On Thu, Jan 21, 2016 at 03:10:19PM -0800, Rafael Antognolli wrote: > This module is heavily based on i2c-dev. Once loaded, it provides one > dev node per DP AUX channel, named drm_dp_auxN, where N is an integer. > > It's possible to know which connector owns this aux channel by looking > at the respective sysfs /sys/class/drm_aux_dev/drm_dp_auxN/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. The > seek position is updated upon read or write. > > v2: > - lseek is used to select the register to read/write > - read/write are used instead of ioctl > - no blocking_notifier is used, just a direct callback > > v3: > - use drm_dp_aux_dev prefix for public functions > - chardev is named drm_dp_auxN > - read/write don't allocate a buffer anymore, and transfer up to 16 bytes a > time > - remove notifier list from the implementation > - option on menuconfig is now a boolean > - add inline stub functions to avoid breakage when this option is disabled > > v4: > - fix build system changes - actually disable this module when not selected. > > v5: > - Use kref to avoid device closing while still in use > - Don't use list, use an idr for storing aux_dev > - Remove "connector" attribute > - set aux.dev to the connector drm_connector device, instead of > drm_device > > v6: > - Use atomic_t for usage count > - Use a mutex instead of spinlock for idr lock > - Destroy chardev immediately on unregister > - other minor suggestions from Ville > > v7: > - style fixes > - error handling fixes > > v8: > - more error handling fixes > > v9: > - remove module_init and module_exit, and add drm_dp_aux_dev_init/exit > to drm_kms_helper_init/exit. > > Signed-off-by: Rafael Antognolli <rafael.antognolli@xxxxxxxxx> Only checked the init/exit stuff since I should have read the rest many times by now. Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > --- > drivers/gpu/drm/Kconfig | 8 + > drivers/gpu/drm/Makefile | 1 + > drivers/gpu/drm/drm_dp_aux_dev.c | 368 ++++++++++++++++++++++++++++++++ > drivers/gpu/drm/drm_dp_helper.c | 16 +- > drivers/gpu/drm/drm_kms_helper_common.c | 15 +- > include/drm/drm_dp_aux_dev.h | 62 ++++++ > 6 files changed, 468 insertions(+), 2 deletions(-) > create mode 100644 drivers/gpu/drm/drm_dp_aux_dev.c > create mode 100644 include/drm/drm_dp_aux_dev.h > > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig > index 59babd5..dff87ca 100644 > --- a/drivers/gpu/drm/Kconfig > +++ b/drivers/gpu/drm/Kconfig > @@ -25,6 +25,14 @@ config DRM_MIPI_DSI > bool > depends on DRM > > +config DRM_DP_AUX_CHARDEV > + bool "DRM DP AUX Interface" > + depends on DRM > + help > + Choose this option to enable a /dev/drm_dp_auxN node that allows to > + read and write values to arbitrary DPCD registers on the DP aux > + channel. > + > config DRM_KMS_HELPER > tristate > depends on DRM > diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile > index dfe513f..424fcb7 100644 > --- a/drivers/gpu/drm/Makefile > +++ b/drivers/gpu/drm/Makefile > @@ -30,6 +30,7 @@ drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_probe_helper.o \ > drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o > drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o > drm_kms_helper-$(CONFIG_DRM_KMS_CMA_HELPER) += drm_fb_cma_helper.o > +drm_kms_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o > > obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o > > diff --git a/drivers/gpu/drm/drm_dp_aux_dev.c b/drivers/gpu/drm/drm_dp_aux_dev.c > new file mode 100644 > index 0000000..f73b38b > --- /dev/null > +++ b/drivers/gpu/drm/drm_dp_aux_dev.c > @@ -0,0 +1,368 @@ > +/* > + * 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/uaccess.h> > +#include <drm/drm_dp_helper.h> > +#include <drm/drm_crtc.h> > +#include <drm/drmP.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 (!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_cyclic(&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(struct file *file, char __user *buf, size_t count, > + loff_t *offset) > +{ > + size_t bytes_pending, num_bytes_processed = 0; > + struct drm_dp_aux_dev *aux_dev = file->private_data; > + ssize_t res = 0; > + > + if (!atomic_inc_not_zero(&aux_dev->usecount)) > + return -ENODEV; > + > + bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - (*offset)); > + > + if (!access_ok(VERIFY_WRITE, buf, bytes_pending)) { > + res = -EFAULT; > + goto out; > + } > + > + while (bytes_pending > 0) { > + uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES]; > + ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf)); > + > + res = drm_dp_dpcd_read(aux_dev->aux, *offset, localbuf, todo); > + if (res <= 0) { > + res = num_bytes_processed ? num_bytes_processed : res; > + goto out; > + } > + if (__copy_to_user(buf + num_bytes_processed, localbuf, res)) { > + res = num_bytes_processed ? > + num_bytes_processed : -EFAULT; > + goto out; > + } > + bytes_pending -= res; > + *offset += res; > + num_bytes_processed += res; > + res = num_bytes_processed; > + } > + > +out: > + atomic_dec(&aux_dev->usecount); > + wake_up_atomic_t(&aux_dev->usecount); > + return res; > +} > + > +static ssize_t auxdev_write(struct file *file, const char __user *buf, > + size_t count, loff_t *offset) > +{ > + size_t bytes_pending, num_bytes_processed = 0; > + struct drm_dp_aux_dev *aux_dev = file->private_data; > + ssize_t res = 0; > + > + if (!atomic_inc_not_zero(&aux_dev->usecount)) > + return -ENODEV; > + > + bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - *offset); > + > + if (!access_ok(VERIFY_READ, buf, bytes_pending)) { > + res = -EFAULT; > + goto out; > + } > + > + while (bytes_pending > 0) { > + uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES]; > + ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf)); > + > + if (__copy_from_user(localbuf, > + buf + num_bytes_processed, todo)) { > + res = num_bytes_processed ? > + num_bytes_processed : -EFAULT; > + goto out; > + } > + > + res = drm_dp_dpcd_write(aux_dev->aux, *offset, localbuf, todo); > + if (res <= 0) { > + res = num_bytes_processed ? num_bytes_processed : res; > + goto out; > + } > + bytes_pending -= res; > + *offset += res; > + num_bytes_processed += res; > + res = num_bytes_processed; > + } > + > +out: > + atomic_dec(&aux_dev->usecount); > + wake_up_atomic_t(&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 = auxdev_read, > + .write = auxdev_write, > + .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; > +} > + > +static int auxdev_wait_atomic_t(atomic_t *p) > +{ > + schedule(); > + return 0; > +} > +/** > + * drm_dp_aux_unregister_devnode() - unregister a devnode for this aux channel > + * @aux: DisplayPort AUX channel > + * > + * Returns 0 on success or a negative error code on failure. > + */ > +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; > + > + mutex_lock(&aux_idr_mutex); > + idr_remove(&aux_idr, aux_dev->index); > + mutex_unlock(&aux_idr_mutex); > + > + atomic_dec(&aux_dev->usecount); > + wait_on_atomic_t(&aux_dev->usecount, auxdev_wait_atomic_t, > + TASK_UNINTERRUPTIBLE); > + > + 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); > +} > +EXPORT_SYMBOL(drm_dp_aux_unregister_devnode); > + > +/** > + * drm_dp_aux_register_devnode() - register a devnode for this aux channel > + * @aux: DisplayPort AUX channel > + * > + * Returns 0 on success or a negative error code on failure. > + */ > +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; > +} > +EXPORT_SYMBOL(drm_dp_aux_register_devnode); > + > +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)) { > + res = PTR_ERR(drm_dp_aux_dev_class); > + goto out; > + } > + 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; > +} > +EXPORT_SYMBOL(drm_dp_aux_dev_init); > + > +void drm_dp_aux_dev_exit(void) > +{ > + unregister_chrdev(drm_dev_major, "aux"); > + class_destroy(drm_dp_aux_dev_class); > +} > +EXPORT_SYMBOL(drm_dp_aux_dev_exit); > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c > index 9535c5b..7d58f59 100644 > --- a/drivers/gpu/drm/drm_dp_helper.c > +++ b/drivers/gpu/drm/drm_dp_helper.c > @@ -28,6 +28,7 @@ > #include <linux/sched.h> > #include <linux/i2c.h> > #include <drm/drm_dp_helper.h> > +#include <drm/drm_dp_aux_dev.h> > #include <drm/drmP.h> > > /** > @@ -754,6 +755,8 @@ static const struct i2c_algorithm drm_dp_i2c_algo = { > */ > int drm_dp_aux_register(struct drm_dp_aux *aux) > { > + int ret; > + > mutex_init(&aux->hw_mutex); > > aux->ddc.algo = &drm_dp_i2c_algo; > @@ -768,7 +771,17 @@ int drm_dp_aux_register(struct drm_dp_aux *aux) > strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev), > sizeof(aux->ddc.name)); > > - return i2c_add_adapter(&aux->ddc); > + ret = drm_dp_aux_register_devnode(aux); > + if (ret) > + return ret; > + > + ret = i2c_add_adapter(&aux->ddc); > + if (ret) { > + drm_dp_aux_unregister_devnode(aux); > + return ret; > + } > + > + return 0; > } > EXPORT_SYMBOL(drm_dp_aux_register); > > @@ -778,6 +791,7 @@ EXPORT_SYMBOL(drm_dp_aux_register); > */ > void drm_dp_aux_unregister(struct drm_dp_aux *aux) > { > + drm_dp_aux_unregister_devnode(aux); > i2c_del_adapter(&aux->ddc); > } > EXPORT_SYMBOL(drm_dp_aux_unregister); > diff --git a/drivers/gpu/drm/drm_kms_helper_common.c b/drivers/gpu/drm/drm_kms_helper_common.c > index d361005..3187c4b 100644 > --- a/drivers/gpu/drm/drm_kms_helper_common.c > +++ b/drivers/gpu/drm/drm_kms_helper_common.c > @@ -27,6 +27,7 @@ > > #include <drm/drmP.h> > #include <drm/drm_fb_helper.h> > +#include <drm/drm_dp_aux_dev.h> > > MODULE_AUTHOR("David Airlie, Jesse Barnes"); > MODULE_DESCRIPTION("DRM KMS helper"); > @@ -34,13 +35,25 @@ MODULE_LICENSE("GPL and additional rights"); > > static int __init drm_kms_helper_init(void) > { > + int ret; > + > /* Call init functions from specific kms helpers here */ > - return drm_fb_helper_modinit(); > + ret = drm_fb_helper_modinit(); > + if (ret < 0) > + goto out; > + > + ret = drm_dp_aux_dev_init(); > + if (ret < 0) > + goto out; > + > +out: > + return ret; > } > > static void __exit drm_kms_helper_exit(void) > { > /* Call exit functions from specific kms helpers here */ > + drm_dp_aux_dev_exit(); > } > > module_init(drm_kms_helper_init); > diff --git a/include/drm/drm_dp_aux_dev.h b/include/drm/drm_dp_aux_dev.h > new file mode 100644 > index 0000000..1b76d99 > --- /dev/null > +++ b/include/drm/drm_dp_aux_dev.h > @@ -0,0 +1,62 @@ > +/* > + * 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 DRM_DP_AUX_DEV > +#define DRM_DP_AUX_DEV > + > +#include <drm/drm_dp_helper.h> > + > +#ifdef CONFIG_DRM_DP_AUX_CHARDEV > + > +int drm_dp_aux_dev_init(void); > +void drm_dp_aux_dev_exit(void); > +int drm_dp_aux_register_devnode(struct drm_dp_aux *aux); > +void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux); > + > +#else > + > +static inline int drm_dp_aux_dev_init(void) > +{ > + return 0; > +} > + > +static inline void drm_dp_aux_dev_exit(void) > +{ > +} > + > +static inline int drm_dp_aux_register_devnode(struct drm_dp_aux *aux) > +{ > + return 0; > +} > + > +static inline void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux) > +{ > +} > + > +#endif > + > +#endif > -- > 2.4.3 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Ville Syrjälä Intel OTC _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel