drivers/media/cec/cec-core.c

   1 /*
   2  * cec-core.c - HDMI Consumer Electronics Control framework - Core
   3  *
   4  * Copyright 2016 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
   5  *
   6  * This program is free software; you may redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2 of the License.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  11  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  12  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  13  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  14  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  15  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  16  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  17  * SOFTWARE.
  18  */
  19
  20 #include <linux/errno.h>
  21 #include <linux/init.h>
  22 #include <linux/module.h>
  23 #include <linux/kernel.h>
  24 #include <linux/kmod.h>
  25 #include <linux/slab.h>
  26 #include <linux/mm.h>
  27 #include <linux/string.h>
  28 #include <linux/types.h>
  29
  30 #include "cec-priv.h"
  31
  32 #define CEC_NUM_DEVICES 256
  33 #define CEC_NAME        "cec"
  34
  35 int cec_debug;
  36 module_param_named(debug, cec_debug, int, 0644);
  37 MODULE_PARM_DESC(debug, "debug level (0-2)");
  38
  39 static dev_t cec_dev_t;
  40
  41 /* Active devices */
  42 static DEFINE_MUTEX(cec_devnode_lock);
  43 static DECLARE_BITMAP(cec_devnode_nums, CEC_NUM_DEVICES);
  44
  45 static struct dentry *top_cec_dir;
  46
  47 /* dev to cec_devnode */
  48 #define to_cec_devnode(cd) container_of(cd, struct cec_devnode, dev)
  49
  50 int cec_get_device(struct cec_devnode *devnode)
  51 {
  52         /*
  53          * Check if the cec device is available. This needs to be done with
  54          * the devnode->lock held to prevent an open/unregister race:
  55          * without the lock, the device could be unregistered and freed between
  56          * the devnode->registered check and get_device() calls, leading to
  57          * a crash.
  58          */
  59         mutex_lock(&devnode->lock);
  60         /*
  61          * return ENXIO if the cec device has been removed
  62          * already or if it is not registered anymore.
  63          */
  64         if (!devnode->registered) {
  65                 mutex_unlock(&devnode->lock);
  66                 return -ENXIO;
  67         }
  68         /* and increase the device refcount */
  69         get_device(&devnode->dev);
  70         mutex_unlock(&devnode->lock);
  71         return 0;
  72 }
  73
  74 void cec_put_device(struct cec_devnode *devnode)
  75 {
  76         put_device(&devnode->dev);
  77 }
  78
  79 /* Called when the last user of the cec device exits. */
  80 static void cec_devnode_release(struct device *cd)
  81 {
  82         struct cec_devnode *devnode = to_cec_devnode(cd);
  83
  84         mutex_lock(&cec_devnode_lock);
  85         /* Mark device node number as free */
  86         clear_bit(devnode->minor, cec_devnode_nums);
  87         mutex_unlock(&cec_devnode_lock);
  88
  89         cec_delete_adapter(to_cec_adapter(devnode));
  90 }
  91
  92 static struct bus_type cec_bus_type = {
  93         .name = CEC_NAME,
  94 };
  95
  96 /*
  97  * Register a cec device node
  98  *
  99  * The registration code assigns minor numbers and registers the new device node
 100  * with the kernel. An error is returned if no free minor number can be found,
 101  * or if the registration of the device node fails.
 102  *
 103  * Zero is returned on success.
 104  *
 105  * Note that if the cec_devnode_register call fails, the release() callback of
 106  * the cec_devnode structure is *not* called, so the caller is responsible for
 107  * freeing any data.
 108  */
 109 static int __must_check cec_devnode_register(struct cec_devnode *devnode,
 110                                              struct module *owner)
 111 {
 112         int minor;
 113         int ret;
 114
 115         /* Part 1: Find a free minor number */
 116         mutex_lock(&cec_devnode_lock);
 117         minor = find_next_zero_bit(cec_devnode_nums, CEC_NUM_DEVICES, 0);
 118         if (minor == CEC_NUM_DEVICES) {
 119                 mutex_unlock(&cec_devnode_lock);
 120                 pr_err("could not get a free minor\n");
 121                 return -ENFILE;
 122         }
 123
 124         set_bit(minor, cec_devnode_nums);
 125         mutex_unlock(&cec_devnode_lock);
 126
 127         devnode->minor = minor;
 128         devnode->dev.bus = &cec_bus_type;
 129         devnode->dev.devt = MKDEV(MAJOR(cec_dev_t), minor);
 130         devnode->dev.release = cec_devnode_release;
 131         dev_set_name(&devnode->dev, "cec%d", devnode->minor);
 132         device_initialize(&devnode->dev);
 133
 134         /* Part 2: Initialize and register the character device */
 135         cdev_init(&devnode->cdev, &cec_devnode_fops);
 136         devnode->cdev.owner = owner;
 137
 138         ret = cdev_device_add(&devnode->cdev, &devnode->dev);
 139         if (ret) {
 140                 pr_err("%s: cdev_device_add failed\n", __func__);
 141                 goto clr_bit;
 142         }
 143
 144         devnode->registered = true;
 145         return 0;
 146
 147 clr_bit:
 148         mutex_lock(&cec_devnode_lock);
 149         clear_bit(devnode->minor, cec_devnode_nums);
 150         mutex_unlock(&cec_devnode_lock);
 151         return ret;
 152 }
 153
 154 /*
 155  * Unregister a cec device node
 156  *
 157  * This unregisters the passed device. Future open calls will be met with
 158  * errors.
 159  *
 160  * This function can safely be called if the device node has never been
 161  * registered or has already been unregistered.
 162  */
 163 static void cec_devnode_unregister(struct cec_adapter *adap)
 164 {
 165         struct cec_devnode *devnode = &adap->devnode;
 166         struct cec_fh *fh;
 167
 168         mutex_lock(&devnode->lock);
 169
 170         /* Check if devnode was never registered or already unregistered */
 171         if (!devnode->registered || devnode->unregistered) {
 172                 mutex_unlock(&devnode->lock);
 173                 return;
 174         }
 175
 176         list_for_each_entry(fh, &devnode->fhs, list)
 177                 wake_up_interruptible(&fh->wait);
 178
 179         devnode->registered = false;
 180         devnode->unregistered = true;
 181         mutex_unlock(&devnode->lock);
 182
 183         mutex_lock(&adap->lock);
 184         __cec_s_phys_addr(adap, CEC_PHYS_ADDR_INVALID, false);
 185         __cec_s_log_addrs(adap, NULL, false);
 186         mutex_unlock(&adap->lock);
 187
 188         cdev_device_del(&devnode->cdev, &devnode->dev);
 189         put_device(&devnode->dev);
 190 }
 191
 192 #ifdef CONFIG_CEC_NOTIFIER
 193 static void cec_cec_notify(struct cec_adapter *adap, u16 pa)
 194 {
 195         cec_s_phys_addr(adap, pa, false);
 196 }
 197
 198 void cec_register_cec_notifier(struct cec_adapter *adap,
 199                                struct cec_notifier *notifier)
 200 {
 201         if (WARN_ON(!cec_is_registered(adap)))
 202                 return;
 203
 204         adap->notifier = notifier;
 205         cec_notifier_register(adap->notifier, adap, cec_cec_notify);
 206 }
 207 EXPORT_SYMBOL_GPL(cec_register_cec_notifier);
 208 #endif
 209
 210 struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops,
 211                                          void *priv, const char *name, u32 caps,
 212                                          u8 available_las)
 213 {
 214         struct cec_adapter *adap;
 215         int res;
 216
 217 #ifndef CONFIG_MEDIA_CEC_RC
 218         caps &= ~CEC_CAP_RC;
 219 #endif
 220
 221         if (WARN_ON(!caps))
 222                 return ERR_PTR(-EINVAL);
 223         if (WARN_ON(!ops))
 224                 return ERR_PTR(-EINVAL);
 225         if (WARN_ON(!available_las || available_las > CEC_MAX_LOG_ADDRS))
 226                 return ERR_PTR(-EINVAL);
 227         adap = kzalloc(sizeof(*adap), GFP_KERNEL);
 228         if (!adap)
 229                 return ERR_PTR(-ENOMEM);
 230         strlcpy(adap->name, name, sizeof(adap->name));
 231         adap->phys_addr = CEC_PHYS_ADDR_INVALID;
 232         adap->cec_pin_is_high = true;
 233         adap->log_addrs.cec_version = CEC_OP_CEC_VERSION_2_0;
 234         adap->log_addrs.vendor_id = CEC_VENDOR_ID_NONE;
 235         adap->capabilities = caps;
 236         adap->needs_hpd = caps & CEC_CAP_NEEDS_HPD;
 237         adap->available_log_addrs = available_las;
 238         adap->sequence = 0;
 239         adap->ops = ops;
 240         adap->priv = priv;
 241         memset(adap->phys_addrs, 0xff, sizeof(adap->phys_addrs));
 242         mutex_init(&adap->lock);
 243         INIT_LIST_HEAD(&adap->transmit_queue);
 244         INIT_LIST_HEAD(&adap->wait_queue);
 245         init_waitqueue_head(&adap->kthread_waitq);
 246
 247         /* adap->devnode initialization */
 248         INIT_LIST_HEAD(&adap->devnode.fhs);
 249         mutex_init(&adap->devnode.lock);
 250
 251         adap->kthread = kthread_run(cec_thread_func, adap, "cec-%s", name);
 252         if (IS_ERR(adap->kthread)) {
 253                 pr_err("cec-%s: kernel_thread() failed\n", name);
 254                 res = PTR_ERR(adap->kthread);
 255                 kfree(adap);
 256                 return ERR_PTR(res);
 257         }
 258
 259 #ifdef CONFIG_MEDIA_CEC_RC
 260         if (!(caps & CEC_CAP_RC))
 261                 return adap;
 262
 263         /* Prepare the RC input device */
 264         adap->rc = rc_allocate_device(RC_DRIVER_SCANCODE);
 265         if (!adap->rc) {
 266                 pr_err("cec-%s: failed to allocate memory for rc_dev\n",
 267                        name);
 268                 kthread_stop(adap->kthread);
 269                 kfree(adap);
 270                 return ERR_PTR(-ENOMEM);
 271         }
 272
 273         snprintf(adap->device_name, sizeof(adap->device_name),
 274                  "RC for %s", name);
 275         snprintf(adap->input_phys, sizeof(adap->input_phys),
 276                  "%s/input0", name);
 277
 278         adap->rc->device_name = adap->device_name;
 279         adap->rc->input_phys = adap->input_phys;
 280         adap->rc->input_id.bustype = BUS_CEC;
 281         adap->rc->input_id.vendor = 0;
 282         adap->rc->input_id.product = 0;
 283         adap->rc->input_id.version = 1;
 284         adap->rc->driver_name = CEC_NAME;
 285         adap->rc->allowed_protocols = RC_PROTO_BIT_CEC;
 286         adap->rc->priv = adap;
 287         adap->rc->map_name = RC_MAP_CEC;
 288         adap->rc->timeout = MS_TO_NS(100);
 289 #endif
 290         return adap;
 291 }
 292 EXPORT_SYMBOL_GPL(cec_allocate_adapter);
 293
 294 int cec_register_adapter(struct cec_adapter *adap,
 295                          struct device *parent)
 296 {
 297         int res;
 298
 299         if (IS_ERR_OR_NULL(adap))
 300                 return 0;
 301
 302         if (WARN_ON(!parent))
 303                 return -EINVAL;
 304
 305         adap->owner = parent->driver->owner;
 306         adap->devnode.dev.parent = parent;
 307
 308 #ifdef CONFIG_MEDIA_CEC_RC
 309         if (adap->capabilities & CEC_CAP_RC) {
 310                 adap->rc->dev.parent = parent;
 311                 res = rc_register_device(adap->rc);
 312
 313                 if (res) {
 314                         pr_err("cec-%s: failed to prepare input device\n",
 315                                adap->name);
 316                         rc_free_device(adap->rc);
 317                         adap->rc = NULL;
 318                         return res;
 319                 }
 320         }
 321 #endif
 322
 323         res = cec_devnode_register(&adap->devnode, adap->owner);
 324         if (res) {
 325 #ifdef CONFIG_MEDIA_CEC_RC
 326                 /* Note: rc_unregister also calls rc_free */
 327                 rc_unregister_device(adap->rc);
 328                 adap->rc = NULL;
 329 #endif
 330                 return res;
 331         }
 332
 333         dev_set_drvdata(&adap->devnode.dev, adap);
 334 #ifdef CONFIG_DEBUG_FS
 335         if (!top_cec_dir)
 336                 return 0;
 337
 338         adap->cec_dir = debugfs_create_dir(dev_name(&adap->devnode.dev), top_cec_dir);
 339         if (IS_ERR_OR_NULL(adap->cec_dir)) {
 340                 pr_warn("cec-%s: Failed to create debugfs dir\n", adap->name);
 341                 return 0;
 342         }
 343         adap->status_file = debugfs_create_devm_seqfile(&adap->devnode.dev,
 344                 "status", adap->cec_dir, cec_adap_status);
 345         if (IS_ERR_OR_NULL(adap->status_file)) {
 346                 pr_warn("cec-%s: Failed to create status file\n", adap->name);
 347                 debugfs_remove_recursive(adap->cec_dir);
 348                 adap->cec_dir = NULL;
 349         }
 350 #endif
 351         return 0;
 352 }
 353 EXPORT_SYMBOL_GPL(cec_register_adapter);
 354
 355 void cec_unregister_adapter(struct cec_adapter *adap)
 356 {
 357         if (IS_ERR_OR_NULL(adap))
 358                 return;
 359
 360 #ifdef CONFIG_MEDIA_CEC_RC
 361         /* Note: rc_unregister also calls rc_free */
 362         rc_unregister_device(adap->rc);
 363         adap->rc = NULL;
 364 #endif
 365         debugfs_remove_recursive(adap->cec_dir);
 366 #ifdef CONFIG_CEC_NOTIFIER
 367         if (adap->notifier)
 368                 cec_notifier_unregister(adap->notifier);
 369 #endif
 370         cec_devnode_unregister(adap);
 371 }
 372 EXPORT_SYMBOL_GPL(cec_unregister_adapter);
 373
 374 void cec_delete_adapter(struct cec_adapter *adap)
 375 {
 376         if (IS_ERR_OR_NULL(adap))
 377                 return;
 378         kthread_stop(adap->kthread);
 379         if (adap->kthread_config)
 380                 kthread_stop(adap->kthread_config);
 381         if (adap->ops->adap_free)
 382                 adap->ops->adap_free(adap);
 383 #ifdef CONFIG_MEDIA_CEC_RC
 384         rc_free_device(adap->rc);
 385 #endif
 386         kfree(adap);
 387 }
 388 EXPORT_SYMBOL_GPL(cec_delete_adapter);
 389
 390 /*
 391  *      Initialise cec for linux
 392  */
 393 static int __init cec_devnode_init(void)
 394 {
 395         int ret = alloc_chrdev_region(&cec_dev_t, 0, CEC_NUM_DEVICES, CEC_NAME);
 396
 397         if (ret < 0) {
 398                 pr_warn("cec: unable to allocate major\n");
 399                 return ret;
 400         }
 401
 402 #ifdef CONFIG_DEBUG_FS
 403         top_cec_dir = debugfs_create_dir("cec", NULL);
 404         if (IS_ERR_OR_NULL(top_cec_dir)) {
 405                 pr_warn("cec: Failed to create debugfs cec dir\n");
 406                 top_cec_dir = NULL;
 407         }
 408 #endif
 409
 410         ret = bus_register(&cec_bus_type);
 411         if (ret < 0) {
 412                 unregister_chrdev_region(cec_dev_t, CEC_NUM_DEVICES);
 413                 pr_warn("cec: bus_register failed\n");
 414                 return -EIO;
 415         }
 416
 417         return 0;
 418 }
 419
 420 static void __exit cec_devnode_exit(void)
 421 {
 422         debugfs_remove_recursive(top_cec_dir);
 423         bus_unregister(&cec_bus_type);
 424         unregister_chrdev_region(cec_dev_t, CEC_NUM_DEVICES);
 425 }
 426
 427 subsys_initcall(cec_devnode_init);
 428 module_exit(cec_devnode_exit)
 429
 430 MODULE_AUTHOR("Hans Verkuil <hans.verkuil@cisco.com>");
 431 MODULE_DESCRIPTION("Device node registration for cec drivers");
 432 MODULE_LICENSE("GPL");