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_blend.h>
8#include <drm/drm_fourcc.h>
9#include <drm/drm_fixed.h>
10#include <drm/drm_gem_framebuffer_helper.h>
11#include <drm/drm_vblank.h>
12#include <linux/minmax.h>
13
14#include "vkms_drv.h"
15
16static u16 pre_mul_blend_channel(u16 src, u16 dst, u16 alpha)
17{
18	u32 new_color;
19
20	new_color = (src * 0xffff + dst * (0xffff - alpha));
21
22	return DIV_ROUND_CLOSEST(new_color, 0xffff);
23}
24
25/**
26 * pre_mul_alpha_blend - alpha blending equation
27 * @frame_info: Source framebuffer's metadata
28 * @stage_buffer: The line with the pixels from src_plane
29 * @output_buffer: A line buffer that receives all the blends output
30 *
31 * Using the information from the `frame_info`, this blends only the
32 * necessary pixels from the `stage_buffer` to the `output_buffer`
33 * using premultiplied blend formula.
34 *
35 * The current DRM assumption is that pixel color values have been already
36 * pre-multiplied with the alpha channel values. See more
37 * drm_plane_create_blend_mode_property(). Also, this formula assumes a
38 * completely opaque background.
39 */
40static void pre_mul_alpha_blend(struct vkms_frame_info *frame_info,
41				struct line_buffer *stage_buffer,
42				struct line_buffer *output_buffer)
43{
44	int x_dst = frame_info->dst.x1;
45	struct pixel_argb_u16 *out = output_buffer->pixels + x_dst;
46	struct pixel_argb_u16 *in = stage_buffer->pixels;
47	int x_limit = min_t(size_t, drm_rect_width(&frame_info->dst),
48			    stage_buffer->n_pixels);
49
50	for (int x = 0; x < x_limit; x++) {
51		out[x].a = (u16)0xffff;
52		out[x].r = pre_mul_blend_channel(in[x].r, out[x].r, in[x].a);
53		out[x].g = pre_mul_blend_channel(in[x].g, out[x].g, in[x].a);
54		out[x].b = pre_mul_blend_channel(in[x].b, out[x].b, in[x].a);
55	}
56}
57
58static int get_y_pos(struct vkms_frame_info *frame_info, int y)
59{
60	if (frame_info->rotation & DRM_MODE_REFLECT_Y)
61		return drm_rect_height(&frame_info->rotated) - y - 1;
62
63	switch (frame_info->rotation & DRM_MODE_ROTATE_MASK) {
64	case DRM_MODE_ROTATE_90:
65		return frame_info->rotated.x2 - y - 1;
66	case DRM_MODE_ROTATE_270:
67		return y + frame_info->rotated.x1;
68	default:
69		return y;
70	}
71}
72
73static bool check_limit(struct vkms_frame_info *frame_info, int pos)
74{
75	if (drm_rotation_90_or_270(frame_info->rotation)) {
76		if (pos >= 0 && pos < drm_rect_width(&frame_info->rotated))
77			return true;
78	} else {
79		if (pos >= frame_info->rotated.y1 && pos < frame_info->rotated.y2)
80			return true;
81	}
82
83	return false;
84}
85
86static void fill_background(const struct pixel_argb_u16 *background_color,
87			    struct line_buffer *output_buffer)
88{
89	for (size_t i = 0; i < output_buffer->n_pixels; i++)
90		output_buffer->pixels[i] = *background_color;
91}
92
93// lerp(a, b, t) = a + (b - a) * t
94static u16 lerp_u16(u16 a, u16 b, s64 t)
95{
96	s64 a_fp = drm_int2fixp(a);
97	s64 b_fp = drm_int2fixp(b);
98
99	s64 delta = drm_fixp_mul(b_fp - a_fp,  t);
100
101	return drm_fixp2int(a_fp + delta);
102}
103
104static s64 get_lut_index(const struct vkms_color_lut *lut, u16 channel_value)
105{
106	s64 color_channel_fp = drm_int2fixp(channel_value);
107
108	return drm_fixp_mul(color_channel_fp, lut->channel_value2index_ratio);
109}
110
111/*
112 * This enum is related to the positions of the variables inside
113 * `struct drm_color_lut`, so the order of both needs to be the same.
114 */
115enum lut_channel {
116	LUT_RED = 0,
117	LUT_GREEN,
118	LUT_BLUE,
119	LUT_RESERVED
120};
121
122static u16 apply_lut_to_channel_value(const struct vkms_color_lut *lut, u16 channel_value,
123				      enum lut_channel channel)
124{
125	s64 lut_index = get_lut_index(lut, channel_value);
126	u16 *floor_lut_value, *ceil_lut_value;
127	u16 floor_channel_value, ceil_channel_value;
128
129	/*
130	 * This checks if `struct drm_color_lut` has any gap added by the compiler
131	 * between the struct fields.
132	 */
133	static_assert(sizeof(struct drm_color_lut) == sizeof(__u16) * 4);
134
135	floor_lut_value = (__u16 *)&lut->base[drm_fixp2int(lut_index)];
136	if (drm_fixp2int(lut_index) == (lut->lut_length - 1))
137		/* We're at the end of the LUT array, use same value for ceil and floor */
138		ceil_lut_value = floor_lut_value;
139	else
140		ceil_lut_value = (__u16 *)&lut->base[drm_fixp2int_ceil(lut_index)];
141
142	floor_channel_value = floor_lut_value[channel];
143	ceil_channel_value = ceil_lut_value[channel];
144
145	return lerp_u16(floor_channel_value, ceil_channel_value,
146			lut_index & DRM_FIXED_DECIMAL_MASK);
147}
148
149static void apply_lut(const struct vkms_crtc_state *crtc_state, struct line_buffer *output_buffer)
150{
151	if (!crtc_state->gamma_lut.base)
152		return;
153
154	if (!crtc_state->gamma_lut.lut_length)
155		return;
156
157	for (size_t x = 0; x < output_buffer->n_pixels; x++) {
158		struct pixel_argb_u16 *pixel = &output_buffer->pixels[x];
159
160		pixel->r = apply_lut_to_channel_value(&crtc_state->gamma_lut, pixel->r, LUT_RED);
161		pixel->g = apply_lut_to_channel_value(&crtc_state->gamma_lut, pixel->g, LUT_GREEN);
162		pixel->b = apply_lut_to_channel_value(&crtc_state->gamma_lut, pixel->b, LUT_BLUE);
163	}
164}
165
166/**
167 * blend - blend the pixels from all planes and compute crc
168 * @wb: The writeback frame buffer metadata
169 * @crtc_state: The crtc state
170 * @crc32: The crc output of the final frame
171 * @output_buffer: A buffer of a row that will receive the result of the blend(s)
172 * @stage_buffer: The line with the pixels from plane being blend to the output
173 * @row_size: The size, in bytes, of a single row
174 *
175 * This function blends the pixels (Using the `pre_mul_alpha_blend`)
176 * from all planes, calculates the crc32 of the output from the former step,
177 * and, if necessary, convert and store the output to the writeback buffer.
178 */
179static void blend(struct vkms_writeback_job *wb,
180		  struct vkms_crtc_state *crtc_state,
181		  u32 *crc32, struct line_buffer *stage_buffer,
182		  struct line_buffer *output_buffer, size_t row_size)
183{
184	struct vkms_plane_state **plane = crtc_state->active_planes;
185	u32 n_active_planes = crtc_state->num_active_planes;
186	int y_pos;
187
188	const struct pixel_argb_u16 background_color = { .a = 0xffff };
189
190	size_t crtc_y_limit = crtc_state->base.crtc->mode.vdisplay;
191
192	for (size_t y = 0; y < crtc_y_limit; y++) {
193		fill_background(&background_color, output_buffer);
194
195		/* The active planes are composed associatively in z-order. */
196		for (size_t i = 0; i < n_active_planes; i++) {
197			y_pos = get_y_pos(plane[i]->frame_info, y);
198
199			if (!check_limit(plane[i]->frame_info, y_pos))
200				continue;
201
202			vkms_compose_row(stage_buffer, plane[i], y_pos);
203			pre_mul_alpha_blend(plane[i]->frame_info, stage_buffer,
204					    output_buffer);
205		}
206
207		apply_lut(crtc_state, output_buffer);
208
209		*crc32 = crc32_le(*crc32, (void *)output_buffer->pixels, row_size);
210
211		if (wb)
212			vkms_writeback_row(wb, output_buffer, y_pos);
213	}
214}
215
216static int check_format_funcs(struct vkms_crtc_state *crtc_state,
217			      struct vkms_writeback_job *active_wb)
218{
219	struct vkms_plane_state **planes = crtc_state->active_planes;
220	u32 n_active_planes = crtc_state->num_active_planes;
221
222	for (size_t i = 0; i < n_active_planes; i++)
223		if (!planes[i]->pixel_read)
224			return -1;
225
226	if (active_wb && !active_wb->pixel_write)
227		return -1;
228
229	return 0;
230}
231
232static int check_iosys_map(struct vkms_crtc_state *crtc_state)
233{
234	struct vkms_plane_state **plane_state = crtc_state->active_planes;
235	u32 n_active_planes = crtc_state->num_active_planes;
236
237	for (size_t i = 0; i < n_active_planes; i++)
238		if (iosys_map_is_null(&plane_state[i]->frame_info->map[0]))
239			return -1;
240
241	return 0;
242}
243
244static int compose_active_planes(struct vkms_writeback_job *active_wb,
245				 struct vkms_crtc_state *crtc_state,
246				 u32 *crc32)
247{
248	size_t line_width, pixel_size = sizeof(struct pixel_argb_u16);
249	struct line_buffer output_buffer, stage_buffer;
250	int ret = 0;
251
252	/*
253	 * This check exists so we can call `crc32_le` for the entire line
254	 * instead doing it for each channel of each pixel in case
255	 * `struct `pixel_argb_u16` had any gap added by the compiler
256	 * between the struct fields.
257	 */
258	static_assert(sizeof(struct pixel_argb_u16) == 8);
259
260	if (WARN_ON(check_iosys_map(crtc_state)))
261		return -EINVAL;
262
263	if (WARN_ON(check_format_funcs(crtc_state, active_wb)))
264		return -EINVAL;
265
266	line_width = crtc_state->base.crtc->mode.hdisplay;
267	stage_buffer.n_pixels = line_width;
268	output_buffer.n_pixels = line_width;
269
270	stage_buffer.pixels = kvmalloc(line_width * pixel_size, GFP_KERNEL);
271	if (!stage_buffer.pixels) {
272		DRM_ERROR("Cannot allocate memory for the output line buffer");
273		return -ENOMEM;
274	}
275
276	output_buffer.pixels = kvmalloc(line_width * pixel_size, GFP_KERNEL);
277	if (!output_buffer.pixels) {
278		DRM_ERROR("Cannot allocate memory for intermediate line buffer");
279		ret = -ENOMEM;
280		goto free_stage_buffer;
281	}
282
283	blend(active_wb, crtc_state, crc32, &stage_buffer,
284	      &output_buffer, line_width * pixel_size);
285
286	kvfree(output_buffer.pixels);
287free_stage_buffer:
288	kvfree(stage_buffer.pixels);
289
290	return ret;
291}
292
293/**
294 * vkms_composer_worker - ordered work_struct to compute CRC
295 *
296 * @work: work_struct
297 *
298 * Work handler for composing and computing CRCs. work_struct scheduled in
299 * an ordered workqueue that's periodically scheduled to run by
300 * vkms_vblank_simulate() and flushed at vkms_atomic_commit_tail().
301 */
302void vkms_composer_worker(struct work_struct *work)
303{
304	struct vkms_crtc_state *crtc_state = container_of(work,
305						struct vkms_crtc_state,
306						composer_work);
307	struct drm_crtc *crtc = crtc_state->base.crtc;
308	struct vkms_writeback_job *active_wb = crtc_state->active_writeback;
309	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
310	bool crc_pending, wb_pending;
311	u64 frame_start, frame_end;
312	u32 crc32 = 0;
313	int ret;
314
315	spin_lock_irq(&out->composer_lock);
316	frame_start = crtc_state->frame_start;
317	frame_end = crtc_state->frame_end;
318	crc_pending = crtc_state->crc_pending;
319	wb_pending = crtc_state->wb_pending;
320	crtc_state->frame_start = 0;
321	crtc_state->frame_end = 0;
322	crtc_state->crc_pending = false;
323
324	if (crtc->state->gamma_lut) {
325		s64 max_lut_index_fp;
326		s64 u16_max_fp = drm_int2fixp(0xffff);
327
328		crtc_state->gamma_lut.base = (struct drm_color_lut *)crtc->state->gamma_lut->data;
329		crtc_state->gamma_lut.lut_length =
330			crtc->state->gamma_lut->length / sizeof(struct drm_color_lut);
331		max_lut_index_fp = drm_int2fixp(crtc_state->gamma_lut.lut_length  - 1);
332		crtc_state->gamma_lut.channel_value2index_ratio = drm_fixp_div(max_lut_index_fp,
333									       u16_max_fp);
334
335	} else {
336		crtc_state->gamma_lut.base = NULL;
337	}
338
339	spin_unlock_irq(&out->composer_lock);
340
341	/*
342	 * We raced with the vblank hrtimer and previous work already computed
343	 * the crc, nothing to do.
344	 */
345	if (!crc_pending)
346		return;
347
348	if (wb_pending)
349		ret = compose_active_planes(active_wb, crtc_state, &crc32);
350	else
351		ret = compose_active_planes(NULL, crtc_state, &crc32);
352
353	if (ret)
354		return;
355
356	if (wb_pending) {
357		drm_writeback_signal_completion(&out->wb_connector, 0);
358		spin_lock_irq(&out->composer_lock);
359		crtc_state->wb_pending = false;
360		spin_unlock_irq(&out->composer_lock);
361	}
362
363	/*
364	 * The worker can fall behind the vblank hrtimer, make sure we catch up.
365	 */
366	while (frame_start <= frame_end)
367		drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);
368}
369
370static const char * const pipe_crc_sources[] = {"auto"};
371
372const char *const *vkms_get_crc_sources(struct drm_crtc *crtc,
373					size_t *count)
374{
375	*count = ARRAY_SIZE(pipe_crc_sources);
376	return pipe_crc_sources;
377}
378
379static int vkms_crc_parse_source(const char *src_name, bool *enabled)
380{
381	int ret = 0;
382
383	if (!src_name) {
384		*enabled = false;
385	} else if (strcmp(src_name, "auto") == 0) {
386		*enabled = true;
387	} else {
388		*enabled = false;
389		ret = -EINVAL;
390	}
391
392	return ret;
393}
394
395int vkms_verify_crc_source(struct drm_crtc *crtc, const char *src_name,
396			   size_t *values_cnt)
397{
398	bool enabled;
399
400	if (vkms_crc_parse_source(src_name, &enabled) < 0) {
401		DRM_DEBUG_DRIVER("unknown source %s\n", src_name);
402		return -EINVAL;
403	}
404
405	*values_cnt = 1;
406
407	return 0;
408}
409
410void vkms_set_composer(struct vkms_output *out, bool enabled)
411{
412	bool old_enabled;
413
414	if (enabled)
415		drm_crtc_vblank_get(&out->crtc);
416
417	spin_lock_irq(&out->lock);
418	old_enabled = out->composer_enabled;
419	out->composer_enabled = enabled;
420	spin_unlock_irq(&out->lock);
421
422	if (old_enabled)
423		drm_crtc_vblank_put(&out->crtc);
424}
425
426int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name)
427{
428	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
429	bool enabled = false;
430	int ret = 0;
431
432	ret = vkms_crc_parse_source(src_name, &enabled);
433
434	vkms_set_composer(out, enabled);
435
436	return ret;
437}
438