2 * Copyright © 2015 Intel Corporation
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
24 * Rafael Antognolli <rafael.antognolli@intel.com>
28 #include <linux/device.h>
30 #include <linux/slab.h>
31 #include <linux/init.h>
32 #include <linux/kernel.h>
33 #include <linux/module.h>
34 #include <linux/uaccess.h>
35 #include <drm/drm_dp_helper.h>
36 #include <drm/drm_crtc.h>
39 #include "drm_crtc_helper_internal.h"
41 struct drm_dp_aux_dev {
43 struct drm_dp_aux *aux;
49 #define DRM_AUX_MINORS 256
50 #define AUX_MAX_OFFSET (1 << 20)
52 static DEFINE_IDR(aux_idr);
53 static DEFINE_MUTEX(aux_idr_mutex);
54 static struct class *drm_dp_aux_dev_class;
55 static int drm_dev_major = -1;
57 static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)
59 struct drm_dp_aux_dev *aux_dev = NULL;
61 mutex_lock(&aux_idr_mutex);
62 aux_dev = idr_find(&aux_idr, index);
63 if (!kref_get_unless_zero(&aux_dev->refcount))
65 mutex_unlock(&aux_idr_mutex);
70 static struct drm_dp_aux_dev *alloc_drm_dp_aux_dev(struct drm_dp_aux *aux)
72 struct drm_dp_aux_dev *aux_dev;
75 aux_dev = kzalloc(sizeof(*aux_dev), GFP_KERNEL);
77 return ERR_PTR(-ENOMEM);
79 atomic_set(&aux_dev->usecount, 1);
80 kref_init(&aux_dev->refcount);
82 mutex_lock(&aux_idr_mutex);
83 index = idr_alloc_cyclic(&aux_idr, aux_dev, 0, DRM_AUX_MINORS,
85 mutex_unlock(&aux_idr_mutex);
88 return ERR_PTR(index);
90 aux_dev->index = index;
95 static void release_drm_dp_aux_dev(struct kref *ref)
97 struct drm_dp_aux_dev *aux_dev =
98 container_of(ref, struct drm_dp_aux_dev, refcount);
103 static ssize_t name_show(struct device *dev,
104 struct device_attribute *attr, char *buf)
107 struct drm_dp_aux_dev *aux_dev =
108 drm_dp_aux_dev_get_by_minor(MINOR(dev->devt));
113 res = sprintf(buf, "%s\n", aux_dev->aux->name);
114 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
118 static DEVICE_ATTR_RO(name);
120 static struct attribute *drm_dp_aux_attrs[] = {
124 ATTRIBUTE_GROUPS(drm_dp_aux);
126 static int auxdev_open(struct inode *inode, struct file *file)
128 unsigned int minor = iminor(inode);
129 struct drm_dp_aux_dev *aux_dev;
131 aux_dev = drm_dp_aux_dev_get_by_minor(minor);
135 file->private_data = aux_dev;
139 static loff_t auxdev_llseek(struct file *file, loff_t offset, int whence)
141 return fixed_size_llseek(file, offset, whence, AUX_MAX_OFFSET);
144 static ssize_t auxdev_read(struct file *file, char __user *buf, size_t count,
147 size_t bytes_pending, num_bytes_processed = 0;
148 struct drm_dp_aux_dev *aux_dev = file->private_data;
151 if (!atomic_inc_not_zero(&aux_dev->usecount))
154 bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - (*offset));
156 if (!access_ok(VERIFY_WRITE, buf, bytes_pending)) {
161 while (bytes_pending > 0) {
162 uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES];
163 ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf));
165 if (signal_pending(current)) {
166 res = num_bytes_processed ?
167 num_bytes_processed : -ERESTARTSYS;
171 res = drm_dp_dpcd_read(aux_dev->aux, *offset, localbuf, todo);
173 res = num_bytes_processed ? num_bytes_processed : res;
176 if (__copy_to_user(buf + num_bytes_processed, localbuf, res)) {
177 res = num_bytes_processed ?
178 num_bytes_processed : -EFAULT;
181 bytes_pending -= res;
183 num_bytes_processed += res;
184 res = num_bytes_processed;
188 atomic_dec(&aux_dev->usecount);
189 wake_up_atomic_t(&aux_dev->usecount);
193 static ssize_t auxdev_write(struct file *file, const char __user *buf,
194 size_t count, loff_t *offset)
196 size_t bytes_pending, num_bytes_processed = 0;
197 struct drm_dp_aux_dev *aux_dev = file->private_data;
200 if (!atomic_inc_not_zero(&aux_dev->usecount))
203 bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - *offset);
205 if (!access_ok(VERIFY_READ, buf, bytes_pending)) {
210 while (bytes_pending > 0) {
211 uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES];
212 ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf));
214 if (signal_pending(current)) {
215 res = num_bytes_processed ?
216 num_bytes_processed : -ERESTARTSYS;
220 if (__copy_from_user(localbuf,
221 buf + num_bytes_processed, todo)) {
222 res = num_bytes_processed ?
223 num_bytes_processed : -EFAULT;
227 res = drm_dp_dpcd_write(aux_dev->aux, *offset, localbuf, todo);
229 res = num_bytes_processed ? num_bytes_processed : res;
232 bytes_pending -= res;
234 num_bytes_processed += res;
235 res = num_bytes_processed;
239 atomic_dec(&aux_dev->usecount);
240 wake_up_atomic_t(&aux_dev->usecount);
244 static int auxdev_release(struct inode *inode, struct file *file)
246 struct drm_dp_aux_dev *aux_dev = file->private_data;
248 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
252 static const struct file_operations auxdev_fops = {
253 .owner = THIS_MODULE,
254 .llseek = auxdev_llseek,
256 .write = auxdev_write,
258 .release = auxdev_release,
261 #define to_auxdev(d) container_of(d, struct drm_dp_aux_dev, aux)
263 static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_aux(struct drm_dp_aux *aux)
265 struct drm_dp_aux_dev *iter, *aux_dev = NULL;
268 /* don't increase kref count here because this function should only be
269 * used by drm_dp_aux_unregister_devnode. Thus, it will always have at
270 * least one reference - the one that drm_dp_aux_register_devnode
273 mutex_lock(&aux_idr_mutex);
274 idr_for_each_entry(&aux_idr, iter, id) {
275 if (iter->aux == aux) {
280 mutex_unlock(&aux_idr_mutex);
284 static int auxdev_wait_atomic_t(atomic_t *p)
290 void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
292 struct drm_dp_aux_dev *aux_dev;
295 aux_dev = drm_dp_aux_dev_get_by_aux(aux);
296 if (!aux_dev) /* attach must have failed */
299 mutex_lock(&aux_idr_mutex);
300 idr_remove(&aux_idr, aux_dev->index);
301 mutex_unlock(&aux_idr_mutex);
303 atomic_dec(&aux_dev->usecount);
304 wait_on_atomic_t(&aux_dev->usecount, auxdev_wait_atomic_t,
305 TASK_UNINTERRUPTIBLE);
307 minor = aux_dev->index;
309 device_destroy(drm_dp_aux_dev_class,
310 MKDEV(drm_dev_major, minor));
312 DRM_DEBUG("drm_dp_aux_dev: aux [%s] unregistering\n", aux->name);
313 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
316 int drm_dp_aux_register_devnode(struct drm_dp_aux *aux)
318 struct drm_dp_aux_dev *aux_dev;
321 aux_dev = alloc_drm_dp_aux_dev(aux);
323 return PTR_ERR(aux_dev);
325 aux_dev->dev = device_create(drm_dp_aux_dev_class, aux->dev,
326 MKDEV(drm_dev_major, aux_dev->index), NULL,
327 "drm_dp_aux%d", aux_dev->index);
328 if (IS_ERR(aux_dev->dev)) {
329 res = PTR_ERR(aux_dev->dev);
334 DRM_DEBUG("drm_dp_aux_dev: aux [%s] registered as minor %d\n",
335 aux->name, aux_dev->index);
338 drm_dp_aux_unregister_devnode(aux);
342 int drm_dp_aux_dev_init(void)
346 drm_dp_aux_dev_class = class_create(THIS_MODULE, "drm_dp_aux_dev");
347 if (IS_ERR(drm_dp_aux_dev_class)) {
348 return PTR_ERR(drm_dp_aux_dev_class);
350 drm_dp_aux_dev_class->dev_groups = drm_dp_aux_groups;
352 res = register_chrdev(0, "aux", &auxdev_fops);
359 class_destroy(drm_dp_aux_dev_class);
363 void drm_dp_aux_dev_exit(void)
365 unregister_chrdev(drm_dev_major, "aux");
366 class_destroy(drm_dp_aux_dev_class);