On Tue, Sep 22, 2015 at 10:59:51AM +0200, Daniel Vetter wrote:
> On Tue, Sep 15, 2015 at 04:55:04PM -0700, Rafael Antognolli wrote:
> > 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.
>
> I think not updating the read position is very surprising. Would it be
> hard to fix that?
No, not hard at all. But I assume then I should update the write
position too, right?
BTW, i2c-dev doesn't update either of them, but I'm not sure why.
> >
> > 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
> >
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > http://lists.freedesktop.org/mailman/listinfo/dri-devel
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
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