1// SPDX-License-Identifier: GPL-2.0+
2
3#include <linux/crc32.h>
4
5#include <drm/drm_atomic.h>
6#include <drm/drm_atomic_helper.h>
7#include <drm/drm_gem_framebuffer_helper.h>
8#include <drm/drm_vblank.h>
9
10#include "vkms_drv.h"
11
12static u32 get_pixel_from_buffer(int x, int y, const u8 *buffer,
13				 const struct vkms_composer *composer)
14{
15	u32 pixel;
16	int src_offset = composer->offset + (y * composer->pitch)
17				      + (x * composer->cpp);
18
19	pixel = *(u32 *)&buffer[src_offset];
20
21	return pixel;
22}
23
24/**
25 * compute_crc - Compute CRC value on output frame
26 *
27 * @vaddr: address to final framebuffer
28 * @composer: framebuffer's metadata
29 *
30 * returns CRC value computed using crc32 on the visible portion of
31 * the final framebuffer at vaddr_out
32 */
33static uint32_t compute_crc(const u8 *vaddr,
34			    const struct vkms_composer *composer)
35{
36	int x, y;
37	u32 crc = 0, pixel = 0;
38	int x_src = composer->src.x1 >> 16;
39	int y_src = composer->src.y1 >> 16;
40	int h_src = drm_rect_height(&composer->src) >> 16;
41	int w_src = drm_rect_width(&composer->src) >> 16;
42
43	for (y = y_src; y < y_src + h_src; ++y) {
44		for (x = x_src; x < x_src + w_src; ++x) {
45			pixel = get_pixel_from_buffer(x, y, vaddr, composer);
46			crc = crc32_le(crc, (void *)&pixel, sizeof(u32));
47		}
48	}
49
50	return crc;
51}
52
53static u8 blend_channel(u8 src, u8 dst, u8 alpha)
54{
55	u32 pre_blend;
56	u8 new_color;
57
58	pre_blend = (src * 255 + dst * (255 - alpha));
59
60	/* Faster div by 255 */
61	new_color = ((pre_blend + ((pre_blend + 257) >> 8)) >> 8);
62
63	return new_color;
64}
65
66static void alpha_blending(const u8 *argb_src, u8 *argb_dst)
67{
68	u8 alpha;
69
70	alpha = argb_src[3];
71	argb_dst[0] = blend_channel(argb_src[0], argb_dst[0], alpha);
72	argb_dst[1] = blend_channel(argb_src[1], argb_dst[1], alpha);
73	argb_dst[2] = blend_channel(argb_src[2], argb_dst[2], alpha);
74	/* Opaque primary */
75	argb_dst[3] = 0xFF;
76}
77
78/**
79 * blend - blend value at vaddr_src with value at vaddr_dst
80 * @vaddr_dst: destination address
81 * @vaddr_src: source address
82 * @dst_composer: destination framebuffer's metadata
83 * @src_composer: source framebuffer's metadata
84 *
85 * Blend the vaddr_src value with the vaddr_dst value using the pre-multiplied
86 * alpha blending equation, since DRM currently assumes that the pixel color
87 * values have already been pre-multiplied with the alpha channel values. See
88 * more drm_plane_create_blend_mode_property(). This function uses buffer's
89 * metadata to locate the new composite values at vaddr_dst.
90 */
91static void blend(void *vaddr_dst, void *vaddr_src,
92		  struct vkms_composer *dst_composer,
93		  struct vkms_composer *src_composer)
94{
95	int i, j, j_dst, i_dst;
96	int offset_src, offset_dst;
97	u8 *pixel_dst, *pixel_src;
98
99	int x_src = src_composer->src.x1 >> 16;
100	int y_src = src_composer->src.y1 >> 16;
101
102	int x_dst = src_composer->dst.x1;
103	int y_dst = src_composer->dst.y1;
104	int h_dst = drm_rect_height(&src_composer->dst);
105	int w_dst = drm_rect_width(&src_composer->dst);
106
107	int y_limit = y_src + h_dst;
108	int x_limit = x_src + w_dst;
109
110	for (i = y_src, i_dst = y_dst; i < y_limit; ++i) {
111		for (j = x_src, j_dst = x_dst; j < x_limit; ++j) {
112			offset_dst = dst_composer->offset
113				     + (i_dst * dst_composer->pitch)
114				     + (j_dst++ * dst_composer->cpp);
115			offset_src = src_composer->offset
116				     + (i * src_composer->pitch)
117				     + (j * src_composer->cpp);
118
119			pixel_src = (u8 *)(vaddr_src + offset_src);
120			pixel_dst = (u8 *)(vaddr_dst + offset_dst);
121			alpha_blending(pixel_src, pixel_dst);
122		}
123		i_dst++;
124	}
125}
126
127static void compose_cursor(struct vkms_composer *cursor_composer,
128			   struct vkms_composer *primary_composer,
129			   void *vaddr_out)
130{
131	struct drm_gem_object *cursor_obj;
132	struct vkms_gem_object *cursor_vkms_obj;
133
134	cursor_obj = drm_gem_fb_get_obj(&cursor_composer->fb, 0);
135	cursor_vkms_obj = drm_gem_to_vkms_gem(cursor_obj);
136
137	if (WARN_ON(!cursor_vkms_obj->vaddr))
138		return;
139
140	blend(vaddr_out, cursor_vkms_obj->vaddr,
141	      primary_composer, cursor_composer);
142}
143
144static int compose_planes(void **vaddr_out,
145			  struct vkms_composer *primary_composer,
146			  struct vkms_composer *cursor_composer)
147{
148	struct drm_framebuffer *fb = &primary_composer->fb;
149	struct drm_gem_object *gem_obj = drm_gem_fb_get_obj(fb, 0);
150	struct vkms_gem_object *vkms_obj = drm_gem_to_vkms_gem(gem_obj);
151
152	if (!*vaddr_out) {
153		*vaddr_out = kzalloc(vkms_obj->gem.size, GFP_KERNEL);
154		if (!*vaddr_out) {
155			DRM_ERROR("Cannot allocate memory for output frame.");
156			return -ENOMEM;
157		}
158	}
159
160	if (WARN_ON(!vkms_obj->vaddr))
161		return -EINVAL;
162
163	memcpy(*vaddr_out, vkms_obj->vaddr, vkms_obj->gem.size);
164
165	if (cursor_composer)
166		compose_cursor(cursor_composer, primary_composer, *vaddr_out);
167
168	return 0;
169}
170
171/**
172 * vkms_composer_worker - ordered work_struct to compute CRC
173 *
174 * @work: work_struct
175 *
176 * Work handler for composing and computing CRCs. work_struct scheduled in
177 * an ordered workqueue that's periodically scheduled to run by
178 * _vblank_handle() and flushed at vkms_atomic_crtc_destroy_state().
179 */
180void vkms_composer_worker(struct work_struct *work)
181{
182	struct vkms_crtc_state *crtc_state = container_of(work,
183						struct vkms_crtc_state,
184						composer_work);
185	struct drm_crtc *crtc = crtc_state->base.crtc;
186	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
187	struct vkms_composer *primary_composer = NULL;
188	struct vkms_composer *cursor_composer = NULL;
189	bool crc_pending, wb_pending;
190	void *vaddr_out = NULL;
191	u32 crc32 = 0;
192	u64 frame_start, frame_end;
193	int ret;
194
195	spin_lock_irq(&out->composer_lock);
196	frame_start = crtc_state->frame_start;
197	frame_end = crtc_state->frame_end;
198	crc_pending = crtc_state->crc_pending;
199	wb_pending = crtc_state->wb_pending;
200	crtc_state->frame_start = 0;
201	crtc_state->frame_end = 0;
202	crtc_state->crc_pending = false;
203	spin_unlock_irq(&out->composer_lock);
204
205	/*
206	 * We raced with the vblank hrtimer and previous work already computed
207	 * the crc, nothing to do.
208	 */
209	if (!crc_pending)
210		return;
211
212	if (crtc_state->num_active_planes >= 1)
213		primary_composer = crtc_state->active_planes[0]->composer;
214
215	if (crtc_state->num_active_planes == 2)
216		cursor_composer = crtc_state->active_planes[1]->composer;
217
218	if (!primary_composer)
219		return;
220
221	if (wb_pending)
222		vaddr_out = crtc_state->active_writeback;
223
224	ret = compose_planes(&vaddr_out, primary_composer, cursor_composer);
225	if (ret) {
226		if (ret == -EINVAL && !wb_pending)
227			kfree(vaddr_out);
228		return;
229	}
230
231	crc32 = compute_crc(vaddr_out, primary_composer);
232
233	if (wb_pending) {
234		drm_writeback_signal_completion(&out->wb_connector, 0);
235		spin_lock_irq(&out->composer_lock);
236		crtc_state->wb_pending = false;
237		spin_unlock_irq(&out->composer_lock);
238	} else {
239		kfree(vaddr_out);
240	}
241
242	/*
243	 * The worker can fall behind the vblank hrtimer, make sure we catch up.
244	 */
245	while (frame_start <= frame_end)
246		drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);
247}
248
249static const char * const pipe_crc_sources[] = {"auto"};
250
251const char *const *vkms_get_crc_sources(struct drm_crtc *crtc,
252					size_t *count)
253{
254	*count = ARRAY_SIZE(pipe_crc_sources);
255	return pipe_crc_sources;
256}
257
258static int vkms_crc_parse_source(const char *src_name, bool *enabled)
259{
260	int ret = 0;
261
262	if (!src_name) {
263		*enabled = false;
264	} else if (strcmp(src_name, "auto") == 0) {
265		*enabled = true;
266	} else {
267		*enabled = false;
268		ret = -EINVAL;
269	}
270
271	return ret;
272}
273
274int vkms_verify_crc_source(struct drm_crtc *crtc, const char *src_name,
275			   size_t *values_cnt)
276{
277	bool enabled;
278
279	if (vkms_crc_parse_source(src_name, &enabled) < 0) {
280		DRM_DEBUG_DRIVER("unknown source %s\n", src_name);
281		return -EINVAL;
282	}
283
284	*values_cnt = 1;
285
286	return 0;
287}
288
289void vkms_set_composer(struct vkms_output *out, bool enabled)
290{
291	bool old_enabled;
292
293	if (enabled)
294		drm_crtc_vblank_get(&out->crtc);
295
296	spin_lock_irq(&out->lock);
297	old_enabled = out->composer_enabled;
298	out->composer_enabled = enabled;
299	spin_unlock_irq(&out->lock);
300
301	if (old_enabled)
302		drm_crtc_vblank_put(&out->crtc);
303}
304
305int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name)
306{
307	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
308	bool enabled = false;
309	int ret = 0;
310
311	ret = vkms_crc_parse_source(src_name, &enabled);
312
313	vkms_set_composer(out, enabled);
314
315	return ret;
316}
317