355 lines
8.4 KiB
C
355 lines
8.4 KiB
C
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/*
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* Copyright © 2015 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*
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* Authors:
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* Rafael Antognolli <rafael.antognolli@intel.com>
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*
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*/
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#include <linux/device.h>
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/sched/signal.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/uio.h>
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#include <drm/display/drm_dp_helper.h>
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#include <drm/display/drm_dp_mst_helper.h>
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#include <drm/drm_crtc.h>
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#include <drm/drm_print.h>
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#include "drm_dp_helper_internal.h"
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struct drm_dp_aux_dev {
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unsigned index;
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struct drm_dp_aux *aux;
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struct device *dev;
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struct kref refcount;
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atomic_t usecount;
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};
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#define DRM_AUX_MINORS 256
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#define AUX_MAX_OFFSET (1 << 20)
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static DEFINE_IDR(aux_idr);
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static DEFINE_MUTEX(aux_idr_mutex);
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static struct class *drm_dp_aux_dev_class;
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static int drm_dev_major = -1;
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static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)
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{
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struct drm_dp_aux_dev *aux_dev = NULL;
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mutex_lock(&aux_idr_mutex);
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aux_dev = idr_find(&aux_idr, index);
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if (aux_dev && !kref_get_unless_zero(&aux_dev->refcount))
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aux_dev = NULL;
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mutex_unlock(&aux_idr_mutex);
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return aux_dev;
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}
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static struct drm_dp_aux_dev *alloc_drm_dp_aux_dev(struct drm_dp_aux *aux)
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{
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struct drm_dp_aux_dev *aux_dev;
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int index;
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aux_dev = kzalloc(sizeof(*aux_dev), GFP_KERNEL);
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if (!aux_dev)
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return ERR_PTR(-ENOMEM);
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aux_dev->aux = aux;
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atomic_set(&aux_dev->usecount, 1);
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kref_init(&aux_dev->refcount);
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mutex_lock(&aux_idr_mutex);
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index = idr_alloc(&aux_idr, aux_dev, 0, DRM_AUX_MINORS, GFP_KERNEL);
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mutex_unlock(&aux_idr_mutex);
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if (index < 0) {
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kfree(aux_dev);
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return ERR_PTR(index);
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}
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aux_dev->index = index;
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return aux_dev;
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}
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static void release_drm_dp_aux_dev(struct kref *ref)
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{
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struct drm_dp_aux_dev *aux_dev =
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container_of(ref, struct drm_dp_aux_dev, refcount);
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kfree(aux_dev);
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}
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static ssize_t name_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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ssize_t res;
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struct drm_dp_aux_dev *aux_dev =
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drm_dp_aux_dev_get_by_minor(MINOR(dev->devt));
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if (!aux_dev)
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return -ENODEV;
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res = sprintf(buf, "%s\n", aux_dev->aux->name);
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kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
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return res;
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}
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static DEVICE_ATTR_RO(name);
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static struct attribute *drm_dp_aux_attrs[] = {
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&dev_attr_name.attr,
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NULL,
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};
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ATTRIBUTE_GROUPS(drm_dp_aux);
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static int auxdev_open(struct inode *inode, struct file *file)
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{
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unsigned int minor = iminor(inode);
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struct drm_dp_aux_dev *aux_dev;
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aux_dev = drm_dp_aux_dev_get_by_minor(minor);
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if (!aux_dev)
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return -ENODEV;
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file->private_data = aux_dev;
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return 0;
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}
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static loff_t auxdev_llseek(struct file *file, loff_t offset, int whence)
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{
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return fixed_size_llseek(file, offset, whence, AUX_MAX_OFFSET);
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}
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static ssize_t auxdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
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{
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struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
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loff_t pos = iocb->ki_pos;
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ssize_t res = 0;
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if (!atomic_inc_not_zero(&aux_dev->usecount))
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return -ENODEV;
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iov_iter_truncate(to, AUX_MAX_OFFSET - pos);
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while (iov_iter_count(to)) {
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uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
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ssize_t todo = min(iov_iter_count(to), sizeof(buf));
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if (signal_pending(current)) {
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res = -ERESTARTSYS;
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break;
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}
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res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);
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if (res <= 0)
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break;
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if (copy_to_iter(buf, res, to) != res) {
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res = -EFAULT;
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break;
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}
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pos += res;
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}
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if (pos != iocb->ki_pos)
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res = pos - iocb->ki_pos;
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iocb->ki_pos = pos;
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if (atomic_dec_and_test(&aux_dev->usecount))
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wake_up_var(&aux_dev->usecount);
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return res;
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}
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static ssize_t auxdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
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{
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struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
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loff_t pos = iocb->ki_pos;
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ssize_t res = 0;
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if (!atomic_inc_not_zero(&aux_dev->usecount))
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return -ENODEV;
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iov_iter_truncate(from, AUX_MAX_OFFSET - pos);
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while (iov_iter_count(from)) {
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uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
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ssize_t todo = min(iov_iter_count(from), sizeof(buf));
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if (signal_pending(current)) {
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res = -ERESTARTSYS;
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break;
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}
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if (!copy_from_iter_full(buf, todo, from)) {
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res = -EFAULT;
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break;
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}
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res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);
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if (res <= 0)
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break;
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pos += res;
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}
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if (pos != iocb->ki_pos)
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res = pos - iocb->ki_pos;
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iocb->ki_pos = pos;
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if (atomic_dec_and_test(&aux_dev->usecount))
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wake_up_var(&aux_dev->usecount);
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return res;
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}
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static int auxdev_release(struct inode *inode, struct file *file)
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{
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struct drm_dp_aux_dev *aux_dev = file->private_data;
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kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
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return 0;
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}
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static const struct file_operations auxdev_fops = {
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.owner = THIS_MODULE,
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.llseek = auxdev_llseek,
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.read_iter = auxdev_read_iter,
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.write_iter = auxdev_write_iter,
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.open = auxdev_open,
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.release = auxdev_release,
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};
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#define to_auxdev(d) container_of(d, struct drm_dp_aux_dev, aux)
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static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_aux(struct drm_dp_aux *aux)
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{
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struct drm_dp_aux_dev *iter, *aux_dev = NULL;
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int id;
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/* don't increase kref count here because this function should only be
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* used by drm_dp_aux_unregister_devnode. Thus, it will always have at
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* least one reference - the one that drm_dp_aux_register_devnode
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* created
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*/
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mutex_lock(&aux_idr_mutex);
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idr_for_each_entry(&aux_idr, iter, id) {
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if (iter->aux == aux) {
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aux_dev = iter;
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break;
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}
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}
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mutex_unlock(&aux_idr_mutex);
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return aux_dev;
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}
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void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
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{
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struct drm_dp_aux_dev *aux_dev;
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unsigned int minor;
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aux_dev = drm_dp_aux_dev_get_by_aux(aux);
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if (!aux_dev) /* attach must have failed */
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return;
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/*
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* As some AUX adapters may exist as platform devices which outlive their respective DRM
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* devices, we clear drm_dev to ensure that we never accidentally reference a stale pointer
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*/
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aux->drm_dev = NULL;
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mutex_lock(&aux_idr_mutex);
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idr_remove(&aux_idr, aux_dev->index);
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mutex_unlock(&aux_idr_mutex);
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atomic_dec(&aux_dev->usecount);
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wait_var_event(&aux_dev->usecount, !atomic_read(&aux_dev->usecount));
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minor = aux_dev->index;
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if (aux_dev->dev)
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device_destroy(drm_dp_aux_dev_class,
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MKDEV(drm_dev_major, minor));
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DRM_DEBUG("drm_dp_aux_dev: aux [%s] unregistering\n", aux->name);
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kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
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}
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int drm_dp_aux_register_devnode(struct drm_dp_aux *aux)
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{
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struct drm_dp_aux_dev *aux_dev;
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int res;
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aux_dev = alloc_drm_dp_aux_dev(aux);
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if (IS_ERR(aux_dev))
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return PTR_ERR(aux_dev);
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aux_dev->dev = device_create(drm_dp_aux_dev_class, aux->dev,
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MKDEV(drm_dev_major, aux_dev->index), NULL,
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"drm_dp_aux%d", aux_dev->index);
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if (IS_ERR(aux_dev->dev)) {
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res = PTR_ERR(aux_dev->dev);
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aux_dev->dev = NULL;
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goto error;
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}
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DRM_DEBUG("drm_dp_aux_dev: aux [%s] registered as minor %d\n",
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aux->name, aux_dev->index);
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return 0;
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error:
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drm_dp_aux_unregister_devnode(aux);
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return res;
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}
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int drm_dp_aux_dev_init(void)
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{
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int res;
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drm_dp_aux_dev_class = class_create(THIS_MODULE, "drm_dp_aux_dev");
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if (IS_ERR(drm_dp_aux_dev_class)) {
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return PTR_ERR(drm_dp_aux_dev_class);
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}
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drm_dp_aux_dev_class->dev_groups = drm_dp_aux_groups;
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res = register_chrdev(0, "aux", &auxdev_fops);
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if (res < 0)
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goto out;
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drm_dev_major = res;
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return 0;
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out:
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class_destroy(drm_dp_aux_dev_class);
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return res;
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}
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void drm_dp_aux_dev_exit(void)
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{
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unregister_chrdev(drm_dev_major, "aux");
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class_destroy(drm_dp_aux_dev_class);
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}
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