priv = clk->priv;
 295         return priv->rate;
 296 }
 297
 298 struct v4l2_clk *__v4l2_clk_register_fixed(const char *dev_id,
 299                                 unsigned long rate, struct module *owner)
 300 {
 301         struct v4l2_clk *clk;
 302         struct v4l2_clk_fixed *priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 303
 304         if (!priv)
 305                 return ERR_PTR(-ENOMEM);
 306
 307         priv->rate = rate;
 308         priv->ops.get_rate = fixed_get_rate;
 309         priv->ops.owner = owner;
 310
 311         clk = v4l2_clk_register(&priv->ops, dev_id, priv);
 312         if (IS_ERR(clk))
 313                 kfree(priv);
 314
 315         return clk;
 316 }
 317 EXPORT_SYMBOL(__v4l2_clk_register_fixed);
 318
 319 void v4l2_clk_unregister_fixed(struct v4l2_clk *clk)
 320 {
 321         kfree(clk->priv);
 322         v4l2_clk_unregister(clk);
 323 }
 324 EXPORT_SYMBOL(v4l2_clk_unregister_fixed);