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 */
16static 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
27static 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
37FB_GEN_DEFAULT_DEFERRED_SYSMEM_OPS(drm_fbdev_generic,
38				   drm_fb_helper_damage_range,
39				   drm_fb_helper_damage_area);
40
41static 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
59static 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 */
71static 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
130err_drm_fb_helper_release_info:
131	drm_fb_helper_release_info(fb_helper);
132err_vfree:
133	vfree(screen_buffer);
134err_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
141static 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
180static 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
209out:
210	mutex_unlock(&fb_helper->lock);
211
212	return ret;
213}
214
215static 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
238static 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
243static 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
256static 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
263static 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
285err_drm_fb_helper_fini:
286	drm_fb_helper_fini(fb_helper);
287err_drm_err:
288	drm_err(dev, "fbdev: Failed to setup generic emulation (ret=%d)\n", ret);
289	return ret;
290}
291
292static 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 */
322void 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
345err_drm_client_init:
346	drm_fb_helper_unprepare(fb_helper);
347	kfree(fb_helper);
348	return;
349}
350EXPORT_SYMBOL(drm_fbdev_generic_setup);
351