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);
+}