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         /* Initialization */
 116         INIT_LIST_HEAD(&devnode->fhs);
 117         mutex_init(&devnode->lock);
 118
 119         /* Part 1: Find a free minor number */
 120         mutex_lock(&cec_devnode_lock);
 121         minor = find_next_zero_bit(cec_devnode_nums, CEC_NUM_DEVICES, 0);
 122         if (minor == CEC_NUM_DEVICES) {
 123                 mutex_unlock(&cec_devnode_lock);
 124                 pr_err("could not get a free minor\n");
 125                 return -ENFILE;
 126         }
 127
 128         set_bit(minor, cec_devnode_nums);
 129         mutex_unlock(&cec_devnode_lock);
 130
 131         devnode->minor = minor;
 132         devnode->dev.bus = &cec_bus_type;
 133         devnode->dev.devt = MKDEV(MAJOR(cec_dev_t), minor);
 134         devnode->dev.release = cec_devnode_release;
 135         dev_set_name(&devnode->dev, "cec%d", devnode->minor);
 136         device_initialize(&devnode->dev);
 137
 138         /* Part 2: Initialize and register the character device */
 139         cdev_init(&devnode->cdev, &cec_devnode_fops);
 140         devnode->cdev.kobj.parent = &devnode->dev.kobj;
 141         devnode->cdev.owner = owner;
 142
 143         ret = cdev_add(&devnode->cdev, devnode->dev.devt, 1);
 144         if (ret < 0) {
 145                 pr_err("%s: cdev_add failed\n", __func__);
 146                 goto clr_bit;
 147         }
 148
 149         ret = device_add(&devnode->dev);
 150         if (ret)
 151                 goto cdev_del;
 152
 153         devnode->registered = true;
 154         return 0;
 155
 156 cdev_del:
 157         cdev_del(&devnode->cdev);
 158 clr_bit:
 159         mutex_lock(&cec_devnode_lock);
 160         clear_bit(devnode->minor, cec_devnode_nums);
 161         mutex_unlock(&cec_devnode_lock);
 162         return ret;
 163 }
 164
 165 /*
 166  * Unregister a cec device node
 167  *
 168  * This unregisters the passed device. Future open calls will be met with
 169  * errors.
 170  *
 171  * This function can safely be called if the device node has never been
 172  * registered or has already been unregistered.
 173  */
 174 static void cec_devnode_unregister(struct cec_devnode *devnode)
 175 {
 176         struct cec_fh *fh;
 177
 178         mutex_lock(&devnode->lock);
 179
 180         /* Check if devnode was never registered or already unregistered */
 181         if (!devnode->registered || devnode->unregistered) {
 182                 mutex_unlock(&devnode->lock);
 183                 return;
 184         }
 185
 186         list_for_each_entry(fh, &devnode->fhs, list)
 187                 wake_up_interruptible(&fh->wait);
 188
 189         devnode->registered = false;
 190         devnode->unregistered = true;
 191         mutex_unlock(&devnode->lock);
 192
 193         device_del(&devnode->dev);
 194         cdev_del(&devnode->cdev);
 195         put_device(&devnode->dev);
 196 }
 197
 198 struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops,
 199                                          void *priv, const char *name, u32 caps,
 200                                          u8 available_las)
 201 {
 202         struct cec_adapter *adap;
 203         int res;
 204
 205         if (WARN_ON(!caps))
 206                 return ERR_PTR(-EINVAL);
 207         if (WARN_ON(!ops))
 208                 return ERR_PTR(-EINVAL);
 209         if (WARN_ON(!available_las || available_las > CEC_MAX_LOG_ADDRS))
 210                 return ERR_PTR(-EINVAL);
 211         adap = kzalloc(sizeof(*adap), GFP_KERNEL);
 212         if (!adap)
 213                 return ERR_PTR(-ENOMEM);
 214         strlcpy(adap->name, name, sizeof(adap->name));
 215         adap->phys_addr = CEC_PHYS_ADDR_INVALID;
 216         adap->log_addrs.cec_version = CEC_OP_CEC_VERSION_2_0;
 217         adap->log_addrs.vendor_id = CEC_VENDOR_ID_NONE;
 218         adap->capabilities = caps;
 219         adap->available_log_addrs = available_las;
 220         adap->sequence = 0;
 221         adap->ops = ops;
 222         adap->priv = priv;
 223         memset(adap->phys_addrs, 0xff, sizeof(adap->phys_addrs));
 224         mutex_init(&adap->lock);
 225         INIT_LIST_HEAD(&adap->transmit_queue);
 226         INIT_LIST_HEAD(&adap->wait_queue);
 227         init_waitqueue_head(&adap->kthread_waitq);
 228
 229         adap->kthread = kthread_run(cec_thread_func, adap, "cec-%s", name);
 230         if (IS_ERR(adap->kthread)) {
 231                 pr_err("cec-%s: kernel_thread() failed\n", name);
 232                 res = PTR_ERR(adap->kthread);
 233                 kfree(adap);
 234                 return ERR_PTR(res);
 235         }
 236
 237         if (!(caps & CEC_CAP_RC))
 238                 return adap;
 239
 240 #if IS_REACHABLE(CONFIG_RC_CORE)
 241         /* Prepare the RC input device */
 242         adap->rc = rc_allocate_device(RC_DRIVER_SCANCODE);
 243         if (!adap->rc) {
 244                 pr_err("cec-%s: failed to allocate memory for rc_dev\n",
 245                        name);
 246                 kthread_stop(adap->kthread);
 247                 kfree(adap);
 248                 return ERR_PTR(-ENOMEM);
 249         }
 250
 251         snprintf(adap->input_name, sizeof(adap->input_name),
 252                  "RC for %s", name);
 253         snprintf(adap->input_phys, sizeof(adap->input_phys),
 254                  "%s/input0", name);
 255
 256         adap->rc->input_name = adap->input_name;
 257         adap->rc->input_phys = adap->input_phys;
 258         adap->rc->input_id.bustype = BUS_CEC;
 259         adap->rc->input_id.vendor = 0;
 260         adap->rc->input_id.product = 0;
 261         adap->rc->input_id.version = 1;
 262         adap->rc->driver_name = CEC_NAME;
 263         adap->rc->allowed_protocols = RC_BIT_CEC;
 264         adap->rc->priv = adap;
 265         adap->rc->map_name = RC_MAP_CEC;
 266         adap->rc->timeout = MS_TO_NS(100);
 267 #else
 268         adap->capabilities &= ~CEC_CAP_RC;
 269 #endif
 270         return adap;
 271 }
 272 EXPORT_SYMBOL_GPL(cec_allocate_adapter);
 273
 274 int cec_register_adapter(struct cec_adapter *adap,
 275                          struct device *parent)
 276 {
 277         int res;
 278
 279         if (IS_ERR_OR_NULL(adap))
 280                 return 0;
 281
 282         if (WARN_ON(!parent))
 283                 return -EINVAL;
 284
 285         adap->owner = parent->driver->owner;
 286         adap->devnode.dev.parent = parent;
 287
 288 #if IS_REACHABLE(CONFIG_RC_CORE)
 289         if (adap->capabilities & CEC_CAP_RC) {
 290                 adap->rc->dev.parent = parent;
 291                 res = rc_register_device(adap->rc);
 292
 293                 if (res) {
 294                         pr_err("cec-%s: failed to prepare input device\n",
 295                                adap->name);
 296                         rc_free_device(adap->rc);
 297                         adap->rc = NULL;
 298                         return res;
 299                 }
 300         }
 301 #endif
 302
 303         res = cec_devnode_register(&adap->devnode, adap->owner);
 304         if (res) {
 305 #if IS_REACHABLE(CONFIG_RC_CORE)
 306                 /* Note: rc_unregister also calls rc_free */
 307                 rc_unregister_device(adap->rc);
 308                 adap->rc = NULL;
 309 #endif
 310                 return res;
 311         }
 312
 313         dev_set_drvdata(&adap->devnode.dev, adap);
 314 #ifdef CONFIG_MEDIA_CEC_DEBUG
 315         if (!top_cec_dir)
 316                 return 0;
 317
 318         adap->cec_dir = debugfs_create_dir(dev_name(&adap->devnode.dev), top_cec_dir);
 319         if (IS_ERR_OR_NULL(adap->cec_dir)) {
 320                 pr_warn("cec-%s: Failed to create debugfs dir\n", adap->name);
 321                 return 0;
 322         }
 323         adap->status_file = debugfs_create_devm_seqfile(&adap->devnode.dev,
 324                 "status", adap->cec_dir, cec_adap_status);
 325         if (IS_ERR_OR_NULL(adap->status_file)) {
 326                 pr_warn("cec-%s: Failed to create status file\n", adap->name);
 327                 debugfs_remove_recursive(adap->cec_dir);
 328                 adap->cec_dir = NULL;
 329         }
 330 #endif
 331         return 0;
 332 }
 333 EXPORT_SYMBOL_GPL(cec_register_adapter);
 334
 335 void cec_unregister_adapter(struct cec_adapter *adap)
 336 {
 337         if (IS_ERR_OR_NULL(adap))
 338                 return;
 339
 340 #if IS_REACHABLE(CONFIG_RC_CORE)
 341         /* Note: rc_unregister also calls rc_free */
 342         rc_unregister_device(adap->rc);
 343         adap->rc = NULL;
 344 #endif
 345         debugfs_remove_recursive(adap->cec_dir);
 346         cec_devnode_unregister(&adap->devnode);
 347 }
 348 EXPORT_SYMBOL_GPL(cec_unregister_adapter);
 349
 350 void cec_delete_adapter(struct cec_adapter *adap)
 351 {
 352         if (IS_ERR_OR_NULL(adap))
 353                 return;
 354         mutex_lock(&adap->lock);
 355         __cec_s_phys_addr(adap, CEC_PHYS_ADDR_INVALID, false);
 356         mutex_unlock(&adap->lock);
 357         kthread_stop(adap->kthread);
 358         if (adap->kthread_config)
 359                 kthread_stop(adap->kthread_config);
 360 #if IS_REACHABLE(CONFIG_RC_CORE)
 361         rc_free_device(adap->rc);
 362 #endif
 363         kfree(adap);
 364 }
 365 EXPORT_SYMBOL_GPL(cec_delete_adapter);
 366
 367 /*
 368  *      Initialise cec for linux
 369  */
 370 static int __init cec_devnode_init(void)
 371 {
 372         int ret;
 373
 374         pr_info("Linux cec interface: v0.10\n");
 375         ret = alloc_chrdev_region(&cec_dev_t, 0, CEC_NUM_DEVICES,
 376                                   CEC_NAME);
 377         if (ret < 0) {
 378                 pr_warn("cec: unable to allocate major\n");
 379                 return ret;
 380         }
 381
 382 #ifdef CONFIG_MEDIA_CEC_DEBUG
 383         top_cec_dir = debugfs_create_dir("cec", NULL);
 384         if (IS_ERR_OR_NULL(top_cec_dir)) {
 385                 pr_warn("cec: Failed to create debugfs cec dir\n");
 386                 top_cec_dir = NULL;
 387         }
 388 #endif
 389
 390         ret = bus_register(&cec_bus_type);
 391         if (ret < 0) {
 392                 unregister_chrdev_region(cec_dev_t, CEC_NUM_DEVICES);
 393                 pr_warn("cec: bus_register failed\n");
 394                 return -EIO;
 395         }
 396
 397         return 0;
 398 }
 399
 400 static void __exit cec_devnode_exit(void)
 401 {
 402         debugfs_remove_recursive(top_cec_dir);
 403         bus_unregister(&cec_bus_type);
 404         unregister_chrdev_region(cec_dev_t, CEC_NUM_DEVICES);
 405 }
 406
 407 subsys_initcall(cec_devnode_init);
 408 module_exit(cec_devnode_exit)
 409
 410 MODULE_AUTHOR("Hans Verkuil <hans.verkuil@cisco.com>");
 411 MODULE_DESCRIPTION("Device node registration for cec drivers");
 412 MODULE_LICENSE("GPL");