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

   1 /*
   2  * V4L2 asynchronous subdevice registration API
   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/device.h>
  12 #include <linux/err.h>
  13 #include <linux/i2c.h>
  14 #include <linux/list.h>
  15 #include <linux/module.h>
  16 #include <linux/mutex.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/slab.h>
  19 #include <linux/types.h>
  20
  21 #include <media/v4l2-async.h>
  22 #include <media/v4l2-device.h>
  23 #include <media/v4l2-subdev.h>
  24
  25 static bool match_i2c(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
  26 {
  27 #if IS_ENABLED(CONFIG_I2C)
  28         struct i2c_client *client = i2c_verify_client(sd->dev);
  29         return client &&
  30                 asd->match.i2c.adapter_id == client->adapter->nr &&
  31                 asd->match.i2c.address == client->addr;
  32 #else
  33         return false;
  34 #endif
  35 }
  36
  37 static bool match_devname(struct v4l2_subdev *sd,
  38                           struct v4l2_async_subdev *asd)
  39 {
  40         return !strcmp(asd->match.device_name.name, dev_name(sd->dev));
  41 }
  42
  43 static bool match_of(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
  44 {
  45         return sd->of_node == asd->match.of.node;
  46 }
  47
  48 static bool match_custom(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
  49 {
  50         if (!asd->match.custom.match)
  51                 /* Match always */
  52                 return true;
  53
  54         return asd->match.custom.match(sd->dev, asd);
  55 }
  56
  57 static LIST_HEAD(subdev_list);
  58 static LIST_HEAD(notifier_list);
  59 static DEFINE_MUTEX(list_lock);
  60
  61 static struct v4l2_async_subdev *v4l2_async_belongs(struct v4l2_async_notifier *notifier,
  62                                                     struct v4l2_subdev *sd)
  63 {
  64         bool (*match)(struct v4l2_subdev *, struct v4l2_async_subdev *);
  65         struct v4l2_async_subdev *asd;
  66
  67         list_for_each_entry(asd, &notifier->waiting, list) {
  68                 /* bus_type has been verified valid before */
  69                 switch (asd->match_type) {
  70                 case V4L2_ASYNC_MATCH_CUSTOM:
  71                         match = match_custom;
  72                         break;
  73                 case V4L2_ASYNC_MATCH_DEVNAME:
  74                         match = match_devname;
  75                         break;
  76                 case V4L2_ASYNC_MATCH_I2C:
  77                         match = match_i2c;
  78                         break;
  79                 case V4L2_ASYNC_MATCH_OF:
  80                         match = match_of;
  81                         break;
  82                 default:
  83                         /* Cannot happen, unless someone breaks us */
  84                         WARN_ON(true);
  85                         return NULL;
  86                 }
  87
  88                 /* match cannot be NULL here */
  89                 if (match(sd, asd))
  90                         return asd;
  91         }
  92
  93         return NULL;
  94 }
  95
  96 static int v4l2_async_test_notify(struct v4l2_async_notifier *notifier,
  97                                   struct v4l2_subdev *sd,
  98                                   struct v4l2_async_subdev *asd)
  99 {
 100         int ret;
 101
 102         /* Remove from the waiting list */
 103         list_del(&asd->list);
 104         sd->asd = asd;
 105         sd->notifier = notifier;
 106
 107         if (notifier->bound) {
 108                 ret = notifier->bound(notifier, sd, asd);
 109                 if (ret < 0)
 110                         return ret;
 111         }
 112         /* Move from the global subdevice list to notifier's done */
 113         list_move(&sd->async_list, &notifier->done);
 114
 115         ret = v4l2_device_register_subdev(notifier->v4l2_dev, sd);
 116         if (ret < 0) {
 117                 if (notifier->unbind)
 118                         notifier->unbind(notifier, sd, asd);
 119                 return ret;
 120         }
 121
 122         if (list_empty(&notifier->waiting) && notifier->complete)
 123                 return notifier->complete(notifier);
 124
 125         return 0;
 126 }
 127
 128 static void v4l2_async_cleanup(struct v4l2_subdev *sd)
 129 {
 130         v4l2_device_unregister_subdev(sd);
 131         /* Subdevice driver will reprobe and put the subdev back onto the list */
 132         list_del_init(&sd->async_list);
 133         sd->asd = NULL;
 134         sd->dev = NULL;
 135 }
 136
 137 int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
 138                                  struct v4l2_async_notifier *notifier)
 139 {
 140         struct v4l2_subdev *sd, *tmp;
 141         struct v4l2_async_subdev *asd;
 142         int i;
 143
 144         if (!notifier->num_subdevs || notifier->num_subdevs > V4L2_MAX_SUBDEVS)
 145                 return -EINVAL;
 146
 147         notifier->v4l2_dev = v4l2_dev;
 148         INIT_LIST_HEAD(&notifier->waiting);
 149         INIT_LIST_HEAD(&notifier->done);
 150
 151         for (i = 0; i < notifier->num_subdevs; i++) {
 152                 asd = notifier->subdevs[i];
 153
 154                 switch (asd->match_type) {
 155                 case V4L2_ASYNC_MATCH_CUSTOM:
 156                 case V4L2_ASYNC_MATCH_DEVNAME:
 157                 case V4L2_ASYNC_MATCH_I2C:
 158                 case V4L2_ASYNC_MATCH_OF:
 159                         break;
 160                 default:
 161                         dev_err(notifier->v4l2_dev ? notifier->v4l2_dev->dev : NULL,
 162                                 "Invalid match type %u on %p\n",
 163                                 asd->match_type, asd);
 164                         return -EINVAL;
 165                 }
 166                 list_add_tail(&asd->list, &notifier->waiting);
 167         }
 168
 169         mutex_lock(&list_lock);
 170
 171         /* Keep also completed notifiers on the list */
 172         list_add(&notifier->list, &notifier_list);
 173
 174         list_for_each_entry_safe(sd, tmp, &subdev_list, async_list) {
 175                 int ret;
 176
 177                 asd = v4l2_async_belongs(notifier, sd);
 178                 if (!asd)
 179                         continue;
 180
 181                 ret = v4l2_async_test_notify(notifier, sd, asd);
 182                 if (ret < 0) {
 183                         mutex_unlock(&list_lock);
 184                         return ret;
 185                 }
 186         }
 187
 188         mutex_unlock(&list_lock);
 189
 190         return 0;
 191 }
 192 EXPORT_SYMBOL(v4l2_async_notifier_register);
 193
 194 void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
 195 {
 196         struct v4l2_subdev *sd, *tmp;
 197         unsigned int notif_n_subdev = notifier->num_subdevs;
 198         unsigned int n_subdev = min(notif_n_subdev, V4L2_MAX_SUBDEVS);
 199         struct device **dev;
 200         int i = 0;
 201
 202         if (!notifier->v4l2_dev)
 203                 return;
 204
 205         dev = kmalloc(n_subdev * sizeof(*dev), GFP_KERNEL);
 206         if (!dev) {
 207                 dev_err(notifier->v4l2_dev->dev,
 208                         "Failed to allocate device cache!\n");
 209         }
 210
 211         mutex_lock(&list_lock);
 212
 213         list_del(&notifier->list);
 214
 215         list_for_each_entry_safe(sd, tmp, &notifier->done, async_list) {
 216                 struct device *d;
 217
 218                 d = get_device(sd->dev);
 219
 220                 v4l2_async_cleanup(sd);
 221
 222                 /* If we handled USB devices, we'd have to lock the parent too */
 223                 device_release_driver(d);
 224
 225                 if (notifier->unbind)
 226                         notifier->unbind(notifier, sd, sd->asd);
 227
 228                 /*
 229                  * Store device at the device cache, in order to call
 230                  * put_device() on the final step
 231                  */
 232                 if (dev)
 233                         dev[i++] = d;
 234                 else
 235                         put_device(d);
 236         }
 237
 238         mutex_unlock(&list_lock);
 239
 240         /*
 241          * Call device_attach() to reprobe devices
 242          *
 243          * NOTE: If dev allocation fails, i is 0, and the whole loop won't be
 244          * executed.
 245          */
 246         while (i--) {
 247                 struct device *d = dev[i];
 248
 249                 if (d && device_attach(d) < 0) {
 250                         const char *name = "(none)";
 251                         int lock = device_trylock(d);
 252
 253                         if (lock && d->driver)
 254                                 name = d->driver->name;
 255                         dev_err(d, "Failed to re-probe to %s\n", name);
 256                         if (lock)
 257                                 device_unlock(d);
 258                 }
 259                 put_device(d);
 260         }
 261         kfree(dev);
 262
 263         notifier->v4l2_dev = NULL;
 264
 265         /*
 266          * Don't care about the waiting list, it is initialised and populated
 267          * upon notifier registration.
 268          */
 269 }
 270 EXPORT_SYMBOL(v4l2_async_notifier_unregister);
 271
 272 int v4l2_async_register_subdev(struct v4l2_subdev *sd)
 273 {
 274         struct v4l2_async_notifier *notifier;
 275
 276         /*
 277          * No reference taken. The reference is held by the device
 278          * (struct v4l2_subdev.dev), and async sub-device does not
 279          * exist independently of the device at any point of time.
 280          */
 281         if (!sd->of_node && sd->dev)
 282                 sd->of_node = sd->dev->of_node;
 283
 284         mutex_lock(&list_lock);
 285
 286         INIT_LIST_HEAD(&sd->async_list);
 287
 288         list_for_each_entry(notifier, &notifier_list, list) {
 289                 struct v4l2_async_subdev *asd = v4l2_async_belongs(notifier, sd);
 290                 if (asd) {
 291                         int ret = v4l2_async_test_notify(notifier, sd, asd);
 292                         mutex_unlock(&list_lock);
 293                         return ret;
 294                 }
 295         }
 296
 297         /* None matched, wait for hot-plugging */
 298         list_add(&sd->async_list, &subdev_list);
 299
 300         mutex_unlock(&list_lock);
 301
 302         return 0;
 303 }
 304 EXPORT_SYMBOL(v4l2_async_register_subdev);
 305
 306 void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)
 307 {
 308         struct v4l2_async_notifier *notifier = sd->notifier;
 309
 310         if (!sd->asd) {
 311                 if (!list_empty(&sd->async_list))
 312                         v4l2_async_cleanup(sd);
 313                 return;
 314         }
 315
 316         mutex_lock(&list_lock);
 317
 318         list_add(&sd->asd->list, &notifier->waiting);
 319
 320         v4l2_async_cleanup(sd);
 321
 322         if (notifier->unbind)
 323                 notifier->unbind(notifier, sd, sd->asd);
 324
 325         mutex_unlock(&list_lock);
 326 }
 327 EXPORT_SYMBOL(v4l2_async_unregister_subdev);