drivers/gpu/drm/drm_fbdev_generic.c - linux - Git at Google

 // SPDX-License-Identifier: MIT

 #include <linux/moduleparam.h>
 #include <linux/vmalloc.h>

 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_print.h>

 #include <drm/drm_fbdev_generic.h>

 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;
 }

 /* @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_fb_destroy(struct fb_info *info)
 {
 	struct drm_fb_helper *fb_helper = info->par;
 	void *shadow = NULL;

 	if (!fb_helper->dev)
 		return;

 	if (info->fbdefio)
 		fb_deferred_io_cleanup(info);
 	if (drm_fbdev_use_shadow_fb(fb_helper))
 		shadow = info->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);
 	drm_client_release(&fb_helper->client);

 	drm_fb_helper_unprepare(fb_helper);
 	kfree(fb_helper);
 }

 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 drm_fbdev_fb_read(struct fb_info *info, char __user *buf,
 				 size_t count, loff_t *ppos)
 {
 	ssize_t ret;

 	if (drm_fbdev_use_iomem(info))
 		ret = drm_fb_helper_cfb_read(info, buf, count, ppos);
 	else
 		ret = drm_fb_helper_sys_read(info, buf, count, ppos);

 	return ret;
 }

 static ssize_t drm_fbdev_fb_write(struct fb_info *info, const char __user *buf,
 				  size_t count, loff_t *ppos)
 {
 	ssize_t ret;

 	if (drm_fbdev_use_iomem(info))
 		ret = drm_fb_helper_cfb_write(info, buf, count, ppos);
 	else
 		ret = drm_fb_helper_sys_write(info, buf, count, ppos);

 	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,
 };

 /*
  * This function uses the client API to create a framebuffer backed by a dumb buffer.
  */
 static int drm_fbdev_fb_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 *info;
 	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;

 	info = drm_fb_helper_alloc_info(fb_helper);
 	if (IS_ERR(info))
 		return PTR_ERR(info);

 	info->fbops = &drm_fbdev_fb_ops;
 	info->screen_size = sizes->surface_height * fb->pitches[0];
 	info->fix.smem_len = info->screen_size;
 	info->flags = FBINFO_DEFAULT;

 	drm_fb_helper_fill_info(info, fb_helper, sizes);

 	if (drm_fbdev_use_shadow_fb(fb_helper)) {
 		info->screen_buffer = vzalloc(info->screen_size);
 		if (!info->screen_buffer)
 			return -ENOMEM;
 		info->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;

 		/* Set a default deferred I/O handler */
 		fb_helper->fbdefio.delay = HZ / 20;
 		fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;

 		info->fbdefio = &fb_helper->fbdefio;
 		ret = fb_deferred_io_init(info);
 		if (ret)
 			return ret;
 	} else {
 		/* buffer is mapped for HW framebuffer */
 		ret = drm_client_buffer_vmap(fb_helper->buffer, &map);
 		if (ret)
 			return ret;
 		if (map.is_iomem) {
 			info->screen_base = map.vaddr_iomem;
 		} else {
 			info->screen_buffer = map.vaddr;
 			info->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 (fb_helper->hint_leak_smem_start && info->fix.smem_start == 0 &&
 		    !drm_WARN_ON_ONCE(dev, map.is_iomem))
 			info->fix.smem_start =
 				page_to_phys(virt_to_page(info->screen_buffer));
 #endif
 	}

 	return 0;
 }

 static void drm_fbdev_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->info->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_fbdev_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_fbdev_damage_blit_real(fb_helper, clip, &dst);

 	drm_client_buffer_vunmap(buffer);

 out:
 	mutex_unlock(&fb_helper->lock);

 	return ret;
 }

 static int drm_fbdev_fb_dirty(struct drm_fb_helper *helper, struct drm_clip_rect *clip)
 {
 	struct drm_device *dev = helper->dev;
 	int ret;

 	if (!drm_fbdev_use_shadow_fb(helper))
 		return 0;

 	/* Call damage handlers only if necessary */
 	if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
 		return 0;

 	if (helper->buffer) {
 		ret = drm_fbdev_damage_blit(helper, clip);
 		if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret))
 			return ret;
 	}

 	if (helper->fb->funcs->dirty) {
 		ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1);
 		if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", ret))
 			return ret;
 	}

 	return 0;
 }

 static const struct drm_fb_helper_funcs drm_fb_helper_generic_funcs = {
 	.fb_probe = drm_fbdev_fb_probe,
 	.fb_dirty = drm_fbdev_fb_dirty,
 };

 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->info) {
 		drm_fb_helper_unregister_info(fb_helper);
 	} else {
 		drm_client_release(&fb_helper->client);
 		drm_fb_helper_unprepare(fb_helper);
 		kfree(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;

 	if (dev->fb_helper)
 		return drm_fb_helper_hotplug_event(dev->fb_helper);

 	ret = drm_fb_helper_init(dev, fb_helper);
 	if (ret)
 		goto err_drm_err;

 	if (!drm_drv_uses_atomic_modeset(dev))
 		drm_helper_disable_unused_functions(dev);

 	ret = drm_fb_helper_initial_config(fb_helper);
 	if (ret)
 		goto err_drm_fb_helper_fini;

 	return 0;

 err_drm_fb_helper_fini:
 	drm_fb_helper_fini(fb_helper);
 err_drm_err:
 	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.
  *
  * 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");

 	fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
 	if (!fb_helper)
 		return;
 	drm_fb_helper_prepare(dev, fb_helper, preferred_bpp, &drm_fb_helper_generic_funcs);

 	ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_client_funcs);
 	if (ret) {
 		drm_err(dev, "Failed to register client: %d\n", ret);
 		goto err_drm_client_init;
 	}

 	ret = drm_fbdev_client_hotplug(&fb_helper->client);
 	if (ret)
 		drm_dbg_kms(dev, "client hotplug ret=%d\n", ret);

 	drm_client_register(&fb_helper->client);

 	return;

 err_drm_client_init:
 	drm_fb_helper_unprepare(fb_helper);
 	kfree(fb_helper);
 	return;
 }
 EXPORT_SYMBOL(drm_fbdev_generic_setup);
	// SPDX-License-Identifier: MIT

	#include <linux/moduleparam.h>
	#include <linux/vmalloc.h>

	#include <drm/drm_crtc_helper.h>
	#include <drm/drm_drv.h>
	#include <drm/drm_fb_helper.h>
	#include <drm/drm_framebuffer.h>
	#include <drm/drm_print.h>

	#include <drm/drm_fbdev_generic.h>

	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;
	}

	/* @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_fb_destroy(struct fb_info *info)
	{
	struct drm_fb_helper *fb_helper = info->par;
	void *shadow = NULL;

	if (!fb_helper->dev)
	return;

	if (info->fbdefio)
	fb_deferred_io_cleanup(info);
	if (drm_fbdev_use_shadow_fb(fb_helper))
	shadow = info->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);
	drm_client_release(&fb_helper->client);

	drm_fb_helper_unprepare(fb_helper);
	kfree(fb_helper);
	}

	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 drm_fbdev_fb_read(struct fb_info info, char __user buf,
	size_t count, loff_t *ppos)
	{
	ssize_t ret;

	if (drm_fbdev_use_iomem(info))
	ret = drm_fb_helper_cfb_read(info, buf, count, ppos);
	else
	ret = drm_fb_helper_sys_read(info, buf, count, ppos);

	return ret;
	}

	static ssize_t drm_fbdev_fb_write(struct fb_info info, const char __user buf,
	size_t count, loff_t *ppos)
	{
	ssize_t ret;

	if (drm_fbdev_use_iomem(info))
	ret = drm_fb_helper_cfb_write(info, buf, count, ppos);
	else
	ret = drm_fb_helper_sys_write(info, buf, count, ppos);

	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,
	};

	/*
	* This function uses the client API to create a framebuffer backed by a dumb buffer.
	*/
	static int drm_fbdev_fb_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 *info;
	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;

	info = drm_fb_helper_alloc_info(fb_helper);
	if (IS_ERR(info))
	return PTR_ERR(info);

	info->fbops = &drm_fbdev_fb_ops;
	info->screen_size = sizes->surface_height * fb->pitches[0];
	info->fix.smem_len = info->screen_size;
	info->flags = FBINFO_DEFAULT;

	drm_fb_helper_fill_info(info, fb_helper, sizes);

	if (drm_fbdev_use_shadow_fb(fb_helper)) {
	info->screen_buffer = vzalloc(info->screen_size);
	if (!info->screen_buffer)
	return -ENOMEM;
	info->flags \|= FBINFO_VIRTFB \| FBINFO_READS_FAST;

	/* Set a default deferred I/O handler */
	fb_helper->fbdefio.delay = HZ / 20;
	fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;

	info->fbdefio = &fb_helper->fbdefio;
	ret = fb_deferred_io_init(info);
	if (ret)
	return ret;
	} else {
	/* buffer is mapped for HW framebuffer */
	ret = drm_client_buffer_vmap(fb_helper->buffer, &map);
	if (ret)
	return ret;
	if (map.is_iomem) {
	info->screen_base = map.vaddr_iomem;
	} else {
	info->screen_buffer = map.vaddr;
	info->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 (fb_helper->hint_leak_smem_start && info->fix.smem_start == 0 &&
	!drm_WARN_ON_ONCE(dev, map.is_iomem))
	info->fix.smem_start =
	page_to_phys(virt_to_page(info->screen_buffer));
	#endif
	}

	return 0;
	}

	static void drm_fbdev_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->info->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_fbdev_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_fbdev_damage_blit_real(fb_helper, clip, &dst);

	drm_client_buffer_vunmap(buffer);

	out:
	mutex_unlock(&fb_helper->lock);

	return ret;
	}

	static int drm_fbdev_fb_dirty(struct drm_fb_helper helper, struct drm_clip_rect clip)
	{
	struct drm_device *dev = helper->dev;
	int ret;

	if (!drm_fbdev_use_shadow_fb(helper))
	return 0;

	/* Call damage handlers only if necessary */
	if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
	return 0;

	if (helper->buffer) {
	ret = drm_fbdev_damage_blit(helper, clip);
	if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret))
	return ret;
	}

	if (helper->fb->funcs->dirty) {
	ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1);
	if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", ret))
	return ret;
	}

	return 0;
	}

	static const struct drm_fb_helper_funcs drm_fb_helper_generic_funcs = {
	.fb_probe = drm_fbdev_fb_probe,
	.fb_dirty = drm_fbdev_fb_dirty,
	};

	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->info) {
	drm_fb_helper_unregister_info(fb_helper);
	} else {
	drm_client_release(&fb_helper->client);
	drm_fb_helper_unprepare(fb_helper);
	kfree(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;

	if (dev->fb_helper)
	return drm_fb_helper_hotplug_event(dev->fb_helper);

	ret = drm_fb_helper_init(dev, fb_helper);
	if (ret)
	goto err_drm_err;

	if (!drm_drv_uses_atomic_modeset(dev))
	drm_helper_disable_unused_functions(dev);

	ret = drm_fb_helper_initial_config(fb_helper);
	if (ret)
	goto err_drm_fb_helper_fini;

	return 0;

	err_drm_fb_helper_fini:
	drm_fb_helper_fini(fb_helper);
	err_drm_err:
	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.
	*
	* 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");

	fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
	if (!fb_helper)
	return;
	drm_fb_helper_prepare(dev, fb_helper, preferred_bpp, &drm_fb_helper_generic_funcs);

	ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_client_funcs);
	if (ret) {
	drm_err(dev, "Failed to register client: %d\n", ret);
	goto err_drm_client_init;
	}

	ret = drm_fbdev_client_hotplug(&fb_helper->client);
	if (ret)
	drm_dbg_kms(dev, "client hotplug ret=%d\n", ret);

	drm_client_register(&fb_helper->client);

	return;

	err_drm_client_init:
	drm_fb_helper_unprepare(fb_helper);
	kfree(fb_helper);
	return;
	}
	EXPORT_SYMBOL(drm_fbdev_generic_setup);