Staging
v0.7.0
v0.7.0
drm_dp_aux_dev.c
/*
* Copyright © 2015 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
* Authors:
* Rafael Antognolli <rafael.antognolli@intel.com>
*
*/
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/uio.h>
#include <drm/drm_crtc.h>
#include <drm/drm_dp_helper.h>
#include <drm/drm_dp_mst_helper.h>
#include <drm/drm_print.h>
#include "drm_crtc_helper_internal.h"
struct drm_dp_aux_dev {
unsigned index;
struct drm_dp_aux *aux;
struct device *dev;
struct kref refcount;
atomic_t usecount;
};
#define DRM_AUX_MINORS 256
#define AUX_MAX_OFFSET (1 << 20)
static DEFINE_IDR(aux_idr);
static DEFINE_MUTEX(aux_idr_mutex);
static struct class *drm_dp_aux_dev_class;
static int drm_dev_major = -1;
static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)
{
struct drm_dp_aux_dev *aux_dev = NULL;
mutex_lock(&aux_idr_mutex);
aux_dev = idr_find(&aux_idr, index);
if (aux_dev && !kref_get_unless_zero(&aux_dev->refcount))
aux_dev = NULL;
mutex_unlock(&aux_idr_mutex);
return aux_dev;
}
static struct drm_dp_aux_dev *alloc_drm_dp_aux_dev(struct drm_dp_aux *aux)
{
struct drm_dp_aux_dev *aux_dev;
int index;
aux_dev = kzalloc(sizeof(*aux_dev), GFP_KERNEL);
if (!aux_dev)
return ERR_PTR(-ENOMEM);
aux_dev->aux = aux;
atomic_set(&aux_dev->usecount, 1);
kref_init(&aux_dev->refcount);
mutex_lock(&aux_idr_mutex);
index = idr_alloc(&aux_idr, aux_dev, 0, DRM_AUX_MINORS, GFP_KERNEL);
mutex_unlock(&aux_idr_mutex);
if (index < 0) {
kfree(aux_dev);
return ERR_PTR(index);
}
aux_dev->index = index;
return aux_dev;
}
static void release_drm_dp_aux_dev(struct kref *ref)
{
struct drm_dp_aux_dev *aux_dev =
container_of(ref, struct drm_dp_aux_dev, refcount);
kfree(aux_dev);
}
static ssize_t name_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
ssize_t res;
struct drm_dp_aux_dev *aux_dev =
drm_dp_aux_dev_get_by_minor(MINOR(dev->devt));
if (!aux_dev)
return -ENODEV;
res = sprintf(buf, "%s\n", aux_dev->aux->name);
kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
return res;
}
static DEVICE_ATTR_RO(name);
static struct attribute *drm_dp_aux_attrs[] = {
&dev_attr_name.attr,
NULL,
};
ATTRIBUTE_GROUPS(drm_dp_aux);
static int auxdev_open(struct inode *inode, struct file *file)
{
unsigned int minor = iminor(inode);
struct drm_dp_aux_dev *aux_dev;
aux_dev = drm_dp_aux_dev_get_by_minor(minor);
if (!aux_dev)
return -ENODEV;
file->private_data = aux_dev;
return 0;
}
static loff_t auxdev_llseek(struct file *file, loff_t offset, int whence)
{
return fixed_size_llseek(file, offset, whence, AUX_MAX_OFFSET);
}
static ssize_t auxdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
loff_t pos = iocb->ki_pos;
ssize_t res = 0;
if (!atomic_inc_not_zero(&aux_dev->usecount))
return -ENODEV;
iov_iter_truncate(to, AUX_MAX_OFFSET - pos);
while (iov_iter_count(to)) {
uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
ssize_t todo = min(iov_iter_count(to), sizeof(buf));
if (signal_pending(current)) {
res = -ERESTARTSYS;
break;
}
res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);
if (res <= 0)
break;
if (copy_to_iter(buf, res, to) != res) {
res = -EFAULT;
break;
}
pos += res;
}
if (pos != iocb->ki_pos)
res = pos - iocb->ki_pos;
iocb->ki_pos = pos;
if (atomic_dec_and_test(&aux_dev->usecount))
wake_up_var(&aux_dev->usecount);
return res;
}
static ssize_t auxdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
loff_t pos = iocb->ki_pos;
ssize_t res = 0;
if (!atomic_inc_not_zero(&aux_dev->usecount))
return -ENODEV;
iov_iter_truncate(from, AUX_MAX_OFFSET - pos);
while (iov_iter_count(from)) {
uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
ssize_t todo = min(iov_iter_count(from), sizeof(buf));
if (signal_pending(current)) {
res = -ERESTARTSYS;
break;
}
if (!copy_from_iter_full(buf, todo, from)) {
res = -EFAULT;
break;
}
res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);
if (res <= 0)
break;
pos += res;
}
if (pos != iocb->ki_pos)
res = pos - iocb->ki_pos;
iocb->ki_pos = pos;
if (atomic_dec_and_test(&aux_dev->usecount))
wake_up_var(&aux_dev->usecount);
return res;
}
static int auxdev_release(struct inode *inode, struct file *file)
{
struct drm_dp_aux_dev *aux_dev = file->private_data;
kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
return 0;
}
static const struct file_operations auxdev_fops = {
.owner = THIS_MODULE,
.llseek = auxdev_llseek,
.read_iter = auxdev_read_iter,
.write_iter = auxdev_write_iter,
.open = auxdev_open,
.release = auxdev_release,
};
#define to_auxdev(d) container_of(d, struct drm_dp_aux_dev, aux)
static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_aux(struct drm_dp_aux *aux)
{
struct drm_dp_aux_dev *iter, *aux_dev = NULL;
int id;
/* don't increase kref count here because this function should only be
* used by drm_dp_aux_unregister_devnode. Thus, it will always have at
* least one reference - the one that drm_dp_aux_register_devnode
* created
*/
mutex_lock(&aux_idr_mutex);
idr_for_each_entry(&aux_idr, iter, id) {
if (iter->aux == aux) {
aux_dev = iter;
break;
}
}
mutex_unlock(&aux_idr_mutex);
return aux_dev;
}
void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
{
struct drm_dp_aux_dev *aux_dev;
unsigned int minor;
aux_dev = drm_dp_aux_dev_get_by_aux(aux);
if (!aux_dev) /* attach must have failed */
return;
mutex_lock(&aux_idr_mutex);
idr_remove(&aux_idr, aux_dev->index);
mutex_unlock(&aux_idr_mutex);
atomic_dec(&aux_dev->usecount);
wait_var_event(&aux_dev->usecount, !atomic_read(&aux_dev->usecount));
minor = aux_dev->index;
if (aux_dev->dev)
device_destroy(drm_dp_aux_dev_class,
MKDEV(drm_dev_major, minor));
DRM_DEBUG("drm_dp_aux_dev: aux [%s] unregistering\n", aux->name);
kref_put(&aux_dev->refcount, release_drm_dp_aux_dev);
}
int drm_dp_aux_register_devnode(struct drm_dp_aux *aux)
{
struct drm_dp_aux_dev *aux_dev;
int res;
aux_dev = alloc_drm_dp_aux_dev(aux);
if (IS_ERR(aux_dev))
return PTR_ERR(aux_dev);
aux_dev->dev = device_create(drm_dp_aux_dev_class, aux->dev,
MKDEV(drm_dev_major, aux_dev->index), NULL,
"drm_dp_aux%d", aux_dev->index);
if (IS_ERR(aux_dev->dev)) {
res = PTR_ERR(aux_dev->dev);
aux_dev->dev = NULL;
goto error;
}
DRM_DEBUG("drm_dp_aux_dev: aux [%s] registered as minor %d\n",
aux->name, aux_dev->index);
return 0;
error:
drm_dp_aux_unregister_devnode(aux);
return res;
}
int drm_dp_aux_dev_init(void)
{
int res;
drm_dp_aux_dev_class = class_create(THIS_MODULE, "drm_dp_aux_dev");
if (IS_ERR(drm_dp_aux_dev_class)) {
return PTR_ERR(drm_dp_aux_dev_class);
}
drm_dp_aux_dev_class->dev_groups = drm_dp_aux_groups;
res = register_chrdev(0, "aux", &auxdev_fops);
if (res < 0)
goto out;
drm_dev_major = res;
return 0;
out:
class_destroy(drm_dp_aux_dev_class);
return res;
}
void drm_dp_aux_dev_exit(void)
{
unregister_chrdev(drm_dev_major, "aux");
class_destroy(drm_dp_aux_dev_class);
}