drm_fbdev_shmem.c

  1// SPDX-License-Identifier: MIT
  2
  3#include <linux/export.h>
  4#include <linux/fb.h>
  5
  6#include <drm/drm_drv.h>
  7#include <drm/drm_fbdev_shmem.h>
  8#include <drm/drm_fb_helper.h>
  9#include <drm/drm_framebuffer.h>
 10#include <drm/drm_gem_framebuffer_helper.h>
 11#include <drm/drm_gem_shmem_helper.h>
 12#include <drm/drm_print.h>
 13
 14/*
 15 * struct fb_ops
 16 */
 17
 18static int drm_fbdev_shmem_fb_open(struct fb_info *info, int user)
 19{
 20	struct drm_fb_helper *fb_helper = info->par;
 21
 22	/* No need to take a ref for fbcon because it unbinds on unregister */
 23	if (user && !try_module_get(fb_helper->dev->driver->fops->owner))
 24		return -ENODEV;
 25
 26	return 0;
 27}
 28
 29static int drm_fbdev_shmem_fb_release(struct fb_info *info, int user)
 30{
 31	struct drm_fb_helper *fb_helper = info->par;
 32
 33	if (user)
 34		module_put(fb_helper->dev->driver->fops->owner);
 35
 36	return 0;
 37}
 38
 39FB_GEN_DEFAULT_DEFERRED_SYSMEM_OPS(drm_fbdev_shmem,
 40				   drm_fb_helper_damage_range,
 41				   drm_fb_helper_damage_area);
 42
 43static int drm_fbdev_shmem_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
 44{
 45	struct drm_fb_helper *fb_helper = info->par;
 46	struct drm_framebuffer *fb = fb_helper->fb;
 47	struct drm_gem_object *obj = drm_gem_fb_get_obj(fb, 0);
 48	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
 49
 50	if (shmem->map_wc)
 51		vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
 52
 53	return fb_deferred_io_mmap(info, vma);
 54}
 55
 56static void drm_fbdev_shmem_fb_destroy(struct fb_info *info)
 57{
 58	struct drm_fb_helper *fb_helper = info->par;
 59
 60	if (!fb_helper->dev)
 61		return;
 62
 63	fb_deferred_io_cleanup(info);
 64	drm_fb_helper_fini(fb_helper);
 65
 66	drm_client_buffer_vunmap(fb_helper->buffer);
 67	drm_client_buffer_delete(fb_helper->buffer);
 68	drm_client_release(&fb_helper->client);
 69}
 70
 71static const struct fb_ops drm_fbdev_shmem_fb_ops = {
 72	.owner = THIS_MODULE,
 73	.fb_open = drm_fbdev_shmem_fb_open,
 74	.fb_release = drm_fbdev_shmem_fb_release,
 75	__FB_DEFAULT_DEFERRED_OPS_RDWR(drm_fbdev_shmem),
 76	DRM_FB_HELPER_DEFAULT_OPS,
 77	__FB_DEFAULT_DEFERRED_OPS_DRAW(drm_fbdev_shmem),
 78	.fb_mmap = drm_fbdev_shmem_fb_mmap,
 79	.fb_destroy = drm_fbdev_shmem_fb_destroy,
 80};
 81
 82static struct page *drm_fbdev_shmem_get_page(struct fb_info *info, unsigned long offset)
 83{
 84	struct drm_fb_helper *fb_helper = info->par;
 85	struct drm_framebuffer *fb = fb_helper->fb;
 86	struct drm_gem_object *obj = drm_gem_fb_get_obj(fb, 0);
 87	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
 88	unsigned int i = offset >> PAGE_SHIFT;
 89	struct page *page;
 90
 91	if (fb_WARN_ON_ONCE(info, offset > obj->size))
 92		return NULL;
 93
 94	page = shmem->pages[i]; // protected by active vmap
 95	if (page)
 96		get_page(page);
 97	fb_WARN_ON_ONCE(info, !page);
 98
 99	return page;
100}
101
102/*
103 * struct drm_fb_helper
104 */
105
106static int drm_fbdev_shmem_helper_fb_dirty(struct drm_fb_helper *helper,
107					   struct drm_clip_rect *clip)
108{
109	struct drm_device *dev = helper->dev;
110	int ret;
111
112	/* Call damage handlers only if necessary */
113	if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
114		return 0;
115
116	if (helper->fb->funcs->dirty) {
117		ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1);
118		if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", ret))
119			return ret;
120	}
121
122	return 0;
123}
124
125static const struct drm_fb_helper_funcs drm_fbdev_shmem_helper_funcs = {
126	.fb_dirty = drm_fbdev_shmem_helper_fb_dirty,
127};
128
129/*
130 * struct drm_driver
131 */
132
133int drm_fbdev_shmem_driver_fbdev_probe(struct drm_fb_helper *fb_helper,
134				       struct drm_fb_helper_surface_size *sizes)
135{
136	struct drm_client_dev *client = &fb_helper->client;
137	struct drm_device *dev = fb_helper->dev;
138	struct fb_info *info = fb_helper->info;
139	struct drm_client_buffer *buffer;
140	struct drm_gem_shmem_object *shmem;
141	struct drm_framebuffer *fb;
142	u32 format;
143	struct iosys_map map;
144	int ret;
145
146	drm_dbg_kms(dev, "surface width(%d), height(%d) and bpp(%d)\n",
147		    sizes->surface_width, sizes->surface_height,
148		    sizes->surface_bpp);
149
150	format = drm_driver_legacy_fb_format(dev, sizes->surface_bpp, sizes->surface_depth);
151	buffer = drm_client_buffer_create_dumb(client, sizes->surface_width,
152					       sizes->surface_height, format);
153	if (IS_ERR(buffer))
154		return PTR_ERR(buffer);
155	shmem = to_drm_gem_shmem_obj(buffer->gem);
156
157	fb = buffer->fb;
158
159	ret = drm_client_buffer_vmap(buffer, &map);
160	if (ret) {
161		goto err_drm_client_buffer_delete;
162	} else if (drm_WARN_ON(dev, map.is_iomem)) {
163		ret = -ENODEV; /* I/O memory not supported; use generic emulation */
164		goto err_drm_client_buffer_delete;
165	}
166
167	fb_helper->funcs = &drm_fbdev_shmem_helper_funcs;
168	fb_helper->buffer = buffer;
169	fb_helper->fb = fb;
170
171	drm_fb_helper_fill_info(info, fb_helper, sizes);
172
173	info->fbops = &drm_fbdev_shmem_fb_ops;
174
175	/* screen */
176	info->flags |= FBINFO_VIRTFB; /* system memory */
177	if (!shmem->map_wc)
178		info->flags |= FBINFO_READS_FAST; /* signal caching */
179	info->screen_size = sizes->surface_height * fb->pitches[0];
180	info->screen_buffer = map.vaddr;
181	info->fix.smem_len = info->screen_size;
182
183	/* deferred I/O */
184	fb_helper->fbdefio.delay = HZ / 20;
185	fb_helper->fbdefio.get_page = drm_fbdev_shmem_get_page;
186	fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;
187
188	info->fbdefio = &fb_helper->fbdefio;
189	ret = fb_deferred_io_init(info);
190	if (ret)
191		goto err_drm_client_buffer_vunmap;
192
193	return 0;
194
195err_drm_client_buffer_vunmap:
196	fb_helper->fb = NULL;
197	fb_helper->buffer = NULL;
198	drm_client_buffer_vunmap(buffer);
199err_drm_client_buffer_delete:
200	drm_client_buffer_delete(buffer);
201	return ret;
202}
203EXPORT_SYMBOL(drm_fbdev_shmem_driver_fbdev_probe);