This module is heavily based on i2c-dev. Once loaded, it provides one
dev node per DP AUX channel, named drm_aux-N.
It's possible to know which connector owns this aux channel by looking
at the respective sysfs /sys/class/drm_aux-dev/drm_aux-N/connector, if
the connector device pointer was correctly set in the aux helper struct.
Two main operations are provided on the registers: read and write. The
address of the register to be read or written is given using lseek.
Reading or writing does not update the offset of the file.
Signed-off-by: Rafael Antognolli <rafael.antognolli@xxxxxxxxx>
---
drivers/gpu/drm/Kconfig | 4 +
drivers/gpu/drm/Makefile | 1 +
drivers/gpu/drm/drm_aux-dev.c | 326 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 331 insertions(+)
create mode 100644 drivers/gpu/drm/drm_aux-dev.c
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 1a0a8df..eae847c 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -25,6 +25,10 @@ config DRM_MIPI_DSI
bool
depends on DRM
+config DRM_AUX_CHARDEV
+ tristate "DRM DP AUX Interface"
+ depends on DRM
+
config DRM_KMS_HELPER
tristate
depends on DRM
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 45e7719..a1a94306 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -32,6 +32,7 @@ CFLAGS_drm_trace_points.o := -I$(src)
obj-$(CONFIG_DRM) += drm.o
obj-$(CONFIG_DRM_MIPI_DSI) += drm_mipi_dsi.o
+obj-$(CONFIG_DRM_AUX_CHARDEV) += drm_aux-dev.o
obj-$(CONFIG_DRM_TTM) += ttm/
obj-$(CONFIG_DRM_TDFX) += tdfx/
obj-$(CONFIG_DRM_R128) += r128/
diff --git a/drivers/gpu/drm/drm_aux-dev.c b/drivers/gpu/drm/drm_aux-dev.c
new file mode 100644
index 0000000..fcc334a
--- /dev/null
+++ b/drivers/gpu/drm/drm_aux-dev.c
@@ -0,0 +1,326 @@
+/*
+ * 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@xxxxxxxxx>
+ *
+ */
+
+#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 <asm/uaccess.h>
+#include <drm/drm_dp_helper.h>
+#include <drm/drm_crtc.h>
+
+struct drm_aux_dev {
+ struct list_head list;
+ unsigned index;
+ struct drm_dp_aux *aux;
+ struct device *dev;
+};
+
+#define DRM_AUX_MINORS 256
+static int drm_aux_dev_count = 0;
+static LIST_HEAD(drm_aux_dev_list);
+static DEFINE_SPINLOCK(drm_aux_dev_list_lock);
+
+static struct drm_aux_dev *drm_aux_dev_get_by_minor(unsigned index)
+{
+ struct drm_aux_dev *aux_dev;
+
+ spin_lock(&drm_aux_dev_list_lock);
+ list_for_each_entry(aux_dev, &drm_aux_dev_list, list) {
+ if (aux_dev->index == index)
+ goto found;
+ }
+
+ aux_dev = NULL;
+found:
+ spin_unlock(&drm_aux_dev_list_lock);
+ return aux_dev;
+}
+
+static struct drm_aux_dev *drm_aux_dev_get_by_aux(struct drm_dp_aux *aux)
+{
+ struct drm_aux_dev *aux_dev;
+
+ spin_lock(&drm_aux_dev_list_lock);
+ list_for_each_entry(aux_dev, &drm_aux_dev_list, list) {
+ if (aux_dev->aux == aux)
+ goto found;
+ }
+
+ aux_dev = NULL;
+found:
+ spin_unlock(&drm_aux_dev_list_lock);
+ return aux_dev;
+}
+
+static struct drm_aux_dev *get_free_drm_aux_dev(struct drm_dp_aux *aux)
+{
+ struct drm_aux_dev *aux_dev;
+ int index;
+
+ spin_lock(&drm_aux_dev_list_lock);
+ index = drm_aux_dev_count;
+ spin_unlock(&drm_aux_dev_list_lock);
+ if (index >= DRM_AUX_MINORS) {
+ printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",
+ index);
+ return ERR_PTR(-ENODEV);
+ }
+
+ aux_dev = kzalloc(sizeof(*aux_dev), GFP_KERNEL);
+ if (!aux_dev)
+ return ERR_PTR(-ENOMEM);
+ aux_dev->aux = aux;
+ aux_dev->index = index;
+
+ spin_lock(&drm_aux_dev_list_lock);
+ drm_aux_dev_count++;
+ list_add_tail(&aux_dev->list, &drm_aux_dev_list);
+ spin_unlock(&drm_aux_dev_list_lock);
+ return aux_dev;
+}
+
+static void return_drm_aux_dev(struct drm_aux_dev *aux_dev)
+{
+ spin_lock(&drm_aux_dev_list_lock);
+ list_del(&aux_dev->list);
+ spin_unlock(&drm_aux_dev_list_lock);
+ kfree(aux_dev);
+}
+
+static ssize_t name_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct drm_aux_dev *aux_dev = drm_aux_dev_get_by_minor(MINOR(dev->devt));
+
+ if (!aux_dev)
+ return -ENODEV;
+ return sprintf(buf, "%s\n", aux_dev->aux->name);
+}
+static DEVICE_ATTR_RO(name);
+
+static ssize_t connector_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct drm_aux_dev *aux_dev = drm_aux_dev_get_by_minor(MINOR(dev->devt));
+ struct drm_dp_aux *aux;
+ struct device *conn_dev;
+ struct drm_connector *connector = NULL;
+
+ if (!aux_dev)
+ return -ENODEV;
+ aux = aux_dev->aux;
+ conn_dev = aux->connector;
+ if (!conn_dev)
+ return sprintf(buf, "unknown\n");
+
+ connector = dev_get_drvdata(aux->connector);
+
+ return sprintf(buf, "%s\n", connector->name);
+}
+static DEVICE_ATTR_RO(connector);
+
+static struct attribute *drm_aux_attrs[] = {
+ &dev_attr_name.attr,
+ &dev_attr_connector.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(drm_aux);
+
+static int auxdev_open(struct inode *inode, struct file *file)
+{
+ unsigned int minor = iminor(inode);
+ struct drm_aux_dev *aux_dev;
+
+ aux_dev = drm_aux_dev_get_by_minor(minor);
+ if (!aux_dev)
+ return -ENODEV;
+
+ file->private_data = aux_dev;
+ return 0;
+}
+
+static ssize_t auxdev_read(struct file *file, char __user *buf, size_t count,
+ loff_t *offset)
+{
+ char *localbuf;
+ ssize_t res;
+ struct drm_aux_dev *aux_dev = file->private_data;
+
+ localbuf = memdup_user(buf, count);
+ if (IS_ERR(localbuf))
+ return PTR_ERR(buf);
+
+ res = drm_dp_dpcd_read(aux_dev->aux, *offset, localbuf, count);
+ if (res < 0)
+ goto finish;
+
+ if (copy_to_user(buf, localbuf, res))
+ res = -EFAULT;
+
+finish:
+ kfree(localbuf);
+ return res;
+}
+
+static ssize_t auxdev_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *offset)
+{
+ char *localbuf;
+ ssize_t res;
+ struct drm_aux_dev *aux_dev = file->private_data;
+
+ localbuf = memdup_user(buf, count);
+ if (IS_ERR(localbuf))
+ return PTR_ERR(buf);
+
+ res = drm_dp_dpcd_write(aux_dev->aux, *offset, localbuf, count);
+ kfree(localbuf);
+
+ return res;
+}
+
+static const struct file_operations auxdev_fops = {
+ .owner = THIS_MODULE,
+ .llseek = generic_file_llseek,
+ .read = auxdev_read,
+ .write = auxdev_write,
+ .open = auxdev_open,
+};
+
+static struct class *drm_aux_dev_class;
+static int drm_dev_major = -1;
+
+#define to_auxdev(d) container_of(d, struct drm_aux_dev, aux)
+
+static int auxdev_attach_aux(struct drm_dp_aux *aux, void *data)
+{
+ int *major = data;
+ struct drm_aux_dev *aux_dev;
+ int res;
+
+ aux_dev = get_free_drm_aux_dev(aux);
+ if (IS_ERR(aux_dev))
+ return PTR_ERR(aux_dev);
+
+ aux_dev->dev = device_create(drm_aux_dev_class, aux->dev,
+ MKDEV(*major, aux_dev->index), NULL,
+ "drm_aux-%d", aux_dev->index);
+ if (IS_ERR(aux_dev->dev)) {
+ res = PTR_ERR(aux_dev->dev);
+ goto error;
+ }
+
+ pr_debug("drm_aux-dev: aux [%s] registered as minor %d\n",
+ aux->name, aux_dev->index);
+ return 0;
+error:
+ return_drm_aux_dev(aux_dev);
+ return res;
+
+}
+
+static int auxdev_detach_aux(struct drm_dp_aux *aux, void *data)
+{
+ int *major = data;
+ int minor;
+ struct drm_aux_dev *aux_dev;
+
+ aux_dev = drm_aux_dev_get_by_aux(aux);
+ if (!aux_dev) /* attach must have failed */
+ return 0;
+
+ minor = aux_dev->index;
+ return_drm_aux_dev(aux_dev);
+ device_destroy(drm_aux_dev_class, MKDEV(*major, minor));
+
+ pr_debug("drm_aux-dev: aux [%s] unregistered\n", aux->name);
+ return 0;
+}
+
+static int auxdev_inform_cb(int action, struct drm_dp_aux *aux)
+{
+ switch (action) {
+ case DRM_DP_ADD_AUX:
+ return auxdev_attach_aux(aux, &drm_dev_major);
+ case DRM_DP_DEL_AUX:
+ return auxdev_detach_aux(aux, &drm_dev_major);
+ }
+
+ return 0;
+}
+
+static int __init drm_aux_dev_init(void)
+{
+ int res;
+
+ printk(KERN_INFO "drm dp aux /dev entries driver\n");
+
+ res = register_chrdev(0, "aux", &auxdev_fops);
+ if (res < 0)
+ goto out;
+ drm_dev_major = res;
+
+ drm_aux_dev_class = class_create(THIS_MODULE, "drm_aux-dev");
+ if (IS_ERR(drm_aux_dev_class)) {
+ res = PTR_ERR(drm_aux_dev_class);
+ goto out_unreg_chrdev;
+ }
+ drm_aux_dev_class->dev_groups = drm_aux_groups;
+
+ /* Keep track of DP aux that will be added or removed later */
+ drm_dp_aux_set_aux_dev(&auxdev_inform_cb);
+
+ /* Bind to already existing DP aux */
+ res = drm_dp_aux_for_each(&drm_dev_major, auxdev_attach_aux);
+
+ return 0;
+
+out_unreg_chrdev:
+ unregister_chrdev(drm_dev_major, "aux");
+out:
+ printk(KERN_ERR "%s: Driver Initialisation failed\n", __FILE__);
+ return res;
+}
+
+static void __exit drm_aux_dev_exit(void)
+{
+ printk(KERN_INFO "drm dp aux /dev entries driver - unloading\n");
+ drm_dp_aux_set_aux_dev(NULL);
+ drm_dp_aux_for_each(&drm_dev_major, auxdev_detach_aux);
+ class_destroy(drm_aux_dev_class);
+ unregister_chrdev(drm_dev_major, "aux");
+}
+
+MODULE_AUTHOR("Rafael Antognolli <rafael.antognolli@xxxxxxxxx>");
+MODULE_DESCRIPTION("DRM DP AUX /dev entries driver");
+MODULE_LICENSE("GPL");
+
+module_init(drm_aux_dev_init);
+module_exit(drm_aux_dev_exit);
--
2.4.3
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