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path: root/drivers/gpu/drm/display/drm_dp_aux_dev.c
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Diffstat (limited to 'drivers/gpu/drm/display/drm_dp_aux_dev.c')
-rw-r--r--drivers/gpu/drm/display/drm_dp_aux_dev.c354
1 files changed, 354 insertions, 0 deletions
diff --git a/drivers/gpu/drm/display/drm_dp_aux_dev.c b/drivers/gpu/drm/display/drm_dp_aux_dev.c
new file mode 100644
index 000000000000..098e482e65a2
--- /dev/null
+++ b/drivers/gpu/drm/display/drm_dp_aux_dev.c
@@ -0,0 +1,354 @@
+/*
+ * 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/display/drm_dp_helper.h>
+#include <drm/display/drm_dp_mst_helper.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_print.h>
+
+#include "drm_dp_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;
+
+ /*
+ * As some AUX adapters may exist as platform devices which outlive their respective DRM
+ * devices, we clear drm_dev to ensure that we never accidentally reference a stale pointer
+ */
+ aux->drm_dev = NULL;
+
+ 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);
+}