--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2018 Noralf Trønnes
+ */
+
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+
+#include <drm/drm_client.h>
+#include <drm/drm_debugfs.h>
+#include <drm/drm_device.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_file.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_gem.h>
+#include <drm/drm_mode.h>
+#include <drm/drm_print.h>
+#include <drm/drmP.h>
+
+#include "drm_crtc_internal.h"
+#include "drm_internal.h"
+
+/**
+ * DOC: overview
+ *
+ * This library provides support for clients running in the kernel like fbdev and bootsplash.
+ * Currently it's only partially implemented, just enough to support fbdev.
+ *
+ * GEM drivers which provide a GEM based dumb buffer with a virtual address are supported.
+ */
+
+static int drm_client_open(struct drm_client_dev *client)
+{
+ struct drm_device *dev = client->dev;
+ struct drm_file *file;
+
+ file = drm_file_alloc(dev->primary);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+
+ mutex_lock(&dev->filelist_mutex);
+ list_add(&file->lhead, &dev->filelist_internal);
+ mutex_unlock(&dev->filelist_mutex);
+
+ client->file = file;
+
+ return 0;
+}
+
+static void drm_client_close(struct drm_client_dev *client)
+{
+ struct drm_device *dev = client->dev;
+
+ mutex_lock(&dev->filelist_mutex);
+ list_del(&client->file->lhead);
+ mutex_unlock(&dev->filelist_mutex);
+
+ drm_file_free(client->file);
+}
+EXPORT_SYMBOL(drm_client_close);
+
+/**
+ * drm_client_new - Create a DRM client
+ * @dev: DRM device
+ * @client: DRM client
+ * @name: Client name
+ * @funcs: DRM client functions (optional)
+ *
+ * The caller needs to hold a reference on @dev before calling this function.
+ * The client is freed when the &drm_device is unregistered. See drm_client_release().
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_new(struct drm_device *dev, struct drm_client_dev *client,
+ const char *name, const struct drm_client_funcs *funcs)
+{
+ bool registered;
+ int ret;
+
+ if (!drm_core_check_feature(dev, DRIVER_MODESET) ||
+ !dev->driver->dumb_create || !dev->driver->gem_prime_vmap)
+ return -ENOTSUPP;
+
+ if (funcs && !try_module_get(funcs->owner))
+ return -ENODEV;
+
+ client->dev = dev;
+ client->name = name;
+ client->funcs = funcs;
+
+ ret = drm_client_open(client);
+ if (ret)
+ goto err_put_module;
+
+ mutex_lock(&dev->clientlist_mutex);
+ registered = dev->registered;
+ if (registered)
+ list_add(&client->list, &dev->clientlist);
+ mutex_unlock(&dev->clientlist_mutex);
+ if (!registered) {
+ ret = -ENODEV;
+ goto err_close;
+ }
+
+ drm_dev_get(dev);
+
+ return 0;
+
+err_close:
+ drm_client_close(client);
+err_put_module:
+ if (funcs)
+ module_put(funcs->owner);
+
+ return ret;
+}
+EXPORT_SYMBOL(drm_client_new);
+
+/**
+ * drm_client_release - Release DRM client resources
+ * @client: DRM client
+ *
+ * Releases resources by closing the &drm_file that was opened by drm_client_new().
+ * It is called automatically if the &drm_client_funcs.unregister callback is _not_ set.
+ *
+ * This function should only be called from the unregister callback. An exception
+ * is fbdev which cannot free the buffer if userspace has open file descriptors.
+ *
+ * Note:
+ * Clients cannot initiate a release by themselves. This is done to keep the code simple.
+ * The driver has to be unloaded before the client can be unloaded.
+ */
+void drm_client_release(struct drm_client_dev *client)
+{
+ struct drm_device *dev = client->dev;
+
+ DRM_DEV_DEBUG_KMS(dev->dev, "%s\n", client->name);
+
+ drm_client_close(client);
+ drm_dev_put(dev);
+ if (client->funcs)
+ module_put(client->funcs->owner);
+}
+EXPORT_SYMBOL(drm_client_release);
+
+void drm_client_dev_unregister(struct drm_device *dev)
+{
+ struct drm_client_dev *client, *tmp;
+
+ if (!drm_core_check_feature(dev, DRIVER_MODESET))
+ return;
+
+ mutex_lock(&dev->clientlist_mutex);
+ list_for_each_entry_safe(client, tmp, &dev->clientlist, list) {
+ list_del(&client->list);
+ if (client->funcs && client->funcs->unregister) {
+ client->funcs->unregister(client);
+ } else {
+ drm_client_release(client);
+ kfree(client);
+ }
+ }
+ mutex_unlock(&dev->clientlist_mutex);
+}
+
+/**
+ * drm_client_dev_hotplug - Send hotplug event to clients
+ * @dev: DRM device
+ *
+ * This function calls the &drm_client_funcs.hotplug callback on the attached clients.
+ *
+ * drm_kms_helper_hotplug_event() calls this function, so drivers that use it
+ * don't need to call this function themselves.
+ */
+void drm_client_dev_hotplug(struct drm_device *dev)
+{
+ struct drm_client_dev *client;
+ int ret;
+
+ if (!drm_core_check_feature(dev, DRIVER_MODESET))
+ return;
+
+ mutex_lock(&dev->clientlist_mutex);
+ list_for_each_entry(client, &dev->clientlist, list) {
+ if (!client->funcs || !client->funcs->hotplug)
+ continue;
+
+ ret = client->funcs->hotplug(client);
+ DRM_DEV_DEBUG_KMS(dev->dev, "%s: ret=%d\n", client->name, ret);
+ }
+ mutex_unlock(&dev->clientlist_mutex);
+}
+EXPORT_SYMBOL(drm_client_dev_hotplug);
+
+void drm_client_dev_restore(struct drm_device *dev)
+{
+ struct drm_client_dev *client;
+ int ret;
+
+ if (!drm_core_check_feature(dev, DRIVER_MODESET))
+ return;
+
+ mutex_lock(&dev->clientlist_mutex);
+ list_for_each_entry(client, &dev->clientlist, list) {
+ if (!client->funcs || !client->funcs->restore)
+ continue;
+
+ ret = client->funcs->restore(client);
+ DRM_DEV_DEBUG_KMS(dev->dev, "%s: ret=%d\n", client->name, ret);
+ if (!ret) /* The first one to return zero gets the privilege to restore */
+ break;
+ }
+ mutex_unlock(&dev->clientlist_mutex);
+}
+
+static void drm_client_buffer_delete(struct drm_client_buffer *buffer)
+{
+ struct drm_device *dev = buffer->client->dev;
+
+ if (buffer->vaddr && dev->driver->gem_prime_vunmap)
+ dev->driver->gem_prime_vunmap(buffer->gem, buffer->vaddr);
+
+ if (buffer->gem)
+ drm_gem_object_put_unlocked(buffer->gem);
+
+ drm_mode_destroy_dumb(dev, buffer->handle, buffer->client->file);
+ kfree(buffer);
+}
+
+static struct drm_client_buffer *
+drm_client_buffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format)
+{
+ struct drm_mode_create_dumb dumb_args = { };
+ struct drm_device *dev = client->dev;
+ struct drm_client_buffer *buffer;
+ struct drm_gem_object *obj;
+ void *vaddr;
+ int ret;
+
+ buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
+ if (!buffer)
+ return ERR_PTR(-ENOMEM);
+
+ buffer->client = client;
+
+ dumb_args.width = width;
+ dumb_args.height = height;
+ dumb_args.bpp = drm_format_plane_cpp(format, 0) * 8;
+ ret = drm_mode_create_dumb(dev, &dumb_args, client->file);
+ if (ret)
+ goto err_free;
+
+ buffer->handle = dumb_args.handle;
+ buffer->pitch = dumb_args.pitch;
+
+ obj = drm_gem_object_lookup(client->file, dumb_args.handle);
+ if (!obj) {
+ ret = -ENOENT;
+ goto err_delete;
+ }
+
+ buffer->gem = obj;
+
+ /*
+ * FIXME: The dependency on GEM here isn't required, we could
+ * convert the driver handle to a dma-buf instead and use the
+ * backend-agnostic dma-buf vmap support instead. This would
+ * require that the handle2fd prime ioctl is reworked to pull the
+ * fd_install step out of the driver backend hooks, to make that
+ * final step optional for internal users.
+ */
+ vaddr = dev->driver->gem_prime_vmap(obj);
+ if (!vaddr) {
+ ret = -ENOMEM;
+ goto err_delete;
+ }
+
+ buffer->vaddr = vaddr;
+
+ return buffer;
+
+err_delete:
+ drm_client_buffer_delete(buffer);
+err_free:
+ kfree(buffer);
+
+ return ERR_PTR(ret);
+}
+
+static void drm_client_buffer_rmfb(struct drm_client_buffer *buffer)
+{
+ int ret;
+
+ if (!buffer->fb)
+ return;
+
+ ret = drm_mode_rmfb(buffer->client->dev, buffer->fb->base.id, buffer->client->file);
+ if (ret)
+ DRM_DEV_ERROR(buffer->client->dev->dev,
+ "Error removing FB:%u (%d)\n", buffer->fb->base.id, ret);
+
+ buffer->fb = NULL;
+}
+
+static int drm_client_buffer_addfb(struct drm_client_buffer *buffer,
+ u32 width, u32 height, u32 format)
+{
+ struct drm_client_dev *client = buffer->client;
+ struct drm_mode_fb_cmd fb_req = { };
+ const struct drm_format_info *info;
+ int ret;
+
+ info = drm_format_info(format);
+ fb_req.bpp = info->cpp[0] * 8;
+ fb_req.depth = info->depth;
+ fb_req.width = width;
+ fb_req.height = height;
+ fb_req.handle = buffer->handle;
+ fb_req.pitch = buffer->pitch;
+
+ ret = drm_mode_addfb(client->dev, &fb_req, client->file);
+ if (ret)
+ return ret;
+
+ buffer->fb = drm_framebuffer_lookup(client->dev, buffer->client->file, fb_req.fb_id);
+ if (WARN_ON(!buffer->fb))
+ return -ENOENT;
+
+ /* drop the reference we picked up in framebuffer lookup */
+ drm_framebuffer_put(buffer->fb);
+
+ strscpy(buffer->fb->comm, client->name, TASK_COMM_LEN);
+
+ return 0;
+}
+
+/**
+ * drm_client_framebuffer_create - Create a client framebuffer
+ * @client: DRM client
+ * @width: Framebuffer width
+ * @height: Framebuffer height
+ * @format: Buffer format
+ *
+ * This function creates a &drm_client_buffer which consists of a
+ * &drm_framebuffer backed by a dumb buffer.
+ * Call drm_client_framebuffer_delete() to free the buffer.
+ *
+ * Returns:
+ * Pointer to a client buffer or an error pointer on failure.
+ */
+struct drm_client_buffer *
+drm_client_framebuffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format)
+{
+ struct drm_client_buffer *buffer;
+ int ret;
+
+ buffer = drm_client_buffer_create(client, width, height, format);
+ if (IS_ERR(buffer))
+ return buffer;
+
+ ret = drm_client_buffer_addfb(buffer, width, height, format);
+ if (ret) {
+ drm_client_buffer_delete(buffer);
+ return ERR_PTR(ret);
+ }
+
+ return buffer;
+}
+EXPORT_SYMBOL(drm_client_framebuffer_create);
+
+/**
+ * drm_client_framebuffer_delete - Delete a client framebuffer
+ * @buffer: DRM client buffer (can be NULL)
+ */
+void drm_client_framebuffer_delete(struct drm_client_buffer *buffer)
+{
+ if (!buffer)
+ return;
+
+ drm_client_buffer_rmfb(buffer);
+ drm_client_buffer_delete(buffer);
+}
+EXPORT_SYMBOL(drm_client_framebuffer_delete);
--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _DRM_CLIENT_H_
+#define _DRM_CLIENT_H_
+
+#include <linux/types.h>
+
+struct drm_client_dev;
+struct drm_device;
+struct drm_file;
+struct drm_framebuffer;
+struct drm_gem_object;
+struct module;
+
+/**
+ * struct drm_client_funcs - DRM client callbacks
+ */
+struct drm_client_funcs {
+ /**
+ * @owner: The module owner
+ */
+ struct module *owner;
+
+ /**
+ * @unregister:
+ *
+ * Called when &drm_device is unregistered. The client should respond by
+ * releasing it's resources using drm_client_release().
+ *
+ * This callback is optional.
+ */
+ void (*unregister)(struct drm_client_dev *client);
+
+ /**
+ * @restore:
+ *
+ * Called on drm_lastclose(). The first client instance in the list that
+ * returns zero gets the privilege to restore and no more clients are
+ * called. This callback is not called after @unregister has been called.
+ *
+ * This callback is optional.
+ */
+ int (*restore)(struct drm_client_dev *client);
+
+ /**
+ * @hotplug:
+ *
+ * Called on drm_kms_helper_hotplug_event().
+ * This callback is not called after @unregister has been called.
+ *
+ * This callback is optional.
+ */
+ int (*hotplug)(struct drm_client_dev *client);
+};
+
+/**
+ * struct drm_client_dev - DRM client instance
+ */
+struct drm_client_dev {
+ /**
+ * @dev: DRM device
+ */
+ struct drm_device *dev;
+
+ /**
+ * @name: Name of the client.
+ */
+ const char *name;
+
+ /**
+ * @list:
+ *
+ * List of all clients of a DRM device, linked into
+ * &drm_device.clientlist. Protected by &drm_device.clientlist_mutex.
+ */
+ struct list_head list;
+
+ /**
+ * @funcs: DRM client functions (optional)
+ */
+ const struct drm_client_funcs *funcs;
+
+ /**
+ * @file: DRM file
+ */
+ struct drm_file *file;
+};
+
+int drm_client_new(struct drm_device *dev, struct drm_client_dev *client,
+ const char *name, const struct drm_client_funcs *funcs);
+void drm_client_release(struct drm_client_dev *client);
+
+void drm_client_dev_unregister(struct drm_device *dev);
+void drm_client_dev_hotplug(struct drm_device *dev);
+void drm_client_dev_restore(struct drm_device *dev);
+
+/**
+ * struct drm_client_buffer - DRM client buffer
+ */
+struct drm_client_buffer {
+ /**
+ * @client: DRM client
+ */
+ struct drm_client_dev *client;
+
+ /**
+ * @handle: Buffer handle
+ */
+ u32 handle;
+
+ /**
+ * @pitch: Buffer pitch
+ */
+ u32 pitch;
+
+ /**
+ * @gem: GEM object backing this buffer
+ */
+ struct drm_gem_object *gem;
+
+ /**
+ * @vaddr: Virtual address for the buffer
+ */
+ void *vaddr;
+
+ /**
+ * @fb: DRM framebuffer
+ */
+ struct drm_framebuffer *fb;
+};
+
+struct drm_client_buffer *
+drm_client_framebuffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format);
+void drm_client_framebuffer_delete(struct drm_client_buffer *buffer);
+
+#endif
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