1 // SPDX-License-Identifier: MIT
2 
3 #include <linux/moduleparam.h>
4 #include <linux/vmalloc.h>
5 
6 #include <drm/drm_crtc_helper.h>
7 #include <drm/drm_drv.h>
8 #include <drm/drm_fb_helper.h>
9 #include <drm/drm_framebuffer.h>
10 #include <drm/drm_gem.h>
11 #include <drm/drm_print.h>
12 
13 #include <drm/drm_fbdev_generic.h>
14 
15 /* @user: 1=userspace, 0=fbcon */
16 static int drm_fbdev_generic_fb_open(struct fb_info *info, int user)
17 {
18 	struct drm_fb_helper *fb_helper = info->par;
19 
20 	/* No need to take a ref for fbcon because it unbinds on unregister */
21 	if (user && !try_module_get(fb_helper->dev->driver->fops->owner))
22 		return -ENODEV;
23 
24 	return 0;
25 }
26 
27 static int drm_fbdev_generic_fb_release(struct fb_info *info, int user)
28 {
29 	struct drm_fb_helper *fb_helper = info->par;
30 
31 	if (user)
32 		module_put(fb_helper->dev->driver->fops->owner);
33 
34 	return 0;
35 }
36 
37 FB_GEN_DEFAULT_DEFERRED_SYSMEM_OPS(drm_fbdev_generic,
38 				   drm_fb_helper_damage_range,
39 				   drm_fb_helper_damage_area);
40 
41 static void drm_fbdev_generic_fb_destroy(struct fb_info *info)
42 {
43 	struct drm_fb_helper *fb_helper = info->par;
44 	void *shadow = info->screen_buffer;
45 
46 	if (!fb_helper->dev)
47 		return;
48 
49 	fb_deferred_io_cleanup(info);
50 	drm_fb_helper_fini(fb_helper);
51 	vfree(shadow);
52 	drm_client_framebuffer_delete(fb_helper->buffer);
53 
54 	drm_client_release(&fb_helper->client);
55 	drm_fb_helper_unprepare(fb_helper);
56 	kfree(fb_helper);
57 }
58 
59 static const struct fb_ops drm_fbdev_generic_fb_ops = {
60 	.owner		= THIS_MODULE,
61 	.fb_open	= drm_fbdev_generic_fb_open,
62 	.fb_release	= drm_fbdev_generic_fb_release,
63 	FB_DEFAULT_DEFERRED_OPS(drm_fbdev_generic),
64 	DRM_FB_HELPER_DEFAULT_OPS,
65 	.fb_destroy	= drm_fbdev_generic_fb_destroy,
66 };
67 
68 /*
69  * This function uses the client API to create a framebuffer backed by a dumb buffer.
70  */
71 static int drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper,
72 					     struct drm_fb_helper_surface_size *sizes)
73 {
74 	struct drm_client_dev *client = &fb_helper->client;
75 	struct drm_device *dev = fb_helper->dev;
76 	struct drm_client_buffer *buffer;
77 	struct fb_info *info;
78 	size_t screen_size;
79 	void *screen_buffer;
80 	u32 format;
81 	int ret;
82 
83 	drm_dbg_kms(dev, "surface width(%d), height(%d) and bpp(%d)\n",
84 		    sizes->surface_width, sizes->surface_height,
85 		    sizes->surface_bpp);
86 
87 	format = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth);
88 	buffer = drm_client_framebuffer_create(client, sizes->surface_width,
89 					       sizes->surface_height, format);
90 	if (IS_ERR(buffer))
91 		return PTR_ERR(buffer);
92 
93 	fb_helper->buffer = buffer;
94 	fb_helper->fb = buffer->fb;
95 
96 	screen_size = buffer->gem->size;
97 	screen_buffer = vzalloc(screen_size);
98 	if (!screen_buffer) {
99 		ret = -ENOMEM;
100 		goto err_drm_client_framebuffer_delete;
101 	}
102 
103 	info = drm_fb_helper_alloc_info(fb_helper);
104 	if (IS_ERR(info)) {
105 		ret = PTR_ERR(info);
106 		goto err_vfree;
107 	}
108 
109 	drm_fb_helper_fill_info(info, fb_helper, sizes);
110 
111 	info->fbops = &drm_fbdev_generic_fb_ops;
112 
113 	/* screen */
114 	info->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
115 	info->screen_buffer = screen_buffer;
116 	info->fix.smem_start = page_to_phys(vmalloc_to_page(info->screen_buffer));
117 	info->fix.smem_len = screen_size;
118 
119 	/* deferred I/O */
120 	fb_helper->fbdefio.delay = HZ / 20;
121 	fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;
122 
123 	info->fbdefio = &fb_helper->fbdefio;
124 	ret = fb_deferred_io_init(info);
125 	if (ret)
126 		goto err_drm_fb_helper_release_info;
127 
128 	return 0;
129 
130 err_drm_fb_helper_release_info:
131 	drm_fb_helper_release_info(fb_helper);
132 err_vfree:
133 	vfree(screen_buffer);
134 err_drm_client_framebuffer_delete:
135 	fb_helper->fb = NULL;
136 	fb_helper->buffer = NULL;
137 	drm_client_framebuffer_delete(buffer);
138 	return ret;
139 }
140 
141 static void drm_fbdev_generic_damage_blit_real(struct drm_fb_helper *fb_helper,
142 					       struct drm_clip_rect *clip,
143 					       struct iosys_map *dst)
144 {
145 	struct drm_framebuffer *fb = fb_helper->fb;
146 	size_t offset = clip->y1 * fb->pitches[0];
147 	size_t len = clip->x2 - clip->x1;
148 	unsigned int y;
149 	void *src;
150 
151 	switch (drm_format_info_bpp(fb->format, 0)) {
152 	case 1:
153 		offset += clip->x1 / 8;
154 		len = DIV_ROUND_UP(len + clip->x1 % 8, 8);
155 		break;
156 	case 2:
157 		offset += clip->x1 / 4;
158 		len = DIV_ROUND_UP(len + clip->x1 % 4, 4);
159 		break;
160 	case 4:
161 		offset += clip->x1 / 2;
162 		len = DIV_ROUND_UP(len + clip->x1 % 2, 2);
163 		break;
164 	default:
165 		offset += clip->x1 * fb->format->cpp[0];
166 		len *= fb->format->cpp[0];
167 		break;
168 	}
169 
170 	src = fb_helper->info->screen_buffer + offset;
171 	iosys_map_incr(dst, offset); /* go to first pixel within clip rect */
172 
173 	for (y = clip->y1; y < clip->y2; y++) {
174 		iosys_map_memcpy_to(dst, 0, src, len);
175 		iosys_map_incr(dst, fb->pitches[0]);
176 		src += fb->pitches[0];
177 	}
178 }
179 
180 static int drm_fbdev_generic_damage_blit(struct drm_fb_helper *fb_helper,
181 					 struct drm_clip_rect *clip)
182 {
183 	struct drm_client_buffer *buffer = fb_helper->buffer;
184 	struct iosys_map map, dst;
185 	int ret;
186 
187 	/*
188 	 * We have to pin the client buffer to its current location while
189 	 * flushing the shadow buffer. In the general case, concurrent
190 	 * modesetting operations could try to move the buffer and would
191 	 * fail. The modeset has to be serialized by acquiring the reservation
192 	 * object of the underlying BO here.
193 	 *
194 	 * For fbdev emulation, we only have to protect against fbdev modeset
195 	 * operations. Nothing else will involve the client buffer's BO. So it
196 	 * is sufficient to acquire struct drm_fb_helper.lock here.
197 	 */
198 	mutex_lock(&fb_helper->lock);
199 
200 	ret = drm_client_buffer_vmap(buffer, &map);
201 	if (ret)
202 		goto out;
203 
204 	dst = map;
205 	drm_fbdev_generic_damage_blit_real(fb_helper, clip, &dst);
206 
207 	drm_client_buffer_vunmap(buffer);
208 
209 out:
210 	mutex_unlock(&fb_helper->lock);
211 
212 	return ret;
213 }
214 
215 static int drm_fbdev_generic_helper_fb_dirty(struct drm_fb_helper *helper,
216 					     struct drm_clip_rect *clip)
217 {
218 	struct drm_device *dev = helper->dev;
219 	int ret;
220 
221 	/* Call damage handlers only if necessary */
222 	if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
223 		return 0;
224 
225 	ret = drm_fbdev_generic_damage_blit(helper, clip);
226 	if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret))
227 		return ret;
228 
229 	if (helper->fb->funcs->dirty) {
230 		ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1);
231 		if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", ret))
232 			return ret;
233 	}
234 
235 	return 0;
236 }
237 
238 static const struct drm_fb_helper_funcs drm_fbdev_generic_helper_funcs = {
239 	.fb_probe = drm_fbdev_generic_helper_fb_probe,
240 	.fb_dirty = drm_fbdev_generic_helper_fb_dirty,
241 };
242 
243 static void drm_fbdev_generic_client_unregister(struct drm_client_dev *client)
244 {
245 	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
246 
247 	if (fb_helper->info) {
248 		drm_fb_helper_unregister_info(fb_helper);
249 	} else {
250 		drm_client_release(&fb_helper->client);
251 		drm_fb_helper_unprepare(fb_helper);
252 		kfree(fb_helper);
253 	}
254 }
255 
256 static int drm_fbdev_generic_client_restore(struct drm_client_dev *client)
257 {
258 	drm_fb_helper_lastclose(client->dev);
259 
260 	return 0;
261 }
262 
263 static int drm_fbdev_generic_client_hotplug(struct drm_client_dev *client)
264 {
265 	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
266 	struct drm_device *dev = client->dev;
267 	int ret;
268 
269 	if (dev->fb_helper)
270 		return drm_fb_helper_hotplug_event(dev->fb_helper);
271 
272 	ret = drm_fb_helper_init(dev, fb_helper);
273 	if (ret)
274 		goto err_drm_err;
275 
276 	if (!drm_drv_uses_atomic_modeset(dev))
277 		drm_helper_disable_unused_functions(dev);
278 
279 	ret = drm_fb_helper_initial_config(fb_helper);
280 	if (ret)
281 		goto err_drm_fb_helper_fini;
282 
283 	return 0;
284 
285 err_drm_fb_helper_fini:
286 	drm_fb_helper_fini(fb_helper);
287 err_drm_err:
288 	drm_err(dev, "fbdev: Failed to setup generic emulation (ret=%d)\n", ret);
289 	return ret;
290 }
291 
292 static const struct drm_client_funcs drm_fbdev_generic_client_funcs = {
293 	.owner		= THIS_MODULE,
294 	.unregister	= drm_fbdev_generic_client_unregister,
295 	.restore	= drm_fbdev_generic_client_restore,
296 	.hotplug	= drm_fbdev_generic_client_hotplug,
297 };
298 
299 /**
300  * drm_fbdev_generic_setup() - Setup generic fbdev emulation
301  * @dev: DRM device
302  * @preferred_bpp: Preferred bits per pixel for the device.
303  *
304  * This function sets up generic fbdev emulation for drivers that supports
305  * dumb buffers with a virtual address and that can be mmap'ed.
306  * drm_fbdev_generic_setup() shall be called after the DRM driver registered
307  * the new DRM device with drm_dev_register().
308  *
309  * Restore, hotplug events and teardown are all taken care of. Drivers that do
310  * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves.
311  * Simple drivers might use drm_mode_config_helper_suspend().
312  *
313  * In order to provide fixed mmap-able memory ranges, generic fbdev emulation
314  * uses a shadow buffer in system memory. The implementation blits the shadow
315  * fbdev buffer onto the real buffer in regular intervals.
316  *
317  * This function is safe to call even when there are no connectors present.
318  * Setup will be retried on the next hotplug event.
319  *
320  * The fbdev is destroyed by drm_dev_unregister().
321  */
322 void drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)
323 {
324 	struct drm_fb_helper *fb_helper;
325 	int ret;
326 
327 	drm_WARN(dev, !dev->registered, "Device has not been registered.\n");
328 	drm_WARN(dev, dev->fb_helper, "fb_helper is already set!\n");
329 
330 	fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
331 	if (!fb_helper)
332 		return;
333 	drm_fb_helper_prepare(dev, fb_helper, preferred_bpp, &drm_fbdev_generic_helper_funcs);
334 
335 	ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_generic_client_funcs);
336 	if (ret) {
337 		drm_err(dev, "Failed to register client: %d\n", ret);
338 		goto err_drm_client_init;
339 	}
340 
341 	drm_client_register(&fb_helper->client);
342 
343 	return;
344 
345 err_drm_client_init:
346 	drm_fb_helper_unprepare(fb_helper);
347 	kfree(fb_helper);
348 	return;
349 }
350 EXPORT_SYMBOL(drm_fbdev_generic_setup);
351