[PATCH v2 4/6] drm/vkms: Add ConfigFS scaffolding to VKMS

From: Jim Shargo
Date: Fri Jun 23 2023 - 18:25:50 EST

This change adds the basic scaffolding for ConfigFS, including setting
up the default directories. It does not allow for the registration of
configfs-backed devices, which is complex and provided in a follow-up
commit.

This CL includes docs about using ConfigFS with VKMS, but I'll summarize
in brief here as well (assuming ConfigFS is mounted at /config/):

To create a new device, you can do so via `mkdir
/config/vkms/my-device`.

This will create a number of directories and files automatically:

/config
`-- vkms
`-- my-device
|-- connectors
|-- crtcs
|-- encoders
|-- planes
`-- enabled

You can then configure objects by mkdir'ing in each of the directories.

When you're satisfied, you can `echo 1 > /config/vkms/my-device/enabled`.
This will create a new device according to your configuration.

For now, this will fail, but the next change will add support for it.

Signed-off-by: Jim Shargo <jshargo@xxxxxxxxxxxx>
---
Documentation/gpu/vkms.rst | 17 +-
drivers/gpu/drm/Kconfig | 1 +
drivers/gpu/drm/vkms/Makefile | 1 +
drivers/gpu/drm/vkms/vkms_configfs.c | 646 +++++++++++++++++++++++++++
drivers/gpu/drm/vkms/vkms_drv.c | 52 ++-
drivers/gpu/drm/vkms/vkms_drv.h | 92 +++-
drivers/gpu/drm/vkms/vkms_output.c | 5 +
7 files changed, 799 insertions(+), 15 deletions(-)
create mode 100644 drivers/gpu/drm/vkms/vkms_configfs.c

diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index ba04ac7c2167..2c342ef0fb7b 100644
--- a/Documentation/gpu/vkms.rst
+++ b/Documentation/gpu/vkms.rst
@@ -51,6 +51,12 @@ To disable the driver, use ::

sudo modprobe -r vkms

+Configuration With ConfigFS
+===========================
+
+.. kernel-doc:: drivers/gpu/drm/vkms/vkms_configfs.c
+ :doc: ConfigFS Support for VKMS
+
Testing With IGT
================

@@ -135,22 +141,15 @@ project.
Runtime Configuration
---------------------

-We want to be able to reconfigure vkms instance without having to reload the
-module. Use/Test-cases:
+We want to vkms instances without having to reload the module. Such
+configuration can be added as extensions to vkms's ConfigFS support. Use-cases:

- Hotplug/hotremove connectors on the fly (to be able to test DP MST handling
of compositors).

-- Configure planes/crtcs/connectors (we'd need some code to have more than 1 of
- them first).
-
- Change output configuration: Plug/unplug screens, change EDID, allow changing
the refresh rate.

-The currently proposed solution is to expose vkms configuration through
-configfs. All existing module options should be supported through configfs
-too.
-
Writeback support
-----------------

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index afb3b2f5f425..71eb913b378f 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -262,6 +262,7 @@ config DRM_VKMS
depends on DRM && MMU
select DRM_KMS_HELPER
select DRM_GEM_SHMEM_HELPER
+ select CONFIGFS_FS
select CRC32
default n
help
diff --git a/drivers/gpu/drm/vkms/Makefile b/drivers/gpu/drm/vkms/Makefile
index 1b28a6a32948..6b83907ad554 100644
--- a/drivers/gpu/drm/vkms/Makefile
+++ b/drivers/gpu/drm/vkms/Makefile
@@ -1,5 +1,6 @@
# SPDX-License-Identifier: GPL-2.0-only
vkms-y := \
+ vkms_configfs.o \
vkms_drv.o \
vkms_plane.o \
vkms_output.o \
diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
new file mode 100644
index 000000000000..544024735d19
--- /dev/null
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -0,0 +1,646 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/configfs.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+
+#include <drm/drm_plane.h>
+#include <drm/drm_print.h>
+
+#include "vkms_drv.h"
+
+/**
+ * DOC: ConfigFS Support for VKMS
+ *
+ * VKMS is instrumented with support for configuration via :doc:`ConfigFS
+ * <../filesystems/configfs>`.
+ *
+ * With VKMS installed, you can mount ConfigFS at ``/config/`` like so::
+ *
+ * mkdir -p /config/
+ * sudo mount -t configfs none /config
+ *
+ * This allows you to configure multiple virtual devices in addition to an
+ * immutable "default" device created by the driver at initialization time. Note
+ * that the default device is immutable because we cannot pre-populate ConfigFS
+ * directories with normal files.
+ *
+ * To set up a new device, create a new directory under the VKMS configfs
+ * directory::
+ *
+ * mkdir /config/vkms/test
+ *
+ * With your device created you'll find an new directory ready to be
+ * configured::
+ *
+ * /config
+ * `-- vkms
+ * |-- default
+ * | `-- enabled
+ * `-- test
+ * |-- connectors
+ * |-- crtcs
+ * |-- encoders
+ * |-- planes
+ * `-- enabled
+ *
+ * Each directory you add within the connectors, crtcs, encoders, and planes
+ * directories will let you configure a new object of that type. Adding new
+ * objects will automatically create a set of default files and folders you can
+ * use to configure that object.
+ *
+ * For instance, we can set up a two-output device like so::
+ *
+ * DRM_PLANE_TYPE_PRIMARY=1
+ * DRM_PLANE_TYPE_CURSOR=2
+ * DRM_PLANE_TYPE_OVERLAY=0
+ *
+ * mkdir /config/vkms/test/planes/primary
+ * echo $DRM_PLANE_TYPE_PRIMARY > /config/vkms/test/planes/primary/type
+ *
+ * mkdir /config/vkms/test/planes/other_primary
+ * echo $DRM_PLANE_TYPE_PRIMARY > /config/vkms/test/planes/other_primary/type
+ *
+ * mkdir /config/vkms/test/planes/cursor
+ * echo $DRM_PLANE_TYPE_CURSOR > /config/vkms/test/planes/cursor/type
+ *
+ * mkdir /config/vkms/test/planes/overlay
+ * echo $DRM_PLANE_TYPE_OVERLAY > /config/vkms/test/planes/overlay/type
+ *
+ * mkdir /config/vkms/test/crtcs/crtc
+ * mkdir /config/vkms/test/crtcs/crtc_other
+ * mkdir /config/vkms/test/encoders/encoder
+ * mkdir /config/vkms/test/connectors/connector
+ *
+ * You can see that specific attributes, such as ``.../<plane>/type``, can be
+ * configured by writing into them. Associating objects together can be done via
+ * symlinks::
+ *
+ * ln -s /config/vkms/test/encoders/encoder /config/vkms/test/connectors/connector/possible_encoders
+ *
+ * ln -s /config/vkms/test/crtcs/crtc /config/vkms/test/encoders/encoder/possible_crtcs/
+ * ln -s /config/vkms/test/crtcs/crtc /config/vkms/test/planes/primary/possible_crtcs/
+ * ln -s /config/vkms/test/crtcs/crtc /config/vkms/test/planes/cursor/possible_crtcs/
+ * ln -s /config/vkms/test/crtcs/crtc /config/vkms/test/planes/overlay/possible_crtcs/
+ *
+ * ln -s /config/vkms/test/crtcs/crtc_other /config/vkms/test/planes/overlay/possible_crtcs/
+ * ln -s /config/vkms/test/crtcs/crtc_other /config/vkms/test/planes/other_primary/possible_crtcs/
+ *
+ * Finally, to enable your configured device, just write 1 to the ``enabled``
+ * file::
+ *
+ * echo 1 > /config/vkms/test/enabled
+ *
+ * When you're done with the virtual device, you can clean up the device like
+ * so::
+ *
+ * echo 0 > /config/vkms/test/enabled
+ *
+ * rm /config/vkms/test/connectors/connector/possible_encoders/encoder
+ * rm /config/vkms/test/encoders/encoder/possible_crtcs/crtc
+ * rm /config/vkms/test/planes/primary/possible_crtcs/crtc
+ * rm /config/vkms/test/planes/cursor/possible_crtcs/crtc
+ * rm /config/vkms/test/planes/overlay/possible_crtcs/crtc
+ * rm /config/vkms/test/planes/overlay/possible_crtcs/crtc_other
+ * rm /config/vkms/test/planes/other_primary/possible_crtcs/crtc_other
+ *
+ * rmdir /config/vkms/test/planes/primary
+ * rmdir /config/vkms/test/planes/other_primary
+ * rmdir /config/vkms/test/planes/cursor
+ * rmdir /config/vkms/test/planes/overlay
+ * rmdir /config/vkms/test/crtcs/crtc
+ * rmdir /config/vkms/test/crtcs/crtc_other
+ * rmdir /config/vkms/test/encoders/encoder
+ * rmdir /config/vkms/test/connectors/connector
+ *
+ * rmdir /config/vkms/test
+ */
+
+/*
+ * Common helpers (i.e. common sub-groups)
+ */
+
+/* Possible CRTCs, e.g. /config/vkms/device/<object>/possible_crtcs/<symlink> */
+
+static struct config_item_type crtc_type;
+
+static int possible_crtcs_allow_link(struct config_item *src,
+ struct config_item *target)
+{
+ struct vkms_config_links *links = item_to_config_links(src);
+ struct vkms_config_crtc *crtc;
+
+ if (target->ci_type != &crtc_type) {
+ DRM_ERROR("Unable to link non-CRTCs.\n");
+ return -EINVAL;
+ }
+
+ crtc = item_to_config_crtc(target);
+
+ if (links->linked_object_bitmap & BIT(crtc->crtc_config_idx)) {
+ DRM_ERROR(
+ "Tried to add two symlinks to the same CRTC from the same object\n");
+ return -EINVAL;
+ }
+
+ links->linked_object_bitmap |= BIT(crtc->crtc_config_idx);
+
+ return 0;
+}
+
+static void possible_crtcs_drop_link(struct config_item *src,
+ struct config_item *target)
+{
+ struct vkms_config_links *links = item_to_config_links(src);
+ struct vkms_config_crtc *crtc = item_to_config_crtc(target);
+
+ links->linked_object_bitmap &= ~BIT(crtc->crtc_config_idx);
+}
+
+static struct configfs_item_operations possible_crtcs_item_ops = {
+ .allow_link = &possible_crtcs_allow_link,
+ .drop_link = &possible_crtcs_drop_link,
+};
+
+static struct config_item_type possible_crtcs_group_type = {
+ .ct_item_ops = &possible_crtcs_item_ops,
+ .ct_owner = THIS_MODULE,
+};
+
+static void add_possible_crtcs(struct config_group *parent,
+ struct config_group *possible_crtcs)
+{
+ config_group_init_type_name(possible_crtcs, "possible_crtcs",
+ &possible_crtcs_group_type);
+ configfs_add_default_group(possible_crtcs, parent);
+}
+
+/* Possible encoders, e.g. /config/vkms/device/connector/possible_encoders/<symlink> */
+
+static struct config_item_type encoder_type;
+
+static int possible_encoders_allow_link(struct config_item *src,
+ struct config_item *target)
+{
+ struct vkms_config_links *links = item_to_config_links(src);
+ struct vkms_config_encoder *encoder;
+
+ if (target->ci_type != &encoder_type) {
+ DRM_ERROR("Unable to link non-encoders.\n");
+ return -EINVAL;
+ }
+
+ encoder = item_to_config_encoder(target);
+
+ if (links->linked_object_bitmap & BIT(encoder->encoder_config_idx)) {
+ DRM_ERROR(
+ "Tried to add two symlinks to the same encoder from the same object\n");
+ return -EINVAL;
+ }
+
+ links->linked_object_bitmap |= BIT(encoder->encoder_config_idx);
+
+ return 0;
+}
+
+static void possible_encoders_drop_link(struct config_item *src,
+ struct config_item *target)
+{
+ struct vkms_config_links *links = item_to_config_links(src);
+ struct vkms_config_encoder *encoder = item_to_config_encoder(target);
+
+ links->linked_object_bitmap &= ~BIT(encoder->encoder_config_idx);
+}
+
+static struct configfs_item_operations possible_encoders_item_ops = {
+ .allow_link = &possible_encoders_allow_link,
+ .drop_link = &possible_encoders_drop_link,
+};
+
+static struct config_item_type possible_encoders_group_type = {
+ .ct_item_ops = &possible_encoders_item_ops,
+ .ct_owner = THIS_MODULE,
+};
+
+static void add_possible_encoders(struct config_group *parent,
+ struct config_group *possible_encoders)
+{
+ config_group_init_type_name(possible_encoders, "possible_encoders",
+ &possible_encoders_group_type);
+ configfs_add_default_group(possible_encoders, parent);
+}
+
+/*
+ * Individual objects (connectors, crtcs, encoders, planes):
+ */
+
+/* Connector item, e.g. /config/vkms/device/connectors/ID */
+
+static struct config_item_type connector_type = {
+ .ct_owner = THIS_MODULE,
+};
+
+/* Crtc item, e.g. /config/vkms/device/crtcs/ID */
+
+static struct config_item_type crtc_type = {
+ .ct_owner = THIS_MODULE,
+};
+
+/* Encoder item, e.g. /config/vkms/device/encoder/ID */
+
+static struct config_item_type encoder_type = {
+ .ct_owner = THIS_MODULE,
+};
+
+/* Plane item, e.g. /config/vkms/device/planes/ID */
+
+static ssize_t plane_type_show(struct config_item *item, char *buf)
+{
+ struct vkms_config_plane *plane = item_to_config_plane(item);
+ struct vkms_configfs *configfs = plane_item_to_configfs(item);
+ enum drm_plane_type plane_type;
+
+ mutex_lock(&configfs->lock);
+ plane_type = plane->type;
+ mutex_unlock(&configfs->lock);
+
+ return sprintf(buf, "%u", plane_type);
+}
+
+static ssize_t plane_type_store(struct config_item *item, const char *buf,
+ size_t len)
+{
+ struct vkms_config_plane *plane = item_to_config_plane(item);
+ struct vkms_configfs *configfs = plane_item_to_configfs(item);
+ int val, ret;
+
+ ret = kstrtouint(buf, 10, &val);
+ if (ret)
+ return ret;
+
+ if (val != DRM_PLANE_TYPE_PRIMARY && val != DRM_PLANE_TYPE_CURSOR &&
+ val != DRM_PLANE_TYPE_OVERLAY)
+ return -EINVAL;
+
+ mutex_lock(&configfs->lock);
+ plane->type = val;
+ mutex_unlock(&configfs->lock);
+
+ return len;
+}
+
+CONFIGFS_ATTR(plane_, type);
+
+static struct configfs_attribute *plane_attrs[] = {
+ &plane_attr_type,
+ NULL,
+};
+
+static struct config_item_type plane_type = {
+ .ct_attrs = plane_attrs,
+ .ct_owner = THIS_MODULE,
+};
+
+/*
+ * Directory groups, e.g. /config/vkms/device/{planes, crtcs, ...}
+ */
+
+/* Connectors group: /config/vkms/device/connectors/ */
+
+static struct config_group *connectors_group_make(struct config_group *group,
+ const char *name)
+{
+ struct vkms_config_connector *connector =
+ kzalloc(sizeof(*connector), GFP_KERNEL);
+ if (!connector)
+ return ERR_PTR(-ENOMEM);
+
+ config_group_init_type_name(&connector->config_group, name,
+ &connector_type);
+ add_possible_encoders(&connector->config_group,
+ &connector->possible_encoders.group);
+
+ return &connector->config_group;
+}
+
+static void connectors_group_drop(struct config_group *group,
+ struct config_item *item)
+{
+ struct vkms_config_connector *connector =
+ item_to_config_connector(item);
+ kfree(connector);
+}
+
+static struct configfs_group_operations connectors_group_ops = {
+ .make_group = &connectors_group_make,
+ .drop_item = &connectors_group_drop,
+};
+
+static struct config_item_type connectors_group_type = {
+ .ct_group_ops = &connectors_group_ops,
+ .ct_owner = THIS_MODULE,
+};
+
+/* CRTCs group: /config/vkms/device/crtcs/ */
+
+static struct config_group *crtcs_group_make(struct config_group *group,
+ const char *name)
+{
+ struct vkms_configfs *configfs =
+ container_of(group, struct vkms_configfs, crtcs_group);
+ unsigned long next_idx;
+ struct vkms_config_crtc *crtc;
+
+ mutex_lock(&configfs->lock);
+
+ next_idx = find_first_zero_bit(&configfs->allocated_crtcs,
+ VKMS_MAX_OUTPUT_OBJECTS);
+
+ if (next_idx == VKMS_MAX_OUTPUT_OBJECTS) {
+ DRM_ERROR("Unable to allocate another CRTC.\n");
+ mutex_unlock(&configfs->lock);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ crtc = kzalloc(sizeof(*crtc), GFP_KERNEL);
+ if (!crtc) {
+ DRM_ERROR("Unable to allocate CRTC.\n");
+ mutex_unlock(&configfs->lock);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ config_group_init_type_name(&crtc->config_group, name, &crtc_type);
+ crtc->crtc_config_idx = next_idx;
+
+ set_bit(next_idx, &configfs->allocated_crtcs);
+
+ mutex_unlock(&configfs->lock);
+
+ return &crtc->config_group;
+}
+
+static void crtcs_group_drop(struct config_group *group,
+ struct config_item *item)
+{
+ struct vkms_config_crtc *crtc = item_to_config_crtc(item);
+ kfree(crtc);
+}
+
+static struct configfs_group_operations crtcs_group_ops = {
+ .make_group = &crtcs_group_make,
+ .drop_item = &crtcs_group_drop,
+};
+
+static struct config_item_type crtcs_group_type = {
+ .ct_group_ops = &crtcs_group_ops,
+ .ct_owner = THIS_MODULE,
+};
+
+/* Encoders group: /config/vkms/device/encoders/ */
+
+static struct config_group *encoders_group_make(struct config_group *group,
+ const char *name)
+{
+ struct vkms_configfs *configfs =
+ container_of(group, struct vkms_configfs, encoders_group);
+ unsigned long next_idx;
+ struct vkms_config_encoder *encoder;
+
+ mutex_lock(&configfs->lock);
+
+ next_idx = find_first_zero_bit(&configfs->allocated_encoders,
+ VKMS_MAX_OUTPUT_OBJECTS);
+
+ if (next_idx == VKMS_MAX_OUTPUT_OBJECTS) {
+ DRM_ERROR("Unable to allocate another encoder.\n");
+ mutex_unlock(&configfs->lock);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ encoder = kzalloc(sizeof(*encoder), GFP_KERNEL);
+ if (!encoder) {
+ DRM_ERROR("Unable to allocate encoder.\n");
+ mutex_unlock(&configfs->lock);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ config_group_init_type_name(&encoder->config_group, name,
+ &encoder_type);
+ add_possible_crtcs(&encoder->config_group,
+ &encoder->possible_crtcs.group);
+ encoder->encoder_config_idx = next_idx;
+ set_bit(next_idx, &configfs->allocated_encoders);
+
+ mutex_unlock(&configfs->lock);
+
+ return &encoder->config_group;
+}
+
+static void encoders_group_drop(struct config_group *group,
+ struct config_item *item)
+{
+ struct vkms_config_encoder *encoder = item_to_config_encoder(item);
+ kfree(encoder);
+}
+
+static struct configfs_group_operations encoders_group_ops = {
+ .make_group = &encoders_group_make,
+ .drop_item = &encoders_group_drop,
+};
+
+static struct config_item_type encoders_group_type = {
+ .ct_group_ops = &encoders_group_ops,
+ .ct_owner = THIS_MODULE,
+};
+
+/* Planes group: /config/vkms/device/planes/ */
+
+static struct config_group *make_plane_group(struct config_group *group,
+ const char *name)
+{
+ struct vkms_config_plane *plane = kzalloc(sizeof(*plane), GFP_KERNEL);
+ if (!plane)
+ return ERR_PTR(-ENOMEM);
+
+ config_group_init_type_name(&plane->config_group, name, &plane_type);
+ add_possible_crtcs(&plane->config_group, &plane->possible_crtcs.group);
+
+ return &plane->config_group;
+}
+
+static void drop_plane_group(struct config_group *group,
+ struct config_item *item)
+{
+ struct vkms_config_plane *plane = item_to_config_plane(item);
+ kfree(plane);
+}
+
+static struct configfs_group_operations plane_group_ops = {
+ .make_group = &make_plane_group,
+ .drop_item = &drop_plane_group,
+};
+
+static struct config_item_type planes_group_type = {
+ .ct_group_ops = &plane_group_ops,
+ .ct_owner = THIS_MODULE,
+};
+
+/* Root directory group, e.g. /config/vkms/device */
+
+static ssize_t device_enabled_show(struct config_item *item, char *buf)
+{
+ struct vkms_configfs *configfs = item_to_configfs(item);
+ bool is_enabled;
+
+ mutex_lock(&configfs->lock);
+ is_enabled = configfs->vkms_device != NULL;
+ mutex_unlock(&configfs->lock);
+
+ return sprintf(buf, "%d", is_enabled);
+}
+
+static ssize_t device_enabled_store(struct config_item *item, const char *buf,
+ size_t len)
+{
+ struct vkms_configfs *configfs = item_to_configfs(item);
+ struct vkms_device *device;
+ int value, ret;
+
+ ret = kstrtoint(buf, 0, &value);
+ if (ret)
+ return ret;
+
+ if (value != 1)
+ return -EINVAL;
+
+ mutex_lock(&configfs->lock);
+
+ if (configfs->vkms_device) {
+ mutex_unlock(&configfs->lock);
+ return len;
+ }
+
+ device = vkms_add_device(configfs);
+ mutex_unlock(&configfs->lock);
+
+ if (IS_ERR(device))
+ return -PTR_ERR(device);
+
+ return len;
+}
+
+CONFIGFS_ATTR(device_, enabled);
+
+static ssize_t device_id_show(struct config_item *item, char *buf)
+{
+ struct vkms_configfs *configfs = item_to_configfs(item);
+ int id = -1;
+
+ mutex_lock(&configfs->lock);
+ if (configfs->vkms_device) {
+ id = configfs->vkms_device->platform->id;
+ }
+ mutex_unlock(&configfs->lock);
+
+ return sprintf(buf, "%d", id);
+}
+
+CONFIGFS_ATTR_RO(device_, id);
+
+static struct configfs_attribute *device_group_attrs[] = {
+ &device_attr_id,
+ &device_attr_enabled,
+ NULL,
+};
+
+static struct config_item_type device_group_type = {
+ .ct_attrs = device_group_attrs,
+ .ct_owner = THIS_MODULE,
+};
+
+static void vkms_configfs_setup_default_groups(struct vkms_configfs *configfs,
+ const char *name)
+{
+ config_group_init_type_name(&configfs->device_group, name,
+ &device_group_type);
+
+ config_group_init_type_name(&configfs->connectors_group, "connectors",
+ &connectors_group_type);
+ configfs_add_default_group(&configfs->connectors_group,
+ &configfs->device_group);
+
+ config_group_init_type_name(&configfs->crtcs_group, "crtcs",
+ &crtcs_group_type);
+ configfs_add_default_group(&configfs->crtcs_group,
+ &configfs->device_group);
+
+ config_group_init_type_name(&configfs->encoders_group, "encoders",
+ &encoders_group_type);
+ configfs_add_default_group(&configfs->encoders_group,
+ &configfs->device_group);
+
+ config_group_init_type_name(&configfs->planes_group, "planes",
+ &planes_group_type);
+ configfs_add_default_group(&configfs->planes_group,
+ &configfs->device_group);
+}
+
+/* Root directory group and subsystem, e.g. /config/vkms/ */
+
+static struct config_group *make_root_group(struct config_group *group,
+ const char *name)
+{
+ struct vkms_configfs *configfs = kzalloc(sizeof(*configfs), GFP_KERNEL);
+
+ if (!configfs)
+ return ERR_PTR(-ENOMEM);
+
+ vkms_configfs_setup_default_groups(configfs, name);
+ mutex_init(&configfs->lock);
+
+ return &configfs->device_group;
+}
+
+static void drop_root_group(struct config_group *group,
+ struct config_item *item)
+{
+ struct vkms_configfs *configfs = item_to_configfs(item);
+
+ mutex_lock(&configfs->lock);
+ if (configfs->vkms_device)
+ vkms_remove_device(configfs->vkms_device);
+ mutex_unlock(&configfs->lock);
+
+ kfree(configfs);
+}
+
+static struct configfs_group_operations root_group_ops = {
+ .make_group = &make_root_group,
+ .drop_item = &drop_root_group,
+};
+
+static struct config_item_type vkms_type = {
+ .ct_group_ops = &root_group_ops,
+ .ct_owner = THIS_MODULE,
+};
+
+static struct configfs_subsystem vkms_subsys = {
+ .su_group = {
+ .cg_item = {
+ .ci_name = "vkms",
+ .ci_type = &vkms_type,
+ },
+ },
+ .su_mutex = __MUTEX_INITIALIZER(vkms_subsys.su_mutex),
+};
+
+int vkms_init_configfs(void)
+{
+ config_group_init(&vkms_subsys.su_group);
+ return configfs_register_subsystem(&vkms_subsys);
+}
+
+void vkms_unregister_configfs(void)
+{
+ configfs_unregister_subsystem(&vkms_subsys);
+}
diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index d43121addf66..1b5b7143792f 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -9,7 +9,10 @@
* the GPU in DRM API tests.
*/

+#include <linux/configfs.h>
#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
@@ -152,8 +155,8 @@ static int vkms_modeset_init(struct vkms_device *vkmsdev)
dev->mode_config.preferred_depth = 0;
dev->mode_config.helper_private = &vkms_mode_config_helpers;

- return vkmsdev->is_default ? vkms_output_init_default(vkmsdev) :
- -ENOSYS;
+ return vkmsdev->configfs ? vkms_output_init(vkmsdev) :
+ vkms_output_init_default(vkmsdev);
}

static int vkms_platform_probe(struct platform_device *pdev)
@@ -165,6 +168,7 @@ static int vkms_platform_probe(struct platform_device *pdev)

grp = devres_open_group(&pdev->dev, NULL, GFP_KERNEL);
if (!grp) {
+ DRM_ERROR("Could not open devres group\n");
return -ENOMEM;
}

@@ -179,7 +183,7 @@ static int vkms_platform_probe(struct platform_device *pdev)
vkms_device->config.cursor = enable_cursor;
vkms_device->config.writeback = enable_writeback;
vkms_device->config.overlay = enable_overlay;
- vkms_device->is_default = vkms_device_setup->is_default;
+ vkms_device->configfs = vkms_device_setup->configfs;

ret = dma_coerce_mask_and_coherent(vkms_device->drm.dev,
DMA_BIT_MASK(64));
@@ -239,12 +243,43 @@ static struct platform_driver vkms_platform_driver = {
.driver.name = DRIVER_NAME,
};

+struct vkms_device *vkms_add_device(struct vkms_configfs *configfs)
+{
+ struct device *dev = NULL;
+ struct platform_device *pdev;
+ int max_id = 1;
+ struct vkms_device_setup vkms_device_setup = {
+ .configfs = configfs,
+ };
+
+ while ((dev = platform_find_device_by_driver(
+ dev, &vkms_platform_driver.driver))) {
+ pdev = to_platform_device(dev);
+ max_id = max(max_id, pdev->id);
+ }
+
+ pdev = platform_device_register_data(NULL, DRIVER_NAME, max_id + 1,
+ &vkms_device_setup,
+ sizeof(vkms_device_setup));
+ if (IS_ERR(pdev)) {
+ DRM_ERROR("Unable to register vkms device'\n");
+ return ERR_PTR(PTR_ERR(pdev));
+ }
+
+ return platform_get_drvdata(pdev);
+}
+
+void vkms_remove_device(struct vkms_device *vkms_device)
+{
+ platform_device_unregister(vkms_device->platform);
+}
+
static int __init vkms_init(void)
{
int ret;
struct platform_device *pdev;
struct vkms_device_setup vkms_device_setup = {
- .is_default = true,
+ .configfs = NULL,
};

ret = platform_driver_register(&vkms_platform_driver);
@@ -262,6 +297,13 @@ static int __init vkms_init(void)
return PTR_ERR(pdev);
}

+ ret = vkms_init_configfs();
+ if (ret) {
+ DRM_ERROR("Unable to initialize configfs\n");
+ platform_device_unregister(pdev);
+ platform_driver_unregister(&vkms_platform_driver);
+ }
+
return 0;
}

@@ -269,6 +311,8 @@ static void __exit vkms_exit(void)
{
struct device *dev;

+ vkms_unregister_configfs();
+
while ((dev = platform_find_device_by_driver(
NULL, &vkms_platform_driver.driver))) {
// platform_find_device_by_driver increments the refcount. Drop
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index 84b35aa1dc5a..3634eeeb4548 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -3,6 +3,7 @@
#ifndef _VKMS_DRV_H_
#define _VKMS_DRV_H_

+#include <linux/configfs.h>
#include <linux/hrtimer.h>

#include <drm/drm.h>
@@ -10,6 +11,7 @@
#include <drm/drm_gem.h>
#include <drm/drm_gem_atomic_helper.h>
#include <drm/drm_encoder.h>
+#include <drm/drm_plane.h>
#include <drm/drm_writeback.h>

#define XRES_MIN 10
@@ -127,14 +129,65 @@ struct vkms_config {
bool overlay;
};

+struct vkms_config_links {
+ struct config_group group;
+ unsigned long linked_object_bitmap;
+};
+
+struct vkms_config_connector {
+ struct config_group config_group;
+ struct vkms_config_links possible_encoders;
+};
+
+struct vkms_config_crtc {
+ struct config_group config_group;
+ unsigned long crtc_config_idx;
+};
+
+struct vkms_config_encoder {
+ struct config_group config_group;
+ struct vkms_config_links possible_crtcs;
+ unsigned long encoder_config_idx;
+};
+
+struct vkms_config_plane {
+ struct vkms_configfs *configfs;
+ struct config_group config_group;
+ struct vkms_config_links possible_crtcs;
+ enum drm_plane_type type;
+};
+
+struct vkms_configfs {
+ /* Directory group containing connector configs, e.g. /config/vkms/device/ */
+ struct config_group device_group;
+ /* Directory group containing connector configs, e.g. /config/vkms/device/connectors/ */
+ struct config_group connectors_group;
+ /* Directory group containing CRTC configs, e.g. /config/vkms/device/crtcs/ */
+ struct config_group crtcs_group;
+ /* Directory group containing encoder configs, e.g. /config/vkms/device/encoders/ */
+ struct config_group encoders_group;
+ /* Directory group containing plane configs, e.g. /config/vkms/device/planes/ */
+ struct config_group planes_group;
+
+ unsigned long allocated_crtcs;
+ unsigned long allocated_encoders;
+
+ struct mutex lock;
+
+ /* The platform device if this is registered, otherwise NULL */
+ struct vkms_device *vkms_device;
+};
+
struct vkms_device_setup {
- bool is_default;
+ // Is NULL in the case of the default card.
+ struct vkms_configfs *configfs;
};

struct vkms_device {
struct drm_device drm;
struct platform_device *platform;
- bool is_default;
+ // Is NULL in the case of the default card.
+ struct vkms_configfs *configfs;
struct vkms_output output;
struct vkms_config config;
};
@@ -153,11 +206,42 @@ struct vkms_device {
#define to_vkms_plane_state(target)\
container_of(target, struct vkms_plane_state, base.base)

+#define item_to_configfs(item) \
+ container_of(to_config_group(item), struct vkms_configfs, device_group)
+
+#define item_to_config_connector(item) \
+ container_of(to_config_group(item), struct vkms_config_connector, \
+ config_group)
+
+#define item_to_config_crtc(item) \
+ container_of(to_config_group(item), struct vkms_config_crtc, \
+ config_group)
+
+#define item_to_config_encoder(item) \
+ container_of(to_config_group(item), struct vkms_config_encoder, \
+ config_group)
+
+#define item_to_config_plane(item) \
+ container_of(to_config_group(item), struct vkms_config_plane, \
+ config_group)
+
+#define item_to_config_links(item) \
+ container_of(to_config_group(item), struct vkms_config_links, group)
+
+#define plane_item_to_configfs(item) \
+ container_of(to_config_group(item->ci_parent), struct vkms_configfs, \
+ planes_group)
+
+/* Devices */
+struct vkms_device *vkms_add_device(struct vkms_configfs *configfs);
+void vkms_remove_device(struct vkms_device *vkms_device);
+
/* CRTC */
struct vkms_crtc *vkms_crtc_init(struct vkms_device *vkmsdev,
struct drm_plane *primary,
struct drm_plane *cursor);

+int vkms_output_init(struct vkms_device *vkmsdev);
int vkms_output_init_default(struct vkms_device *vkmsdev);

struct vkms_plane *vkms_plane_init(struct vkms_device *vkmsdev,
@@ -179,4 +263,8 @@ void vkms_compose_row(struct line_buffer *stage_buffer, struct vkms_plane_state
int vkms_enable_writeback_connector(struct vkms_device *vkmsdev,
struct vkms_crtc *vkms_crtc);

+/* ConfigFS Support */
+int vkms_init_configfs(void);
+void vkms_unregister_configfs(void);
+
#endif /* _VKMS_DRV_H_ */
diff --git a/drivers/gpu/drm/vkms/vkms_output.c b/drivers/gpu/drm/vkms/vkms_output.c
index 3b5e272a8b33..c9e6c653de19 100644
--- a/drivers/gpu/drm/vkms/vkms_output.c
+++ b/drivers/gpu/drm/vkms/vkms_output.c
@@ -177,3 +177,8 @@ int vkms_output_init_default(struct vkms_device *vkmsdev)

return ret;
}
+
+int vkms_output_init(struct vkms_device *vkmsdev)
+{
+ return -ENOTSUPP;
+}
--
2.41.0.162.gfafddb0af9-goog