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
cec_get_device(struct cec_devnode * devnode)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
cec_put_device(struct cec_devnode * devnode)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. */
cec_devnode_release(struct device * cd)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 */
cec_devnode_register(struct cec_devnode * devnode,struct module * owner)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 */
cec_devnode_unregister(struct cec_adapter * adap)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 devnode->registered = false;
170 devnode->unregistered = true;
171
172 mutex_lock(&devnode->lock_fhs);
173 list_for_each_entry(fh, &devnode->fhs, list)
174 wake_up_interruptible(&fh->wait);
175 mutex_unlock(&devnode->lock_fhs);
176
177 mutex_unlock(&devnode->lock);
178
179 mutex_lock(&adap->lock);
180 __cec_s_phys_addr(adap, CEC_PHYS_ADDR_INVALID, false);
181 __cec_s_log_addrs(adap, NULL, false);
182 mutex_unlock(&adap->lock);
183
184 cdev_device_del(&devnode->cdev, &devnode->dev);
185 put_device(&devnode->dev);
186 }
187
188 #ifdef CONFIG_DEBUG_FS
cec_error_inj_write(struct file * file,const char __user * ubuf,size_t count,loff_t * ppos)189 static ssize_t cec_error_inj_write(struct file *file,
190 const char __user *ubuf, size_t count, loff_t *ppos)
191 {
192 struct seq_file *sf = file->private_data;
193 struct cec_adapter *adap = sf->private;
194 char *buf;
195 char *line;
196 char *p;
197
198 buf = memdup_user_nul(ubuf, min_t(size_t, PAGE_SIZE, count));
199 if (IS_ERR(buf))
200 return PTR_ERR(buf);
201 p = buf;
202 while (p && *p) {
203 p = skip_spaces(p);
204 line = strsep(&p, "\n");
205 if (!*line || *line == '#')
206 continue;
207 if (!adap->ops->error_inj_parse_line(adap, line)) {
208 kfree(buf);
209 return -EINVAL;
210 }
211 }
212 kfree(buf);
213 return count;
214 }
215
cec_error_inj_show(struct seq_file * sf,void * unused)216 static int cec_error_inj_show(struct seq_file *sf, void *unused)
217 {
218 struct cec_adapter *adap = sf->private;
219
220 return adap->ops->error_inj_show(adap, sf);
221 }
222
cec_error_inj_open(struct inode * inode,struct file * file)223 static int cec_error_inj_open(struct inode *inode, struct file *file)
224 {
225 return single_open(file, cec_error_inj_show, inode->i_private);
226 }
227
228 static const struct file_operations cec_error_inj_fops = {
229 .open = cec_error_inj_open,
230 .write = cec_error_inj_write,
231 .read = seq_read,
232 .llseek = seq_lseek,
233 .release = single_release,
234 };
235 #endif
236
cec_allocate_adapter(const struct cec_adap_ops * ops,void * priv,const char * name,u32 caps,u8 available_las)237 struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops,
238 void *priv, const char *name, u32 caps,
239 u8 available_las)
240 {
241 struct cec_adapter *adap;
242 int res;
243
244 #ifndef CONFIG_MEDIA_CEC_RC
245 caps &= ~CEC_CAP_RC;
246 #endif
247
248 if (WARN_ON(!caps))
249 return ERR_PTR(-EINVAL);
250 if (WARN_ON(!ops))
251 return ERR_PTR(-EINVAL);
252 if (WARN_ON(!available_las || available_las > CEC_MAX_LOG_ADDRS))
253 return ERR_PTR(-EINVAL);
254 adap = kzalloc(sizeof(*adap), GFP_KERNEL);
255 if (!adap)
256 return ERR_PTR(-ENOMEM);
257 strscpy(adap->name, name, sizeof(adap->name));
258 adap->phys_addr = CEC_PHYS_ADDR_INVALID;
259 adap->cec_pin_is_high = true;
260 adap->log_addrs.cec_version = CEC_OP_CEC_VERSION_2_0;
261 adap->log_addrs.vendor_id = CEC_VENDOR_ID_NONE;
262 adap->capabilities = caps;
263 if (debug_phys_addr)
264 adap->capabilities |= CEC_CAP_PHYS_ADDR;
265 adap->needs_hpd = caps & CEC_CAP_NEEDS_HPD;
266 adap->available_log_addrs = available_las;
267 adap->sequence = 0;
268 adap->ops = ops;
269 adap->priv = priv;
270 mutex_init(&adap->lock);
271 INIT_LIST_HEAD(&adap->transmit_queue);
272 INIT_LIST_HEAD(&adap->wait_queue);
273 init_waitqueue_head(&adap->kthread_waitq);
274
275 /* adap->devnode initialization */
276 INIT_LIST_HEAD(&adap->devnode.fhs);
277 mutex_init(&adap->devnode.lock_fhs);
278 mutex_init(&adap->devnode.lock);
279
280 adap->kthread = kthread_run(cec_thread_func, adap, "cec-%s", name);
281 if (IS_ERR(adap->kthread)) {
282 pr_err("cec-%s: kernel_thread() failed\n", name);
283 res = PTR_ERR(adap->kthread);
284 kfree(adap);
285 return ERR_PTR(res);
286 }
287
288 #ifdef CONFIG_MEDIA_CEC_RC
289 if (!(caps & CEC_CAP_RC))
290 return adap;
291
292 /* Prepare the RC input device */
293 adap->rc = rc_allocate_device(RC_DRIVER_SCANCODE);
294 if (!adap->rc) {
295 pr_err("cec-%s: failed to allocate memory for rc_dev\n",
296 name);
297 kthread_stop(adap->kthread);
298 kfree(adap);
299 return ERR_PTR(-ENOMEM);
300 }
301
302 snprintf(adap->input_phys, sizeof(adap->input_phys),
303 "%s/input0", adap->name);
304
305 adap->rc->device_name = adap->name;
306 adap->rc->input_phys = adap->input_phys;
307 adap->rc->input_id.bustype = BUS_CEC;
308 adap->rc->input_id.vendor = 0;
309 adap->rc->input_id.product = 0;
310 adap->rc->input_id.version = 1;
311 adap->rc->driver_name = CEC_NAME;
312 adap->rc->allowed_protocols = RC_PROTO_BIT_CEC;
313 adap->rc->priv = adap;
314 adap->rc->map_name = RC_MAP_CEC;
315 adap->rc->timeout = MS_TO_US(550);
316 #endif
317 return adap;
318 }
319 EXPORT_SYMBOL_GPL(cec_allocate_adapter);
320
cec_register_adapter(struct cec_adapter * adap,struct device * parent)321 int cec_register_adapter(struct cec_adapter *adap,
322 struct device *parent)
323 {
324 int res;
325
326 if (IS_ERR_OR_NULL(adap))
327 return 0;
328
329 if (WARN_ON(!parent))
330 return -EINVAL;
331
332 adap->owner = parent->driver->owner;
333 adap->devnode.dev.parent = parent;
334
335 #ifdef CONFIG_MEDIA_CEC_RC
336 if (adap->capabilities & CEC_CAP_RC) {
337 adap->rc->dev.parent = parent;
338 res = rc_register_device(adap->rc);
339
340 if (res) {
341 pr_err("cec-%s: failed to prepare input device\n",
342 adap->name);
343 rc_free_device(adap->rc);
344 adap->rc = NULL;
345 return res;
346 }
347 }
348 #endif
349
350 res = cec_devnode_register(&adap->devnode, adap->owner);
351 if (res) {
352 #ifdef CONFIG_MEDIA_CEC_RC
353 /* Note: rc_unregister also calls rc_free */
354 rc_unregister_device(adap->rc);
355 adap->rc = NULL;
356 #endif
357 return res;
358 }
359
360 dev_set_drvdata(&adap->devnode.dev, adap);
361 #ifdef CONFIG_DEBUG_FS
362 if (!top_cec_dir)
363 return 0;
364
365 adap->cec_dir = debugfs_create_dir(dev_name(&adap->devnode.dev),
366 top_cec_dir);
367
368 debugfs_create_devm_seqfile(&adap->devnode.dev, "status", adap->cec_dir,
369 cec_adap_status);
370
371 if (!adap->ops->error_inj_show || !adap->ops->error_inj_parse_line)
372 return 0;
373 debugfs_create_file("error-inj", 0644, adap->cec_dir, adap,
374 &cec_error_inj_fops);
375 #endif
376 return 0;
377 }
378 EXPORT_SYMBOL_GPL(cec_register_adapter);
379
cec_unregister_adapter(struct cec_adapter * adap)380 void cec_unregister_adapter(struct cec_adapter *adap)
381 {
382 if (IS_ERR_OR_NULL(adap))
383 return;
384
385 #ifdef CONFIG_MEDIA_CEC_RC
386 /* Note: rc_unregister also calls rc_free */
387 rc_unregister_device(adap->rc);
388 adap->rc = NULL;
389 #endif
390 debugfs_remove_recursive(adap->cec_dir);
391 #ifdef CONFIG_CEC_NOTIFIER
392 cec_notifier_cec_adap_unregister(adap->notifier, adap);
393 #endif
394 cec_devnode_unregister(adap);
395 }
396 EXPORT_SYMBOL_GPL(cec_unregister_adapter);
397
cec_delete_adapter(struct cec_adapter * adap)398 void cec_delete_adapter(struct cec_adapter *adap)
399 {
400 if (IS_ERR_OR_NULL(adap))
401 return;
402 if (adap->kthread_config)
403 kthread_stop(adap->kthread_config);
404 kthread_stop(adap->kthread);
405 if (adap->ops->adap_free)
406 adap->ops->adap_free(adap);
407 #ifdef CONFIG_MEDIA_CEC_RC
408 rc_free_device(adap->rc);
409 #endif
410 kfree(adap);
411 }
412 EXPORT_SYMBOL_GPL(cec_delete_adapter);
413
414 /*
415 * Initialise cec for linux
416 */
cec_devnode_init(void)417 static int __init cec_devnode_init(void)
418 {
419 int ret = alloc_chrdev_region(&cec_dev_t, 0, CEC_NUM_DEVICES, CEC_NAME);
420
421 if (ret < 0) {
422 pr_warn("cec: unable to allocate major\n");
423 return ret;
424 }
425
426 #ifdef CONFIG_DEBUG_FS
427 top_cec_dir = debugfs_create_dir("cec", NULL);
428 if (IS_ERR_OR_NULL(top_cec_dir)) {
429 pr_warn("cec: Failed to create debugfs cec dir\n");
430 top_cec_dir = NULL;
431 }
432 #endif
433
434 ret = bus_register(&cec_bus_type);
435 if (ret < 0) {
436 unregister_chrdev_region(cec_dev_t, CEC_NUM_DEVICES);
437 pr_warn("cec: bus_register failed\n");
438 return -EIO;
439 }
440
441 return 0;
442 }
443
cec_devnode_exit(void)444 static void __exit cec_devnode_exit(void)
445 {
446 debugfs_remove_recursive(top_cec_dir);
447 bus_unregister(&cec_bus_type);
448 unregister_chrdev_region(cec_dev_t, CEC_NUM_DEVICES);
449 }
450
451 subsys_initcall(cec_devnode_init);
452 module_exit(cec_devnode_exit)
453
454 MODULE_AUTHOR("Hans Verkuil <hans.verkuil@cisco.com>");
455 MODULE_DESCRIPTION("Device node registration for cec drivers");
456 MODULE_LICENSE("GPL");
457