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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * V4L2 clock service
   4  *
   5  * Copyright (C) 2012-2013, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
   6  */
   7
   8 #include <linux/atomic.h>
   9 #include <linux/clk.h>
  10 #include <linux/device.h>
  11 #include <linux/errno.h>
  12 #include <linux/list.h>
  13 #include <linux/module.h>
  14 #include <linux/mutex.h>
  15 #include <linux/of.h>
  16 #include <linux/slab.h>
  17 #include <linux/string.h>
  18
  19 #include <media/v4l2-clk.h>
  20 #include <media/v4l2-subdev.h>
  21
  22 static DEFINE_MUTEX(clk_lock);
  23 static LIST_HEAD(clk_list);
  24
  25 static struct v4l2_clk *v4l2_clk_find(const char *dev_id)
  26 {
  27         struct v4l2_clk *clk;
  28
  29         list_for_each_entry(clk, &clk_list, list)
  30                 if (!strcmp(dev_id, clk->dev_id))
  31                         return clk;
  32
  33         return ERR_PTR(-ENODEV);
  34 }
  35
  36 struct v4l2_clk *v4l2_clk_get(struct device *dev, const char *id)
  37 {
  38         struct v4l2_clk *clk;
  39         struct clk *ccf_clk = clk_get(dev, id);
  40         char clk_name[V4L2_CLK_NAME_SIZE];
  41
  42         if (PTR_ERR(ccf_clk) == -EPROBE_DEFER)
  43                 return ERR_PTR(-EPROBE_DEFER);
  44
  45         if (!IS_ERR_OR_NULL(ccf_clk)) {
  46                 clk = kzalloc(sizeof(*clk), GFP_KERNEL);
  47                 if (!clk) {
  48                         clk_put(ccf_clk);
  49                         return ERR_PTR(-ENOMEM);
  50                 }
  51                 clk->clk = ccf_clk;
  52
  53                 return clk;
  54         }
  55
  56         mutex_lock(&clk_lock);
  57         clk = v4l2_clk_find(dev_name(dev));
  58
  59         /* if dev_name is not found, try use the OF name to find again  */
  60         if (PTR_ERR(clk) == -ENODEV && dev->of_node) {
  61                 v4l2_clk_name_of(clk_name, sizeof(clk_name), dev->of_node);
  62                 clk = v4l2_clk_find(clk_name);
  63         }
  64
  65         if (!IS_ERR(clk))
  66                 atomic_inc(&clk->use_count);
  67         mutex_unlock(&clk_lock);
  68
  69         return clk;
  70 }
  71 EXPORT_SYMBOL(v4l2_clk_get);
  72
  73 void v4l2_clk_put(struct v4l2_clk *clk)
  74 {
  75         struct v4l2_clk *tmp;
  76
  77         if (IS_ERR(clk))
  78                 return;
  79
  80         if (clk->clk) {
  81                 clk_put(clk->clk);
  82                 kfree(clk);
  83                 return;
  84         }
  85
  86         mutex_lock(&clk_lock);
  87
  88         list_for_each_entry(tmp, &clk_list, list)
  89                 if (tmp == clk)
  90                         atomic_dec(&clk->use_count);
  91
  92         mutex_unlock(&clk_lock);
  93 }
  94 EXPORT_SYMBOL(v4l2_clk_put);
  95
  96 static int v4l2_clk_lock_driver(struct v4l2_clk *clk)
  97 {
  98         struct v4l2_clk *tmp;
  99         int ret = -ENODEV;
 100
 101         mutex_lock(&clk_lock);
 102
 103         list_for_each_entry(tmp, &clk_list, list)
 104                 if (tmp == clk) {
 105                         ret = !try_module_get(clk->ops->owner);
 106                         if (ret)
 107                                 ret = -EFAULT;
 108                         break;
 109                 }
 110
 111         mutex_unlock(&clk_lock);
 112
 113         return ret;
 114 }
 115
 116 static void v4l2_clk_unlock_driver(struct v4l2_clk *clk)
 117 {
 118         module_put(clk->ops->owner);
 119 }
 120
 121 int v4l2_clk_enable(struct v4l2_clk *clk)
 122 {
 123         int ret;
 124
 125         if (clk->clk)
 126                 return clk_prepare_enable(clk->clk);
 127
 128         ret = v4l2_clk_lock_driver(clk);
 129         if (ret < 0)
 130                 return ret;
 131
 132         mutex_lock(&clk->lock);
 133
 134         if (++clk->enable == 1 && clk->ops->enable) {
 135                 ret = clk->ops->enable(clk);
 136                 if (ret < 0)
 137                         clk->enable--;
 138         }
 139
 140         mutex_unlock(&clk->lock);
 141
 142         return ret;
 143 }
 144 EXPORT_SYMBOL(v4l2_clk_enable);
 145
 146 /*
 147  * You might Oops if you try to disabled a disabled clock, because then the
 148  * driver isn't locked and could have been unloaded by now, so, don't do that
 149  */
 150 void v4l2_clk_disable(struct v4l2_clk *clk)
 151 {
 152         int enable;
 153
 154         if (clk->clk)
 155                 return clk_disable_unprepare(clk->clk);
 156
 157         mutex_lock(&clk->lock);
 158
 159         enable = --clk->enable;
 160         if (WARN(enable < 0, "Unbalanced %s() on %s!\n", __func__,
 161                  clk->dev_id))
 162                 clk->enable++;
 163         else if (!enable && clk->ops->disable)
 164                 clk->ops->disable(clk);
 165
 166         mutex_unlock(&clk->lock);
 167
 168         v4l2_clk_unlock_driver(clk);
 169 }
 170 EXPORT_SYMBOL(v4l2_clk_disable);
 171
 172 unsigned long v4l2_clk_get_rate(struct v4l2_clk *clk)
 173 {
 174         int ret;
 175
 176         if (clk->clk)
 177                 return clk_get_rate(clk->clk);
 178
 179         ret = v4l2_clk_lock_driver(clk);
 180         if (ret < 0)
 181                 return ret;
 182
 183         mutex_lock(&clk->lock);
 184         if (!clk->ops->get_rate)
 185                 ret = -ENOSYS;
 186         else
 187                 ret = clk->ops->get_rate(clk);
 188         mutex_unlock(&clk->lock);
 189
 190         v4l2_clk_unlock_driver(clk);
 191
 192         return ret;
 193 }
 194 EXPORT_SYMBOL(v4l2_clk_get_rate);
 195
 196 int v4l2_clk_set_rate(struct v4l2_clk *clk, unsigned long rate)
 197 {
 198         int ret;
 199
 200         if (clk->clk) {
 201                 long r = clk_round_rate(clk->clk, rate);
 202                 if (r < 0)
 203                         return r;
 204                 return clk_set_rate(clk->clk, r);
 205         }
 206
 207         ret = v4l2_clk_lock_driver(clk);
 208
 209         if (ret < 0)
 210                 return ret;
 211
 212         mutex_lock(&clk->lock);
 213         if (!clk->ops->set_rate)
 214                 ret = -ENOSYS;
 215         else
 216                 ret = clk->ops->set_rate(clk, rate);
 217         mutex_unlock(&clk->lock);
 218
 219         v4l2_clk_unlock_driver(clk);
 220
 221         return ret;
 222 }
 223 EXPORT_SYMBOL(v4l2_clk_set_rate);
 224
 225 struct v4l2_clk *v4l2_clk_register(const struct v4l2_clk_ops *ops,
 226                                    const char *dev_id,
 227                                    void *priv)
 228 {
 229         struct v4l2_clk *clk;
 230         int ret;
 231
 232         if (!ops || !dev_id)
 233                 return ERR_PTR(-EINVAL);
 234
 235         clk = kzalloc(sizeof(struct v4l2_clk), GFP_KERNEL);
 236         if (!clk)
 237                 return ERR_PTR(-ENOMEM);
 238
 239         clk->dev_id = kstrdup(dev_id, GFP_KERNEL);
 240         if (!clk->dev_id) {
 241                 ret = -ENOMEM;
 242                 goto ealloc;
 243         }
 244         clk->ops = ops;
 245         clk->priv = priv;
 246         atomic_set(&clk->use_count, 0);
 247         mutex_init(&clk->lock);
 248
 249         mutex_lock(&clk_lock);
 250         if (!IS_ERR(v4l2_clk_find(dev_id))) {
 251                 mutex_unlock(&clk_lock);
 252                 ret = -EEXIST;
 253                 goto eexist;
 254         }
 255         list_add_tail(&clk->list, &clk_list);
 256         mutex_unlock(&clk_lock);
 257
 258         return clk;
 259
 260 eexist:
 261 ealloc:
 262         kfree(clk->dev_id);
 263         kfree(clk);
 264         return ERR_PTR(ret);
 265 }
 266 EXPORT_SYMBOL(v4l2_clk_register);
 267
 268 void v4l2_clk_unregister(struct v4l2_clk *clk)
 269 {
 270         if (WARN(atomic_read(&clk->use_count),
 271                  "%s(): Refusing to unregister ref-counted %s clock!\n",
 272                  __func__, clk->dev_id))
 273                 return;
 274
 275         mutex_lock(&clk_lock);
 276         list_del(&clk->list);
 277         mutex_unlock(&clk_lock);
 278
 279         kfree(clk->dev_id);
 280         kfree(clk);
 281 }
 282 EXPORT_SYMBOL(v4l2_clk_unregister);
 283
 284 struct v4l2_clk_fixed {
 285         unsigned long rate;
 286         struct v4l2_clk_ops ops;
 287 };
 288
 289 static unsigned long fixed_get_rate(struct v4l2_clk *clk)
 290 {
 291         struct v4l2_clk_fixed *priv = clk->priv;
 292         return priv->rate;
 293 }
 294
 295 struct v4l2_clk *__v4l2_clk_register_fixed(const char *dev_id,
 296                                 unsigned long rate, struct module *owner)
 297 {
 298         struct v4l2_clk *clk;
 299         struct v4l2_clk_fixed *priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 300
 301         if (!priv)
 302                 return ERR_PTR(-ENOMEM);
 303
 304         priv->rate = rate;
 305         priv->ops.get_rate = fixed_get_rate;
 306         priv->ops.owner = owner;
 307
 308         clk = v4l2_clk_register(&priv->ops, dev_id, priv);
 309         if (IS_ERR(clk))
 310                 kfree(priv);
 311
 312         return clk;
 313 }
 314 EXPORT_SYMBOL(__v4l2_clk_register_fixed);
 315
 316 void v4l2_clk_unregister_fixed(struct v4l2_clk *clk)
 317 {
 318         kfree(clk->priv);
 319         v4l2_clk_unregister(clk);
 320 }
 321 EXPORT_SYMBOL(v4l2_clk_unregister_fixed);