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1/*2 * Copyright © 2015 Intel Corporation3 *4 * Permission is hereby granted, free of charge, to any person obtaining a5 * copy of this software and associated documentation files (the "Software"),6 * to deal in the Software without restriction, including without limitation7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,8 * and/or sell copies of the Software, and to permit persons to whom the9 * Software is furnished to do so, subject to the following conditions:10 *11 * The above copyright notice and this permission notice (including the next12 * paragraph) shall be included in all copies or substantial portions of the13 * Software.14 *15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS21 * IN THE SOFTWARE.22 *23 * Authors:24 * Rafael Antognolli <rafael.antognolli@intel.com>25 *26 */27 28#include <linux/device.h>29#include <linux/fs.h>30#include <linux/init.h>31#include <linux/kernel.h>32#include <linux/module.h>33#include <linux/sched/signal.h>34#include <linux/slab.h>35#include <linux/uaccess.h>36#include <linux/uio.h>37 38#include <drm/display/drm_dp_helper.h>39#include <drm/display/drm_dp_mst_helper.h>40#include <drm/drm_crtc.h>41#include <drm/drm_print.h>42 43#include "drm_dp_helper_internal.h"44 45struct drm_dp_aux_dev {46 unsigned index;47 struct drm_dp_aux *aux;48 struct device *dev;49 struct kref refcount;50 atomic_t usecount;51};52 53#define DRM_AUX_MINORS 25654#define AUX_MAX_OFFSET (1 << 20)55static DEFINE_IDR(aux_idr);56static DEFINE_MUTEX(aux_idr_mutex);57static struct class *drm_dp_aux_dev_class;58static int drm_dev_major = -1;59 60static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)61{62 struct drm_dp_aux_dev *aux_dev = NULL;63 64 mutex_lock(&aux_idr_mutex);65 aux_dev = idr_find(&aux_idr, index);66 if (aux_dev && !kref_get_unless_zero(&aux_dev->refcount))67 aux_dev = NULL;68 mutex_unlock(&aux_idr_mutex);69 70 return aux_dev;71}72 73static struct drm_dp_aux_dev *alloc_drm_dp_aux_dev(struct drm_dp_aux *aux)74{75 struct drm_dp_aux_dev *aux_dev;76 int index;77 78 aux_dev = kzalloc(sizeof(*aux_dev), GFP_KERNEL);79 if (!aux_dev)80 return ERR_PTR(-ENOMEM);81 aux_dev->aux = aux;82 atomic_set(&aux_dev->usecount, 1);83 kref_init(&aux_dev->refcount);84 85 mutex_lock(&aux_idr_mutex);86 index = idr_alloc(&aux_idr, aux_dev, 0, DRM_AUX_MINORS, GFP_KERNEL);87 mutex_unlock(&aux_idr_mutex);88 if (index < 0) {89 kfree(aux_dev);90 return ERR_PTR(index);91 }92 aux_dev->index = index;93 94 return aux_dev;95}96 97static void release_drm_dp_aux_dev(struct kref *ref)98{99 struct drm_dp_aux_dev *aux_dev =100 container_of(ref, struct drm_dp_aux_dev, refcount);101 102 kfree(aux_dev);103}104 105static ssize_t name_show(struct device *dev,106 struct device_attribute *attr, char *buf)107{108 ssize_t res;109 struct drm_dp_aux_dev *aux_dev =110 drm_dp_aux_dev_get_by_minor(MINOR(dev->devt));111 112 if (!aux_dev)113 return -ENODEV;114 115 res = sprintf(buf, "%s\n", aux_dev->aux->name);116 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);117 118 return res;119}120static DEVICE_ATTR_RO(name);121 122static struct attribute *drm_dp_aux_attrs[] = {123 &dev_attr_name.attr,124 NULL,125};126ATTRIBUTE_GROUPS(drm_dp_aux);127 128static int auxdev_open(struct inode *inode, struct file *file)129{130 unsigned int minor = iminor(inode);131 struct drm_dp_aux_dev *aux_dev;132 133 aux_dev = drm_dp_aux_dev_get_by_minor(minor);134 if (!aux_dev)135 return -ENODEV;136 137 file->private_data = aux_dev;138 return 0;139}140 141static loff_t auxdev_llseek(struct file *file, loff_t offset, int whence)142{143 return fixed_size_llseek(file, offset, whence, AUX_MAX_OFFSET);144}145 146static ssize_t auxdev_read_iter(struct kiocb *iocb, struct iov_iter *to)147{148 struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;149 loff_t pos = iocb->ki_pos;150 ssize_t res = 0;151 152 if (!atomic_inc_not_zero(&aux_dev->usecount))153 return -ENODEV;154 155 iov_iter_truncate(to, AUX_MAX_OFFSET - pos);156 157 while (iov_iter_count(to)) {158 uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];159 ssize_t todo = min(iov_iter_count(to), sizeof(buf));160 161 if (signal_pending(current)) {162 res = -ERESTARTSYS;163 break;164 }165 166 res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);167 168 if (res <= 0)169 break;170 171 if (copy_to_iter(buf, res, to) != res) {172 res = -EFAULT;173 break;174 }175 176 pos += res;177 }178 179 if (pos != iocb->ki_pos)180 res = pos - iocb->ki_pos;181 iocb->ki_pos = pos;182 183 if (atomic_dec_and_test(&aux_dev->usecount))184 wake_up_var(&aux_dev->usecount);185 186 return res;187}188 189static ssize_t auxdev_write_iter(struct kiocb *iocb, struct iov_iter *from)190{191 struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;192 loff_t pos = iocb->ki_pos;193 ssize_t res = 0;194 195 if (!atomic_inc_not_zero(&aux_dev->usecount))196 return -ENODEV;197 198 iov_iter_truncate(from, AUX_MAX_OFFSET - pos);199 200 while (iov_iter_count(from)) {201 uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];202 ssize_t todo = min(iov_iter_count(from), sizeof(buf));203 204 if (signal_pending(current)) {205 res = -ERESTARTSYS;206 break;207 }208 209 if (!copy_from_iter_full(buf, todo, from)) {210 res = -EFAULT;211 break;212 }213 214 res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);215 216 if (res <= 0)217 break;218 219 pos += res;220 }221 222 if (pos != iocb->ki_pos)223 res = pos - iocb->ki_pos;224 iocb->ki_pos = pos;225 226 if (atomic_dec_and_test(&aux_dev->usecount))227 wake_up_var(&aux_dev->usecount);228 229 return res;230}231 232static int auxdev_release(struct inode *inode, struct file *file)233{234 struct drm_dp_aux_dev *aux_dev = file->private_data;235 236 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);237 return 0;238}239 240static const struct file_operations auxdev_fops = {241 .owner = THIS_MODULE,242 .llseek = auxdev_llseek,243 .read_iter = auxdev_read_iter,244 .write_iter = auxdev_write_iter,245 .open = auxdev_open,246 .release = auxdev_release,247};248 249#define to_auxdev(d) container_of(d, struct drm_dp_aux_dev, aux)250 251static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_aux(struct drm_dp_aux *aux)252{253 struct drm_dp_aux_dev *iter, *aux_dev = NULL;254 int id;255 256 /* don't increase kref count here because this function should only be257 * used by drm_dp_aux_unregister_devnode. Thus, it will always have at258 * least one reference - the one that drm_dp_aux_register_devnode259 * created260 */261 mutex_lock(&aux_idr_mutex);262 idr_for_each_entry(&aux_idr, iter, id) {263 if (iter->aux == aux) {264 aux_dev = iter;265 break;266 }267 }268 mutex_unlock(&aux_idr_mutex);269 return aux_dev;270}271 272void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)273{274 struct drm_dp_aux_dev *aux_dev;275 unsigned int minor;276 277 aux_dev = drm_dp_aux_dev_get_by_aux(aux);278 if (!aux_dev) /* attach must have failed */279 return;280 281 /*282 * As some AUX adapters may exist as platform devices which outlive their respective DRM283 * devices, we clear drm_dev to ensure that we never accidentally reference a stale pointer284 */285 aux->drm_dev = NULL;286 287 mutex_lock(&aux_idr_mutex);288 idr_remove(&aux_idr, aux_dev->index);289 mutex_unlock(&aux_idr_mutex);290 291 atomic_dec(&aux_dev->usecount);292 wait_var_event(&aux_dev->usecount, !atomic_read(&aux_dev->usecount));293 294 minor = aux_dev->index;295 if (aux_dev->dev)296 device_destroy(drm_dp_aux_dev_class,297 MKDEV(drm_dev_major, minor));298 299 DRM_DEBUG("drm_dp_aux_dev: aux [%s] unregistering\n", aux->name);300 kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);301}302 303int drm_dp_aux_register_devnode(struct drm_dp_aux *aux)304{305 struct drm_dp_aux_dev *aux_dev;306 int res;307 308 aux_dev = alloc_drm_dp_aux_dev(aux);309 if (IS_ERR(aux_dev))310 return PTR_ERR(aux_dev);311 312 aux_dev->dev = device_create(drm_dp_aux_dev_class, aux->dev,313 MKDEV(drm_dev_major, aux_dev->index), NULL,314 "drm_dp_aux%d", aux_dev->index);315 if (IS_ERR(aux_dev->dev)) {316 res = PTR_ERR(aux_dev->dev);317 aux_dev->dev = NULL;318 goto error;319 }320 321 DRM_DEBUG("drm_dp_aux_dev: aux [%s] registered as minor %d\n",322 aux->name, aux_dev->index);323 return 0;324error:325 drm_dp_aux_unregister_devnode(aux);326 return res;327}328 329int drm_dp_aux_dev_init(void)330{331 int res;332 333 drm_dp_aux_dev_class = class_create("drm_dp_aux_dev");334 if (IS_ERR(drm_dp_aux_dev_class)) {335 return PTR_ERR(drm_dp_aux_dev_class);336 }337 drm_dp_aux_dev_class->dev_groups = drm_dp_aux_groups;338 339 res = register_chrdev(0, "aux", &auxdev_fops);340 if (res < 0)341 goto out;342 drm_dev_major = res;343 344 return 0;345out:346 class_destroy(drm_dp_aux_dev_class);347 return res;348}349 350void drm_dp_aux_dev_exit(void)351{352 unregister_chrdev(drm_dev_major, "aux");353 class_destroy(drm_dp_aux_dev_class);354}355