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sys/dev/drm/core/drm_dp_aux_dev.c
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/* | |||||
* 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 (!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; | |||||
} | |||||
if (aux_dev->aux->is_remote) | |||||
res = drm_dp_mst_dpcd_read(aux_dev->aux, pos, buf, | |||||
todo); | |||||
else | |||||
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; | |||||
} | |||||
if (aux_dev->aux->is_remote) | |||||
res = drm_dp_mst_dpcd_write(aux_dev->aux, pos, buf, | |||||
todo); | |||||
else | |||||
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); | |||||
} |