Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2639 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
new file mode 100644
index 000000000..442746d97
--- /dev/null
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -0,0 +1,2639 @@
+/*
+ * Copyright (c) 2006-2009 Red Hat Inc.
+ * Copyright (c) 2006-2008 Intel Corporation
+ * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
+ *
+ * DRM framebuffer helper functions
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ *
+ * Authors:
+ *      Dave Airlie <airlied@linux.ie>
+ *      Jesse Barnes <jesse.barnes@intel.com>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/console.h>
+#include <linux/dma-buf.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sysrq.h>
+#include <linux/vmalloc.h>
+
+#include <drm/drm_atomic.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_print.h>
+#include <drm/drm_vblank.h>
+
+#include "drm_crtc_helper_internal.h"
+#include "drm_internal.h"
+
+static bool drm_fbdev_emulation = true;
+module_param_named(fbdev_emulation, drm_fbdev_emulation, bool, 0600);
+MODULE_PARM_DESC(fbdev_emulation,
+		 "Enable legacy fbdev emulation [default=true]");
+
+static int drm_fbdev_overalloc = CONFIG_DRM_FBDEV_OVERALLOC;
+module_param(drm_fbdev_overalloc, int, 0444);
+MODULE_PARM_DESC(drm_fbdev_overalloc,
+		 "Overallocation of the fbdev buffer (%) [default="
+		 __MODULE_STRING(CONFIG_DRM_FBDEV_OVERALLOC) "]");
+
+/*
+ * In order to keep user-space compatibility, we want in certain use-cases
+ * to keep leaking the fbdev physical address to the user-space program
+ * handling the fbdev buffer.
+ * This is a bad habit essentially kept into closed source opengl driver
+ * that should really be moved into open-source upstream projects instead
+ * of using legacy physical addresses in user space to communicate with
+ * other out-of-tree kernel modules.
+ *
+ * This module_param *should* be removed as soon as possible and be
+ * considered as a broken and legacy behaviour from a modern fbdev device.
+ */
+#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
+static bool drm_leak_fbdev_smem = false;
+module_param_unsafe(drm_leak_fbdev_smem, bool, 0600);
+MODULE_PARM_DESC(drm_leak_fbdev_smem,
+		 "Allow unsafe leaking fbdev physical smem address [default=false]");
+#endif
+
+static LIST_HEAD(kernel_fb_helper_list);
+static DEFINE_MUTEX(kernel_fb_helper_lock);
+
+/**
+ * DOC: fbdev helpers
+ *
+ * The fb helper functions are useful to provide an fbdev on top of a drm kernel
+ * mode setting driver. They can be used mostly independently from the crtc
+ * helper functions used by many drivers to implement the kernel mode setting
+ * interfaces.
+ *
+ * Drivers that support a dumb buffer with a virtual address and mmap support,
+ * should try out the generic fbdev emulation using drm_fbdev_generic_setup().
+ * It will automatically set up deferred I/O if the driver requires a shadow
+ * buffer.
+ *
+ * At runtime drivers should restore the fbdev console by using
+ * drm_fb_helper_lastclose() as their &drm_driver.lastclose callback.
+ * They should also notify the fb helper code from updates to the output
+ * configuration by using drm_fb_helper_output_poll_changed() as their
+ * &drm_mode_config_funcs.output_poll_changed callback.
+ *
+ * For suspend/resume consider using drm_mode_config_helper_suspend() and
+ * drm_mode_config_helper_resume() which takes care of fbdev as well.
+ *
+ * All other functions exported by the fb helper library can be used to
+ * implement the fbdev driver interface by the driver.
+ *
+ * It is possible, though perhaps somewhat tricky, to implement race-free
+ * hotplug detection using the fbdev helpers. The drm_fb_helper_prepare()
+ * helper must be called first to initialize the minimum required to make
+ * hotplug detection work. Drivers also need to make sure to properly set up
+ * the &drm_mode_config.funcs member. After calling drm_kms_helper_poll_init()
+ * it is safe to enable interrupts and start processing hotplug events. At the
+ * same time, drivers should initialize all modeset objects such as CRTCs,
+ * encoders and connectors. To finish up the fbdev helper initialization, the
+ * drm_fb_helper_init() function is called. To probe for all attached displays
+ * and set up an initial configuration using the detected hardware, drivers
+ * should call drm_fb_helper_initial_config().
+ *
+ * If &drm_framebuffer_funcs.dirty is set, the
+ * drm_fb_helper_{cfb,sys}_{write,fillrect,copyarea,imageblit} functions will
+ * accumulate changes and schedule &drm_fb_helper.dirty_work to run right
+ * away. This worker then calls the dirty() function ensuring that it will
+ * always run in process context since the fb_*() function could be running in
+ * atomic context. If drm_fb_helper_deferred_io() is used as the deferred_io
+ * callback it will also schedule dirty_work with the damage collected from the
+ * mmap page writes.
+ *
+ * Deferred I/O is not compatible with SHMEM. Such drivers should request an
+ * fbdev shadow buffer and call drm_fbdev_generic_setup() instead.
+ */
+
+static void drm_fb_helper_restore_lut_atomic(struct drm_crtc *crtc)
+{
+	uint16_t *r_base, *g_base, *b_base;
+
+	if (crtc->funcs->gamma_set == NULL)
+		return;
+
+	r_base = crtc->gamma_store;
+	g_base = r_base + crtc->gamma_size;
+	b_base = g_base + crtc->gamma_size;
+
+	crtc->funcs->gamma_set(crtc, r_base, g_base, b_base,
+			       crtc->gamma_size, NULL);
+}
+
+/**
+ * drm_fb_helper_debug_enter - implementation for &fb_ops.fb_debug_enter
+ * @info: fbdev registered by the helper
+ */
+int drm_fb_helper_debug_enter(struct fb_info *info)
+{
+	struct drm_fb_helper *helper = info->par;
+	const struct drm_crtc_helper_funcs *funcs;
+	struct drm_mode_set *mode_set;
+
+	list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
+		mutex_lock(&helper->client.modeset_mutex);
+		drm_client_for_each_modeset(mode_set, &helper->client) {
+			if (!mode_set->crtc->enabled)
+				continue;
+
+			funcs =	mode_set->crtc->helper_private;
+			if (funcs->mode_set_base_atomic == NULL)
+				continue;
+
+			if (drm_drv_uses_atomic_modeset(mode_set->crtc->dev))
+				continue;
+
+			funcs->mode_set_base_atomic(mode_set->crtc,
+						    mode_set->fb,
+						    mode_set->x,
+						    mode_set->y,
+						    ENTER_ATOMIC_MODE_SET);
+		}
+		mutex_unlock(&helper->client.modeset_mutex);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_debug_enter);
+
+/**
+ * drm_fb_helper_debug_leave - implementation for &fb_ops.fb_debug_leave
+ * @info: fbdev registered by the helper
+ */
+int drm_fb_helper_debug_leave(struct fb_info *info)
+{
+	struct drm_fb_helper *helper = info->par;
+	struct drm_client_dev *client = &helper->client;
+	struct drm_device *dev = helper->dev;
+	struct drm_crtc *crtc;
+	const struct drm_crtc_helper_funcs *funcs;
+	struct drm_mode_set *mode_set;
+	struct drm_framebuffer *fb;
+
+	mutex_lock(&client->modeset_mutex);
+	drm_client_for_each_modeset(mode_set, client) {
+		crtc = mode_set->crtc;
+		if (drm_drv_uses_atomic_modeset(crtc->dev))
+			continue;
+
+		funcs = crtc->helper_private;
+		fb = crtc->primary->fb;
+
+		if (!crtc->enabled)
+			continue;
+
+		if (!fb) {
+			drm_err(dev, "no fb to restore?\n");
+			continue;
+		}
+
+		if (funcs->mode_set_base_atomic == NULL)
+			continue;
+
+		drm_fb_helper_restore_lut_atomic(mode_set->crtc);
+		funcs->mode_set_base_atomic(mode_set->crtc, fb, crtc->x,
+					    crtc->y, LEAVE_ATOMIC_MODE_SET);
+	}
+	mutex_unlock(&client->modeset_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_debug_leave);
+
+static int
+__drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper,
+					    bool force)
+{
+	bool do_delayed;
+	int ret;
+
+	if (!drm_fbdev_emulation || !fb_helper)
+		return -ENODEV;
+
+	if (READ_ONCE(fb_helper->deferred_setup))
+		return 0;
+
+	mutex_lock(&fb_helper->lock);
+	if (force) {
+		/*
+		 * Yes this is the _locked version which expects the master lock
+		 * to be held. But for forced restores we're intentionally
+		 * racing here, see drm_fb_helper_set_par().
+		 */
+		ret = drm_client_modeset_commit_locked(&fb_helper->client);
+	} else {
+		ret = drm_client_modeset_commit(&fb_helper->client);
+	}
+
+	do_delayed = fb_helper->delayed_hotplug;
+	if (do_delayed)
+		fb_helper->delayed_hotplug = false;
+	mutex_unlock(&fb_helper->lock);
+
+	if (do_delayed)
+		drm_fb_helper_hotplug_event(fb_helper);
+
+	return ret;
+}
+
+/**
+ * drm_fb_helper_restore_fbdev_mode_unlocked - restore fbdev configuration
+ * @fb_helper: driver-allocated fbdev helper, can be NULL
+ *
+ * This should be called from driver's drm &drm_driver.lastclose callback
+ * when implementing an fbcon on top of kms using this helper. This ensures that
+ * the user isn't greeted with a black screen when e.g. X dies.
+ *
+ * RETURNS:
+ * Zero if everything went ok, negative error code otherwise.
+ */
+int drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper)
+{
+	return __drm_fb_helper_restore_fbdev_mode_unlocked(fb_helper, false);
+}
+EXPORT_SYMBOL(drm_fb_helper_restore_fbdev_mode_unlocked);
+
+#ifdef CONFIG_MAGIC_SYSRQ
+/* emergency restore, don't bother with error reporting */
+static void drm_fb_helper_restore_work_fn(struct work_struct *ignored)
+{
+	struct drm_fb_helper *helper;
+
+	mutex_lock(&kernel_fb_helper_lock);
+	list_for_each_entry(helper, &kernel_fb_helper_list, kernel_fb_list) {
+		struct drm_device *dev = helper->dev;
+
+		if (dev->switch_power_state == DRM_SWITCH_POWER_OFF)
+			continue;
+
+		mutex_lock(&helper->lock);
+		drm_client_modeset_commit_locked(&helper->client);
+		mutex_unlock(&helper->lock);
+	}
+	mutex_unlock(&kernel_fb_helper_lock);
+}
+
+static DECLARE_WORK(drm_fb_helper_restore_work, drm_fb_helper_restore_work_fn);
+
+static void drm_fb_helper_sysrq(int dummy1)
+{
+	schedule_work(&drm_fb_helper_restore_work);
+}
+
+static const struct sysrq_key_op sysrq_drm_fb_helper_restore_op = {
+	.handler = drm_fb_helper_sysrq,
+	.help_msg = "force-fb(v)",
+	.action_msg = "Restore framebuffer console",
+};
+#else
+static const struct sysrq_key_op sysrq_drm_fb_helper_restore_op = { };
+#endif
+
+static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+
+	mutex_lock(&fb_helper->lock);
+	drm_client_modeset_dpms(&fb_helper->client, dpms_mode);
+	mutex_unlock(&fb_helper->lock);
+}
+
+/**
+ * drm_fb_helper_blank - implementation for &fb_ops.fb_blank
+ * @blank: desired blanking state
+ * @info: fbdev registered by the helper
+ */
+int drm_fb_helper_blank(int blank, struct fb_info *info)
+{
+	if (oops_in_progress)
+		return -EBUSY;
+
+	switch (blank) {
+	/* Display: On; HSync: On, VSync: On */
+	case FB_BLANK_UNBLANK:
+		drm_fb_helper_dpms(info, DRM_MODE_DPMS_ON);
+		break;
+	/* Display: Off; HSync: On, VSync: On */
+	case FB_BLANK_NORMAL:
+		drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
+		break;
+	/* Display: Off; HSync: Off, VSync: On */
+	case FB_BLANK_HSYNC_SUSPEND:
+		drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
+		break;
+	/* Display: Off; HSync: On, VSync: Off */
+	case FB_BLANK_VSYNC_SUSPEND:
+		drm_fb_helper_dpms(info, DRM_MODE_DPMS_SUSPEND);
+		break;
+	/* Display: Off; HSync: Off, VSync: Off */
+	case FB_BLANK_POWERDOWN:
+		drm_fb_helper_dpms(info, DRM_MODE_DPMS_OFF);
+		break;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_blank);
+
+static void drm_fb_helper_resume_worker(struct work_struct *work)
+{
+	struct drm_fb_helper *helper = container_of(work, struct drm_fb_helper,
+						    resume_work);
+
+	console_lock();
+	fb_set_suspend(helper->fbdev, 0);
+	console_unlock();
+}
+
+static void drm_fb_helper_damage_blit_real(struct drm_fb_helper *fb_helper,
+					   struct drm_clip_rect *clip,
+					   struct iosys_map *dst)
+{
+	struct drm_framebuffer *fb = fb_helper->fb;
+	size_t offset = clip->y1 * fb->pitches[0];
+	size_t len = clip->x2 - clip->x1;
+	unsigned int y;
+	void *src;
+
+	switch (drm_format_info_bpp(fb->format, 0)) {
+	case 1:
+		offset += clip->x1 / 8;
+		len = DIV_ROUND_UP(len + clip->x1 % 8, 8);
+		break;
+	case 2:
+		offset += clip->x1 / 4;
+		len = DIV_ROUND_UP(len + clip->x1 % 4, 4);
+		break;
+	case 4:
+		offset += clip->x1 / 2;
+		len = DIV_ROUND_UP(len + clip->x1 % 2, 2);
+		break;
+	default:
+		offset += clip->x1 * fb->format->cpp[0];
+		len *= fb->format->cpp[0];
+		break;
+	}
+
+	src = fb_helper->fbdev->screen_buffer + offset;
+	iosys_map_incr(dst, offset); /* go to first pixel within clip rect */
+
+	for (y = clip->y1; y < clip->y2; y++) {
+		iosys_map_memcpy_to(dst, 0, src, len);
+		iosys_map_incr(dst, fb->pitches[0]);
+		src += fb->pitches[0];
+	}
+}
+
+static int drm_fb_helper_damage_blit(struct drm_fb_helper *fb_helper,
+				     struct drm_clip_rect *clip)
+{
+	struct drm_client_buffer *buffer = fb_helper->buffer;
+	struct iosys_map map, dst;
+	int ret;
+
+	/*
+	 * We have to pin the client buffer to its current location while
+	 * flushing the shadow buffer. In the general case, concurrent
+	 * modesetting operations could try to move the buffer and would
+	 * fail. The modeset has to be serialized by acquiring the reservation
+	 * object of the underlying BO here.
+	 *
+	 * For fbdev emulation, we only have to protect against fbdev modeset
+	 * operations. Nothing else will involve the client buffer's BO. So it
+	 * is sufficient to acquire struct drm_fb_helper.lock here.
+	 */
+	mutex_lock(&fb_helper->lock);
+
+	ret = drm_client_buffer_vmap(buffer, &map);
+	if (ret)
+		goto out;
+
+	dst = map;
+	drm_fb_helper_damage_blit_real(fb_helper, clip, &dst);
+
+	drm_client_buffer_vunmap(buffer);
+
+out:
+	mutex_unlock(&fb_helper->lock);
+
+	return ret;
+}
+
+static void drm_fb_helper_damage_work(struct work_struct *work)
+{
+	struct drm_fb_helper *helper = container_of(work, struct drm_fb_helper,
+						    damage_work);
+	struct drm_device *dev = helper->dev;
+	struct drm_clip_rect *clip = &helper->damage_clip;
+	struct drm_clip_rect clip_copy;
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&helper->damage_lock, flags);
+	clip_copy = *clip;
+	clip->x1 = clip->y1 = ~0;
+	clip->x2 = clip->y2 = 0;
+	spin_unlock_irqrestore(&helper->damage_lock, flags);
+
+	/* Call damage handlers only if necessary */
+	if (!(clip_copy.x1 < clip_copy.x2 && clip_copy.y1 < clip_copy.y2))
+		return;
+
+	if (helper->buffer) {
+		ret = drm_fb_helper_damage_blit(helper, &clip_copy);
+		if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret))
+			goto err;
+	}
+
+	if (helper->fb->funcs->dirty) {
+		ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, &clip_copy, 1);
+		if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", ret))
+			goto err;
+	}
+
+	return;
+
+err:
+	/*
+	 * Restore damage clip rectangle on errors. The next run
+	 * of the damage worker will perform the update.
+	 */
+	spin_lock_irqsave(&helper->damage_lock, flags);
+	clip->x1 = min_t(u32, clip->x1, clip_copy.x1);
+	clip->y1 = min_t(u32, clip->y1, clip_copy.y1);
+	clip->x2 = max_t(u32, clip->x2, clip_copy.x2);
+	clip->y2 = max_t(u32, clip->y2, clip_copy.y2);
+	spin_unlock_irqrestore(&helper->damage_lock, flags);
+}
+
+/**
+ * drm_fb_helper_prepare - setup a drm_fb_helper structure
+ * @dev: DRM device
+ * @helper: driver-allocated fbdev helper structure to set up
+ * @funcs: pointer to structure of functions associate with this helper
+ *
+ * Sets up the bare minimum to make the framebuffer helper usable. This is
+ * useful to implement race-free initialization of the polling helpers.
+ */
+void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper,
+			   const struct drm_fb_helper_funcs *funcs)
+{
+	INIT_LIST_HEAD(&helper->kernel_fb_list);
+	spin_lock_init(&helper->damage_lock);
+	INIT_WORK(&helper->resume_work, drm_fb_helper_resume_worker);
+	INIT_WORK(&helper->damage_work, drm_fb_helper_damage_work);
+	helper->damage_clip.x1 = helper->damage_clip.y1 = ~0;
+	mutex_init(&helper->lock);
+	helper->funcs = funcs;
+	helper->dev = dev;
+}
+EXPORT_SYMBOL(drm_fb_helper_prepare);
+
+/**
+ * drm_fb_helper_init - initialize a &struct drm_fb_helper
+ * @dev: drm device
+ * @fb_helper: driver-allocated fbdev helper structure to initialize
+ *
+ * This allocates the structures for the fbdev helper with the given limits.
+ * Note that this won't yet touch the hardware (through the driver interfaces)
+ * nor register the fbdev. This is only done in drm_fb_helper_initial_config()
+ * to allow driver writes more control over the exact init sequence.
+ *
+ * Drivers must call drm_fb_helper_prepare() before calling this function.
+ *
+ * RETURNS:
+ * Zero if everything went ok, nonzero otherwise.
+ */
+int drm_fb_helper_init(struct drm_device *dev,
+		       struct drm_fb_helper *fb_helper)
+{
+	int ret;
+
+	if (!drm_fbdev_emulation) {
+		dev->fb_helper = fb_helper;
+		return 0;
+	}
+
+	/*
+	 * If this is not the generic fbdev client, initialize a drm_client
+	 * without callbacks so we can use the modesets.
+	 */
+	if (!fb_helper->client.funcs) {
+		ret = drm_client_init(dev, &fb_helper->client, "drm_fb_helper", NULL);
+		if (ret)
+			return ret;
+	}
+
+	dev->fb_helper = fb_helper;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_init);
+
+/**
+ * drm_fb_helper_alloc_fbi - allocate fb_info and some of its members
+ * @fb_helper: driver-allocated fbdev helper
+ *
+ * A helper to alloc fb_info and the members cmap and apertures. Called
+ * by the driver within the fb_probe fb_helper callback function. Drivers do not
+ * need to release the allocated fb_info structure themselves, this is
+ * automatically done when calling drm_fb_helper_fini().
+ *
+ * RETURNS:
+ * fb_info pointer if things went okay, pointer containing error code
+ * otherwise
+ */
+struct fb_info *drm_fb_helper_alloc_fbi(struct drm_fb_helper *fb_helper)
+{
+	struct device *dev = fb_helper->dev->dev;
+	struct fb_info *info;
+	int ret;
+
+	info = framebuffer_alloc(0, dev);
+	if (!info)
+		return ERR_PTR(-ENOMEM);
+
+	ret = fb_alloc_cmap(&info->cmap, 256, 0);
+	if (ret)
+		goto err_release;
+
+	/*
+	 * TODO: We really should be smarter here and alloc an aperture
+	 * for each IORESOURCE_MEM resource helper->dev->dev has and also
+	 * init the ranges of the appertures based on the resources.
+	 * Note some drivers currently count on there being only 1 empty
+	 * aperture and fill this themselves, these will need to be dealt
+	 * with somehow when fixing this.
+	 */
+	info->apertures = alloc_apertures(1);
+	if (!info->apertures) {
+		ret = -ENOMEM;
+		goto err_free_cmap;
+	}
+
+	fb_helper->fbdev = info;
+	info->skip_vt_switch = true;
+
+	return info;
+
+err_free_cmap:
+	fb_dealloc_cmap(&info->cmap);
+err_release:
+	framebuffer_release(info);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(drm_fb_helper_alloc_fbi);
+
+/**
+ * drm_fb_helper_unregister_fbi - unregister fb_info framebuffer device
+ * @fb_helper: driver-allocated fbdev helper, can be NULL
+ *
+ * A wrapper around unregister_framebuffer, to release the fb_info
+ * framebuffer device. This must be called before releasing all resources for
+ * @fb_helper by calling drm_fb_helper_fini().
+ */
+void drm_fb_helper_unregister_fbi(struct drm_fb_helper *fb_helper)
+{
+	if (fb_helper && fb_helper->fbdev)
+		unregister_framebuffer(fb_helper->fbdev);
+}
+EXPORT_SYMBOL(drm_fb_helper_unregister_fbi);
+
+/**
+ * drm_fb_helper_fini - finialize a &struct drm_fb_helper
+ * @fb_helper: driver-allocated fbdev helper, can be NULL
+ *
+ * This cleans up all remaining resources associated with @fb_helper.
+ */
+void drm_fb_helper_fini(struct drm_fb_helper *fb_helper)
+{
+	struct fb_info *info;
+
+	if (!fb_helper)
+		return;
+
+	fb_helper->dev->fb_helper = NULL;
+
+	if (!drm_fbdev_emulation)
+		return;
+
+	cancel_work_sync(&fb_helper->resume_work);
+	cancel_work_sync(&fb_helper->damage_work);
+
+	info = fb_helper->fbdev;
+	if (info) {
+		if (info->cmap.len)
+			fb_dealloc_cmap(&info->cmap);
+		framebuffer_release(info);
+	}
+	fb_helper->fbdev = NULL;
+
+	mutex_lock(&kernel_fb_helper_lock);
+	if (!list_empty(&fb_helper->kernel_fb_list)) {
+		list_del(&fb_helper->kernel_fb_list);
+		if (list_empty(&kernel_fb_helper_list))
+			unregister_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
+	}
+	mutex_unlock(&kernel_fb_helper_lock);
+
+	mutex_destroy(&fb_helper->lock);
+
+	if (!fb_helper->client.funcs)
+		drm_client_release(&fb_helper->client);
+}
+EXPORT_SYMBOL(drm_fb_helper_fini);
+
+static bool drm_fbdev_use_shadow_fb(struct drm_fb_helper *fb_helper)
+{
+	struct drm_device *dev = fb_helper->dev;
+	struct drm_framebuffer *fb = fb_helper->fb;
+
+	return dev->mode_config.prefer_shadow_fbdev ||
+	       dev->mode_config.prefer_shadow ||
+	       fb->funcs->dirty;
+}
+
+static void drm_fb_helper_damage(struct fb_info *info, u32 x, u32 y,
+				 u32 width, u32 height)
+{
+	struct drm_fb_helper *helper = info->par;
+	struct drm_clip_rect *clip = &helper->damage_clip;
+	unsigned long flags;
+
+	if (!drm_fbdev_use_shadow_fb(helper))
+		return;
+
+	spin_lock_irqsave(&helper->damage_lock, flags);
+	clip->x1 = min_t(u32, clip->x1, x);
+	clip->y1 = min_t(u32, clip->y1, y);
+	clip->x2 = max_t(u32, clip->x2, x + width);
+	clip->y2 = max_t(u32, clip->y2, y + height);
+	spin_unlock_irqrestore(&helper->damage_lock, flags);
+
+	schedule_work(&helper->damage_work);
+}
+
+/*
+ * Convert memory region into area of scanlines and pixels per
+ * scanline. The parameters off and len must not reach beyond
+ * the end of the framebuffer.
+ */
+static void drm_fb_helper_memory_range_to_clip(struct fb_info *info, off_t off, size_t len,
+					       struct drm_rect *clip)
+{
+	u32 line_length = info->fix.line_length;
+	u32 fb_height = info->var.yres;
+	off_t end = off + len;
+	u32 x1 = 0;
+	u32 y1 = off / line_length;
+	u32 x2 = info->var.xres;
+	u32 y2 = DIV_ROUND_UP(end, line_length);
+
+	/* Don't allow any of them beyond the bottom bound of display area */
+	if (y1 > fb_height)
+		y1 = fb_height;
+	if (y2 > fb_height)
+		y2 = fb_height;
+
+	if ((y2 - y1) == 1) {
+		/*
+		 * We've only written to a single scanline. Try to reduce
+		 * the number of horizontal pixels that need an update.
+		 */
+		off_t bit_off = (off % line_length) * 8;
+		off_t bit_end = (end % line_length) * 8;
+
+		x1 = bit_off / info->var.bits_per_pixel;
+		x2 = DIV_ROUND_UP(bit_end, info->var.bits_per_pixel);
+	}
+
+	drm_rect_init(clip, x1, y1, x2 - x1, y2 - y1);
+}
+
+/**
+ * drm_fb_helper_deferred_io() - fbdev deferred_io callback function
+ * @info: fb_info struct pointer
+ * @pagereflist: list of mmap framebuffer pages that have to be flushed
+ *
+ * This function is used as the &fb_deferred_io.deferred_io
+ * callback function for flushing the fbdev mmap writes.
+ */
+void drm_fb_helper_deferred_io(struct fb_info *info, struct list_head *pagereflist)
+{
+	unsigned long start, end, min_off, max_off;
+	struct fb_deferred_io_pageref *pageref;
+	struct drm_rect damage_area;
+
+	min_off = ULONG_MAX;
+	max_off = 0;
+	list_for_each_entry(pageref, pagereflist, list) {
+		start = pageref->offset;
+		end = start + PAGE_SIZE;
+		min_off = min(min_off, start);
+		max_off = max(max_off, end);
+	}
+	if (min_off >= max_off)
+		return;
+
+	/*
+	 * As we can only track pages, we might reach beyond the end
+	 * of the screen and account for non-existing scanlines. Hence,
+	 * keep the covered memory area within the screen buffer.
+	 */
+	max_off = min(max_off, info->screen_size);
+
+	drm_fb_helper_memory_range_to_clip(info, min_off, max_off - min_off, &damage_area);
+	drm_fb_helper_damage(info, damage_area.x1, damage_area.y1,
+			     drm_rect_width(&damage_area),
+			     drm_rect_height(&damage_area));
+}
+EXPORT_SYMBOL(drm_fb_helper_deferred_io);
+
+/**
+ * drm_fb_helper_sys_read - wrapper around fb_sys_read
+ * @info: fb_info struct pointer
+ * @buf: userspace buffer to read from framebuffer memory
+ * @count: number of bytes to read from framebuffer memory
+ * @ppos: read offset within framebuffer memory
+ *
+ * A wrapper around fb_sys_read implemented by fbdev core
+ */
+ssize_t drm_fb_helper_sys_read(struct fb_info *info, char __user *buf,
+			       size_t count, loff_t *ppos)
+{
+	return fb_sys_read(info, buf, count, ppos);
+}
+EXPORT_SYMBOL(drm_fb_helper_sys_read);
+
+/**
+ * drm_fb_helper_sys_write - wrapper around fb_sys_write
+ * @info: fb_info struct pointer
+ * @buf: userspace buffer to write to framebuffer memory
+ * @count: number of bytes to write to framebuffer memory
+ * @ppos: write offset within framebuffer memory
+ *
+ * A wrapper around fb_sys_write implemented by fbdev core
+ */
+ssize_t drm_fb_helper_sys_write(struct fb_info *info, const char __user *buf,
+				size_t count, loff_t *ppos)
+{
+	loff_t pos = *ppos;
+	ssize_t ret;
+	struct drm_rect damage_area;
+
+	ret = fb_sys_write(info, buf, count, ppos);
+	if (ret <= 0)
+		return ret;
+
+	drm_fb_helper_memory_range_to_clip(info, pos, ret, &damage_area);
+	drm_fb_helper_damage(info, damage_area.x1, damage_area.y1,
+			     drm_rect_width(&damage_area),
+			     drm_rect_height(&damage_area));
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_fb_helper_sys_write);
+
+/**
+ * drm_fb_helper_sys_fillrect - wrapper around sys_fillrect
+ * @info: fbdev registered by the helper
+ * @rect: info about rectangle to fill
+ *
+ * A wrapper around sys_fillrect implemented by fbdev core
+ */
+void drm_fb_helper_sys_fillrect(struct fb_info *info,
+				const struct fb_fillrect *rect)
+{
+	sys_fillrect(info, rect);
+	drm_fb_helper_damage(info, rect->dx, rect->dy, rect->width, rect->height);
+}
+EXPORT_SYMBOL(drm_fb_helper_sys_fillrect);
+
+/**
+ * drm_fb_helper_sys_copyarea - wrapper around sys_copyarea
+ * @info: fbdev registered by the helper
+ * @area: info about area to copy
+ *
+ * A wrapper around sys_copyarea implemented by fbdev core
+ */
+void drm_fb_helper_sys_copyarea(struct fb_info *info,
+				const struct fb_copyarea *area)
+{
+	sys_copyarea(info, area);
+	drm_fb_helper_damage(info, area->dx, area->dy, area->width, area->height);
+}
+EXPORT_SYMBOL(drm_fb_helper_sys_copyarea);
+
+/**
+ * drm_fb_helper_sys_imageblit - wrapper around sys_imageblit
+ * @info: fbdev registered by the helper
+ * @image: info about image to blit
+ *
+ * A wrapper around sys_imageblit implemented by fbdev core
+ */
+void drm_fb_helper_sys_imageblit(struct fb_info *info,
+				 const struct fb_image *image)
+{
+	sys_imageblit(info, image);
+	drm_fb_helper_damage(info, image->dx, image->dy, image->width, image->height);
+}
+EXPORT_SYMBOL(drm_fb_helper_sys_imageblit);
+
+/**
+ * drm_fb_helper_cfb_fillrect - wrapper around cfb_fillrect
+ * @info: fbdev registered by the helper
+ * @rect: info about rectangle to fill
+ *
+ * A wrapper around cfb_fillrect implemented by fbdev core
+ */
+void drm_fb_helper_cfb_fillrect(struct fb_info *info,
+				const struct fb_fillrect *rect)
+{
+	cfb_fillrect(info, rect);
+	drm_fb_helper_damage(info, rect->dx, rect->dy, rect->width, rect->height);
+}
+EXPORT_SYMBOL(drm_fb_helper_cfb_fillrect);
+
+/**
+ * drm_fb_helper_cfb_copyarea - wrapper around cfb_copyarea
+ * @info: fbdev registered by the helper
+ * @area: info about area to copy
+ *
+ * A wrapper around cfb_copyarea implemented by fbdev core
+ */
+void drm_fb_helper_cfb_copyarea(struct fb_info *info,
+				const struct fb_copyarea *area)
+{
+	cfb_copyarea(info, area);
+	drm_fb_helper_damage(info, area->dx, area->dy, area->width, area->height);
+}
+EXPORT_SYMBOL(drm_fb_helper_cfb_copyarea);
+
+/**
+ * drm_fb_helper_cfb_imageblit - wrapper around cfb_imageblit
+ * @info: fbdev registered by the helper
+ * @image: info about image to blit
+ *
+ * A wrapper around cfb_imageblit implemented by fbdev core
+ */
+void drm_fb_helper_cfb_imageblit(struct fb_info *info,
+				 const struct fb_image *image)
+{
+	cfb_imageblit(info, image);
+	drm_fb_helper_damage(info, image->dx, image->dy, image->width, image->height);
+}
+EXPORT_SYMBOL(drm_fb_helper_cfb_imageblit);
+
+/**
+ * drm_fb_helper_set_suspend - wrapper around fb_set_suspend
+ * @fb_helper: driver-allocated fbdev helper, can be NULL
+ * @suspend: whether to suspend or resume
+ *
+ * A wrapper around fb_set_suspend implemented by fbdev core.
+ * Use drm_fb_helper_set_suspend_unlocked() if you don't need to take
+ * the lock yourself
+ */
+void drm_fb_helper_set_suspend(struct drm_fb_helper *fb_helper, bool suspend)
+{
+	if (fb_helper && fb_helper->fbdev)
+		fb_set_suspend(fb_helper->fbdev, suspend);
+}
+EXPORT_SYMBOL(drm_fb_helper_set_suspend);
+
+/**
+ * drm_fb_helper_set_suspend_unlocked - wrapper around fb_set_suspend that also
+ *                                      takes the console lock
+ * @fb_helper: driver-allocated fbdev helper, can be NULL
+ * @suspend: whether to suspend or resume
+ *
+ * A wrapper around fb_set_suspend() that takes the console lock. If the lock
+ * isn't available on resume, a worker is tasked with waiting for the lock
+ * to become available. The console lock can be pretty contented on resume
+ * due to all the printk activity.
+ *
+ * This function can be called multiple times with the same state since
+ * &fb_info.state is checked to see if fbdev is running or not before locking.
+ *
+ * Use drm_fb_helper_set_suspend() if you need to take the lock yourself.
+ */
+void drm_fb_helper_set_suspend_unlocked(struct drm_fb_helper *fb_helper,
+					bool suspend)
+{
+	if (!fb_helper || !fb_helper->fbdev)
+		return;
+
+	/* make sure there's no pending/ongoing resume */
+	flush_work(&fb_helper->resume_work);
+
+	if (suspend) {
+		if (fb_helper->fbdev->state != FBINFO_STATE_RUNNING)
+			return;
+
+		console_lock();
+
+	} else {
+		if (fb_helper->fbdev->state == FBINFO_STATE_RUNNING)
+			return;
+
+		if (!console_trylock()) {
+			schedule_work(&fb_helper->resume_work);
+			return;
+		}
+	}
+
+	fb_set_suspend(fb_helper->fbdev, suspend);
+	console_unlock();
+}
+EXPORT_SYMBOL(drm_fb_helper_set_suspend_unlocked);
+
+static int setcmap_pseudo_palette(struct fb_cmap *cmap, struct fb_info *info)
+{
+	u32 *palette = (u32 *)info->pseudo_palette;
+	int i;
+
+	if (cmap->start + cmap->len > 16)
+		return -EINVAL;
+
+	for (i = 0; i < cmap->len; ++i) {
+		u16 red = cmap->red[i];
+		u16 green = cmap->green[i];
+		u16 blue = cmap->blue[i];
+		u32 value;
+
+		red >>= 16 - info->var.red.length;
+		green >>= 16 - info->var.green.length;
+		blue >>= 16 - info->var.blue.length;
+		value = (red << info->var.red.offset) |
+			(green << info->var.green.offset) |
+			(blue << info->var.blue.offset);
+		if (info->var.transp.length > 0) {
+			u32 mask = (1 << info->var.transp.length) - 1;
+
+			mask <<= info->var.transp.offset;
+			value |= mask;
+		}
+		palette[cmap->start + i] = value;
+	}
+
+	return 0;
+}
+
+static int setcmap_legacy(struct fb_cmap *cmap, struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct drm_mode_set *modeset;
+	struct drm_crtc *crtc;
+	u16 *r, *g, *b;
+	int ret = 0;
+
+	drm_modeset_lock_all(fb_helper->dev);
+	drm_client_for_each_modeset(modeset, &fb_helper->client) {
+		crtc = modeset->crtc;
+		if (!crtc->funcs->gamma_set || !crtc->gamma_size) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		if (cmap->start + cmap->len > crtc->gamma_size) {
+			ret = -EINVAL;
+			goto out;
+		}
+
+		r = crtc->gamma_store;
+		g = r + crtc->gamma_size;
+		b = g + crtc->gamma_size;
+
+		memcpy(r + cmap->start, cmap->red, cmap->len * sizeof(*r));
+		memcpy(g + cmap->start, cmap->green, cmap->len * sizeof(*g));
+		memcpy(b + cmap->start, cmap->blue, cmap->len * sizeof(*b));
+
+		ret = crtc->funcs->gamma_set(crtc, r, g, b,
+					     crtc->gamma_size, NULL);
+		if (ret)
+			goto out;
+	}
+out:
+	drm_modeset_unlock_all(fb_helper->dev);
+
+	return ret;
+}
+
+static struct drm_property_blob *setcmap_new_gamma_lut(struct drm_crtc *crtc,
+						       struct fb_cmap *cmap)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_property_blob *gamma_lut;
+	struct drm_color_lut *lut;
+	int size = crtc->gamma_size;
+	int i;
+
+	if (!size || cmap->start + cmap->len > size)
+		return ERR_PTR(-EINVAL);
+
+	gamma_lut = drm_property_create_blob(dev, sizeof(*lut) * size, NULL);
+	if (IS_ERR(gamma_lut))
+		return gamma_lut;
+
+	lut = gamma_lut->data;
+	if (cmap->start || cmap->len != size) {
+		u16 *r = crtc->gamma_store;
+		u16 *g = r + crtc->gamma_size;
+		u16 *b = g + crtc->gamma_size;
+
+		for (i = 0; i < cmap->start; i++) {
+			lut[i].red = r[i];
+			lut[i].green = g[i];
+			lut[i].blue = b[i];
+		}
+		for (i = cmap->start + cmap->len; i < size; i++) {
+			lut[i].red = r[i];
+			lut[i].green = g[i];
+			lut[i].blue = b[i];
+		}
+	}
+
+	for (i = 0; i < cmap->len; i++) {
+		lut[cmap->start + i].red = cmap->red[i];
+		lut[cmap->start + i].green = cmap->green[i];
+		lut[cmap->start + i].blue = cmap->blue[i];
+	}
+
+	return gamma_lut;
+}
+
+static int setcmap_atomic(struct fb_cmap *cmap, struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct drm_device *dev = fb_helper->dev;
+	struct drm_property_blob *gamma_lut = NULL;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_crtc_state *crtc_state;
+	struct drm_atomic_state *state;
+	struct drm_mode_set *modeset;
+	struct drm_crtc *crtc;
+	u16 *r, *g, *b;
+	bool replaced;
+	int ret = 0;
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+	state = drm_atomic_state_alloc(dev);
+	if (!state) {
+		ret = -ENOMEM;
+		goto out_ctx;
+	}
+
+	state->acquire_ctx = &ctx;
+retry:
+	drm_client_for_each_modeset(modeset, &fb_helper->client) {
+		crtc = modeset->crtc;
+
+		if (!gamma_lut)
+			gamma_lut = setcmap_new_gamma_lut(crtc, cmap);
+		if (IS_ERR(gamma_lut)) {
+			ret = PTR_ERR(gamma_lut);
+			gamma_lut = NULL;
+			goto out_state;
+		}
+
+		crtc_state = drm_atomic_get_crtc_state(state, crtc);
+		if (IS_ERR(crtc_state)) {
+			ret = PTR_ERR(crtc_state);
+			goto out_state;
+		}
+
+		/*
+		 * FIXME: This always uses gamma_lut. Some HW have only
+		 * degamma_lut, in which case we should reset gamma_lut and set
+		 * degamma_lut. See drm_crtc_legacy_gamma_set().
+		 */
+		replaced  = drm_property_replace_blob(&crtc_state->degamma_lut,
+						      NULL);
+		replaced |= drm_property_replace_blob(&crtc_state->ctm, NULL);
+		replaced |= drm_property_replace_blob(&crtc_state->gamma_lut,
+						      gamma_lut);
+		crtc_state->color_mgmt_changed |= replaced;
+	}
+
+	ret = drm_atomic_commit(state);
+	if (ret)
+		goto out_state;
+
+	drm_client_for_each_modeset(modeset, &fb_helper->client) {
+		crtc = modeset->crtc;
+
+		r = crtc->gamma_store;
+		g = r + crtc->gamma_size;
+		b = g + crtc->gamma_size;
+
+		memcpy(r + cmap->start, cmap->red, cmap->len * sizeof(*r));
+		memcpy(g + cmap->start, cmap->green, cmap->len * sizeof(*g));
+		memcpy(b + cmap->start, cmap->blue, cmap->len * sizeof(*b));
+	}
+
+out_state:
+	if (ret == -EDEADLK)
+		goto backoff;
+
+	drm_property_blob_put(gamma_lut);
+	drm_atomic_state_put(state);
+out_ctx:
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+
+	return ret;
+
+backoff:
+	drm_atomic_state_clear(state);
+	drm_modeset_backoff(&ctx);
+	goto retry;
+}
+
+/**
+ * drm_fb_helper_setcmap - implementation for &fb_ops.fb_setcmap
+ * @cmap: cmap to set
+ * @info: fbdev registered by the helper
+ */
+int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct drm_device *dev = fb_helper->dev;
+	int ret;
+
+	if (oops_in_progress)
+		return -EBUSY;
+
+	mutex_lock(&fb_helper->lock);
+
+	if (!drm_master_internal_acquire(dev)) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	mutex_lock(&fb_helper->client.modeset_mutex);
+	if (info->fix.visual == FB_VISUAL_TRUECOLOR)
+		ret = setcmap_pseudo_palette(cmap, info);
+	else if (drm_drv_uses_atomic_modeset(fb_helper->dev))
+		ret = setcmap_atomic(cmap, info);
+	else
+		ret = setcmap_legacy(cmap, info);
+	mutex_unlock(&fb_helper->client.modeset_mutex);
+
+	drm_master_internal_release(dev);
+unlock:
+	mutex_unlock(&fb_helper->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_fb_helper_setcmap);
+
+/**
+ * drm_fb_helper_ioctl - legacy ioctl implementation
+ * @info: fbdev registered by the helper
+ * @cmd: ioctl command
+ * @arg: ioctl argument
+ *
+ * A helper to implement the standard fbdev ioctl. Only
+ * FBIO_WAITFORVSYNC is implemented for now.
+ */
+int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
+			unsigned long arg)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct drm_device *dev = fb_helper->dev;
+	struct drm_crtc *crtc;
+	int ret = 0;
+
+	mutex_lock(&fb_helper->lock);
+	if (!drm_master_internal_acquire(dev)) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	switch (cmd) {
+	case FBIO_WAITFORVSYNC:
+		/*
+		 * Only consider the first CRTC.
+		 *
+		 * This ioctl is supposed to take the CRTC number as
+		 * an argument, but in fbdev times, what that number
+		 * was supposed to be was quite unclear, different
+		 * drivers were passing that argument differently
+		 * (some by reference, some by value), and most of the
+		 * userspace applications were just hardcoding 0 as an
+		 * argument.
+		 *
+		 * The first CRTC should be the integrated panel on
+		 * most drivers, so this is the best choice we can
+		 * make. If we're not smart enough here, one should
+		 * just consider switch the userspace to KMS.
+		 */
+		crtc = fb_helper->client.modesets[0].crtc;
+
+		/*
+		 * Only wait for a vblank event if the CRTC is
+		 * enabled, otherwise just don't do anythintg,
+		 * not even report an error.
+		 */
+		ret = drm_crtc_vblank_get(crtc);
+		if (!ret) {
+			drm_crtc_wait_one_vblank(crtc);
+			drm_crtc_vblank_put(crtc);
+		}
+
+		ret = 0;
+		break;
+	default:
+		ret = -ENOTTY;
+	}
+
+	drm_master_internal_release(dev);
+unlock:
+	mutex_unlock(&fb_helper->lock);
+	return ret;
+}
+EXPORT_SYMBOL(drm_fb_helper_ioctl);
+
+static bool drm_fb_pixel_format_equal(const struct fb_var_screeninfo *var_1,
+				      const struct fb_var_screeninfo *var_2)
+{
+	return var_1->bits_per_pixel == var_2->bits_per_pixel &&
+	       var_1->grayscale == var_2->grayscale &&
+	       var_1->red.offset == var_2->red.offset &&
+	       var_1->red.length == var_2->red.length &&
+	       var_1->red.msb_right == var_2->red.msb_right &&
+	       var_1->green.offset == var_2->green.offset &&
+	       var_1->green.length == var_2->green.length &&
+	       var_1->green.msb_right == var_2->green.msb_right &&
+	       var_1->blue.offset == var_2->blue.offset &&
+	       var_1->blue.length == var_2->blue.length &&
+	       var_1->blue.msb_right == var_2->blue.msb_right &&
+	       var_1->transp.offset == var_2->transp.offset &&
+	       var_1->transp.length == var_2->transp.length &&
+	       var_1->transp.msb_right == var_2->transp.msb_right;
+}
+
+static void drm_fb_helper_fill_pixel_fmt(struct fb_var_screeninfo *var,
+					 const struct drm_format_info *format)
+{
+	u8 depth = format->depth;
+
+	if (format->is_color_indexed) {
+		var->red.offset = 0;
+		var->green.offset = 0;
+		var->blue.offset = 0;
+		var->red.length = depth;
+		var->green.length = depth;
+		var->blue.length = depth;
+		var->transp.offset = 0;
+		var->transp.length = 0;
+		return;
+	}
+
+	switch (depth) {
+	case 15:
+		var->red.offset = 10;
+		var->green.offset = 5;
+		var->blue.offset = 0;
+		var->red.length = 5;
+		var->green.length = 5;
+		var->blue.length = 5;
+		var->transp.offset = 15;
+		var->transp.length = 1;
+		break;
+	case 16:
+		var->red.offset = 11;
+		var->green.offset = 5;
+		var->blue.offset = 0;
+		var->red.length = 5;
+		var->green.length = 6;
+		var->blue.length = 5;
+		var->transp.offset = 0;
+		break;
+	case 24:
+		var->red.offset = 16;
+		var->green.offset = 8;
+		var->blue.offset = 0;
+		var->red.length = 8;
+		var->green.length = 8;
+		var->blue.length = 8;
+		var->transp.offset = 0;
+		var->transp.length = 0;
+		break;
+	case 32:
+		var->red.offset = 16;
+		var->green.offset = 8;
+		var->blue.offset = 0;
+		var->red.length = 8;
+		var->green.length = 8;
+		var->blue.length = 8;
+		var->transp.offset = 24;
+		var->transp.length = 8;
+		break;
+	default:
+		break;
+	}
+}
+
+/**
+ * drm_fb_helper_check_var - implementation for &fb_ops.fb_check_var
+ * @var: screeninfo to check
+ * @info: fbdev registered by the helper
+ */
+int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
+			    struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct drm_framebuffer *fb = fb_helper->fb;
+	const struct drm_format_info *format = fb->format;
+	struct drm_device *dev = fb_helper->dev;
+	unsigned int bpp;
+
+	if (in_dbg_master())
+		return -EINVAL;
+
+	if (var->pixclock != 0) {
+		drm_dbg_kms(dev, "fbdev emulation doesn't support changing the pixel clock, value of pixclock is ignored\n");
+		var->pixclock = 0;
+	}
+
+	switch (format->format) {
+	case DRM_FORMAT_C1:
+	case DRM_FORMAT_C2:
+	case DRM_FORMAT_C4:
+		/* supported format with sub-byte pixels */
+		break;
+
+	default:
+		if ((drm_format_info_block_width(format, 0) > 1) ||
+		    (drm_format_info_block_height(format, 0) > 1))
+			return -EINVAL;
+		break;
+	}
+
+	/*
+	 * Changes struct fb_var_screeninfo are currently not pushed back
+	 * to KMS, hence fail if different settings are requested.
+	 */
+	bpp = drm_format_info_bpp(format, 0);
+	if (var->bits_per_pixel > bpp ||
+	    var->xres > fb->width || var->yres > fb->height ||
+	    var->xres_virtual > fb->width || var->yres_virtual > fb->height) {
+		drm_dbg_kms(dev, "fb requested width/height/bpp can't fit in current fb "
+			  "request %dx%d-%d (virtual %dx%d) > %dx%d-%d\n",
+			  var->xres, var->yres, var->bits_per_pixel,
+			  var->xres_virtual, var->yres_virtual,
+			  fb->width, fb->height, bpp);
+		return -EINVAL;
+	}
+
+	var->xres_virtual = fb->width;
+	var->yres_virtual = fb->height;
+
+	/*
+	 * Workaround for SDL 1.2, which is known to be setting all pixel format
+	 * fields values to zero in some cases. We treat this situation as a
+	 * kind of "use some reasonable autodetected values".
+	 */
+	if (!var->red.offset     && !var->green.offset    &&
+	    !var->blue.offset    && !var->transp.offset   &&
+	    !var->red.length     && !var->green.length    &&
+	    !var->blue.length    && !var->transp.length   &&
+	    !var->red.msb_right  && !var->green.msb_right &&
+	    !var->blue.msb_right && !var->transp.msb_right) {
+		drm_fb_helper_fill_pixel_fmt(var, format);
+	}
+
+	/*
+	 * Likewise, bits_per_pixel should be rounded up to a supported value.
+	 */
+	var->bits_per_pixel = bpp;
+
+	/*
+	 * drm fbdev emulation doesn't support changing the pixel format at all,
+	 * so reject all pixel format changing requests.
+	 */
+	if (!drm_fb_pixel_format_equal(var, &info->var)) {
+		drm_dbg_kms(dev, "fbdev emulation doesn't support changing the pixel format\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_check_var);
+
+/**
+ * drm_fb_helper_set_par - implementation for &fb_ops.fb_set_par
+ * @info: fbdev registered by the helper
+ *
+ * This will let fbcon do the mode init and is called at initialization time by
+ * the fbdev core when registering the driver, and later on through the hotplug
+ * callback.
+ */
+int drm_fb_helper_set_par(struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct fb_var_screeninfo *var = &info->var;
+	bool force;
+
+	if (oops_in_progress)
+		return -EBUSY;
+
+	if (var->pixclock != 0) {
+		drm_err(fb_helper->dev, "PIXEL CLOCK SET\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Normally we want to make sure that a kms master takes precedence over
+	 * fbdev, to avoid fbdev flickering and occasionally stealing the
+	 * display status. But Xorg first sets the vt back to text mode using
+	 * the KDSET IOCTL with KD_TEXT, and only after that drops the master
+	 * status when exiting.
+	 *
+	 * In the past this was caught by drm_fb_helper_lastclose(), but on
+	 * modern systems where logind always keeps a drm fd open to orchestrate
+	 * the vt switching, this doesn't work.
+	 *
+	 * To not break the userspace ABI we have this special case here, which
+	 * is only used for the above case. Everything else uses the normal
+	 * commit function, which ensures that we never steal the display from
+	 * an active drm master.
+	 */
+	force = var->activate & FB_ACTIVATE_KD_TEXT;
+
+	__drm_fb_helper_restore_fbdev_mode_unlocked(fb_helper, force);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_set_par);
+
+static void pan_set(struct drm_fb_helper *fb_helper, int x, int y)
+{
+	struct drm_mode_set *mode_set;
+
+	mutex_lock(&fb_helper->client.modeset_mutex);
+	drm_client_for_each_modeset(mode_set, &fb_helper->client) {
+		mode_set->x = x;
+		mode_set->y = y;
+	}
+	mutex_unlock(&fb_helper->client.modeset_mutex);
+}
+
+static int pan_display_atomic(struct fb_var_screeninfo *var,
+			      struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	int ret;
+
+	pan_set(fb_helper, var->xoffset, var->yoffset);
+
+	ret = drm_client_modeset_commit_locked(&fb_helper->client);
+	if (!ret) {
+		info->var.xoffset = var->xoffset;
+		info->var.yoffset = var->yoffset;
+	} else
+		pan_set(fb_helper, info->var.xoffset, info->var.yoffset);
+
+	return ret;
+}
+
+static int pan_display_legacy(struct fb_var_screeninfo *var,
+			      struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct drm_client_dev *client = &fb_helper->client;
+	struct drm_mode_set *modeset;
+	int ret = 0;
+
+	mutex_lock(&client->modeset_mutex);
+	drm_modeset_lock_all(fb_helper->dev);
+	drm_client_for_each_modeset(modeset, client) {
+		modeset->x = var->xoffset;
+		modeset->y = var->yoffset;
+
+		if (modeset->num_connectors) {
+			ret = drm_mode_set_config_internal(modeset);
+			if (!ret) {
+				info->var.xoffset = var->xoffset;
+				info->var.yoffset = var->yoffset;
+			}
+		}
+	}
+	drm_modeset_unlock_all(fb_helper->dev);
+	mutex_unlock(&client->modeset_mutex);
+
+	return ret;
+}
+
+/**
+ * drm_fb_helper_pan_display - implementation for &fb_ops.fb_pan_display
+ * @var: updated screen information
+ * @info: fbdev registered by the helper
+ */
+int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
+			      struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct drm_device *dev = fb_helper->dev;
+	int ret;
+
+	if (oops_in_progress)
+		return -EBUSY;
+
+	mutex_lock(&fb_helper->lock);
+	if (!drm_master_internal_acquire(dev)) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	if (drm_drv_uses_atomic_modeset(dev))
+		ret = pan_display_atomic(var, info);
+	else
+		ret = pan_display_legacy(var, info);
+
+	drm_master_internal_release(dev);
+unlock:
+	mutex_unlock(&fb_helper->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_fb_helper_pan_display);
+
+/*
+ * Allocates the backing storage and sets up the fbdev info structure through
+ * the ->fb_probe callback.
+ */
+static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
+					 int preferred_bpp)
+{
+	struct drm_client_dev *client = &fb_helper->client;
+	struct drm_device *dev = fb_helper->dev;
+	struct drm_mode_config *config = &dev->mode_config;
+	int ret = 0;
+	int crtc_count = 0;
+	struct drm_connector_list_iter conn_iter;
+	struct drm_fb_helper_surface_size sizes;
+	struct drm_connector *connector;
+	struct drm_mode_set *mode_set;
+	int best_depth = 0;
+
+	memset(&sizes, 0, sizeof(struct drm_fb_helper_surface_size));
+	sizes.surface_depth = 24;
+	sizes.surface_bpp = 32;
+	sizes.fb_width = (u32)-1;
+	sizes.fb_height = (u32)-1;
+
+	/*
+	 * If driver picks 8 or 16 by default use that for both depth/bpp
+	 * to begin with
+	 */
+	if (preferred_bpp != sizes.surface_bpp)
+		sizes.surface_depth = sizes.surface_bpp = preferred_bpp;
+
+	drm_connector_list_iter_begin(fb_helper->dev, &conn_iter);
+	drm_client_for_each_connector_iter(connector, &conn_iter) {
+		struct drm_cmdline_mode *cmdline_mode;
+
+		cmdline_mode = &connector->cmdline_mode;
+
+		if (cmdline_mode->bpp_specified) {
+			switch (cmdline_mode->bpp) {
+			case 8:
+				sizes.surface_depth = sizes.surface_bpp = 8;
+				break;
+			case 15:
+				sizes.surface_depth = 15;
+				sizes.surface_bpp = 16;
+				break;
+			case 16:
+				sizes.surface_depth = sizes.surface_bpp = 16;
+				break;
+			case 24:
+				sizes.surface_depth = sizes.surface_bpp = 24;
+				break;
+			case 32:
+				sizes.surface_depth = 24;
+				sizes.surface_bpp = 32;
+				break;
+			}
+			break;
+		}
+	}
+	drm_connector_list_iter_end(&conn_iter);
+
+	/*
+	 * If we run into a situation where, for example, the primary plane
+	 * supports RGBA5551 (16 bpp, depth 15) but not RGB565 (16 bpp, depth
+	 * 16) we need to scale down the depth of the sizes we request.
+	 */
+	mutex_lock(&client->modeset_mutex);
+	drm_client_for_each_modeset(mode_set, client) {
+		struct drm_crtc *crtc = mode_set->crtc;
+		struct drm_plane *plane = crtc->primary;
+		int j;
+
+		drm_dbg_kms(dev, "test CRTC %u primary plane\n", drm_crtc_index(crtc));
+
+		for (j = 0; j < plane->format_count; j++) {
+			const struct drm_format_info *fmt;
+
+			fmt = drm_format_info(plane->format_types[j]);
+
+			/*
+			 * Do not consider YUV or other complicated formats
+			 * for framebuffers. This means only legacy formats
+			 * are supported (fmt->depth is a legacy field) but
+			 * the framebuffer emulation can only deal with such
+			 * formats, specifically RGB/BGA formats.
+			 */
+			if (fmt->depth == 0)
+				continue;
+
+			/* We found a perfect fit, great */
+			if (fmt->depth == sizes.surface_depth) {
+				best_depth = fmt->depth;
+				break;
+			}
+
+			/* Skip depths above what we're looking for */
+			if (fmt->depth > sizes.surface_depth)
+				continue;
+
+			/* Best depth found so far */
+			if (fmt->depth > best_depth)
+				best_depth = fmt->depth;
+		}
+	}
+	if (sizes.surface_depth != best_depth && best_depth) {
+		drm_info(dev, "requested bpp %d, scaled depth down to %d",
+			 sizes.surface_bpp, best_depth);
+		sizes.surface_depth = best_depth;
+	}
+
+	/* first up get a count of crtcs now in use and new min/maxes width/heights */
+	crtc_count = 0;
+	drm_client_for_each_modeset(mode_set, client) {
+		struct drm_display_mode *desired_mode;
+		int x, y, j;
+		/* in case of tile group, are we the last tile vert or horiz?
+		 * If no tile group you are always the last one both vertically
+		 * and horizontally
+		 */
+		bool lastv = true, lasth = true;
+
+		desired_mode = mode_set->mode;
+
+		if (!desired_mode)
+			continue;
+
+		crtc_count++;
+
+		x = mode_set->x;
+		y = mode_set->y;
+
+		sizes.surface_width  = max_t(u32, desired_mode->hdisplay + x, sizes.surface_width);
+		sizes.surface_height = max_t(u32, desired_mode->vdisplay + y, sizes.surface_height);
+
+		for (j = 0; j < mode_set->num_connectors; j++) {
+			struct drm_connector *connector = mode_set->connectors[j];
+
+			if (connector->has_tile &&
+			    desired_mode->hdisplay == connector->tile_h_size &&
+			    desired_mode->vdisplay == connector->tile_v_size) {
+				lasth = (connector->tile_h_loc == (connector->num_h_tile - 1));
+				lastv = (connector->tile_v_loc == (connector->num_v_tile - 1));
+				/* cloning to multiple tiles is just crazy-talk, so: */
+				break;
+			}
+		}
+
+		if (lasth)
+			sizes.fb_width  = min_t(u32, desired_mode->hdisplay + x, sizes.fb_width);
+		if (lastv)
+			sizes.fb_height = min_t(u32, desired_mode->vdisplay + y, sizes.fb_height);
+	}
+	mutex_unlock(&client->modeset_mutex);
+
+	if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height == -1) {
+		drm_info(dev, "Cannot find any crtc or sizes\n");
+
+		/* First time: disable all crtc's.. */
+		if (!fb_helper->deferred_setup)
+			drm_client_modeset_commit(client);
+		return -EAGAIN;
+	}
+
+	/* Handle our overallocation */
+	sizes.surface_height *= drm_fbdev_overalloc;
+	sizes.surface_height /= 100;
+	if (sizes.surface_height > config->max_height) {
+		drm_dbg_kms(dev, "Fbdev over-allocation too large; clamping height to %d\n",
+			    config->max_height);
+		sizes.surface_height = config->max_height;
+	}
+
+	/* push down into drivers */
+	ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes);
+	if (ret < 0)
+		return ret;
+
+	strcpy(fb_helper->fb->comm, "[fbcon]");
+	return 0;
+}
+
+static void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
+				   bool is_color_indexed)
+{
+	info->fix.type = FB_TYPE_PACKED_PIXELS;
+	info->fix.visual = is_color_indexed ? FB_VISUAL_PSEUDOCOLOR
+					    : FB_VISUAL_TRUECOLOR;
+	info->fix.mmio_start = 0;
+	info->fix.mmio_len = 0;
+	info->fix.type_aux = 0;
+	info->fix.xpanstep = 1; /* doing it in hw */
+	info->fix.ypanstep = 1; /* doing it in hw */
+	info->fix.ywrapstep = 0;
+	info->fix.accel = FB_ACCEL_NONE;
+
+	info->fix.line_length = pitch;
+}
+
+static void drm_fb_helper_fill_var(struct fb_info *info,
+				   struct drm_fb_helper *fb_helper,
+				   uint32_t fb_width, uint32_t fb_height)
+{
+	struct drm_framebuffer *fb = fb_helper->fb;
+	const struct drm_format_info *format = fb->format;
+
+	switch (format->format) {
+	case DRM_FORMAT_C1:
+	case DRM_FORMAT_C2:
+	case DRM_FORMAT_C4:
+		/* supported format with sub-byte pixels */
+		break;
+
+	default:
+		WARN_ON((drm_format_info_block_width(format, 0) > 1) ||
+			(drm_format_info_block_height(format, 0) > 1));
+		break;
+	}
+
+	info->pseudo_palette = fb_helper->pseudo_palette;
+	info->var.xres_virtual = fb->width;
+	info->var.yres_virtual = fb->height;
+	info->var.bits_per_pixel = drm_format_info_bpp(format, 0);
+	info->var.accel_flags = FB_ACCELF_TEXT;
+	info->var.xoffset = 0;
+	info->var.yoffset = 0;
+	info->var.activate = FB_ACTIVATE_NOW;
+
+	drm_fb_helper_fill_pixel_fmt(&info->var, format);
+
+	info->var.xres = fb_width;
+	info->var.yres = fb_height;
+}
+
+/**
+ * drm_fb_helper_fill_info - initializes fbdev information
+ * @info: fbdev instance to set up
+ * @fb_helper: fb helper instance to use as template
+ * @sizes: describes fbdev size and scanout surface size
+ *
+ * Sets up the variable and fixed fbdev metainformation from the given fb helper
+ * instance and the drm framebuffer allocated in &drm_fb_helper.fb.
+ *
+ * Drivers should call this (or their equivalent setup code) from their
+ * &drm_fb_helper_funcs.fb_probe callback after having allocated the fbdev
+ * backing storage framebuffer.
+ */
+void drm_fb_helper_fill_info(struct fb_info *info,
+			     struct drm_fb_helper *fb_helper,
+			     struct drm_fb_helper_surface_size *sizes)
+{
+	struct drm_framebuffer *fb = fb_helper->fb;
+
+	drm_fb_helper_fill_fix(info, fb->pitches[0],
+			       fb->format->is_color_indexed);
+	drm_fb_helper_fill_var(info, fb_helper,
+			       sizes->fb_width, sizes->fb_height);
+
+	info->par = fb_helper;
+	/*
+	 * The DRM drivers fbdev emulation device name can be confusing if the
+	 * driver name also has a "drm" suffix on it. Leading to names such as
+	 * "simpledrmdrmfb" in /proc/fb. Unfortunately, it's an uAPI and can't
+	 * be changed due user-space tools (e.g: pm-utils) matching against it.
+	 */
+	snprintf(info->fix.id, sizeof(info->fix.id), "%sdrmfb",
+		 fb_helper->dev->driver->name);
+
+}
+EXPORT_SYMBOL(drm_fb_helper_fill_info);
+
+/*
+ * This is a continuation of drm_setup_crtcs() that sets up anything related
+ * to the framebuffer. During initialization, drm_setup_crtcs() is called before
+ * the framebuffer has been allocated (fb_helper->fb and fb_helper->fbdev).
+ * So, any setup that touches those fields needs to be done here instead of in
+ * drm_setup_crtcs().
+ */
+static void drm_setup_crtcs_fb(struct drm_fb_helper *fb_helper)
+{
+	struct drm_client_dev *client = &fb_helper->client;
+	struct drm_connector_list_iter conn_iter;
+	struct fb_info *info = fb_helper->fbdev;
+	unsigned int rotation, sw_rotations = 0;
+	struct drm_connector *connector;
+	struct drm_mode_set *modeset;
+
+	mutex_lock(&client->modeset_mutex);
+	drm_client_for_each_modeset(modeset, client) {
+		if (!modeset->num_connectors)
+			continue;
+
+		modeset->fb = fb_helper->fb;
+
+		if (drm_client_rotation(modeset, &rotation))
+			/* Rotating in hardware, fbcon should not rotate */
+			sw_rotations |= DRM_MODE_ROTATE_0;
+		else
+			sw_rotations |= rotation;
+	}
+	mutex_unlock(&client->modeset_mutex);
+
+	drm_connector_list_iter_begin(fb_helper->dev, &conn_iter);
+	drm_client_for_each_connector_iter(connector, &conn_iter) {
+
+		/* use first connected connector for the physical dimensions */
+		if (connector->status == connector_status_connected) {
+			info->var.width = connector->display_info.width_mm;
+			info->var.height = connector->display_info.height_mm;
+			break;
+		}
+	}
+	drm_connector_list_iter_end(&conn_iter);
+
+	switch (sw_rotations) {
+	case DRM_MODE_ROTATE_0:
+		info->fbcon_rotate_hint = FB_ROTATE_UR;
+		break;
+	case DRM_MODE_ROTATE_90:
+		info->fbcon_rotate_hint = FB_ROTATE_CCW;
+		break;
+	case DRM_MODE_ROTATE_180:
+		info->fbcon_rotate_hint = FB_ROTATE_UD;
+		break;
+	case DRM_MODE_ROTATE_270:
+		info->fbcon_rotate_hint = FB_ROTATE_CW;
+		break;
+	default:
+		/*
+		 * Multiple bits are set / multiple rotations requested
+		 * fbcon cannot handle separate rotation settings per
+		 * output, so fallback to unrotated.
+		 */
+		info->fbcon_rotate_hint = FB_ROTATE_UR;
+	}
+}
+
+/* Note: Drops fb_helper->lock before returning. */
+static int
+__drm_fb_helper_initial_config_and_unlock(struct drm_fb_helper *fb_helper,
+					  int bpp_sel)
+{
+	struct drm_device *dev = fb_helper->dev;
+	struct fb_info *info;
+	unsigned int width, height;
+	int ret;
+
+	width = dev->mode_config.max_width;
+	height = dev->mode_config.max_height;
+
+	drm_client_modeset_probe(&fb_helper->client, width, height);
+	ret = drm_fb_helper_single_fb_probe(fb_helper, bpp_sel);
+	if (ret < 0) {
+		if (ret == -EAGAIN) {
+			fb_helper->preferred_bpp = bpp_sel;
+			fb_helper->deferred_setup = true;
+			ret = 0;
+		}
+		mutex_unlock(&fb_helper->lock);
+
+		return ret;
+	}
+	drm_setup_crtcs_fb(fb_helper);
+
+	fb_helper->deferred_setup = false;
+
+	info = fb_helper->fbdev;
+	info->var.pixclock = 0;
+	/* Shamelessly allow physical address leaking to userspace */
+#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
+	if (!drm_leak_fbdev_smem)
+#endif
+		/* don't leak any physical addresses to userspace */
+		info->flags |= FBINFO_HIDE_SMEM_START;
+
+	/* Need to drop locks to avoid recursive deadlock in
+	 * register_framebuffer. This is ok because the only thing left to do is
+	 * register the fbdev emulation instance in kernel_fb_helper_list. */
+	mutex_unlock(&fb_helper->lock);
+
+	ret = register_framebuffer(info);
+	if (ret < 0)
+		return ret;
+
+	drm_info(dev, "fb%d: %s frame buffer device\n",
+		 info->node, info->fix.id);
+
+	mutex_lock(&kernel_fb_helper_lock);
+	if (list_empty(&kernel_fb_helper_list))
+		register_sysrq_key('v', &sysrq_drm_fb_helper_restore_op);
+
+	list_add(&fb_helper->kernel_fb_list, &kernel_fb_helper_list);
+	mutex_unlock(&kernel_fb_helper_lock);
+
+	return 0;
+}
+
+/**
+ * drm_fb_helper_initial_config - setup a sane initial connector configuration
+ * @fb_helper: fb_helper device struct
+ * @bpp_sel: bpp value to use for the framebuffer configuration
+ *
+ * Scans the CRTCs and connectors and tries to put together an initial setup.
+ * At the moment, this is a cloned configuration across all heads with
+ * a new framebuffer object as the backing store.
+ *
+ * Note that this also registers the fbdev and so allows userspace to call into
+ * the driver through the fbdev interfaces.
+ *
+ * This function will call down into the &drm_fb_helper_funcs.fb_probe callback
+ * to let the driver allocate and initialize the fbdev info structure and the
+ * drm framebuffer used to back the fbdev. drm_fb_helper_fill_info() is provided
+ * as a helper to setup simple default values for the fbdev info structure.
+ *
+ * HANG DEBUGGING:
+ *
+ * When you have fbcon support built-in or already loaded, this function will do
+ * a full modeset to setup the fbdev console. Due to locking misdesign in the
+ * VT/fbdev subsystem that entire modeset sequence has to be done while holding
+ * console_lock. Until console_unlock is called no dmesg lines will be sent out
+ * to consoles, not even serial console. This means when your driver crashes,
+ * you will see absolutely nothing else but a system stuck in this function,
+ * with no further output. Any kind of printk() you place within your own driver
+ * or in the drm core modeset code will also never show up.
+ *
+ * Standard debug practice is to run the fbcon setup without taking the
+ * console_lock as a hack, to be able to see backtraces and crashes on the
+ * serial line. This can be done by setting the fb.lockless_register_fb=1 kernel
+ * cmdline option.
+ *
+ * The other option is to just disable fbdev emulation since very likely the
+ * first modeset from userspace will crash in the same way, and is even easier
+ * to debug. This can be done by setting the drm_kms_helper.fbdev_emulation=0
+ * kernel cmdline option.
+ *
+ * RETURNS:
+ * Zero if everything went ok, nonzero otherwise.
+ */
+int drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel)
+{
+	int ret;
+
+	if (!drm_fbdev_emulation)
+		return 0;
+
+	mutex_lock(&fb_helper->lock);
+	ret = __drm_fb_helper_initial_config_and_unlock(fb_helper, bpp_sel);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_fb_helper_initial_config);
+
+/**
+ * drm_fb_helper_hotplug_event - respond to a hotplug notification by
+ *                               probing all the outputs attached to the fb
+ * @fb_helper: driver-allocated fbdev helper, can be NULL
+ *
+ * Scan the connectors attached to the fb_helper and try to put together a
+ * setup after notification of a change in output configuration.
+ *
+ * Called at runtime, takes the mode config locks to be able to check/change the
+ * modeset configuration. Must be run from process context (which usually means
+ * either the output polling work or a work item launched from the driver's
+ * hotplug interrupt).
+ *
+ * Note that drivers may call this even before calling
+ * drm_fb_helper_initial_config but only after drm_fb_helper_init. This allows
+ * for a race-free fbcon setup and will make sure that the fbdev emulation will
+ * not miss any hotplug events.
+ *
+ * RETURNS:
+ * 0 on success and a non-zero error code otherwise.
+ */
+int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
+{
+	int err = 0;
+
+	if (!drm_fbdev_emulation || !fb_helper)
+		return 0;
+
+	mutex_lock(&fb_helper->lock);
+	if (fb_helper->deferred_setup) {
+		err = __drm_fb_helper_initial_config_and_unlock(fb_helper,
+				fb_helper->preferred_bpp);
+		return err;
+	}
+
+	if (!fb_helper->fb || !drm_master_internal_acquire(fb_helper->dev)) {
+		fb_helper->delayed_hotplug = true;
+		mutex_unlock(&fb_helper->lock);
+		return err;
+	}
+
+	drm_master_internal_release(fb_helper->dev);
+
+	drm_dbg_kms(fb_helper->dev, "\n");
+
+	drm_client_modeset_probe(&fb_helper->client, fb_helper->fb->width, fb_helper->fb->height);
+	drm_setup_crtcs_fb(fb_helper);
+	mutex_unlock(&fb_helper->lock);
+
+	drm_fb_helper_set_par(fb_helper->fbdev);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_fb_helper_hotplug_event);
+
+/**
+ * drm_fb_helper_lastclose - DRM driver lastclose helper for fbdev emulation
+ * @dev: DRM device
+ *
+ * This function can be used as the &drm_driver->lastclose callback for drivers
+ * that only need to call drm_fb_helper_restore_fbdev_mode_unlocked().
+ */
+void drm_fb_helper_lastclose(struct drm_device *dev)
+{
+	drm_fb_helper_restore_fbdev_mode_unlocked(dev->fb_helper);
+}
+EXPORT_SYMBOL(drm_fb_helper_lastclose);
+
+/**
+ * drm_fb_helper_output_poll_changed - DRM mode config \.output_poll_changed
+ *                                     helper for fbdev emulation
+ * @dev: DRM device
+ *
+ * This function can be used as the
+ * &drm_mode_config_funcs.output_poll_changed callback for drivers that only
+ * need to call drm_fb_helper_hotplug_event().
+ */
+void drm_fb_helper_output_poll_changed(struct drm_device *dev)
+{
+	drm_fb_helper_hotplug_event(dev->fb_helper);
+}
+EXPORT_SYMBOL(drm_fb_helper_output_poll_changed);
+
+/* @user: 1=userspace, 0=fbcon */
+static int drm_fbdev_fb_open(struct fb_info *info, int user)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+
+	/* No need to take a ref for fbcon because it unbinds on unregister */
+	if (user && !try_module_get(fb_helper->dev->driver->fops->owner))
+		return -ENODEV;
+
+	return 0;
+}
+
+static int drm_fbdev_fb_release(struct fb_info *info, int user)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+
+	if (user)
+		module_put(fb_helper->dev->driver->fops->owner);
+
+	return 0;
+}
+
+static void drm_fbdev_cleanup(struct drm_fb_helper *fb_helper)
+{
+	struct fb_info *fbi = fb_helper->fbdev;
+	void *shadow = NULL;
+
+	if (!fb_helper->dev)
+		return;
+
+	if (fbi) {
+		if (fbi->fbdefio)
+			fb_deferred_io_cleanup(fbi);
+		if (drm_fbdev_use_shadow_fb(fb_helper))
+			shadow = fbi->screen_buffer;
+	}
+
+	drm_fb_helper_fini(fb_helper);
+
+	if (shadow)
+		vfree(shadow);
+	else if (fb_helper->buffer)
+		drm_client_buffer_vunmap(fb_helper->buffer);
+
+	drm_client_framebuffer_delete(fb_helper->buffer);
+}
+
+static void drm_fbdev_release(struct drm_fb_helper *fb_helper)
+{
+	drm_fbdev_cleanup(fb_helper);
+	drm_client_release(&fb_helper->client);
+	kfree(fb_helper);
+}
+
+/*
+ * fb_ops.fb_destroy is called by the last put_fb_info() call at the end of
+ * unregister_framebuffer() or fb_release().
+ */
+static void drm_fbdev_fb_destroy(struct fb_info *info)
+{
+	drm_fbdev_release(info->par);
+}
+
+static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+
+	if (drm_fbdev_use_shadow_fb(fb_helper))
+		return fb_deferred_io_mmap(info, vma);
+	else if (fb_helper->dev->driver->gem_prime_mmap)
+		return fb_helper->dev->driver->gem_prime_mmap(fb_helper->buffer->gem, vma);
+	else
+		return -ENODEV;
+}
+
+static bool drm_fbdev_use_iomem(struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct drm_client_buffer *buffer = fb_helper->buffer;
+
+	return !drm_fbdev_use_shadow_fb(fb_helper) && buffer->map.is_iomem;
+}
+
+static ssize_t fb_read_screen_base(struct fb_info *info, char __user *buf, size_t count,
+				   loff_t pos)
+{
+	const char __iomem *src = info->screen_base + pos;
+	size_t alloc_size = min_t(size_t, count, PAGE_SIZE);
+	ssize_t ret = 0;
+	int err = 0;
+	char *tmp;
+
+	tmp = kmalloc(alloc_size, GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+
+	while (count) {
+		size_t c = min_t(size_t, count, alloc_size);
+
+		memcpy_fromio(tmp, src, c);
+		if (copy_to_user(buf, tmp, c)) {
+			err = -EFAULT;
+			break;
+		}
+
+		src += c;
+		buf += c;
+		ret += c;
+		count -= c;
+	}
+
+	kfree(tmp);
+
+	return ret ? ret : err;
+}
+
+static ssize_t fb_read_screen_buffer(struct fb_info *info, char __user *buf, size_t count,
+				     loff_t pos)
+{
+	const char *src = info->screen_buffer + pos;
+
+	if (copy_to_user(buf, src, count))
+		return -EFAULT;
+
+	return count;
+}
+
+static ssize_t drm_fbdev_fb_read(struct fb_info *info, char __user *buf,
+				 size_t count, loff_t *ppos)
+{
+	loff_t pos = *ppos;
+	size_t total_size;
+	ssize_t ret;
+
+	if (info->screen_size)
+		total_size = info->screen_size;
+	else
+		total_size = info->fix.smem_len;
+
+	if (pos >= total_size)
+		return 0;
+	if (count >= total_size)
+		count = total_size;
+	if (total_size - count < pos)
+		count = total_size - pos;
+
+	if (drm_fbdev_use_iomem(info))
+		ret = fb_read_screen_base(info, buf, count, pos);
+	else
+		ret = fb_read_screen_buffer(info, buf, count, pos);
+
+	if (ret > 0)
+		*ppos += ret;
+
+	return ret;
+}
+
+static ssize_t fb_write_screen_base(struct fb_info *info, const char __user *buf, size_t count,
+				    loff_t pos)
+{
+	char __iomem *dst = info->screen_base + pos;
+	size_t alloc_size = min_t(size_t, count, PAGE_SIZE);
+	ssize_t ret = 0;
+	int err = 0;
+	u8 *tmp;
+
+	tmp = kmalloc(alloc_size, GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+
+	while (count) {
+		size_t c = min_t(size_t, count, alloc_size);
+
+		if (copy_from_user(tmp, buf, c)) {
+			err = -EFAULT;
+			break;
+		}
+		memcpy_toio(dst, tmp, c);
+
+		dst += c;
+		buf += c;
+		ret += c;
+		count -= c;
+	}
+
+	kfree(tmp);
+
+	return ret ? ret : err;
+}
+
+static ssize_t fb_write_screen_buffer(struct fb_info *info, const char __user *buf, size_t count,
+				      loff_t pos)
+{
+	char *dst = info->screen_buffer + pos;
+
+	if (copy_from_user(dst, buf, count))
+		return -EFAULT;
+
+	return count;
+}
+
+static ssize_t drm_fbdev_fb_write(struct fb_info *info, const char __user *buf,
+				  size_t count, loff_t *ppos)
+{
+	loff_t pos = *ppos;
+	size_t total_size;
+	ssize_t ret;
+	struct drm_rect damage_area;
+	int err = 0;
+
+	if (info->screen_size)
+		total_size = info->screen_size;
+	else
+		total_size = info->fix.smem_len;
+
+	if (pos > total_size)
+		return -EFBIG;
+	if (count > total_size) {
+		err = -EFBIG;
+		count = total_size;
+	}
+	if (total_size - count < pos) {
+		if (!err)
+			err = -ENOSPC;
+		count = total_size - pos;
+	}
+
+	/*
+	 * Copy to framebuffer even if we already logged an error. Emulates
+	 * the behavior of the original fbdev implementation.
+	 */
+	if (drm_fbdev_use_iomem(info))
+		ret = fb_write_screen_base(info, buf, count, pos);
+	else
+		ret = fb_write_screen_buffer(info, buf, count, pos);
+
+	if (ret < 0)
+		return ret; /* return last error, if any */
+	else if (!ret)
+		return err; /* return previous error, if any */
+
+	*ppos += ret;
+
+	drm_fb_helper_memory_range_to_clip(info, pos, ret, &damage_area);
+	drm_fb_helper_damage(info, damage_area.x1, damage_area.y1,
+			     drm_rect_width(&damage_area),
+			     drm_rect_height(&damage_area));
+
+	return ret;
+}
+
+static void drm_fbdev_fb_fillrect(struct fb_info *info,
+				  const struct fb_fillrect *rect)
+{
+	if (drm_fbdev_use_iomem(info))
+		drm_fb_helper_cfb_fillrect(info, rect);
+	else
+		drm_fb_helper_sys_fillrect(info, rect);
+}
+
+static void drm_fbdev_fb_copyarea(struct fb_info *info,
+				  const struct fb_copyarea *area)
+{
+	if (drm_fbdev_use_iomem(info))
+		drm_fb_helper_cfb_copyarea(info, area);
+	else
+		drm_fb_helper_sys_copyarea(info, area);
+}
+
+static void drm_fbdev_fb_imageblit(struct fb_info *info,
+				   const struct fb_image *image)
+{
+	if (drm_fbdev_use_iomem(info))
+		drm_fb_helper_cfb_imageblit(info, image);
+	else
+		drm_fb_helper_sys_imageblit(info, image);
+}
+
+static const struct fb_ops drm_fbdev_fb_ops = {
+	.owner		= THIS_MODULE,
+	DRM_FB_HELPER_DEFAULT_OPS,
+	.fb_open	= drm_fbdev_fb_open,
+	.fb_release	= drm_fbdev_fb_release,
+	.fb_destroy	= drm_fbdev_fb_destroy,
+	.fb_mmap	= drm_fbdev_fb_mmap,
+	.fb_read	= drm_fbdev_fb_read,
+	.fb_write	= drm_fbdev_fb_write,
+	.fb_fillrect	= drm_fbdev_fb_fillrect,
+	.fb_copyarea	= drm_fbdev_fb_copyarea,
+	.fb_imageblit	= drm_fbdev_fb_imageblit,
+};
+
+static struct fb_deferred_io drm_fbdev_defio = {
+	.delay		= HZ / 20,
+	.deferred_io	= drm_fb_helper_deferred_io,
+};
+
+/*
+ * This function uses the client API to create a framebuffer backed by a dumb buffer.
+ *
+ * The _sys_ versions are used for &fb_ops.fb_read, fb_write, fb_fillrect,
+ * fb_copyarea, fb_imageblit.
+ */
+static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
+				       struct drm_fb_helper_surface_size *sizes)
+{
+	struct drm_client_dev *client = &fb_helper->client;
+	struct drm_device *dev = fb_helper->dev;
+	struct drm_client_buffer *buffer;
+	struct drm_framebuffer *fb;
+	struct fb_info *fbi;
+	u32 format;
+	struct iosys_map map;
+	int ret;
+
+	drm_dbg_kms(dev, "surface width(%d), height(%d) and bpp(%d)\n",
+		    sizes->surface_width, sizes->surface_height,
+		    sizes->surface_bpp);
+
+	format = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth);
+	buffer = drm_client_framebuffer_create(client, sizes->surface_width,
+					       sizes->surface_height, format);
+	if (IS_ERR(buffer))
+		return PTR_ERR(buffer);
+
+	fb_helper->buffer = buffer;
+	fb_helper->fb = buffer->fb;
+	fb = buffer->fb;
+
+	fbi = drm_fb_helper_alloc_fbi(fb_helper);
+	if (IS_ERR(fbi))
+		return PTR_ERR(fbi);
+
+	fbi->fbops = &drm_fbdev_fb_ops;
+	fbi->screen_size = sizes->surface_height * fb->pitches[0];
+	fbi->fix.smem_len = fbi->screen_size;
+	fbi->flags = FBINFO_DEFAULT;
+
+	drm_fb_helper_fill_info(fbi, fb_helper, sizes);
+
+	if (drm_fbdev_use_shadow_fb(fb_helper)) {
+		fbi->screen_buffer = vzalloc(fbi->screen_size);
+		if (!fbi->screen_buffer)
+			return -ENOMEM;
+		fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
+
+		fbi->fbdefio = &drm_fbdev_defio;
+		fb_deferred_io_init(fbi);
+	} else {
+		/* buffer is mapped for HW framebuffer */
+		ret = drm_client_buffer_vmap(fb_helper->buffer, &map);
+		if (ret)
+			return ret;
+		if (map.is_iomem) {
+			fbi->screen_base = map.vaddr_iomem;
+		} else {
+			fbi->screen_buffer = map.vaddr;
+			fbi->flags |= FBINFO_VIRTFB;
+		}
+
+		/*
+		 * Shamelessly leak the physical address to user-space. As
+		 * page_to_phys() is undefined for I/O memory, warn in this
+		 * case.
+		 */
+#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
+		if (drm_leak_fbdev_smem && fbi->fix.smem_start == 0 &&
+		    !drm_WARN_ON_ONCE(dev, map.is_iomem))
+			fbi->fix.smem_start =
+				page_to_phys(virt_to_page(fbi->screen_buffer));
+#endif
+	}
+
+	return 0;
+}
+
+static const struct drm_fb_helper_funcs drm_fb_helper_generic_funcs = {
+	.fb_probe = drm_fb_helper_generic_probe,
+};
+
+static void drm_fbdev_client_unregister(struct drm_client_dev *client)
+{
+	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
+
+	if (fb_helper->fbdev)
+		/* drm_fbdev_fb_destroy() takes care of cleanup */
+		drm_fb_helper_unregister_fbi(fb_helper);
+	else
+		drm_fbdev_release(fb_helper);
+}
+
+static int drm_fbdev_client_restore(struct drm_client_dev *client)
+{
+	drm_fb_helper_lastclose(client->dev);
+
+	return 0;
+}
+
+static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
+{
+	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
+	struct drm_device *dev = client->dev;
+	int ret;
+
+	/* Setup is not retried if it has failed */
+	if (!fb_helper->dev && fb_helper->funcs)
+		return 0;
+
+	if (dev->fb_helper)
+		return drm_fb_helper_hotplug_event(dev->fb_helper);
+
+	if (!dev->mode_config.num_connector) {
+		drm_dbg_kms(dev, "No connectors found, will not create framebuffer!\n");
+		return 0;
+	}
+
+	drm_fb_helper_prepare(dev, fb_helper, &drm_fb_helper_generic_funcs);
+
+	ret = drm_fb_helper_init(dev, fb_helper);
+	if (ret)
+		goto err;
+
+	if (!drm_drv_uses_atomic_modeset(dev))
+		drm_helper_disable_unused_functions(dev);
+
+	ret = drm_fb_helper_initial_config(fb_helper, fb_helper->preferred_bpp);
+	if (ret)
+		goto err_cleanup;
+
+	return 0;
+
+err_cleanup:
+	drm_fbdev_cleanup(fb_helper);
+err:
+	fb_helper->dev = NULL;
+	fb_helper->fbdev = NULL;
+
+	drm_err(dev, "fbdev: Failed to setup generic emulation (ret=%d)\n", ret);
+
+	return ret;
+}
+
+static const struct drm_client_funcs drm_fbdev_client_funcs = {
+	.owner		= THIS_MODULE,
+	.unregister	= drm_fbdev_client_unregister,
+	.restore	= drm_fbdev_client_restore,
+	.hotplug	= drm_fbdev_client_hotplug,
+};
+
+/**
+ * drm_fbdev_generic_setup() - Setup generic fbdev emulation
+ * @dev: DRM device
+ * @preferred_bpp: Preferred bits per pixel for the device.
+ *                 @dev->mode_config.preferred_depth is used if this is zero.
+ *
+ * This function sets up generic fbdev emulation for drivers that supports
+ * dumb buffers with a virtual address and that can be mmap'ed.
+ * drm_fbdev_generic_setup() shall be called after the DRM driver registered
+ * the new DRM device with drm_dev_register().
+ *
+ * Restore, hotplug events and teardown are all taken care of. Drivers that do
+ * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves.
+ * Simple drivers might use drm_mode_config_helper_suspend().
+ *
+ * Drivers that set the dirty callback on their framebuffer will get a shadow
+ * fbdev buffer that is blitted onto the real buffer. This is done in order to
+ * make deferred I/O work with all kinds of buffers. A shadow buffer can be
+ * requested explicitly by setting struct drm_mode_config.prefer_shadow or
+ * struct drm_mode_config.prefer_shadow_fbdev to true beforehand. This is
+ * required to use generic fbdev emulation with SHMEM helpers.
+ *
+ * This function is safe to call even when there are no connectors present.
+ * Setup will be retried on the next hotplug event.
+ *
+ * The fbdev is destroyed by drm_dev_unregister().
+ */
+void drm_fbdev_generic_setup(struct drm_device *dev,
+			     unsigned int preferred_bpp)
+{
+	struct drm_fb_helper *fb_helper;
+	int ret;
+
+	drm_WARN(dev, !dev->registered, "Device has not been registered.\n");
+	drm_WARN(dev, dev->fb_helper, "fb_helper is already set!\n");
+
+	if (!drm_fbdev_emulation)
+		return;
+
+	fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
+	if (!fb_helper) {
+		drm_err(dev, "Failed to allocate fb_helper\n");
+		return;
+	}
+
+	ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_client_funcs);
+	if (ret) {
+		kfree(fb_helper);
+		drm_err(dev, "Failed to register client: %d\n", ret);
+		return;
+	}
+
+	/*
+	 * FIXME: This mixes up depth with bpp, which results in a glorious
+	 * mess, resulting in some drivers picking wrong fbdev defaults and
+	 * others wrong preferred_depth defaults.
+	 */
+	if (!preferred_bpp)
+		preferred_bpp = dev->mode_config.preferred_depth;
+	if (!preferred_bpp)
+		preferred_bpp = 32;
+	fb_helper->preferred_bpp = preferred_bpp;
+
+	drm_client_register(&fb_helper->client);
+}
+EXPORT_SYMBOL(drm_fbdev_generic_setup);