/* * 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/slab.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/uaccess.h> #include <drm/drm_dp_helper.h> #include <drm/drm_crtc.h> #include <drm/drmP.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_cyclic(&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(struct file *file, char __user *buf, size_t count, loff_t *offset) { size_t bytes_pending, num_bytes_processed = 0; struct drm_dp_aux_dev *aux_dev = file->private_data; ssize_t res = 0; if (!atomic_inc_not_zero(&aux_dev->usecount)) return -ENODEV; bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - (*offset)); if (!access_ok(VERIFY_WRITE, buf, bytes_pending)) { res = -EFAULT; goto out; } while (bytes_pending > 0) { uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES]; ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf)); res = drm_dp_dpcd_read(aux_dev->aux, *offset, localbuf, todo); if (res <= 0) { res = num_bytes_processed ? num_bytes_processed : res; goto out; } if (__copy_to_user(buf + num_bytes_processed, localbuf, res)) { res = num_bytes_processed ? num_bytes_processed : -EFAULT; goto out; } bytes_pending -= res; *offset += res; num_bytes_processed += res; res = num_bytes_processed; } out: atomic_dec(&aux_dev->usecount); wake_up_atomic_t(&aux_dev->usecount); return res; } static ssize_t auxdev_write(struct file *file, const char __user *buf, size_t count, loff_t *offset) { size_t bytes_pending, num_bytes_processed = 0; struct drm_dp_aux_dev *aux_dev = file->private_data; ssize_t res = 0; if (!atomic_inc_not_zero(&aux_dev->usecount)) return -ENODEV; bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - *offset); if (!access_ok(VERIFY_READ, buf, bytes_pending)) { res = -EFAULT; goto out; } while (bytes_pending > 0) { uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES]; ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf)); if (__copy_from_user(localbuf, buf + num_bytes_processed, todo)) { res = num_bytes_processed ? num_bytes_processed : -EFAULT; goto out; } res = drm_dp_dpcd_write(aux_dev->aux, *offset, localbuf, todo); if (res <= 0) { res = num_bytes_processed ? num_bytes_processed : res; goto out; } bytes_pending -= res; *offset += res; num_bytes_processed += res; res = num_bytes_processed; } out: atomic_dec(&aux_dev->usecount); wake_up_atomic_t(&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 = auxdev_read, .write = auxdev_write, .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; } static int auxdev_wait_atomic_t(atomic_t *p) { schedule(); return 0; } /** * drm_dp_aux_unregister_devnode() - unregister a devnode for this aux channel * @aux: DisplayPort AUX channel * * Returns 0 on success or a negative error code on failure. */ 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_on_atomic_t(&aux_dev->usecount, auxdev_wait_atomic_t, TASK_UNINTERRUPTIBLE); 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); } EXPORT_SYMBOL(drm_dp_aux_unregister_devnode); /** * drm_dp_aux_register_devnode() - register a devnode for this aux channel * @aux: DisplayPort AUX channel * * Returns 0 on success or a negative error code on failure. */ 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; } EXPORT_SYMBOL(drm_dp_aux_register_devnode); 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)) { res = PTR_ERR(drm_dp_aux_dev_class); goto out; } 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; } EXPORT_SYMBOL(drm_dp_aux_dev_init); void drm_dp_aux_dev_exit(void) { unregister_chrdev(drm_dev_major, "aux"); class_destroy(drm_dp_aux_dev_class); } EXPORT_SYMBOL(drm_dp_aux_dev_exit);