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 through ioctls: read
and write; and a helper struct is provided for that, used as:
- address is the address of the register to read/write;
- len is the number of bytes to read/write;
- buf is a pointer to a buffer where to store the read data, or
where the data to be written is already stored;
- the return value is the number of bytes read/written, on
success, or the error code otherwise. The number of
read/written bytes is also stored on the len field of the
struct.
Signed-off-by: Rafael Antognolli <rafael.antognolli@xxxxxxxxx>
---
Documentation/ioctl/ioctl-number.txt | 1 +
drivers/gpu/drm/Kconfig | 4 +
drivers/gpu/drm/Makefile | 1 +
drivers/gpu/drm/drm_aux-dev.c | 390 +++++++++++++++++++++++++++++++++++
include/uapi/linux/Kbuild | 1 +
include/uapi/linux/drm_aux-dev.h | 45 ++++
6 files changed, 442 insertions(+)
create mode 100644 drivers/gpu/drm/drm_aux-dev.c
create mode 100644 include/uapi/linux/drm_aux-dev.h
diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
index 611c522..ea76980 100644
--- a/Documentation/ioctl/ioctl-number.txt
+++ b/Documentation/ioctl/ioctl-number.txt
@@ -93,6 +93,7 @@ Code Seq#(hex) Include File Comments
';' 64-7F linux/vfio.h
'@' 00-0F linux/radeonfb.h conflict!
'@' 00-0F drivers/video/aty/aty128fb.c conflict!
+'@' 10-2F drm_aux-dev
'A' 00-1F linux/apm_bios.h conflict!
'A' 00-0F linux/agpgart.h conflict!
and drivers/char/agp/compat_ioctl.h
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..3ae9064
--- /dev/null
+++ b/drivers/gpu/drm/drm_aux-dev.c
@@ -0,0 +1,390 @@
+/*
+ * 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 <linux/drm_aux-dev.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 long auxdev_ioctl_read(struct drm_aux_dev *aux_dev, unsigned long arg)
+{
+ struct drm_aux_dev_data rdwr_arg;
+ __u8 *buf;
+ int res;
+
+ /* Get register address, buffer and read length from user */
+ if (copy_from_user(&rdwr_arg,
+ (struct drm_aux_dev_data __user *)arg,
+ sizeof(rdwr_arg)))
+ return -EFAULT;
+
+ buf = memdup_user(rdwr_arg.buf, rdwr_arg.len * sizeof(__u8));
+ if (IS_ERR(buf))
+ return PTR_ERR(buf);
+
+ /* read register */
+ res = drm_dp_dpcd_read(aux_dev->aux, rdwr_arg.address, buf, rdwr_arg.len);
+ if (res < 0) {
+ kfree(buf);
+ return res;
+ }
+
+ /* return number of read bytes to user */
+ rdwr_arg.len = res;
+ if (copy_to_user((struct drm_aux_dev_data __user *)arg,
+ &rdwr_arg, sizeof(rdwr_arg))) {
+ kfree(buf);
+ return -EFAULT;
+ }
+
+ /* return the read bytes to user */
+ if (copy_to_user((__u8 __user *)rdwr_arg.buf,
+ buf, rdwr_arg.len)) {
+ kfree(buf);
+ return -EFAULT;
+ }
+
+ kfree(buf);
+ return res;
+}
+
+static long auxdev_ioctl_write(struct drm_aux_dev *aux_dev, unsigned long arg)
+{
+ struct drm_aux_dev_data rdwr_arg;
+ __u8 *buf;
+ int res;
+
+ /* Get register address and data to write */
+ if (copy_from_user(&rdwr_arg,
+ (struct drm_aux_dev_data __user *)arg,
+ sizeof(rdwr_arg)))
+ return -EFAULT;
+
+ buf = memdup_user(rdwr_arg.buf, rdwr_arg.len * sizeof(__u8));
+ if (IS_ERR(buf))
+ return PTR_ERR(buf);
+
+ /* write register */
+ res = drm_dp_dpcd_write(aux_dev->aux, rdwr_arg.address, buf, rdwr_arg.len);
+ if (res < 0) {
+ kfree(buf);
+ return res;
+ }
+
+ /* return length of written data */
+ rdwr_arg.len = res;
+ if (copy_to_user((struct drm_aux_dev_data __user *)arg,
+ &rdwr_arg, sizeof(rdwr_arg))) {
+ kfree(buf);
+ return -EFAULT;
+ }
+
+ kfree(buf);
+ return res;
+}
+
+static long auxdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ struct drm_aux_dev *aux_dev = file->private_data;
+ dev_dbg(aux_dev->aux->dev, "ioctl, cmd=0x%02x, arg=0x%02lx\n",
+ cmd, arg);
+ switch (cmd) {
+ case DRM_AUX_DEV_READ:
+ return auxdev_ioctl_read(aux_dev, arg);
+ case DRM_AUX_DEV_WRITE:
+ return auxdev_ioctl_write(aux_dev, arg);
+ default:
+ return -ENOTTY;
+ }
+
+ return 0;
+}
+
+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 const struct file_operations auxdev_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .unlocked_ioctl = auxdev_ioctl,
+ .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_notifier_call(struct notifier_block *nb, unsigned long action,
+ void *data)
+{
+ struct drm_dp_aux *aux = data;
+ 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 struct notifier_block auxdev_notifier = {
+ .notifier_call = auxdev_notifier_call,
+};
+
+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 */
+ res = drm_dp_aux_register_notifier(&auxdev_notifier);
+ if (res)
+ goto out_unreg_class;
+
+ /* Bind to already existing DP aux */
+ res = drm_dp_aux_for_each(&drm_dev_major, auxdev_attach_aux);
+
+ return 0;
+
+out_unreg_class:
+ class_destroy(drm_aux_dev_class);
+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_unregister_notifier(&auxdev_notifier);
+ 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);
diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
index 1ff9942..07cdc8c 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -105,6 +105,7 @@ header-y += dm-ioctl.h
header-y += dm-log-userspace.h
header-y += dn.h
header-y += dqblk_xfs.h
+header-y += drm_aux-dev.h
header-y += edd.h
header-y += efs_fs_sb.h
header-y += elfcore.h
diff --git a/include/uapi/linux/drm_aux-dev.h b/include/uapi/linux/drm_aux-dev.h
new file mode 100644
index 0000000..668b631
--- /dev/null
+++ b/include/uapi/linux/drm_aux-dev.h
@@ -0,0 +1,45 @@
+/*
+ * 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>
+ *
+ */
+
+#ifndef _UAPI_LINUX_DRM_AUX_DEV_H
+#define _UAPI_LINUX_DRM_AUX_DEV_H
+
+#include <linux/ioctl.h>
+#include <linux/types.h>
+
+#define DRM_AUX_DEV_MAGIC '@'
+
+struct drm_aux_dev_data {
+ __u32 address; /* of the register */
+ __u16 len; /* size of the read/write */
+ __u8 *buf;
+};
+
+#define DRM_AUX_DEV_READ _IOWR(DRM_AUX_DEV_MAGIC, 0x10, struct drm_aux_dev_data)
+#define DRM_AUX_DEV_WRITE _IOW(DRM_AUX_DEV_MAGIC, 0x11, struct drm_aux_dev_data)
+
+#endif // _UAPI_LINUX_DRM_AUX_DEV_H
--
2.4.0
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