/* * 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; } 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); }