drivers/media/cec/cec-core.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * cec-core.c - HDMI Consumer Electronics Control framework - Core
   4  *
   5  * Copyright 2016 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
   6  */
   7
   8 #include <linux/errno.h>
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/kernel.h>
  12 #include <linux/kmod.h>
  13 #include <linux/slab.h>
  14 #include <linux/mm.h>
  15 #include <linux/string.h>
  16 #include <linux/types.h>
  17
  18 #include "cec-priv.h"
  19
  20 #define CEC_NUM_DEVICES 256
  21 #define CEC_NAME        "cec"
  22
  23 int cec_debug;
  24 module_param_named(debug, cec_debug, int, 0644);
  25 MODULE_PARM_DESC(debug, "debug level (0-2)");
  26
  27 static bool debug_phys_addr;
  28 module_param(debug_phys_addr, bool, 0644);
  29 MODULE_PARM_DESC(debug_phys_addr, "add CEC_CAP_PHYS_ADDR if set");
  30
  31 static dev_t cec_dev_t;
  32
  33 /* Active devices */
  34 static DEFINE_MUTEX(cec_devnode_lock);
  35 static DECLARE_BITMAP(cec_devnode_nums, CEC_NUM_DEVICES);
  36
  37 static struct dentry *top_cec_dir;
  38
  39 /* dev to cec_devnode */
  40 #define to_cec_devnode(cd) container_of(cd, struct cec_devnode, dev)
  41
  42 int cec_get_device(struct cec_devnode *devnode)
  43 {
  44         /*
  45          * Check if the cec device is available. This needs to be done with
  46          * the devnode->lock held to prevent an open/unregister race:
  47          * without the lock, the device could be unregistered and freed between
  48          * the devnode->registered check and get_device() calls, leading to
  49          * a crash.
  50          */
  51         mutex_lock(&devnode->lock);
  52         /*
  53          * return ENXIO if the cec device has been removed
  54          * already or if it is not registered anymore.
  55          */
  56         if (!devnode->registered) {
  57                 mutex_unlock(&devnode->lock);
  58                 return -ENXIO;
  59         }
  60         /* and increase the device refcount */
  61         get_device(&devnode->dev);
  62         mutex_unlock(&devnode->lock);
  63         return 0;
  64 }
  65
  66 void cec_put_device(struct cec_devnode *devnode)
  67 {
  68         put_device(&devnode->dev);
  69 }
  70
  71 /* Called when the last user of the cec device exits. */
  72 static void cec_devnode_release(struct device *cd)
  73 {
  74         struct cec_devnode *devnode = to_cec_devnode(cd);
  75
  76         mutex_lock(&cec_devnode_lock);
  77         /* Mark device node number as free */
  78         clear_bit(devnode->minor, cec_devnode_nums);
  79         mutex_unlock(&cec_devnode_lock);
  80
  81         cec_delete_adapter(to_cec_adapter(devnode));
  82 }
  83
  84 static struct bus_type cec_bus_type = {
  85         .name = CEC_NAME,
  86 };
  87
  88 /*
  89  * Register a cec device node
  90  *
  91  * The registration code assigns minor numbers and registers the new device node
  92  * with the kernel. An error is returned if no free minor number can be found,
  93  * or if the registration of the device node fails.
  94  *
  95  * Zero is returned on success.
  96  *
  97  * Note that if the cec_devnode_register call fails, the release() callback of
  98  * the cec_devnode structure is *not* called, so the caller is responsible for
  99  * freeing any data.
 100  */
 101 static int __must_check cec_devnode_register(struct cec_devnode *devnode,
 102                                              struct module *owner)
 103 {
 104         int minor;
 105         int ret;
 106
 107         /* Part 1: Find a free minor number */
 108         mutex_lock(&cec_devnode_lock);
 109         minor = find_next_zero_bit(cec_devnode_nums, CEC_NUM_DEVICES, 0);
 110         if (minor == CEC_NUM_DEVICES) {
 111                 mutex_unlock(&cec_devnode_lock);
 112                 pr_err("could not get a free minor\n");
 113                 return -ENFILE;
 114         }
 115
 116         set_bit(minor, cec_devnode_nums);
 117         mutex_unlock(&cec_devnode_lock);
 118
 119         devnode->minor = minor;
 120         devnode->dev.bus = &cec_bus_type;
 121         devnode->dev.devt = MKDEV(MAJOR(cec_dev_t), minor);
 122         devnode->dev.release = cec_devnode_release;
 123         dev_set_name(&devnode->dev, "cec%d", devnode->minor);
 124         device_initialize(&devnode->dev);
 125
 126         /* Part 2: Initialize and register the character device */
 127         cdev_init(&devnode->cdev, &cec_devnode_fops);
 128         devnode->cdev.owner = owner;
 129         kobject_set_name(&devnode->cdev.kobj, "cec%d", devnode->minor);
 130
 131         devnode->registered = true;
 132         ret = cdev_device_add(&devnode->cdev, &devnode->dev);
 133         if (ret) {
 134                 devnode->registered = false;
 135                 pr_err("%s: cdev_device_add failed\n", __func__);
 136                 goto clr_bit;
 137         }
 138
 139         return 0;
 140
 141 clr_bit:
 142         mutex_lock(&cec_devnode_lock);
 143         clear_bit(devnode->minor, cec_devnode_nums);
 144         mutex_unlock(&cec_devnode_lock);
 145         return ret;
 146 }
 147
 148 /*
 149  * Unregister a cec device node
 150  *
 151  * This unregisters the passed device. Future open calls will be met with
 152  * errors.
 153  *
 154  * This function can safely be called if the device node has never been
 155  * registered or has already been unregistered.
 156  */
 157 static void cec_devnode_unregister(struct cec_adapter *adap)
 158 {
 159         struct cec_devnode *devnode = &adap->devnode;
 160         struct cec_fh *fh;
 161
 162         mutex_lock(&devnode->lock);
 163
 164         /* Check if devnode was never registered or already unregistered */
 165         if (!devnode->registered || devnode->unregistered) {
 166                 mutex_unlock(&devnode->lock);
 167                 return;
 168         }
 169
 170         list_for_each_entry(fh, &devnode->fhs, list)
 171                 wake_up_interruptible(&fh->wait);
 172
 173         devnode->registered = false;
 174         devnode->unregistered = true;
 175         mutex_unlock(&devnode->lock);
 176
 177         mutex_lock(&adap->lock);
 178         __cec_s_phys_addr(adap, CEC_PHYS_ADDR_INVALID, false);
 179         __cec_s_log_addrs(adap, NULL, false);
 180         mutex_unlock(&adap->lock);
 181
 182         cdev_device_del(&devnode->cdev, &devnode->dev);
 183         put_device(&devnode->dev);
 184 }
 185
 186 #ifdef CONFIG_DEBUG_FS
 187 static ssize_t cec_error_inj_write(struct file *file,
 188         const char __user *ubuf, size_t count, loff_t *ppos)
 189 {
 190         struct seq_file *sf = file->private_data;
 191         struct cec_adapter *adap = sf->private;
 192         char *buf;
 193         char *line;
 194         char *p;
 195
 196         buf = memdup_user_nul(ubuf, min_t(size_t, PAGE_SIZE, count));
 197         if (IS_ERR(buf))
 198                 return PTR_ERR(buf);
 199         p = buf;
 200         while (p && *p) {
 201                 p = skip_spaces(p);
 202                 line = strsep(&p, "\n");
 203                 if (!*line || *line == '#')
 204                         continue;
 205                 if (!adap->ops->error_inj_parse_line(adap, line)) {
 206                         kfree(buf);
 207                         return -EINVAL;
 208                 }
 209         }
 210         kfree(buf);
 211         return count;
 212 }
 213
 214 static int cec_error_inj_show(struct seq_file *sf, void *unused)
 215 {
 216         struct cec_adapter *adap = sf->private;
 217
 218         return adap->ops->error_inj_show(adap, sf);
 219 }
 220
 221 static int cec_error_inj_open(struct inode *inode, struct file *file)
 222 {
 223         return single_open(file, cec_error_inj_show, inode->i_private);
 224 }
 225
 226 static const struct file_operations cec_error_inj_fops = {
 227         .open = cec_error_inj_open,
 228         .write = cec_error_inj_write,
 229         .read = seq_read,
 230         .llseek = seq_lseek,
 231         .release = single_release,
 232 };
 233 #endif
 234
 235 struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops,
 236                                          void *priv, const char *name, u32 caps,
 237                                          u8 available_las)
 238 {
 239         struct cec_adapter *adap;
 240         int res;
 241
 242 #ifndef CONFIG_MEDIA_CEC_RC
 243         caps &= ~CEC_CAP_RC;
 244 #endif
 245
 246         if (WARN_ON(!caps))
 247                 return ERR_PTR(-EINVAL);
 248         if (WARN_ON(!ops))
 249                 return ERR_PTR(-EINVAL);
 250         if (WARN_ON(!available_las || available_las > CEC_MAX_LOG_ADDRS))
 251                 return ERR_PTR(-EINVAL);
 252         adap = kzalloc(sizeof(*adap), GFP_KERNEL);
 253         if (!adap)
 254                 return ERR_PTR(-ENOMEM);
 255         strscpy(adap->name, name, sizeof(adap->name));
 256         adap->phys_addr = CEC_PHYS_ADDR_INVALID;
 257         adap->cec_pin_is_high = true;
 258         adap->log_addrs.cec_version = CEC_OP_CEC_VERSION_2_0;
 259         adap->log_addrs.vendor_id = CEC_VENDOR_ID_NONE;
 260         adap->capabilities = caps;
 261         if (debug_phys_addr)
 262                 adap->capabilities |= CEC_CAP_PHYS_ADDR;
 263         adap->needs_hpd = caps & CEC_CAP_NEEDS_HPD;
 264         adap->available_log_addrs = available_las;
 265         adap->sequence = 0;
 266         adap->ops = ops;
 267         adap->priv = priv;
 268         memset(adap->phys_addrs, 0xff, sizeof(adap->phys_addrs));
 269         mutex_init(&adap->lock);
 270         INIT_LIST_HEAD(&adap->transmit_queue);
 271         INIT_LIST_HEAD(&adap->wait_queue);
 272         init_waitqueue_head(&adap->kthread_waitq);
 273
 274         /* adap->devnode initialization */
 275         INIT_LIST_HEAD(&adap->devnode.fhs);
 276         mutex_init(&adap->devnode.lock);
 277
 278         adap->kthread = kthread_run(cec_thread_func, adap, "cec-%s", name);
 279         if (IS_ERR(adap->kthread)) {
 280                 pr_err("cec-%s: kernel_thread() failed\n", name);
 281                 res = PTR_ERR(adap->kthread);
 282                 kfree(adap);
 283                 return ERR_PTR(res);
 284         }
 285
 286 #ifdef CONFIG_MEDIA_CEC_RC
 287         if (!(caps & CEC_CAP_RC))
 288                 return adap;
 289
 290         /* Prepare the RC input device */
 291         adap->rc = rc_allocate_device(RC_DRIVER_SCANCODE);
 292         if (!adap->rc) {
 293                 pr_err("cec-%s: failed to allocate memory for rc_dev\n",
 294                        name);
 295                 kthread_stop(adap->kthread);
 296                 kfree(adap);
 297                 return ERR_PTR(-ENOMEM);
 298         }
 299
 300         snprintf(adap->input_phys, sizeof(adap->input_phys),
 301                  "%s/input0", adap->name);
 302
 303         adap->rc->device_name = adap->name;
 304         adap->rc->input_phys = adap->input_phys;
 305         adap->rc->input_id.bustype = BUS_CEC;
 306         adap->rc->input_id.vendor = 0;
 307         adap->rc->input_id.product = 0;
 308         adap->rc->input_id.version = 1;
 309         adap->rc->driver_name = CEC_NAME;
 310         adap->rc->allowed_protocols = RC_PROTO_BIT_CEC;
 311         adap->rc->priv = adap;
 312         adap->rc->map_name = RC_MAP_CEC;
 313         adap->rc->timeout = MS_TO_NS(550);
 314 #endif
 315         return adap;
 316 }
 317 EXPORT_SYMBOL_GPL(cec_allocate_adapter);
 318
 319 int cec_register_adapter(struct cec_adapter *adap,
 320                          struct device *parent)
 321 {
 322         int res;
 323
 324         if (IS_ERR_OR_NULL(adap))
 325                 return 0;
 326
 327         if (WARN_ON(!parent))
 328                 return -EINVAL;
 329
 330         adap->owner = parent->driver->owner;
 331         adap->devnode.dev.parent = parent;
 332
 333 #ifdef CONFIG_MEDIA_CEC_RC
 334         if (adap->capabilities & CEC_CAP_RC) {
 335                 adap->rc->dev.parent = parent;
 336                 res = rc_register_device(adap->rc);
 337
 338                 if (res) {
 339                         pr_err("cec-%s: failed to prepare input device\n",
 340                                adap->name);
 341                         rc_free_device(adap->rc);
 342                         adap->rc = NULL;
 343                         return res;
 344                 }
 345         }
 346 #endif
 347
 348         res = cec_devnode_register(&adap->devnode, adap->owner);
 349         if (res) {
 350 #ifdef CONFIG_MEDIA_CEC_RC
 351                 /* Note: rc_unregister also calls rc_free */
 352                 rc_unregister_device(adap->rc);
 353                 adap->rc = NULL;
 354 #endif
 355                 return res;
 356         }
 357
 358         dev_set_drvdata(&adap->devnode.dev, adap);
 359 #ifdef CONFIG_DEBUG_FS
 360         if (!top_cec_dir)
 361                 return 0;
 362
 363         adap->cec_dir = debugfs_create_dir(dev_name(&adap->devnode.dev), top_cec_dir);
 364         if (IS_ERR_OR_NULL(adap->cec_dir)) {
 365                 pr_warn("cec-%s: Failed to create debugfs dir\n", adap->name);
 366                 return 0;
 367         }
 368         adap->status_file = debugfs_create_devm_seqfile(&adap->devnode.dev,
 369                 "status", adap->cec_dir, cec_adap_status);
 370         if (IS_ERR_OR_NULL(adap->status_file)) {
 371                 pr_warn("cec-%s: Failed to create status file\n", adap->name);
 372                 debugfs_remove_recursive(adap->cec_dir);
 373                 adap->cec_dir = NULL;
 374                 return 0;
 375         }
 376         if (!adap->ops->error_inj_show || !adap->ops->error_inj_parse_line)
 377                 return 0;
 378         adap->error_inj_file = debugfs_create_file("error-inj", 0644,
 379                                                    adap->cec_dir, adap,
 380                                                    &cec_error_inj_fops);
 381         if (IS_ERR_OR_NULL(adap->error_inj_file))
 382                 pr_warn("cec-%s: Failed to create error-inj file\n",
 383                         adap->name);
 384 #endif
 385         return 0;
 386 }
 387 EXPORT_SYMBOL_GPL(cec_register_adapter);
 388
 389 void cec_unregister_adapter(struct cec_adapter *adap)
 390 {
 391         if (IS_ERR_OR_NULL(adap))
 392                 return;
 393
 394 #ifdef CONFIG_MEDIA_CEC_RC
 395         /* Note: rc_unregister also calls rc_free */
 396         rc_unregister_device(adap->rc);
 397         adap->rc = NULL;
 398 #endif
 399         debugfs_remove_recursive(adap->cec_dir);
 400 #ifdef CONFIG_CEC_NOTIFIER
 401         cec_notifier_cec_adap_unregister(adap->notifier, adap);
 402 #endif
 403         cec_devnode_unregister(adap);
 404 }
 405 EXPORT_SYMBOL_GPL(cec_unregister_adapter);
 406
 407 void cec_delete_adapter(struct cec_adapter *adap)
 408 {
 409         if (IS_ERR_OR_NULL(adap))
 410                 return;
 411         kthread_stop(adap->kthread);
 412         if (adap->kthread_config)
 413                 kthread_stop(adap->kthread_config);
 414         if (adap->ops->adap_free)
 415                 adap->ops->adap_free(adap);
 416 #ifdef CONFIG_MEDIA_CEC_RC
 417         rc_free_device(adap->rc);
 418 #endif
 419         kfree(adap);
 420 }
 421 EXPORT_SYMBOL_GPL(cec_delete_adapter);
 422
 423 /*
 424  *      Initialise cec for linux
 425  */
 426 static int __init cec_devnode_init(void)
 427 {
 428         int ret = alloc_chrdev_region(&cec_dev_t, 0, CEC_NUM_DEVICES, CEC_NAME);
 429
 430         if (ret < 0) {
 431                 pr_warn("cec: unable to allocate major\n");
 432                 return ret;
 433         }
 434
 435 #ifdef CONFIG_DEBUG_FS
 436         top_cec_dir = debugfs_create_dir("cec", NULL);
 437         if (IS_ERR_OR_NULL(top_cec_dir)) {
 438                 pr_warn("cec: Failed to create debugfs cec dir\n");
 439                 top_cec_dir = NULL;
 440         }
 441 #endif
 442
 443         ret = bus_register(&cec_bus_type);
 444         if (ret < 0) {
 445                 unregister_chrdev_region(cec_dev_t, CEC_NUM_DEVICES);
 446                 pr_warn("cec: bus_register failed\n");
 447                 return -EIO;
 448         }
 449
 450         return 0;
 451 }
 452
 453 static void __exit cec_devnode_exit(void)
 454 {
 455         debugfs_remove_recursive(top_cec_dir);
 456         bus_unregister(&cec_bus_type);
 457         unregister_chrdev_region(cec_dev_t, CEC_NUM_DEVICES);
 458 }
 459
 460 subsys_initcall(cec_devnode_init);
 461 module_exit(cec_devnode_exit)
 462
 463 MODULE_AUTHOR("Hans Verkuil <hans.verkuil@cisco.com>");
 464 MODULE_DESCRIPTION("Device node registration for cec drivers");
 465 MODULE_LICENSE("GPL");